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Query: UMLS:C0018681 (headache)
 56,091 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Terazosin is a post-synaptic alpha 1-adrenoceptor antagonist with a similar pharmacodynamic profile to prazosin. It differs from prazosin in having a longer duration of action, with an elimination half-life some 2 to 3 times that of prazosin, allowing the convenience of once daily administration. Moreover, its absorption from the gastrointestinal tract is more complete and predictable than that of prazosin which may facilitate dose titration. Terazosin therapy results in a significant reduction in blood pressure in patients with mild to moderate essential hypertension, with little influence on heart rate. The drug is an effective antihypertensive when administered as monotherapy or in combination with a range of antihypertensive agents including beta-blockers, diuretics and combinations of the two. In the few patients with congestive heart failure studied, terazosin produced an increase in cardiac output with a reduction in ventricular filling pressure and systemic vascular resistance, but no studies have been performed to assess the therapeutic potential of terazosin in this indication. Reductions in total plasma cholesterol and low density plus very low density lipoprotein cholesterol fractions have been reported after terazosin therapy, while high density lipoprotein cholesterol concentrations have tended to increase. Should such beneficial changes be confirmed in long term clinical studies they would suggest a therapeutic advantage of terazosin over some other antihypertensive drugs, particularly diuretics, which have been reported to adversely affect the plasma lipid profile. The most common side effects associated with terazosin treatment are dizziness, headache, asthenia and nasal congestion, but these are usually mild and do not require treatment discontinuation. Terazosin is normally administered once daily, starting at a dose of 1 mg/day and gradually titrating upwards as the blood pressure stabilises at each new dose, until blood pressure is adequately controlled or to a maximum dose of 20mg daily. First-dose syncope occurs rarely after terazosin, and can largely be avoided by giving the first dose at bedtime. Thus, terazosin offers a useful alternative to the drugs currently available for the management of mild to moderate essential hypertension either as monotherapy or in combination with other antihypertensive drugs.
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PMID:Terazosin. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in essential hypertension. 288 69

Enalapril maleate is a new angiotensin converting enzyme inhibitor marketed in the U.S. by Merck Sharp and Dohme. It has been demonstrated to actively interfere with the renin-angiotensin-aldosterone system. This is reflected by both hemodynamic (decreased blood pressure) and humoral (increased plasma renin, angiotensin I, and decreased angiotensin II) responses to enalapril therapy. Activity in the kallikrein-bradykinin system is still controversial. Enalapril maleate is a prodrug which is quickly absorbed, hydrolyzed by the liver to the active metabolite enalaprilic acid, and excreted 33 percent in the bile and 61 percent in the urine. The therapeutic dosage range is 10-40 mg/d, maximum of 40 mg, given once or twice daily. The onset and duration of action are dose related. Vertigo and headache have been the most commonly reported side effects. Clinical comparison of enalapril to hydrochlorothiazide, beta-adrenergic blockers, and captopril find it efficacious in the treatment of essential hypertension. Efficacy in treating congestive heart failure and hypertension secondary to renal artery stenosis has also been demonstrated for both angiotensin converting enzyme inhibitors. The overall efficacy and safety of enalapril and captopril appear equivalent when used at low doses in patients with uncomplicated hypertension.
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PMID:Enalapril: a new angiotensin converting enzyme inhibitor. 300 62

A 49 year-old woman was hospitalized with headache and left-sided weakness. Computed tomographic scan and carotid angiogram revealed mycotic aneurysms of the bilateral middle cerebral artery with intracranial bleeding. Although all blood cultures were sterile, her physical examination suspected mitral regurgitation due to infective endocarditis and mycotic cerebral aneurysms. Severe congestive heart failure developed immediately after successful clipping for ruptured mycotic aneurysm of the right middle cerebral artery and then mitral valve replacement with prosthetic valve was performed 3 months after craniotomy. At operation, infective endocarditis on the mitral valve was confirmed. Her postoperative course was uneventful and the second craniotomy for aneurysm of the left middle cerebral artery has been planning.
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PMID:[Valve replacement in infective endocarditis with mycotic cerebral aneurysm. Report of a case with successful operation]. 305 69

Intravenous nitroglycerin is frequently used in the treatment of acute myocardial infarction for its vasodilating effect on lowering both preload and afterload and in the control of ischemic heart pain. The end point for doses of nitroglycerin infusion is either relief of persistent or recurrent angina or controlling congestive heart failure by lowering left ventricular end diastolic pressure and volume. Nitroglycerin accomplishes these end points primarily through its venodilating property. Intolerable headaches or symptomatic hypotension may prevent achieving the clinical end point. Nevertheless, high doses of intravenous nitroglycerin may need to be administered to achieve a desired hemodynamic and therapeutic effect. Changes in mental status, i.e., lethargy and confusion, should be a warning sign of possible ethanol intoxication. An alcohol blood level verifies the clinical impression and gradually withdrawing the intravenous nitroglycerin is all that is necessary to effect a total recovery from this reaction.
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PMID:An unusual complication of intravenous nitroglycerin. 309 6

