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Also 500mg cipro with visa antibiotic clindamycin, there is 131 concern that administration of I to young patients may carry a slight risk for 131 cancer buy cipro 500 mg fast delivery infection 2 cheats. It should be noted cheap 500mg cipro with visa bacteria 33 000 feet, however discount cipro 750 mg on line antibiotics oral thrush, that there is no evidence that the use of I in Graves disease has ever caused cancer of the thyroid or any other tissue. Exposure of the fetus to I after the first trimester may damage the immature thyroid, and exposure to radiation at any point in fetal life carries a risk for generalized developmental 131 harm. Dosage 131 Dosage of I is determined by thyroid size and by the rate of thyroidal iodine uptake. However, because most forms of thyroid cancer do not accumulate iodine, only a small percentage of patients 131 are candidates for I therapy. Because high amounts of radioactivity are involved, body wastes must be disposed of properly. Diagnostic Use 131 I is employed to diagnose a variety of thyroid disorders, including 131 hyperthyroidism, hypothyroidism, and goiter. After I administration, the 131 thyroid is scanned for uptake of radioactivity; the amount and location of I uptake reveal the extent of thyroid activity. Doses for diagnosis are minuscule (less than 1 microcurie for children and less than 10 microcuries for adults). Please note that, although 131 123 I can be used for diagnosis, the preferred isotope is I. Nonradioactive Iodine: Lugol Solution Description Lugol solution, also known as strong iodine solution, is a mixture containing 5% elemental iodine and 10% potassium iodide. Mechanism of Action When present in high concentrations, iodide has a paradoxical suppressant effect on the thyroid. Second, high concentrations of iodide inhibit thyroid hormone synthesis by suppressing both the iodination of tyrosine and the coupling of iodinated tyrosine residues. Third, high concentrations of iodine inhibit release of thyroid hormone into the blood. Therapeutic Use Strong iodine solution can be given to hyperthyroid individuals to suppress thyroid function in preparation for thyroidectomy. In most cases, plasma levels of thyroid hormone are reduced with methimazole before initiating strong iodine solution. In addition to its use before thyroidectomy, strong iodine solution is employed in thyrotoxic crisis. Signs and symptoms include a brassy taste, a burning sensation in the mouth and throat, soreness of the teeth and gums, frontal headache, coryza (nasal inflammation and sneezing), salivation, and various skin eruptions. Treatment consists of gastric lavage (to remove iodine from the stomach) and giving sodium thiosulfate (to reduce iodine to iodide). Dosage and Administration When employed to prepare hyperthyroid patients for thyroidectomy, strong iodine solution is administered in a dosage of 5 to 7 drops 3 times daily for 10 days immediately preceding surgery. Iodine solution should be mixed with juice or some other beverage to mask its unpleasant taste. Beta Blockers Propranolol and other beta blockers can suppress tachycardia and other symptoms of Graves disease. Benefits derive from beta-adrenergic blockade, not from reducing levels of T or T. We begin this chapter with a discussion of how estrogens and progestins regulate physiologic processes. Estrogens and progestins (also known as progestogens) are hormones with multiple actions. They promote female maturation and help regulate the ongoing activity of female reproductive organs. In addition, small amounts of estrogens and progestins are produced in peripheral tissues. The Menstrual Cycle Because much of the clinical pharmacology of the estrogens and progestins is related to their actions during the menstrual cycle, understanding the menstrual cycle is central to understanding these hormones. The anatomic and hormonal changes that take place during the cycle are shown in Fig. As indicated, the first half of the cycle (days 1 through 14) is called the follicular phase, and the second half is called the luteal phase. Ovarian and Uterine Events The menstrual cycle consists of a coordinated series of ovarian and uterine events. In the ovary, the following sequence occurs: (1) several ovarian follicles ripen; (2) one of the ripe follicles ruptures, causing ovulation; (3) the ruptured follicle evolves into a corpus luteum; and (4) if fertilization does not occur, the corpus luteum atrophies. As these ovarian events are taking place, parallel events take place in the uterus: (1) while ovarian follicles ripen, the endometrium prepares for nidation (implantation of a fertilized ovum) by increasing in thickness and vascularity; (2) after ovulation, the uterus continues its preparation by increasing secretory activity; and (3) if implantation fails to occur, the thickened endometrium breaks down, causing menstruation, and the cycle begins anew. The Roles of Estrogens and Progesterone The uterine changes that