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Drug Interactions: Antacids and laxatives containing aluminum and magnesium can decrease absorption and must not be given within 4 hours of oral chloroquine administration symptoms vitamin d deficiency cheap 100mg dilantin overnight delivery. Ammonium chloride may be used to acidify the urine to hasten excretion of chloroquine. Lifespan and Diversity Considerations: Monitor hepatic function laboratory values, and vision and retinal screenings more frequently in the older adult because normal physiological changes related to aging may increase the risk of adverse drug effects. Patient and Family Education: Be aware that urine may be colored rusty yellow or brown. Drugs Similar to Chloroquine (Aralen) Other antimalarials include artemether-lumefantrine, atovaquone, halofantrine, hydroxychloroquine, mefloquine, primaquine, proguanil, and quinine. The combination drug pyrimethaminesulfadoxine (Fansidar) is a prototype drug in Section 56. Because it has no activity against the blood forms of Plasmodium, it must always be used in combination with other antimalarials. Unlike some of the other drugs in this class, resistance is not a major clinical problem with primaquine. Quinine (Qualaquin): First described in the 1600s, quinine is the oldest drug used to treat malaria, and it is still obtained from the bark of the South American cinchona tree. Although safer alternatives have since been discovered, quinine is still used for chloroquine-resistant Plasmodia, in combination with other antimalarials. It is only approved for the treatment (not prophylaxis) of uncomplicated malaria caused by P. For many years, the majority of quinine use in the United States was to treat nighttime leg cramps, an offlabel indication. Cinchonism, a syndrome characterized by tinnitus, deafness, headache, vision abnormalities, and diarrhea, can occur at therapeutic doses. A major limiting factor is cardiotoxicity, which produces quinidine-like dysrhythmias at high doses. Rarely, it may be used to treat symptomatic atrial dysrhythmias and life-threatening ventricular dysrhythmias when safer and more effective drugs have proven ineffective. Amebiasis, giardiasis, and cryptosporidiosis are protozoan infections of the intestines, spread primarily by poor sanitation. Worldwide, it is the third leading cause of death due to parasites (Dhawan, 2010). Although infection by Plasmodium is the most significant protozoan disease worldwide, infections caused by other protozoa affect significant numbers of people in endemic areas. Each of the organisms has unique differences in its distribution pattern and physiology. Many areas of the world do not enjoy the high level of sanitation found in the United States and Canada. In developing countries, drinking water may not be disinfected before consumption and may be contaminated with pathogens from human waste. The infection may be carried to the United States by travelers from regions where the disease is endemic, such as Mexico, India, Western and Southern Africa, and portions of Central and South America. The parasite is spread by drinking contaminated water, or by food handlers who transfer the cysts to raw vegetables or other consumables. The trophozoite form of the protozoan invades the colon mucosa, causing ulcerations and considerable abdominal pain, distention, cramping, and bloody diarrhea. Diagnosis of amebiasis is generally through identification of the trophozoites in the stool; however, serum and stool antigen detection tests specific for E. The trophozoite may gain access to the general circulation through colon ulcers and travel to other organs, particularly the liver, where it produces hepatic abscesses. Regimens for amebiasis include combination therapy with two to three agents to eliminate the parasites from their many potential sites. The drug of choice for both intestinal and hepatic amebiasis is metronidazole, due to its safety and efficacy. If the infection is limited to the intestine, paromomycin (Humatin) and iodoquinol (Yodoxin) are preferred drugs because these agents are able to reach high concentrations in the intestinal lumen without producing significant systemic toxicity. These drugs are sometimes prescribed to eliminate the protozoan in patients who are asymptomatic carriers of the infection. Pharmacotherapy for amebiasis is continued until multiple negative stool specimens are obtained. Drugs for amebiasis and other nonmalarial protozoan infections are listed in Table 56. Giardiasis: Giardiasis is an infection caused by the protozoan Giardia lamblia that has much in common with amebiasis. They are both endemic to regions with poor sanitation, where the water supply is contaminated with human fecal matter. Mature cyst Immature cyst Invasive infection through the bloodstream, infecting sites such as the liver, brain, and lungs. Excystation One trophozoite emerges and divides to produce eight trophozoites from each cyst. Both affect the intestine, causing acute cramping pain, severe diarrhea, fatigue, and marked weight loss. Identification of Giardia trophozoites or cysts in the stool can help distinguish between the two diseases. Another potential cause of giardiasis in the United States is the unsanitary handling of soiled diapers in day care centers. It is interesting to note that Giardia was the very first protozoan discovered, originally identified by the inventor of the microscope, von Leeuwenhoek, in the 1600s. It is the most common intestinal parasite responsible for diarrhea symptoms throughout the world. When contaminated food or water is ingested, the acidic environment of the stomach causes the parasite to transform from the cyst to the trophozoite stage. A chronic form of giardiasis, however, can last for months and lead to malabsorption, steatorrhea, weakness, and chronic diarrhea. Although giardiasis is not fatal, it can weaken patients and make them susceptible to infection by opportunistic pathogens. Family members of infected patients, food handlers, and day care workers who are asymptomatic carriers should receive treatment. Pharmacotherapy of giardiasis includes metronidazole (Flagyl), tinidazole (Tindamax), nitazoxanide (Alinia), or paromomycin (Humatin). Diarrhea generally stops within 48 hours after pharmacotherapy is initiated and a typical regimen continues for 3 to 5 days. Follow-up stool specimens are analyzed to confirm that the pharmacotherapy has been successful. Cryptosporidiosis: Cryptosporidiosis is an infection caused by the protozoan Cryptosporidium parvum that causes severe diarrhea. A waterborne outbreak of cryptosporidiosis led to 400,000 cases in Milwaukee, Wisconsin, in 1993, and resulted in at least 100 deaths. Although only about 3,000 cases of cryptosporidiosis are reported in the United States each year, it is responsible for a significant proportion of infectious diarrhea worldwide. Pharmacotherapy of cryptosporidiosis is targeted at stopping the severe diarrhea through the symptomatic use of antidiarrheal agents. In patients with healthy immune systems, the disease is self-limiting and no antiprotozoan drugs are necessary. Antiprotozoan drug therapy is necessary for these patients, with paromomycin (Humatin) being a preferred drug. Other agents that may be of benefit include azithromycin and nitazoxanide (Alinia). Combination therapy with these drugs may continue for 14 to 28 days, depending on patient response. Use of the vaginal gel may lead to vaginal candidiasis in more than 10% of patients. Black Box Warning: Metronidazole (oral and injection) is carcinogenic in laboratory animals and should only be used for approved indications. Liver function tests should be carefully monitored in patients with alcoholism or hepatic impairment, because metronidazole is extensively metabolized in the liver. The injectable form of metronidazole contains significant amounts of sodium, which can lead to edema in patients with heart failure. Classification: Therapeutic: Anti-infective, antiprotozoan Pharmacologic: Nitroimidazole agent Therapeutic Effects and Uses: Approved in 1963, metronidazole is the prototype medication for amebiasis, being effective against both the intestinal and hepatic phases of the disease.

