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By: Homer A. Boushey MD Chief, Asthma Clinical Research Center and Division of Allergy & Immunology; Professor of Medicine, Department of Medicine, University of California, San Francisco
Therefore discount 80 mg propranolol amex heart disease bracelets awareness, antimuscarinic agents purchase propranolol amex capillaries of the skin, administered topically as eye drops or ointment order 80 mg propranolol visa cardiovascular system heart and blood vessels, are very helpful in doing a complete examination generic 120 mg silvitra visa. For younger children cheap levitra online visa, the greater efficacy of atropine is sometimes necessary, but the possibility of antimuscarinic poisoning is correspondingly increased. Drug loss from the conjunctival sac via the nasolacrimal duct into the nasopharynx can be diminished by the use of the ointment form rather than drops. Formerly, ophthalmic antimuscarinic drugs were selected from the tertiary amine subgroup to ensure good penetration after conjunctival application. Antimuscarinic drugs should never be used for mydriasis unless cycloplegia or prolonged action is required. Alpha- adrenoceptor stimulant drugs, eg, phenylephrine, produce a short-lasting mydriasis that is usually sufficient for funduscopic examination (see Chapter 9). Respiratory Disorders The use of atropine became part of routine preoperative medication when anesthetics such as ether were used, because these irritant anesthetics markedly increased airway secretions and were associated with frequent episodes of laryngospasm. Scopolamine also produces significant amnesia for the events associated with surgery and obstetric delivery, an adverse effect that was considered desirable. On the other hand, urinary retention and intestinal hypomotility following surgery were often exacerbated by antimuscarinic drugs. The aerosol route of administration has the advantage of maximal concentration at the bronchial target tissue with reduced systemic effects. Tiotropium and aclidinium have a longer bronchodilator action than ipratropium and can be given once daily because they dissociate slowly from M receptors. They have a terminal elimination half-life3 of 5–6 days; steady-state plasma levels are achieved in about 25 days with single daily administration. The hyperactive neural bronchoconstrictor reflex present in most individuals with asthma is mediated by the vagus, acting on muscarinic receptors on bronchial smooth muscle cells. Cardiovascular Disorders Marked reflex vagal discharge sometimes accompanies the pain of myocardial infarction (eg, vasovagal attack) and may depress sinoatrial or atrioventricular node function sufficiently to impair cardiac output. Rare individuals without other detectable cardiac disease have hyperactive carotid sinus reflexes and may experience faintness or even syncope as a result of vagal discharge in response to pressure on the neck, eg, from a tight collar. Circulating autoantibodies against the second extracellular loop of cardiac M muscarinic receptors have been detected in some patients with idiopathic dilated2 cardiomyopathy and those afflicted with Chagas’ disease caused by the protozoan Trypanosoma cruzi. Patients with Graves’ disease (hyperthyroidism) also have such autoantibodies that may facilitate the development of atrial fibrillation. In animals immunized with a peptide from the second extracellular loop of the M receptor, the antibody is an allosteric modulator of the receptor. Antimuscarinic agents can provide some relief in the treatment of common traveler’s diarrhea and other mild or self-limited conditions of hypermotility. In this combination, however, the very low dosage of the antimuscarinic drug functions primarily to discourage abuse of the opioid agent.
Reduction in arterial blood pressure by clonidine is accompanied by decreased renal vascular resistance and maintenance of renal blood flow buy propranolol 80 mg otc blood vessels rupture. As with methyldopa order discount propranolol line capillaries per pound of fat, clonidine reduces blood pressure in the supine position and only rarely causes postural hypotension cheapest generic propranolol uk cardiovascular system overall function. Pressor effects of clonidine are not observed after ingestion of therapeutic doses of clonidine prednisolone 40mg with amex, but severe hypertension can complicate a massive overdose levitra super active 40mg for sale. Because of its relatively short half-life and the fact that its antihypertensive effect is directly related to blood concentration, oral clonidine must be given twice a day (or as a patch, below) to maintain smooth blood pressure control. However, as is not the case with methyldopa, the dose-response curve of clonidine is such that increasing doses are more effective (but also more toxic). A transdermal preparation of clonidine that reduces blood pressure for 7 days after a single application is also available. This preparation appears to produce less sedation than clonidine tablets but is often associated with local skin reactions. Both effects are centrally mediated and dose-dependent and coincide temporally with the drug’s antihypertensive effect. Clonidine should not be given to patients who are at risk for mental depression and should be withdrawn if depression occurs during therapy. Concomitant treatment with tricyclic antidepressants may block the antihypertensive effect of clonidine. Withdrawal of clonidine after protracted use, particularly with high dosages (more than 1 mg/d), can result in life- threatening hypertensive crisis mediated by increased sympathetic nervous activity. Patients exhibit nervousness, tachycardia, headache, and sweating after omitting one or two doses of the drug. Because of the risk of severe hypertensive crisis when clonidine is suddenly withdrawn, all patients who take clonidine should be warned of the possibility. If the drug must be stopped, it should be done gradually while other antihypertensive agents are being substituted. Treatment of the hypertensive crisis consists of reinstitution of clonidine therapy or administration of α- and β-adrenoceptor-blocking agents. Most such drugs are no longer available clinically because of intolerable toxicities related to their primary action (see below). Ganglion blockers competitively block nicotinic cholinoceptors on postganglionic neurons in both sympathetic and parasympathetic ganglia. In addition, these drugs may directly block the nicotinic acetylcholine channel, in the same fashion as neuromuscular nicotinic blockers. These effects include both sympathoplegia (excessive orthostatic hypotension and sexual dysfunction) and parasympathoplegia (constipation, urinary retention, precipitation of glaucoma, blurred vision, dry mouth, etc). These severe toxicities are the major reason for the abandonment of ganglion blockers for the therapy of hypertension. The resulting high maximal efficacy of this agent made it the mainstay of outpatient therapy of severe hypertension for many years. For the same reason, guanethidine can produce all of the toxicities expected from “pharmacologic sympathectomy,” including marked postural hypotension, diarrhea, and impaired ejaculation.