occur during the cycle are brought about under the influence of estrogens and progesterone produced by the ovaries. During the first half of the cycle, estrogens are secreted by the maturing ovarian follicles. At midcycle, one of the ovarian follicles ruptures and then evolves into a corpus luteum. For most of the second half of the cycle, estrogens and progesterone are produced by the newly formed corpus luteum. At the end of the cycle, the corpus luteum atrophies, causing production of estrogens and progesterone to decline. In response to the diminished supply of ovarian hormones, the endometrium breaks down. Precisely timed alterations in the secretion of these hormones are responsible for coordinating the structural and secretory changes that occur throughout the menstrual cycle. Estrogens Biosynthesis and Elimination Females In premenopausal women, the ovary is the principal source of estrogen. During the follicular phase of the menstrual cycle, estrogens are synthesized by ovarian follicles; during the luteal phase, estrogens are synthesized by the corpus luteum. In the periphery, some of the estradiol secreted by the ovaries is converted into estrone and estriol, hormones that are less potent than estradiol itself. Estrogens are eliminated by a combination of hepatic metabolism and urinary excretion. In the human male, small amounts of testosterone are converted into estradiol and estrone by the testes. Activating these surface receptors produces a rapid response—more rapid than can be produced by activating nuclear receptors. Physiologic and Pharmacologic Effects Effects on Primary and Secondary Sex Characteristics of Females Estrogens support the development and maintenance of the female reproductive tract and secondary sex characteristics. These hormones are required for the growth and maturation of the uterus, vagina, fallopian tubes, and breasts.
Major adverse effects are pancreatitis and neutropenia (secondary to bone marrow suppression) buy cipro 1000 mg antimicrobial agents. Cyclosporine Cyclosporine [Sandimmune purchase cipro 750mg overnight delivery infection 6 months after surgery, Neoral buy 500 mg cipro otc antibiotics for dogs with salivary gland infection, Gengraf] is a stronger immunosuppressant than azathioprine or mercaptopurine—and acts faster order cipro 1000 mg mastercard antibiotic before surgery, too. Cyclosporine is a potentially toxic compound that can cause renal impairment, neurotoxicity, and generalized suppression of the immune system. Methotrexate In patients with Crohn disease, methotrexate can promote short-term remission and thereby reduce the need for glucocorticoids. Because the doses employed are low (25 mg once a week), the toxicity associated with high-dose therapy in cancer patients is avoided. Immunomodulators The drugs discussed in this section are monoclonal antibody products that modulate immune responses. However, some authorities now recommend their use early in treatment, with the hope of inducing remission quickly and maintaining remission longer. The drug is indicated for moderate to severe Crohn disease and ulcerative colitis. In clinical trials, infliximab reduced symptoms in 65% of patients with moderate to severe Crohn disease and produced clinical remission in 33%. During clinical trials, 5% of patients dropped out because of serious adverse effects. Infusion reactions include fever, chills, pruritus, urticaria, and cardiopulmonary reactions (chest pain, hypotension, hypertension, dyspnea). Infliximab may also increase the risk for lymphoma, especially among patients with highly active disease or those on long-term immunosuppressive therapy. For patients with Crohn disease or ulcerative colitis, treatment consists of an induction regimen (5 mg/kg infused at 0, 2, and 6 weeks) followed by maintenance infusions of 5 mg/kg every 8 weeks thereafter. Antibiotics Antibiotics, such as metronidazole and ciprofloxacin, can help control symptoms in patients with mild or moderate Crohn disease. Metronidazole In patients with mild or moderate Crohn disease, metronidazole [Flagyl] is as effective as sulfasalazine. Furthermore, because relapse is likely if metronidazole is discontinued, long-term therapy is required. Unfortunately, prolonged use of high-dose metronidazole poses a risk of peripheral neuropathy. Although metronidazole can help patients with Crohn disease, benefits are minimal in those with ulcerative colitis. Ciprofloxacin Like metronidazole, ciprofloxacin [Cipro] is highly effective in patients with mild or moderate Crohn disease. In one study, ciprofloxacin produced complete or partial remission in 72% of those treated. Oral metoclopramide has two approved uses: diabetic gastroparesis and suppression of gastroesophageal reflux. Off- label uses include for hiccups and for nausea and vomiting of early pregnancy. Long-term high- dose therapy can cause irreversible tardive dyskinesia, characterized by repetitive, involuntary movements of the arms, legs, and facial muscles. To reduce the risk for