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Abdullah has accidentally overdosed by taking 12 isoniazid tablets instead of ethambutol tablets treatment 4 water cheap 100mg dilantin visa. The organism invades peripheral nervous tissue, causing nerve thickening that results in loss of sensation or paresthesia. If left untreated, the infection causes extreme disfigurement and bone resorption, resulting in loss of digits. The disease is diagnosed through identification of the pathogen from a skin biopsy. Leprosy may be infectious or noninfectious, depending on the stage of the disease and the progress of pharmacotherapy. The disease may have a very long incubation period extending from several months to years. Nearly all cases are diagnosed in immigrants from countries where leprosy is endemic, such as Southeast Asia, Central Africa, and Central and South America (Lewis, 2011). Depression and drowsiness are common, and seizures have been reported with ethionamide. Hepatic function should be monitored regularly because hepatitis occurs in about 5% of the patients taking the drug. Alcohol use should be discouraged during ethionamide therapy because of additive harmful effects on the liver. Fluoroquinolones: Ciprofloxacin (Cipro) and ofloxacin (Floxin) have undergone considerable testing for use as antituberculosis agents. There are two presentations of leprosy, and pharmacotherapy differs for the different types. Lepromatous leprosy occurs in patients with defective cell-mediated immunity, and is characterized by a slow, progressive development of nodular skin lesions and nerve involvement. Because the patient has an impaired immune system, the mycobacteria may disseminate throughout the body and cause death. Tuberculoid leprosy is less progressive and may have long periods of remission followed by reactivation with more severe nerve involvement. These patients have an intact cell-mediated immune response; thus, the disease is more benign and less often fatal. Like tuberculosis, leprosy is treated with prolonged combination pharmacotherapy because monotherapy causes rapid development of resistant strains. Although improvement in skin lesions may occur within a few months, therapy must continue during the entire treatment period to eliminate all the mycobacteria. Initial three-drug regimen that includes dapsone, clofazimine (Lamprene), and rifampin (Rifadin) given for 2 to 5 years. Initial two-drug regimen with dapsone and rifampin for 6 to 12 months, followed by dapsone alone for 2 to 3 years. Leprosy has been known for thousands of years but the term leper has been used by different cultures to designate someone sinful or unclean, not necessarily someone with the disease we now call leprosy. Although rare in the United States, it is estimated that 6 million people worldwide have leprosy. Patients with leprosy Other drugs may be substituted when the patient cannot tolerate the standard regimen. Ofloxacin (Floxin), clarithromycin (Biaxin), and minocycline (Minocin) are antibacterials that have activity against M. During the first year of pharmacotherapy, skin lesions may actually worsen because of activation of the cell-mediated immune response. Most of these reactions occur because immune cells are attacking antigens released by the mycobacteria. If this occurs, corticosteroids such as prednisone are added to the regimen to reduce the severe inflammation. Leprosy patients are examined monthly throughout the initial course of treatment and less frequently as therapy progresses. Follow-up may continue for 3 years or longer after the completion of pharmacotherapy. Increased dapsone levels have been reported in patients receiving trimethoprim, and patients receiving this combination may be at increased risk for dapsone toxicity. Therapeutic Effects and Uses: Approved in 1955, dapsone is a drug of choice for the treatment of M. It has several off-label uses that include the chemoprophylaxis of malaria in combination with pyrimethamine. Pharmacotherapy for the prophylaxis of toxoplasmosis combines dapsone, pyrimethamine, and leucovorin. In 2005 dapsone 5% gel (Aczone) was approved as topical therapy for acne vulgaris. Dapsone is the primary therapy for dermatitis herpetiformis and for autoimmune disease characterized by severe blistering skin lesions. Although its name implies herpes virus as a causative agent, the etiology of the disorder is sensitivity to gluten in the diet. Although reactions are usually reversible, they may require months or years to diminish. Assess for any reddish-brown discoloration of the skin, cornea, conjunctiva, and body fluids. This adverse effect occurs in 75% to 90% of patients within a few weeks of treatment. Assess for tender, erythematous nodules with lymphadenopathy, joint swelling, epistaxis, and iritis, which can suggest a type 2 leprosy reactional state. Patient and Family Education: Maintain strict adherence to the established drug regimen and do not change the drug dosage without the approval of the health care provider. Aplastic anemia and agranulocytosis are rare, though potentially severe, adverse effects. The drug concentrates in the skin, causing dermatologic reactions that include photosensitivity and toxic epidermal necrolysis. Contraindications/Precautions: Contraindications include hypersensitivity to dapsone or related drugs, such as sulfonamides. Because of its adverse effects on the hematologic system, caution should be used in treating patients with preexisting blood disorders. Frequent blood assessments are conducted during therapy to avoid serious adverse effects. Frequent liver enzyme testing should be conducted to monitor for hepatotoxicity, especially in patients with preexisting liver impairment. Eye pain, acute blurring of vision or loss of color sense, sudden or increasing numbness or tingling in extremities, decreased hearing or significant tinnitus, or increase in bruising or bleeding should be reported immediately. Potential Nursing Diagnoses Infection Fatigue Imbalanced Nutrition: Less than Body Requirements, related to fatigue, adverse drug effects Deficient Knowledge (Drug Therapy) Noncompliance, related to adverse drug effects, deficient knowledge, length of treatment required, or cost of medication Social Isolation Planning: Patient Goals and Expected Outcomes the patient will: Experience therapeutic effects dependent on the reason the drug is being given. Immediately report undiminished fever, increases in sputum production, hemoptysis, or increase in adventitious breath sounds to the health care provider. Vitamin B6 may be ordered to decrease the risk of peripheral neuropathy, especially that associated with isoniazid use. Eye pain, acute blurring of vision or loss of color sense, sudden or increasing numbness or tingling in extremities should be reported immediately. If there is reason to believe they need medication, they should be assessed by a health care provider. If instructed to take the drug on an empty stomach, take with a full glass of water. Clofazimine (Lamprene): Clofazimine is a drug that exhibits selective activity toward mycobacteria. Clofazimine, a bright-red dye, can cause a reddish-brown discoloration of the skin, conjunctiva, and body fluids that may take years to disappear after discontinuing therapy. Therapy of dapsone-resistant infections may require daily administration of clofazimine for several years. The pathogen may travel through the lymphatics and bloodstream to infect any organ. High doses of clarithromycin (1,000 mg bid) are associated with increased mortality rates. Rifabutin, however, can cause many drug interactions, and high doses (600 mg/day) are associated with greater risk of serious uveitis with eye pain.