Nitrate usage worldwide is on the increase as the indications for therapy expand. Present indications for nitrate therapy include chronic stable angina pectoris, unstable angina pectoris, complications of acute myocardial infarction, and 'unloading' therapy for acute and chronic congestive heart failure. Nitrates are also being used in the operating suite by anaesthesiologists to control systolic blood pressure during various surgical procedures. New nitrate delivery systems have recently become available which provide considerable dosing flexibility, further increasing the interest in this group of compounds. The dominant action of nitrates is a direct effect on vascular smooth muscle, producing vasodilation of the veins and arteries. These drugs decrease myocardial work by lowering systolic blood pressure, systemic vascular resistance, and reducing intracardiac dimensions. In addition, nitrates have a potent effect on cardiac preload as a result of systemic venodilatation. There is also some evidence that nitrates exert direct effects on the coronary circulation (vasodilatation of coronary arteries and coronary collateral vessels, and direct atherosclerotic stenosis dilatation). These actions may play a role in relieving myocardial ischaemia. Adverse sequelae of nitrate therapy are well known and serious adverse reactions are uncommon. Headache and dizziness are the most frequent side effects. Nitrate tolerance is a definite problem - present evidence indicates that long acting formulations, high doses, or frequent dosing regimens are particularly likely to induce vascular tolerance to nitrates. Consequently, provision of a nitrate-free interval has taken on increasing significance as a strategy to avoid tolerance. Nitrate delivery systems are numerous. Although availability varies from country to country, in most countries there are a wide variety of formulations of glyceryl trinitrate (nitroglycerin) available, including sublingual and oral tablets, oral spray, topical ointment as well as discs or patches for transdermal administration, a transmucosal tablet and an intravenous formulation. Similar formulations of isosorbide dinitrate, except buccal tablets, are available in some countries. Isosorbide 5-mononitrate, a potent metabolite of isosorbide dinitrate, is achieving increasing popularity as an antianginal drug. Optimum nitrate therapy requires a good understanding of the properties of the various formulations, particularly onset and duration of action and propensity to induce tolerance.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Glyceryl trinitrate (nitroglycerin) and the organic nitrates. Choosing the method of administration. 311 8

The safety issues relevant to treatment with encainide in patients with supraventricular arrhythmia were reviewed based on 349 patients enrolled in clinical trials in the United States and Europe. Although 20% of patients had a history of congestive heart failure, cardiomegaly, or cardiomyopathy at entry, there was no case of new or worsened heart failure. There were 5 cases (1.4%) of proarrhythmia in adults, reflecting a worsening of the arrhythmia being treated or of a coexisting ventricular arrhythmia. The profile of drug-related adverse effects was comparable to that previously reported, causing discontinuance in 6% of patients. The effects most often seen were dizziness, visual disturbance, headache, nausea and vertigo. Only 1 patient had clinically significant abnormal laboratory values, possibly reflecting hepatocellular injury in conjunction with viral hepatitis. Most responders received a daily dose of 75 to 200 mg/day, generally given in 3 divided doses. Encainide has a very favorable safety profile for use in the treatment of supraventricular arrhythmias.
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PMID:Safety considerations and dosing guidelines for encainide in supraventricular arrhythmias. 314 70

The major antihypertensive mechanism of calcium antagonists is by decreasing the systemic vascular resistance, modified by the counter-regulatory responses of the baroreflexes and the renin-angiotensin-aldosterone system. In severe hypertension, the concept that calcium overload of the vascular myocyte could precipitate or aggravate peripheral vasoconstriction provides a logical basis for the use of these agents as first choice therapy; nifedipine, especially, has been well tested. As monotherapy for mild to moderate hypertension each of the three first-generation agents compares well with beta-blockers. Calcium antagonists may have a special role in the therapy of certain patient groups (elderly, black) or in those subjects whose life style involves intense physical or mental exertion (hemodynamics better maintained than with beta-blockade) or in patients with early end-organ damage such as left ventricular hypertrophy or renal insufficiency. However, the goal blood pressure may not be reached during monotherapy so that drug combinations may be required. Further indications for these compounds are as follows. Verapamil and diltiazem are frequently used in supraventricular tachycardias including acute and chronic atrial fibrillation. In the arrhythmias of the Wolff-Parkinson-White syndrome, there is the potential danger of provocation of anterograde conduction. Further indications for calcium antagonists, still under evaluation, include congestive heart failure (controversial), hypertrophic cardiomyopathy (verapamil), primary pulmonary hypertension (high doses required), Raynaud's phenomenon (nifedipine and diltiazem effective), peripheral vascular disease (proof not yet documented), cerebral insufficiency and subarachnoid hemorrhage (nimodipine promising), migraine, exertional bronchospasm, renal disease, atherosclerosis (experimental), and primary aldosteronism (nifedipine inhibits aldosterone release). Second-generation agents include dihydropyridines, such as nitrendipine, nicardipine, felodipine, amlodipine, nisoldipine, nimodipine, and isradipine. From these will be selected agents that are longer acting and provide higher vascular selectivity. New preparations of existing agents include slow-release formulations of nifedipine, verapamil, and diltiazem. Minor side effects include those caused by vasodilation (flushing and headaches), constipation (verapamil), and ankle edema. Serious side effects are rare and result from improper use of these agents, as when intravenous verapamil is given to patients with sinus or atrioventricular nodal depression from drugs or disease, or nifedipine to patients with aortic stenosis. The potential of a marked negative inotropic effect is usually offset by afterload reduction, especially in the case of nifedipine. Yet caution is required when calcium antagonists, especially verapamil, are given to patients with myocardial failure unless caused by hypertensive heart disease. Drug interactions of calcium antagonists occur with other cardiovascular agents such as alpha-adrenergic blockers, beta-adrenergic blockers, digoxin, quinidine, and disopyramide.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Calcium channel antagonists. Part III: Use and comparative efficacy in hypertension and supraventricular arrhythmias. Minor indications. 315 29