tardive dyskinesia, treatment should be as brief as possible using the lowest effective dose. Of note, exposure to metoclopramide during the first trimester of pregnancy is not associated with an excess risk for congenital malformations. Pancreatic Enzymes The pancreas produces three types of digestive enzymes: lipases, amylases, and proteases. These enzymes are secreted into the duodenum, where they help digest fats, carbohydrates, and proteins. To protect the enzymes from stomach acid and pepsin, the pancreas secretes bicarbonate. The bicarbonate neutralizes acid in the duodenum, and the resulting elevation in pH inactivates pepsin. Deficiency of pancreatic enzymes can compromise digestion, especially digestion of fats. Causes of deficiency include cystic fibrosis, pancreatectomy, pancreatitis, and obstruction of the pancreatic duct. Pancreatic enzymes for clinical use are available as pancrelipase, a mixture of lipases, amylases, and proteases prepared from hog pancreas. All drugs, with the exception of Viokace, are supplied in delayed-release capsules designed to dissolve in the duodenum and upper jejunum. The capsules should not be crushed, chewed, or retained in the mouth, owing to a risk for irritating the oral mucosa. The most common adverse effects are abdominal discomfort, flatulence, headache, and cough. The most serious concern is fibrosing colonopathy, seen rarely during high-dose therapy in patients with cystic fibrosis. Porcine pancrelipase contains high levels of purines and hence may pose a risk to patients with gout or hyperuricemia. Determining factors include the extent of enzyme deficiency, dietary fat content, and enzyme activity of the preparation selected. The efficacy of therapy can be evaluated by measuring the reduction in 24-hour fat excretion. These fissures afflict about 700,000 Americans every year, often causing unrelenting and debilitating pain. Topical nitroglycerin relieves pain and promotes healing by relaxing the internal anal sphincter. Nitroglycerin ointment has been used in other countries for years and is considered by many experts to be a first-line therapy. Other Anorectal Preparations Various preparations can help relieve discomfort from hemorrhoids and other anorectal disorders. Anorectal preparations are available in multiple formulations: suppositories, creams, ointments, lotions, foams, tissues, and pads. Several vitamins are inactive in their native form and must be converted to active compounds in the body. Basic Considerations Dietary Reference Intakes Reference values on dietary vitamin intake, as set by the Food and Nutrition Board of the Institute of Medicine of the National Academy of Sciences, were established to provide a standard for good nutrition. In addition, they often differ for males and females and typically increase for women who are pregnant or breastfeeding. Intake of a nutrient below the established range for that nutrient increases the risk for malnourishment.
If the respiratory rate is high trusted 750mg cipro antibiotic resistance world map, set the percentage assist to 85%; if the respiratory rate does not change 250 mg cipro with amex how quickly do antibiotics work for sinus infection, it is unlikely to be related to respiratory distress and under-support discount cipro 1000mg on line antibiotics for acne that are safe during pregnancy. Patient ventilator interaction is influenced by the co-ordination of ventilator triggering and off-cycling with the patient’s breathing efforts buy generic cipro 750mg virus alive. In addition, patient–ventilator interaction involves adjusting the magnitude of assist in relation to the degree of patient effort. Asynchrony can result in trigger failure or, at the other extreme, ‘fighting the ventilator’ and has been associated with prolonged duration of mechanical ventilation. Traditionally, the patient communicates with the ventilator through pneumatic triggers. In critical illness, with neuromuscular dysfunction, reduced compliance, and increased resistance, these delays will be compounded, with consequent effects on patient–ventilator synchrony. Central nervous system Ideal technology Phrenic nerve New Ventilator Diaphragm excitation technology unit Diaphragm contraction Chest wall and lung expansion Current Airway pressure, flow and volume technology Fig. The steps necessary to transform central respiratory drive into an inspi- ration are shown (that is, the neuro–ventilatory coupling with indications for the levels at which technology able to control a mechanical ventilator could be imple- mented). It unloads inspiratory muscles while upholding spontaneous breathing in patients with acute res- piratory failure. As the respiratory muscles and the ventilator receive the same signal, synchronization is improved compared with other spontaneous modes of ventilatory support. Using this, it is possible to perform bedside evaluation of patient–ventilator interaction and determine if spontaneous breathing is present. Circuit dead space Rebreathing caused