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The active metabolite of imipramine is desipramine medicine abbreviations purchase cheap dilantin line, which is marketed separately as Norpramin. Mechanism of Action: Imipramine blocks the reuptake of norepinephrine and serotonin into presynaptic nerve terminals. Imipramine also blocks acetylcholine receptors, which is likely responsible for its effectiveness in treating enuresis. Serious adverse reactions include seizures, hepatitis, acute renal failure, paralytic ileus, leukopenia, agranulocytosis, thrombocytopenia, or eosinophilia. If anticholinergic effects become prominent in a patient, what class of drugs can be used to counteract the cardiovascular adverse effects Although very effective, a drawback to the use of imipramine is that it takes 2 to 6 weeks to achieve full Contraindications/Precautions: Imipramine should not be used by patients with seizure disorders because it lowers the seizure threshold. Some simple ways to decrease symptoms are to increase fluids, suck on sugarless hard candy, chew sugarless gum, or take frequent sips of water. Drug interactions causing decreased effects of imipramine include oral contraceptives, clonidine, carbamazepine, and indirect-acting sympathomimetics. Herbal/Food: Several commonly used herbal products may lead to increased imipramine effects, including kava, hops, lavender, valerian, skullcap, and chamomile. An increased anticholinergic effect can occur with the use of belladonna, jimsonweed, or henbane. Medical management includes treating possible seizures, hypotension, and dysrhythmias. Desipramine is an active metabolite of imipramine, and the two drugs have the same actions and adverse effects, as previously described. It is metabolized in the liver to nortriptyline, which is marketed as a separate drug. Both amitriptyline and nortriptyline produce significant anticholinergic adverse effects. The drug produces significant anticholinergic effects and orthostatic hypotension; thus it is not a first-line drug for depression. A topical form of doxepin (Zonalon) is available for pruritus associated with atopic dermatitis. Because doxepin is absorbed through the skin, topical applications can result in systemic adverse effects. Provide assistance with ambulation as needed if dizziness or blurred vision occur. Patient and Family Education: the full therapeutic effects of the medication will take 2 to 6 weeks or more to appear. Monitor the patient more closely during the early stages of therapy because suicide risk may increase during this time. Protriptyline (Vivactil): Protriptyline is an oral antidepressant that was approved in 1967. These respiratory effects have led to its occasional off-label use for treating chronic obstructive pulmonary disease or sleep apnea. Drowsiness is a serious problem; however, the incidence of anticholinergic effects is one of the lowest of any drug in its class. In the 1970s, it became increasingly clear that serotonin had a more substantial role in depression than once thought. Increased levels of serotonin in the synaptic spaces induce complex neurotransmitter changes in presynaptic and postsynaptic neurons in the brain. Essentially, presynaptic receptors become less sensitive, and postsynaptic receptors become more sensitive. Up to 70% of both men and women can experience decreased libido and lack of ability to reach orgasm. For patients who are sexually active, these adverse effects may be serious enough to cause nonadherence with pharmacotherapy, and a different antidepressant may be indicated. Symptoms can begin as early as 2 hours after taking the first dose or as late as several weeks after initiating pharmacotherapy. Conservative treatment is to discontinue the drugs responsible for causing the syndrome and to provide supportive care; the condition usually resolves in 24 hours. In severe cases, mechanical ventilation and administration of muscle relaxants such as benzodiazepines may be necessary. The most common adverse effects are nausea and vomiting, which diminish as therapy progresses. Fluoxetine does not cause sedation; in fact, insomnia may occur in as many as 25% of patients receiving the drug. Significant anorexia and weight loss occur in 10% to 15% of patients, whereas others experience a weight gain of as much as 20 pounds or more. Patients may experience various types of sexual dysfunction, including delayed ejaculation, impotence, anorgasmia, decreased libido, and priapism. The drug may induce seizures in patients with preexisting seizure disorders or during overdoses. Other adverse effects include cramping, constipation, poor concentration, diarrhea, hot flashes, palpitations, and nervousness. These symptoms usually begin 1 to 7 days after the last dose and may continue for 1 to 3 weeks. Fluoxetine was subsequently approved to treat bulimia nervosa, the first medication ever approved for this condition. Fluoxetine is available as tablets, capsules, oral solution, and delayed release capsules. Sarafem is a formulation of fluoxetine specifically marketed for premenstrual dysphoric disorder in a pulvule-a gelatin-based capsule. Patients who have stabilized on daily fluoxetine can be switched to Prozac Weekly, which offers the convenience of once-a-week dosing. Symbyax is a fixed-dose combination of fluoxetine and olanzapine that is indicated for bipolar disorder. Olanzapine, an antipsychotic agent, is marketed by itself as Zyprexa for schizophrenia and the manic phase of bipolar disorder. Fluoxetine is used off-label to treat many other disorders involving multiple body systems. Off-label indications include anorexia nervosa, obesity, alcohol dependence in patients with alcoholism, fibromyalgia, autism, refractory orthostatic hypotension, premature ejaculation, premenstrual dysphoric disorder, and menopausal hot flashes. Although patients gradually begin to feel less depressed after about 2 weeks of therapy, optimal response may take 8 weeks or longer. Fluoxetine is extensively metabolized in the liver to norfluoxetine, which has about the same pharmacologic activity as the parent drug. Fluoxetine and norfluoxetine have long half-lives; it takes 30 to 60 days after discontinuing the drug for them to be eliminated by the body. Contraindications/Precautions: Hypersensitivity to fluoxetine is a contraindication to using the drug. The drug should not be administered to patients with bipolar disorder because it may precipitate a manic episode. It must be used cautiously in persons with cardiac dysfunction, diabetes, or seizure disorders. Children or young adults with a history of attempted suicide should not receive fluoxetine. There are no known age-related precautions for use in the elderly, but children may experience more behavioral adverse effects such as restlessness and insomnia. The neonate may exhibit symptoms of Mechanism of Action: As with other serotonin reuptake inhibitors, fluoxetine blocks the uptake of the neurotransmitter serotonin (but not norepinephrine) at the neuronal presynaptic membrane. This increases the amount of neurotransmitter available at the postsynaptic receptor sites, thus enhancing the actions of serotonin. With supportive care, symptoms of withdrawal in the neonate will disappear in a few days. In most cases, the benefits of treating pregnant women who have major depression with fluoxetine are greater than the potential risks to the neonate. Fluoxetine may cause an increased risk of toxicity to phenytoin, digoxin, or carbamazepine. Concurrent use with certain antipsychotic agents may lead to increased extrapyramidal symptoms such as akathisia, dystonia, tardive dyskinesia, and pseudoparkinsonism.