Af nity disturbance; and profiles of “classical” neuroleptics (pheno- ¼ Negative signs purchase propranolol in united states online cardiovascular disease x chromosome, such as social isolation effective 40mg propranolol cardiovascular disease factors, thiazine and butyrophenone derivatives) affective flattening generic propranolol 80 mg overnight delivery what blood vessels join arteries to veins, avolition order propranolol 40mg amex, poverty of differ significantlyfromthose of newer atyp- speech proven kamagra soft 100mg, and anhedonia ical drugs (see p. Because they inhibit the thermoreg- Neuroleptics ulatory center, neuroleptics can be employed After neuroleptic treatment of a psychotic for controlled hypothermia (“artificial hiber- episode is initiated, the antipsychotic effect nation”). Chronicuseofneurolepticscanonoccasion Acutely, psychomotor damping with an- give rise to hepatic damage associated with xiolysis and distancing is noted. A very rare, but dramatic, ad- paranoid ideas and hallucinations lose their verse effect is the malignant neuroleptic syn- subjective importance (A, dimming of flashy drome (skeletal muscle rigidity, hyperther- colors); initially, however, the psychotic mia,stupor),whichcanhaveafataloutcome process persists but then wanes gradually in the absence of intensive countermeasures overthecourseofseveralweeks. Even though a “cure” is unrealiz- azine with a piperazine side chain substitu- able, these changes signify success because ent), antagonism at other receptor types (a)thepatientobtainsrelieffromthetorment tends to recede into the background vis-à- of psychotic personality changes; (b) care of vis the blockade of D2 dopamine receptors. Neuroleptic therapy utilizes different while the differences in absolute af nity for drugclasses,namelyphenothiazines,butyro- the other receptors are ignored. The butyrophenones (prototype haloper- The phenothiazines were developed idol) were introduced after the phenothia- from the H1-antihistamine promethazine: zines. With these agents, blockade of D2 re- prototype chlorpromazine and congeners ceptors predominates entirely (p. The “extrapyramidal” motor Phenothiazines exhibit af nity for various disturbances that result from D2 receptor receptors and exert corresponding antago- blockade are, however, preserved and con- nistic actions. Blockade of dopamine recep- stitute the clinically most important adverse tors, specifically in the mesolimbic prefron- reactions that often limit therapy. After treatment of which translates into an antidepressant ef- several weeks to months, a parkinsonian fect. The earlier ther- The butyrophenones carry an increased apy is started, the better is the clinical out- risk of adverse motor reactions because they come. Most schizophrenic patients require lack anticholinergic activity and, hence, are maintenance therapy for which a low dosage prone to upset the balance between striatal can be selected. The pa- pharmacological properties from the afore- tients need good care and, if possible, inte- mentioned drug groups. To circumvent lack Inthecaseofclozapine, it was assumed at of compliance, depot preparations have been first that the drug acted as a selective antag- developed, e. Clozapine can be used whenotherneurolepticshavetobediscon- tinued because of extrapyramidal motor re- actions. Olanzapine is structurally related to cloza- pine; thus far the risk of agranulocytosis appears to be low or absent. Risperidone differs in structure from the aforementioned drugs; it possesses rela- tively lower af nity for all “non–D2-recep- Luellmann, Color Atlas of Pharmacology © 2005 Thieme Therapy of Schizophrenia 235 A.