by insufficient tidal volume relative to anatomical/ physiological and respiratory circuit dead space may result in: • Excessive minute ventilation. Limitation of the external (respiratory circuit) dead space is hence very important to ensure adequate respiratory feedback and avoid unnecessary load and stress on the respiratory system. In situations of severe dynamic hyperinflation and severely increased respiratory drive, the neural expiratory time can become too short to allow full expiration. Improved synchrony between patient and ventilator may paradoxically exacerbate this incomplete emptying and aggravate dynamic hyperinflation. If this second increase results in a pressure well below 20cmH2O, this indicates that the patient is ‘satisfied’ with the unloading and has reduced his or her respiratory drive (i. This also allows optimization of patient–ventilator synchrony in the conventional mode. Upper pressure limits As delivered pressure is a function of patient effort, upper pressure limits need to be manually set to avoid the risk of barotrauma. Should this signal be lost, the backup ventilator settings allow the patient to be ventilated using traditional pneumatic triggers and inspiratory pressure support. It can be used in patients from 34 weeks gestation up to the elderly for any form of potentially reversible respiratory or cardiac failure. Patient selection There are three main questions to be answered during the selection process: • Does the patient’s pre-morbid condition preclude recovery, i. The co-ordinator is usually a senior nurse who handles referrals and allocates appropriate personnel. Each programme is sup- ported by perfusion technicians, blood transfusion, cardiology, radiology, physiotherapy, and other specialities. The circuit consists of vascular access cannulae, tubing, a pump, an oxygenator with integral heat exchanger, and monitoring devices (see Fig. Cannulae For respiratory support veno-venous access is preferred, usually through a double lumen cannula (27-31F) placed percutaneously via the right internal jugular vein under X-ray control. Pump This can be a roller pump (which must have a compliance chamber, servo- regulation, and super-durable raceway tubing) or a centrifugal pump (which must have inlet pressure monitoring), depending on institutional preference. Bridge This is a short length of tubing joining the drainage tube (blood from the patient) to the return tubing (blood to the patient). This is necessary when air is being removed from the circuit or components are being changed. Recently, many teams have removed the bridge from the circuit and have it as a component that can be added as required: this eliminates a potential area of clot formation. Sweep gas flows through the oxy- genator in a counter-current direction to the blood, controlled by a flow- meter. Adjusting the FiO2 of the sweep gas can alter the amount of oxygenation, but many centres use 100% O2 to simplify management and also to reduce the risk of nitrogen embolus in the event of a membrane rupture. Monitoring Monitoring should consist of a minimum of: • Inlet pressure monitoring and ultrasonic flow meter for a centrifugal pump • Servo-regulation alarm for a roller pump • Pre- and post-membrane pressure monitoring • Gas supply disconnection alarms for all circuits Optional extras such as in-line blood gas analysis (i. Extracorporeal flow is increased until the venous line pressure is around –50 to –70mmHg (centrifugal pump) or until 4–5L/min flow is obtained. If they are absolutely necessary they are undertaken by the most skilled operators available. High-frequency oscillation can also be used to achieve lung rest with the same FiO2 and a mean airway pressure of around 15cmH2O. Full nutrition is provided, a negative fluid balance is initiated and maintained, and antibiotics are given as appropriate. Although it would have been more elegant to design a study where both groups have carefully regulated treatment, this is practically nearly impossible. It has minimal effect on oxygenation and is therefore only suitable for patients with hypercapnoeic respiratory failure. There is a 10% incidence of leg ischaemia associated with the arterial cannulation. Conclusion We know that lung rest and avoidance of tissue oedema result in improved survival for adults with respiratory failure. Unfortunately, a small minority of patients with aggressive disease can quickly end up in a viscous spiral of increasing ventilator pressures, fluid loading, hypoxia, and acidosis, which eliminates any prospect of lung recovery and leads to multiorgan failure and death. It is of the utmost importance to remember two important tenets: “Primum non nocere” (Hippocrates) and “The art of medicine consists of amusing the patient while nature cures the disease. In our current world of evidence-based practice it may be depressing to find that none of these therapies has produced a significant reduction in mortality. There may be many reasons for this: the studies are often small, the