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Joe frequently finds her sitting in a rocking chair on their front porch during the night medicine keppra discount dilantin 100 mg free shipping, rather than being in bed. Which adverse effect associated with this drug therapy is the highest priority for the nurse Poor nutritional intake the client, who is receiving benzodiazepines, is a two-pack per day cigarette smoker. With the economy, his income has dropped significantly because it is partially based on commission and he is worried that he is not able to provide for his family. He begins to experience insomnia, difficulty concentrating, and other symptoms related to his anxiety. His health care provider prescribes a short-term course of lorazepam (Ativan) to help him through this difficult period. What nonpharmacologic measures can the nurse recommend to Craig to assist him in feeling better about his current situation Sleep disorders frequent in college students; linked to poor academic performance. Better sleep and daytime functioning with combined therapy for insomnia and anxiety. International statistical classification of diseases and related health problems, 10th revision, version for 2007. Anxiolytic effects of a combi- nation of Melissa officinalis and Valeriana officinalis during laboratory induced stress. Antidepressant drug therapy and suicide in severely depressed children and adults: A case-control study. Apply the nursing process to care for patients receiving pharmacotherapy for mood disorders. Although mood changes are a normal part of life, when they become prolonged and severe and impair functioning within the family, work environment, or interpersonal relationships, a patient may be diagnosed as having a mood disorder. The purpose of this chapter is to explain the role of pharmacotherapy in treating the two primary categories of mood disorders: major depression and bipolar disorder. Includes mania symptoms that last for at least 1 week and significantly impact social functioning. Hypomania is less intense, lasting only 4 days and has less impact on social or work functioning. A mild form of bipolar disorder in which the patient alternates between hypomania and mild depression. Largely undiagnosed, 33% of these patients will eventually develop bipolar disorder. Depression affects people of all ethnic groups, income levels, ages, and cultural backgrounds (Dryden-Edwards, n. For example, about 50% of patients diagnosed with major depression also meet the criteria for an anxiety disorder (see Chapter 22). Of those patients with mood disorder 25% to 40% have a comorbid substance abuse condition. The most serious of the comorbid conditions is completed or attempted suicide (see Section 23. Depression is a disorder characterized by a sad or despondent mood that becomes out of proportion to actual life events. Depression can manifest as an extremely diverse set of symptoms, including lack of energy, sleep disturbances, abnormal eating patterns, or feelings of despair, guilt, and hopelessness. Depression is the most common mental health disorder, affecting approximately 10% to 20% of the population. Although women between the ages of 25 and 45 are more likely to have a depressive disorder than any other group, depression in men more frequently results in suicide. For the purposes of this text, the terms depression and major depressive disorder are considered interchangeable unless otherwise specified. Once a diagnosis of a mood disorder is made, additional details about the condition may be provided by the health care provider in the form of "specifiers. Specifiers are best thought of as subcategories of major depressive disorder and bipolar disorder. Some of the specifiers used with depression include with or without Types of Mood Disorders 23. Mood disorders form a cluster of mental health conditions that occur fretricyclic quently in the population. Mood disortyramine, 315 ders are a major cause of disability and can significantly strain social relationships. They are a leading cause of absenteeism and diminished productivity in the workplace. Defining and diagnosing mood disorders is sometimes difficult; the line between normal emotion and a mood disorder is often unclear. Because health care providers see patients for such brief periods, they must rely on patient self-reports or caregiver information, both of which are often unreliable. According to this manual, mood disorders may be classified as follows: Major depressive disorder. When people use the word depression, they are most often referring to major depressive disorder. Formerly called manic depression, the patient alternates between intense excitement (mania) and major depressive disorder. Up to 80% of women experience brief "baby blues" or postpartum onset depression during the first 2 weeks after the birth of a baby. About 10% of new mothers will experience major depression within the first 6 months postdelivery, which is related to the dramatic hormonal shifts that occur during that period. Along with the hormonal changes, additional situational stresses such as changing responsibilities at work and at home, single parenthood, and caring for children and for aging parents may contribute to the onset of symptoms. Because of the potentially serious consequences of postpartum onset depression, some states mandate that all new mothers receive information about these mood disorders prior to their discharge after giving birth. During the dark winter months, some patients experience a type of depression known as seasonal affective disorder. Seasonal affective disorder is more common in areas such as Alaska, where the days are very short during the winter months and there is little natural sunlight. This type of depression is associated with a reduced release of the hormone melatonin from the pineal gland. Exposing patients on a regular basis to specific wavelengths of light may relieve this type of depression and prevent future episodes. Overall, 25% of patients who have had a major depressive episode will have chronic, recurrent depression (Ikezu & Gendelman, 2008). Depression is one of the oldest known mental health conditions and one of the most frequently diagnosed. Several theories have been proposed to explain the causes of depression and why some people are predisposed to developing the disease. The etiology and pathogenesis are likely influenced by multiple, complex variables. Research attempting to identify the biologic causes of depression has focused on the levels and function of neurotransmitters in the limbic system of the brain. Major depression has been associated with abnormally low levels of neurotransmitters such as norepinephrine, serotonin, and dopamine in the limbic system. Although it is well known that some of the antidepressant medications act by increasing the levels of these neurotransmitters, scientists are many years from discovering what role each specific neurotransmitter plays in the development of major depressive disorder. Does having depression deplete the brain of these neurotransmitters, or does a loss of neurotransmitters cause depression Certain hormonal abnormalities are associated with depression, suggesting that the endocrine system also plays an important physiological role in the pathogenesis of the disease. Cortisol mobilizes the body for stress situations and is thought to reduce serotonin levels in the brain, bringing about symptoms of depression. In some patients, therapy with thyroid hormone (T3) results in a marked improvement in depression symptoms. In identical twins, when one twin is diagnosed with depression, the other twin has a 50% probability of acquiring the disorder. This relationship holds true whether the twins were raised together or separately. Even fraternal twins have a 19% chance of developing depression when the other twin is diagnosed, which is a percentage higher than that of the general population. Environmental causes of depression include prolonged stress at work or at home, loss of a loved one, and other traumatic life events. Various childhood events have been associated with an increased risk of adult depression, including sexual or physical abuse, and death of, separation from, or mental illness of a parent. The majority of people who are depressed are not found in psychiatric hospitals but in mainstream everyday settings.