variation in study design makes direct comparison difficult, and changes in ventilation strategy over the last 20 years may have overtaken the impact of these novel therapies. However, most of the therapies improve gas exchange, and this may allow some extra time for other proven interventions to work. Many of the trials into these interventions have used surrogate outcome measures such as length of stay or time on a ventilator. We have to consider whether significant changes in these surrogate end points can be used as a justification for integrating the use of novel therapies into everyday practice. Bryan went on to produce two randomized controlled studies (1976 and 1977) showing benefit in oxygenation. Concepts Prone position produces transpulmonary pressure gradients sufficient to exceed the opening pressure in dorsal and juxtadiaphragmatic regions where atelactasis and shunt are most severe. Gravity does not influence blood flow as much as was once thought, and so as ventilation is redirected dorsally, blood flow to this region remains high. Care should be taken when positioning to avoid pressure areas, particularly to the face and eyes, but also to ensure the thorax and hips are elevated high enough off the bed on supports such that the neck is slightly flexed and the abdomen is free.
It has a short dura- Nondepolarizing Neuromuscular tion of action (about 1 hour) and is often preferable to Blocking Agents atropine and scopolamine for short-term mydriasis purchase cipro 1000 mg on line antibiotics for acne brand names. The nondepolarizing neuromuscular blocking agents buy cipro 250mg fast delivery antibiotic eye drops over the counter, also known as curariform drugs order cipro 1000mg antibiotics zinc deficiency, include Pirenzepine atracurium cheap 250mg cipro mastercard bacteria class 8, cisatracurium, pancuronium, rocuronium, Pirenzepine, a muscarinic receptor antagonist that is selec- and vecuronium. One of the original drugs, tubocurarine, tive for M1 receptors, was developed to reduce vagally stimu- was extracted from plants used by native South Americans lated gastric acid secretion in patients with peptic ulcers. Curare is another blocks M1 receptors on paracrine cells and inhibits the name for the arrow poisons and their chemical derivatives. Pirenz- The curariform drugs are not well absorbed from the gut epine is available in Canada and Europe but not in the and do not cross the blood-brain barrier. The pharmacologic The acetylcholine nicotinic receptor antagonists include properties of curariform drugs are listed in Table 7-1. These ganglionic blocking agents and neuromuscular blocking drugs are positively charged quaternary amines having an agents. The nondepolarizing neu- Drugs that block autonomic ganglia were among the frst romuscular blocking agents are administered only by the drugs to be developed for reducing excessive activity of the intravenous route. Chapter 7 y Acetylcholine Receptor Antagonists 67 the specifc isomer known as cisatracurium spontaneously respiratory tract so as to enable ventilation and endoscopic decomposes by nonenzymatic chemical (Hoffman) degrada- procedures (e. Hence, cisatracurium is the preferred paralytic agent neuromuscular blocking agents, the degree of neuromuscular for critically ill patients with impaired hepatic and renal blockade can be determined by monitoring the contraction function. In patients with normal renal and hepatic function, of a small limb muscle in response to nerve stimulation. The selection of a nondepolarizing agent of action comparable to that of vecuronium and rocuronium. The curariform drugs act as relative duration of action and the degree of drug-induced competitive antagonists of acetylcholine at nicotinic changes in blood pressure and heart rate. Atracurium, cisa receptors in skeletal muscle, and this accounts for their tracurium, rocuronium, and vecuronium provide an inter- muscle-relaxing effects. After a curariform drug is adminis- mediate duration of action (30 to 60 minutes). With the tered, it frst paralyzes the small and rapidly moving muscles exception of atracurium, which can cause histamine release of the eyes and face and then paralyzes the larger muscles at higher doses, the intermediate-acting drugs have minimal of the limbs and trunk. Finally, it paralyzes the intercostal effects on cardiovascular and respiratory function. This rium or pancuronium might be selected when a longer dura- sequence of paralysis is fortunate in that it enables relaxation tion of action is required. Tubocurarine is no longer used of abdominal muscles for surgical procedures without pro- clinically because it is associated with a higher incidence of ducing apnea. Respiratory function should always be closely histamine release and adverse effects. Depolarizing Neuromuscular Blocking Agents Curariform drugs stimulate the release of histamine Succinylcholine, the only depolarizing agent available for from mast cells, and they block autonomic ganglia and clinical use today, is composed of two covalently linked muscarinic receptors (see Table 7-1). Newer tinic receptors in skeletal muscle and causes persistent drugs, such as doxacurium, cisatracurium, rocuronium, and depolarization of the motor end plate. When the drug is vecuronium, tend to cause less histamine release and fewer frst administered, it produces transient muscle contractions autonomic side effects than does pancuronium. Succinylcholine is drugs are potentiated by volatile inhalational anesthetic not hydrolyzed as rapidly by cholinesterase as is acetylcho- agents (e. The effects of paralytic agents are also more pronounced Table 7-1 compares the properties of succinylcholine with in patients who have neuromuscular disorders such as myas- those of the curariform drugs. The sequence of muscle paralysis reversed by administering a cholinesterase inhibitor (e. The effects of succinylcholine, however, at the neuromuscular junction and counteracting the neuro- are not reversed by cholinesterase inhibitors, and no muscular blockade. Neostigmine reversal should not be pharmacologic antidote exists to reverse an overdose of attempted until patients have demonstrated partial recovery succinylcholine. Because of its shorter duration of action, succinyl- for reversing steroidal neuromuscular blocking agents such choline offers the best chance for resumption of spontaneous as rocuronium. Sugammadex forms a tight water-soluble breathing if endotracheal intubation proves diffcult; thus it complex with rocuronium and removes the drug from the is the preferred neuromuscular blocker for adults with emer- neuromuscular junction, producing a fast recovery of neuro- gency airway situations. Before the drug is administered in muscular function and reducing the risk of postoperative a nonemergent situation, patients should be interviewed to respiratory dysfunction. In contrast to cholinesterase inhibi- screen for personal or family history suggestive of atypical tors, sugammadex is effective in subjects demonstrating cholinesterase. Individuals with this inherited disorder complete paralysis when tested with a nerve stimulator. The neuromuscular blockers are primarily in persons with unhealed skeletal muscle injury such as used to induce muscle relaxation during surgery and thereby follows thirddegree burns, and it should not be used in facilitate surgical manipulations. Many conditions used as an adjunct to electroconvulsive therapy to prevent involving muscle weakness, such as paralysis caused by spinal injuries that might be caused by involuntary muscle contrac- cord injury, also present an increased risk of hyperkalemia tions. Succi- (A) hallucinations nylcholine can also cause postoperative myalgia, particularly (B) bronchospasm in the muscles of the neck, back, and abdomen. This effect (C) hyperthermia probably results from the muscle fasciculations produced by (D) urinary retention the drug. Finally, succinylcholine has been associated with a (E) blurred vision rare complication known as malignant hyperthermia, 3. Topical ocular administration of tropicamide will cause which is also associated with inhalation anesthetics (see (A) contraction of the ciliary muscle Chapter 21). The therapeutic use of darifenacin is based on its • Muscarinic acetylcholine receptor antagonists relax ability to smooth muscle, increase heart rate and cardiac con- (A) relax bronchial smooth muscle duction, and inhibit exocrine gland secretion. They are also used to reduce Answers And explAnAtions salivary and respiratory secretions and to produce mydriasis and cycloplegia. Succinylcholine is the • Atropine toxicity can cause dryness of the mouth and only depolarizing neuromuscular blocking agent that skin, blurred vision, tachycardia, palpitations, urinary produces persistent depolarization of the motor end plate, retention, delirium, and hallucinations. Cholinesterase inhibitors, acting to increase depolarizing neuromuscular blocking agents known as acetylcholine levels, do not counteract the muscle curariform drugs, such as rocuronium and cisatracu- paralysis produced by succinylcholine and can actually rium. These drugs are used to produce muscle relax- increase the degree of paralysis by prolonging muscle ation during surgery. They do not cause muscle such as atropine and scopolamine cause relaxation of fasciculations, and their effects can be reversed by bronchial smooth muscle and bronchodilation. It produces Scopolamine causes blurred vision by relaxing the muscle fasciculations that are followed by muscle ciliary muscle, thereby producing cycloplegia (paralysis of paralysis. Tropicamide binds to muscarinic receptors and competi- tively blocks acetylcholine released by the parasympa- review Questions thetic oculomotor nerve. This action leads to relaxation of the iris sphincter muscle and dilation of the pupil 1. Which drug produces transient muscle fasciculations (mydriasis), thereby facilitating ophthalmoscopic exami- followed by muscle paralysis that is not reversed by nation of the peripheral retina.