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Beta-adrenergic antagonists block the actions of these catecholamines medications ending in zole cheap generic dilantin canada, slowing the heart rate and reducing blood pressure, thus decreasing the cardiac workload. After several months of therapy, heart size, shape, and function return to normal in some patients, in essence producing a reverse remodeling of the heart. Adherence to beta-blocker therapy can be a major clinical challenge for some patients. The patient may not report symptomatic improvement with the drug and, in fact, may feel worse at the initiation of therapy. Vasodilators relax blood vessels and lower blood pressure, creating less workload on the heart. Hydralazine with isosorbide dinitrate (BiDil): Hydralazine and isosorbide dinitrate were used off-label for many years in patients who did not respond well to drugs from other classes. The drug was shown to be particularly effective in treating African American patients, who are sometimes resistant to therapy for hypertension and heart failure. Hydralazine acts on arterioles to decrease peripheral resistance, reduce afterload, and increase cardiac output. It is an effective antihypertensive drug, although it is not a drug of first choice for this indication because hypotension and reflex tachycardia are common, and may limit therapy. Isosorbide dinitrate (Isordil) is a long-acting organic nitrate that reduces preload by directly dilating veins. The drug is not very effective as monotherapy, and tolerance develops to its actions with continued use. The high incidence of adverse effects in some patients such as reflex tachycardia and orthostatic hypotension limits their use. The use of isosorbide dinitrate in the pharmacotherapy of angina pectoris is presented in Chapter 38. In therapeutic doses, nesiritide causes vasodilation, which contributes to reduced preload. By reducing preload and afterload, the drug compensates for diminished cardiac function. The use of nesiritide is very limited because it can rapidly cause severe hypotension, which can persist several hours after the infusion is discontinued. From what you learned in Chapter 38, why is nitroglycerin a preferred drug for acute angina, rather than isosorbide dinitrate Once used as arrow poisons by African tribes and as medicines by the ancient Egyptians and Romans, the value of the cardiac glycosides in treating heart disorders has been known for over 2,000 years. The two primary cardiac glycosides, digoxin and digitoxin, are quite similar in efficacy; the primary difference is that the latter has a more prolonged half-life. The margin of safety between a therapeutic dose and a toxic dose of cardiac glycosides is very narrow, and severe adverse effects may result from poorly managed therapy. In either case, the goal is to determine the proper dose of medication to be administered, without undue adverse effects. In addition to its positive inotropic effect, digoxin also affects the speed of myocardial conduction. Digoxin has the ability to suppress the sinoatrial node and slow electrical conduction through the atrioventricular node. Because the heart rate may decline too much, health care providers establish parameters for each patient. As a general rule, if the apical pulse falls below 60 beats per minute, the medication is withheld and the health care provider notified. The capsule formulation (Lanoxicaps) has a more predictable bioavailability than the tablet form, but it is more expensive. Because differences in bioavailability of digoxin formulations can potentially affect drug action and the potential for adverse effects, it is advisable to continue with the same brand name, unless otherwise changed by the prescriber. Raising the dose does not increase the therapeutic effect, but it does increase the risk of serious digoxin toxicity. For each patient, the health care provider should establish acceptable parameters for serum digoxin levels, and the drug should be discontinued should the level rise above the maximum. However, the nurse should remember that toxicity should be based on patient symptoms rather than serum level. Levels should be taken 6 to 12 hours after a dose, because digoxin has a prolonged distribution time. Digoxin should be administered with caution to older adults because these patients experience a higher incidence of adverse effects. Patients with renal impairment should receive lower doses of digoxin, because the drug is excreted by this route. As sodium ions accumulate in myocytes, calcium ions are released from their storage areas in the cell to activate contractile elements. The release of calcium ions produces a more forceful contraction of myocardial fibers. Concurrent use of digoxin with diuretics must be carefully monitored, since diuretics can cause hypokalemia and increase the risk of dysrhythmias. Administration of digoxin with other positive inotropic agents can cause additive effects on myocardial contractility. If calcium is administered intravenously together with digoxin, it can increase the risk of dysrhythmias. Quinidine, verapamil, amiodarone, and alprazolam will decrease the distribution and excretion of digoxin, thus increasing the risk of digoxin toxicity. Herbal/Food: the drug should be used with caution with ginseng, which may increase the risk of digoxin toxicity. Treatment of Overdose: Digoxin overdose can be fatal and the nurse should be prepared to administer digoxin immune Fab (Digibind). Digoxin immune Fab consists of digoxin-specific antibodies, which form a complex with digoxin that prevents the drug from reaching the tissues, and is removed through renal excretion. Nursing Responsibilities: Key nursing implications for patients receiving digoxin are included in the Nursing Practice Adverse Effects: Adverse effects of digoxin involve multiple body systems and can be severe. The most dangerous adverse effect is its ability to cause ventricular dysrhythmias, which may result in sudden cardiac death. The most common cause of digoxin-induced dysrhythmias is hypokalemia due to diuretic use. Other factors placing patients at risk for digoxin-induced dysrhythmias include hypomagnesemia, hypercalcemia, and impaired renal function. Noncardiac adverse effects include general malaise, dizziness, headache, anorexia, nausea, and vomiting. Lifespan and Diversity Considerations: Digoxin is included in the Beers list of potentially inappropriate drugs for the older adult and warrants careful monitoring. Because of decreased excretion related to renal changes associated with aging, closely monitor for adverse effects. Do not skip or double a dose or change dose intervals, and take it at the same time each day. Dobutamine has been a traditional drug of choice in this class because it has the ability to rapidly increase myocardial contractility, with minimal changes to heart rate or blood pressure. Therapy with dobutamine is usually limited to 72 hours, as continuous infusion of the drug causes the heart to become tolerant to beta adrenergic activation, making the drug less effective. The two most common adverse effects with betaagonists are tachycardia and dysrhythmias. The basic pharmacology of the beta-adrenergic agonists was presented in Chapter 19, where epinephrine and isoproterenol were featured as prototypes for this drug class. Drugs Similar to Digoxin (Lanoxin, Lanoxicaps) Digoxin is the only cardiac glycoside available in the United States. From what you learned in Chapter 32, what is the primary indication for cholestyramine and what is the likely reason this drug causes a decrease in digoxin bioavailability Its primary function in metabolism is to move fatty acids from the bloodstream into cells, where it assists in the breakdown of lipids in the mitochondria. This breakdown produces energy and increases the availability of oxygen, particularly in muscle cells. A congenital deficiency of carnitine leads to severe brain, liver, and heart damage. The best food sources of carnitine are organ meats, fish, muscle meats, and milk products. History and Claims: Carnitine has been claimed to enhance energy and sports performance, heart health, memory, immune function, and male fertility. Standardization: Carnitine is available as a supplement in several forms, including L-carnitine, D-carnitine, and L-acetylcarnitine.

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However medications pregnancy order dilantin toronto, it is still available as an ophthalmic solution for the treatment of bacterial conjunctivitis. The most frequently reported adverse reactions after ophthalmic administration include increased worsening of conjunctivitis, eye irritation, dysgeusia, and eye pain. Gemifloxacin (Factive): Gemifloxacin was approved in 2003 for acute bacterial exacerbations of chronic bronchitis and community-acquired pneumonia. The drug undergoes only minimal metabolism by the liver and is excreted almost equally by the kidneys and in the feces. Assessment throughout administration: Potential Nursing Diagnoses Infection (bacterial) Acute Pain Hyperthermia Impaired Physical Mobility, related to adverse drug effects Deficient Knowledge (Drug Therapy) Risk for Injury, related to adverse drug effects Risk for Deficient Fluid Volume, related to diarrhea caused by adverse drug effects Assess for desired therapeutic effects. Severe diarrhea, especially containing mucus, blood, or pus, or decreased urine output should be reported immediately. Immediately report undiminished fever, changes in level of consciousness, or febrile seizures to the health care provider. Continued fever may be a sign of worsening infection, adverse drug effects, or antibiotic resistance. Immediately report febrile seizures, changes in behavior, or changes in level of consciousness to the provider. Periodic C&S tests may be ordered if infections are severe or are slow to resolve to confirm appropriate therapy. Post-use, residual drug levels may cause delayed reactions, dependent on the length of half-life. Fluoroquinolones may be taken with food, but consumption of dairy products at the same time as the drug will inhibit absorption. Do not take antacids or preparations such as vitamins containing iron or zinc at the same time as the fluoroquinolones dose. While receiving the medication, she reported itching and a slight swelling of the tongue and lips (angioedema). However, later that day she had no discomfort or presence of the previous symptoms. In addition to creams and ointments, bacitracin solutions may be used to soak compresses that can be applied to large areas of the skin. Daptomycin (Cubicin): Approved in 2003, daptomycin belongs to a class of antibiotics known as the cyclic lipopeptides. The spectrum of activity of daptomycin includes a wide variety of gram-positive pathogens. It is indicated for the treatment of complicated skin infections caused by organisms such as S. Daptomycin is bacteriocidal and its mechanism of action is clearly distinct from that of any other antibiotic. Myopathy has been recorded in a small percentage of patients taking daptomycin; therefore, the nurse should carefully monitor for muscle pain or weakness. Metronidazole (Flagyl): Metronidazole is another older antiinfective, approved in 1963, that is effective against a large number of anaerobes. Several drugs act by miscellaneous mechanisms or are the only drugs in their class. Bacitracin: Bacitracin is an older antibiotic, approved in 1948, that acts by inhibiting cell wall synthesis. It is effective against a variety of gram-positive and a few gram-negative microbes. Metronidazole is one of only a few drugs that have dual activity against both bacteria and multicellular parasites. When given orally, adverse effects are generally minor, and include nausea, dry mouth, and headache. As an antibacterial, metronidazole has two indications: serious infections due to anaerobic bacteria, and peptic ulcer disease. Few antibacterials are effective against anaerobes because the organisms reside in sites that have tissue destruction and a poor blood supply. Anaerobic bacteria are common causes of abscesses, gangrene, diabetic skin ulcers, and deep wound infections. Metronidazole has found a relatively new use in the treatment of Helicobacter pylori infections of the stomach associated with peptic ulcer disease. Polymyxin B: Approved in 1951, polymyxin B is an older, bacteriocidal drug that acts by disrupting the bacterial cell membrane. The drug is able to penetrate the phospholipid layer, make the membrane leaky, and cause the death of the bacterium. Although parenteral formulations are available, polymyxin B is rarely prescribed by these routes due to potential nephrotoxicity and neurotoxicity (black box warnings). Its primary application is in the treatment of topical infections of the skin, mucous membranes, or eye, caused by gram-negative organisms. Topical application, including to denuded skin, results in negligible systemic absorption. Polymyxin B is combined with neomycin and hydrocortisone in prescription otic preparations. The drug, however, is effective against a wide range of both gram-positive and gram-negative organisms. As an antibacterial, it is used for prophylaxis in contacts of patients with Haemophilus influenzae type B and for the prophylaxis of asymptomatic carriers of meningococcal disease. The reason its applications are limited is because of the rapid development of resistance, which can appear after only a few days of therapy. The use of rifampin in the pharmacotherapy of tuberculosis is presented in Chapter 54. Telithromycin blocks bacterial protein synthesis by binding to two different sites on the 50S ribosomal subunit. Telithromycin is an oral drug, with the most common adverse effects being diarrhea, nausea, and headache. The drug may cause mild to moderate visual disturbances, including blurred vision, diplopia, and difficulty focusing. Telithromycin carries a black box warning that it should not be used in patients with myasthenia gravis because fatal respiratory depression may occur. Additional medications prescribed include a nasal decongestant and a mild analgesic. As Mike is leaving the health clinic, he comments that he is responsible for multiple corporate offices and will soon be traveling. He is worried about remembering to take the medication, and admits to a history of nonadherence with medication regimens because he sometimes forgets to take medications. Prepare a patient teaching handout for Mike that provides him with information about the antibiotics he is being prescribed. His vital signs are normal with the exception of a slight increase in body temperature, 37. Until this most recent illness, he had started efforts toward a healthier lifestyle and weight reduction. The client tells the nurse that he experienced an allergic reaction when he took ciprofloxacin (Cipro) previously. As reported by the client, which of the following would be most indicative of an allergic reaction to this drug group Nervousness or anxiety the nurse is instructing a client on a new prescription for ciprofloxacin (Cipro), and will include which instructions Coffee or tea without milk, cream, or coffee-lightener are the preferred beverages for taking the antibiotic dose. Which discharge instruction would be most appropriate for the nurse to give this client Exposure to direct sunlight will help increase absorption of vitamin D, which is impaired by this medication. She wonders whether she should keep it or not and asks you, the nurse who lives next door, what she should do with the tube. What would you teach Carolyn about the use of topical antibiotic ointments such as the bacitracin Do fluoroquinolones predispose patients to Clostridium difficile associated disease Fluoroquinolones in communityacquired pneumonia: Guide to selection and appropriate use. Yesterday, when I began having a fever, I took some antibiotic tablets that a doctor prescribed when I was sick last month. Compare and contrast the pharmacotherapy of complicated versus uncomplicated urinary tract infections. Describe modifications in the pharmacotherapy of urinary tract infections for infants and children, pregnancy, older adults, and those with recurring infections.

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It is believed that melatonin helps to reset the circadian rhythm for these patients treatment regimen generic dilantin 100mg, rather than cause drowsiness. If a patient does not respond to these agents with relaxation or sleep, it indicates a serious underlying psychiatric or medical condition that requires further assessment by behavioral specialists. This is especially true if the drug worsens insomnia or produces bizarre thinking or unusual behaviors. Examples of such behaviors that should be immediately reported to the health care provider include aggressiveness, hallucinations, suicidal thinking, and unusual extroversion or depersonalization. The benzodiazepines are versatile drugs used for a diverse collection of medical conditions, including anxiety, seizure disorders, muscle spasms, premedication for medical procedures and anesthesia, and alcohol withdrawal. Diazepam (Valium) is featured as a prototype drug in Chapter 26 for its use in treating acute seizure disorders. Since the introduction of the first benzodiazepines-chlordiazepoxide (Librium) and diazepam (Valium)-in the 1960s, the class has become one of the most widely prescribed in medicine. Benzodiazepines account for approximately three fourths of all prescriptions for anxiety because they are effective, have a low incidence of drug interactions, and have less abuse potential compared to other drugs for anxiety and insomnia. In addition, there is a wide margin of safety between therapeutic and lethal doses. Although about 15 benzodiazepines are available, all have very similar actions and adverse effects; the various benzodiazepines differ primarily in their onset and duration of action. Some, such as midazolam (Versed), have a rapid onset time of 15 to 30 minutes; others, such as halazepam (Paxipam), take 1 to 3 hours to reach peak serum levels. The student should refer to current reference sources for updated information on approved and off-label indications. Although their actions are similar, they have different indications, which are shown in Table 22. Most are metabolized in the liver to active metabolites and are excreted primarily in urine. One major advantage of the benzodiazepines is that they do not produce respiratory depression when taken in therapeutic doses. Benzodiazepines are given parenterally for serious conditions such as status epilepticus or severe symptoms of acute schizophrenia. The benzodiazepines have replaced the barbiturates for the short-term treatment of insomnia caused by anxiety because of their greater margin of safety. Benzodiazepines shorten the length of time it takes to fall asleep and reduce the frequency of interrupted sleep. These anti-insomnia benzodiazepines are administered as hypnotics to induce sleep. Like other benzodiazepines tolerance develops to their therapeutic effects, and all have the potential for physical and psychological dependence. Most produce excessive daytime drowsiness, although this diminishes after a few days of therapy. They are indicated for short-term therapy of insomnia, approximately 4 weeks, although in clinical practice they may be used for longer periods. Rebound insomnia may be significant if these agents are used for prolonged therapy. These include sleepwalking, sleep-eating, and even making phone calls or driving a car (sleep-driving) while not fully awake. It has a very short duration of action and multiple doses, given every 30 to 45 seconds, may be necessary. Flumazenil must be used cautiously because the patient may awaken abruptly with dysphoria, agitation, and even seizures. Mechanically ventilated patients may receive lorazepam infusions to manage excessive anxiety and agitation that are characteristic of being connected to this device. Lorazepam is also used for several off-label indications, including insomnia, seizures, and the prevention or control of acute symptoms associated with ethanol withdrawal. Although used off-label, it is a drug of choice for treating life-threatening status epilepticus. Precautions must be taken in older adults, those who are debilitated, or those who have hepatic or renal dysfunction. Oral contraceptives inhibit the metabolism of benzodiazepines that undergo oxidation (alprazolam, chlordiazepoxide, diazepam, and others); thus the effectiveness of these antianxiety drugs may be increased. On the other hand, oral contraceptives increase the metabolism of benzodiazepines that undergo conjugation. There may be increased sedation if lorazepam is taken concurrently with disulfiram. Herbal/Food: Kava, melatonin, and valerian may cause excessive drowsiness if taken with lorazepam. Excessive ingestion of caffeinated food and drinks may decrease the effectiveness of lorazepam. Lifespan and Diversity Considerations: Many benzodiazepines are included in the Beers List of potentially inappropriate drugs for older adults and warrant careful monitoring. Use special caution in administering this drug to the older adult who is at increased risk of falls, and provide assistance with ambulation as needed. These effects are dose related and tolerance to them may develop as therapy progresses. Patients may experience nightmares, talkativeness, mania, sleep disorders, acute rage reactions, anxiety, restlessness, and euphoria. Do not consume alcoholic beverages while taking this medication because this may cause increased sedation. Immediately notify the health care provider of any known or suspected pregnancy because this drug has the potential to cause birth defects. It is also approved to produce relaxation or sedation prior to medical procedures. Off-label uses include reduction of agitation in intensive care patients, treatment of acute chloroquine overdose, and treatment of withdrawal symptoms associated with benzodiazepine abuse. Oxazepam (Serax): Drugs Similar to Lorazepam (Ativan) Benzodiazepines for anxiety: Benzodiazepines that are primarily used to treat anxiety are discussed next and include alprazolam, chlordiazepoxide, clorazepate, diazepam, and oxazepam. Benzodiazepines that are used to treat seizures (see Chapter 26) and those that are used as adjuncts to anesthesia (see Chapter 30) are presented in their respective chapters. It is used off-label for the short-term treatment of insomnia and for premenstrual dysphoric disorder that is unresponsive to nonpharmacologic therapies. Patients are encouraged to refrain from consuming grapefruit and grapefruit juice while taking alprazolam, because the combination may inhibit the metabolism of the drug. Older adults should receive a small dose, which can then be gradually increased as indicated, to prevent ataxia or excessive sedation. Care must be taken when treating women of childbearing age because alprazolam is a pregnancy category D drug. It may be used off-label for the short-term management of insomnia associated with situational anxiety. Benzodiazepines primarily for insomnia: Benzodiazepines primarily used as hypnotics to treat insomnia include estazolam, flurazepam, quazepam, temazepam, and triazolam. Estazolam (ProSom): Approved in 1990, estazolam is an intermediate-duration benzodiazepine approved as a hypnotic in the short-term management of insomnia. This drug should be given at bedtime because it causes significant drowsiness and promotes sleep. The most common adverse effects are somnolence, hypokinesia, abnormal coordination, and dizziness. After several weeks of therapy, patients may exhibit tolerance to the sedative effects of the drug and will experience difficulty sleeping during the early morning hours. Flurazepam has a longer duration of action than some drugs in this class because it is converted to long-acting active metabolites in the liver.

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Like chemical classes symptoms pneumonia cheap dilantin 100 mg overnight delivery, placing an antibiotic into a pharmacologic class allows the nurse to develop a mental framework on which to organize these medications and to predict similar actions and adverse effects. Examples of pharmacologic classes along with their prototype drugs are listed in Table 49. Although the immune system provides elaborate defenses against microbial invaders, there are times when the body defenses become overwhelmed by an infection. Furthermore, there are times when acquiring an infection could be a serious health challenge for a patient, and it is best to prevent it. Whether it is used for treating or preventing disease, the primary goal of anti-infective therapy is to assist the body in eliminating a pathogen. Some drugs do not kill pathogens but instead slow their growth, allowing natural body defenses to eliminate the microorganisms. Bacteria incorporate different chemicals into their membranes and use unique biochemical pathways and enzymes to manage their rapid growth. Even the more complex pathogens such as fungi and protozoans have different cell structures and use certain metabolic pathways not found in human cells. Antibiotics exert selective toxicity by targeting these unique differences between human and bacterial, fungal, and protozoan cells. Through this selective action, these pathogens can be killed, or their growth severely hampered, without any major effects on human cells. Of course, there are limits to this selective toxicity, depending on the specific antibiotic and the dose employed. There are five major methods by which antibacterials exert their selective toxicity: inhibition of cell wall synthesis, inhibition of protein synthesis, disruption of the plasma cell membrane, inhibition of nucleic acid synthesis, and inhibition of metabolic pathways (antimetabolites). The antifungal drug amphotericin B shuts down the synthesis of ergosterol, a lipid essential to the integrity of fungal plasma membranes. Inhibition of Metabolic Pathways (Antimetabolites) Because they divide rapidly, bacterial cells need a steady supply of nutrients and metabolites. A few drugs structurally resemble these building blocks and "fool" the bacterial cell into using them for growth. Folic acid, a B vitamin that is essential to human metabolism, is also essential to bacteria. When the bacteria attempt to use the sulfonamides, bacterial protein synthesis is blocked. Inhibition of Cell Wall Synthesis Unlike human cells, bacteria have rigid cell walls that create a high osmotic pressure within the cells. The cell wall primarily consists of peptidoglycan, a strong, repeating network of carbohydrate and protein chains found only in bacteria and that contains sugars bound to peptides. The presence of a unique cell wall gives several means by which antibiotics may act. Fungi also have a unique cell wall that contains lipids that are not used in human cells. The penicillins and cephalosporins bind to specific proteins that are essential to building the bacterial cell wall. Vancomycin acts by preventing the formation of peptide chains that are used in the construction of the cell wall. Several drugs that are effective against Mycobacterium tuberculosis, including isoniazid, act by inhibiting the incorporation of mycolic acid, an important component of the cell wall of this mycobacterium. Other Mechanisms of Action Anti-infectives act by a number of other miscellaneous mechanisms. As the understanding of bacterial physiology increases, it is likely that pharmacologists will develop anti-infectives with entirely new mechanisms of action. The primary mechanisms of action of antibacterial drugs are shown in Pharmacotherapy Illustrated 49. Inhibition of Protein Synthesis Both bacterial and human cells conduct protein synthesis, so this may seem an unlikely target for antibiotics. However, proteins are constructed on the surface of ribosomes, and these organelles have different structures in humans and bacteria. This difference in ribosomal structure accounts for the selective toxicity of certain antibiotics for bacterial cells. The fact that protein synthesis occurs in several steps affords different mechanisms by which antibiotics may act. The aminoglycosides change the shape of the ribosome so that protein synthesis is impeded. In the 1950s, health care providers called antibiotics "miracle drugs" and predicted that all infectious disease would one day be eliminated. It did not take long, however, to discover that these miracle drugs were rapidly becoming ineffective. How could a drug that once killed nearly 100% of a species of bacteria soon prove to be ineffective Acquired resistance is the ability of an organism to become unresponsive over time to the effects of an anti-infective. Resistance occurs in antibacterials, antifungals, antivirals, and antiprotozoal drugs. Medicine has discovered a number of mechanisms by which pathogens acquire resistance: Destruction of the drug. For example, some bacteria are able to produce beta lactamase, an enzyme that splits the active portion of the drug molecule. Organisms that produce beta lactamase are resistant to many of the penicillin and cephalosporin antibiotics. Some bacteria have developed enzymes that inactivate the drug as it crosses the cell wall. Others have changed the structure of the channels or pores that the antibiotic normally uses to enter the cell. Some bacteria have developed a system that rapidly pumps the antibiotic out of the bacterial cell before it can reach intracellular targets such as ribosomes. Resistant bacteria have developed several types of pumps, each of which is used to remove different antibiotics. Most antibiotics bind to a specific receptor that is located on the cell surface or inside the bacteria. Certain bacteria have changed the shape of these receptors, so they no longer bind the drug. For the macrolide antibiotics, mutations have resulted in changes to the structure of the bacterial ribosome, which is the receptor for macrolide binding. Some antibiotics act by depleting the pathogen of an essential substance necessary for growth. Some resistant organisms have survived antibiotic application by synthesizing larger amounts of the essential substance or by finding an alternative means of obtaining it from the environment. During exponential division, bacteria make frequent errors, or mutations, while duplicating their genetic code. These mutations, which occur spontaneously and randomly, occasionally result in a change in physiology that gives a bacterial cell a reproductive advantage over its neighbors. For example, the mutated bacterium may be able to survive in harsher conditions, change the shape of its organelles, or perhaps grow faster than other bacterial cells. One such mutation that is of particular importance to medicine is that which confers drug resistance on a microorganism. Once a resistant strain appears, it permanently loses sensitivity to that specific drug and often to other drugs in the same pharmacologic and chemical class. Over several decades, these drug-resistant mutants may colonize a large segment of the human population, thus making the medication essentially useless as a first-line antibiotic. Promotion of Resistance the widespread and sometimes unwarranted use of antibiotics has promoted the development of drug-resistant bacterial strains. By killing strains of bacteria that are sensitive to the drug, the only bacteria remaining to replicate are those that acquire the mutations that make them insensitive to the effects of the antibiotic. These drug-resistant bacteria are then free to grow, unrestrained by their neighbors that are killed by the antibiotic. Soon the patient develops an infection that is resistant to conventional drug therapy.