Nicardipine is an antagonist of calcium influx through the slow channel of the cell membrane and has been shown to be an effective and relatively well-tolerated treatment for stable effort angina and rest angina due to coronary artery spasm, and mild to moderate hypertension. Although its exact mechanism of action in these disease states has not been precisely defined, the potent coronary and peripheral arterial dilator properties of nicardipine, with concomitant improvements in oxygen supply/demand and reductions in systemic vascular resistance, are of major importance. Clinical studies have shown that nicardipine appears to be effective in the treatment of chronic stable exercise-induced angina pectoris and possibly in angina at rest due to coronary artery spasm. In the treatment of stable angina, nicardipine has proved to be equally as effective as nifedipine. However, haemodynamic and clinical studies indicate that nicardipine may have a further advantage of not depressing cardiac conduction or left ventricular function, even in patients with compromised cardiac pumping ability. Nicardipine also appears to be useful as initial monotherapy or in combination with other antihypertensive drugs when used in the treatment of mild to moderate hypertension, and may have some advantages over other vasodilators in this regard in that it may not be as frequently associated with fluid retention or weight gain as other similar drugs. In the treatment of hypertension nicardipine has been shown to be as effective as drugs such as hydrochlorothiazide, cyclopenthiazide, propranolol and verapamil in short term studies although confirmation of its long term usefulness in well-designed clinical trials is still required. Similarly, although the use of nicardipine in other disorders such as congestive heart failure and cerebrovascular disease has provided encouraging preliminary results, more studies are needed to clarify its place in their treatment. Side effects appear to be dose related and more frequent within the first few weeks of therapy. Most of these effects are minor and transient in nature and include headache, flushing and peripheral oedema. Thus, there is no doubt that nicardipine provides a suitable alternative to other drugs available for the treatment of angina and hypertension. However, further well-designed comparative clinical trials are needed to clarify its relative place in the long term management of these disorders.
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PMID:Nicardipine. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy, in the treatment of angina pectoris, hypertension and related cardiovascular disorders. 329 16

The administration of digitalis glycosides causes a variety of extracardiac effects. In both normal human subjects and in other species, digitalis increases smooth muscle tone of resistance and capacitance vessels. The vasoconstriction is mediated, in part, by a direct action of these glycosides on smooth muscle and, in part, by an increase in alpha-adrenergic tone. Constriction of coronary and splanchnic vessels may lead to myocardial or mesenteric ischemia. In contrast to normal subjects, patients with congestive heart failure demonstrate arteriolar and venodilation in response to these glycosides, possibly because the myocardial effect, to increase cardiac output and peripheral blood flow, overcomes the vasoconstrictor properties of these drugs. Other important actions of digitalis glycosides occur in the central and peripheral nervous systems. Their effects on the area postrema of the medulla oblongata are largely responsible for the alpha-adrenergic-mediated peripheral vasoconstriction, as well as the nausea and vomiting that frequently accompany digitalis intoxication. Actions of glycosides on the cerebral cortex are responsible for the wide range of neurotoxic effects that range from visual disturbances and headaches to seizures and coma. Finally, peripheral neurologic effects of digitalis glycosides on baroreceptor and cardiac afferent fibers may: improve the depressed function of these receptors in the situation of heart failure, and reflexly lower peripheral vascular resistance, thereby partially preventing the vascular constrictor action of these glycosides.
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PMID:Extracardiac and coronary vascular effects of digitalis. 388 56

Nitrates are vasodilators of venous and arterial smooth muscle commonly prescribed both for angina and congestive heart failure. Primarily venodilators, nitrates also affect the systemic circulation if administered in sufficient dosage. In the coronary circulation, the principal effect is on the large epicardial and collateral vessels. Blood is shunted toward the ischemic subendocardium. In the majority of patients with angina, relief of symptoms by nitrates is primarily due to hemodynamic effects on preload and afterload, unless the patient has coronary spasm. In patients with congestive heart failure, nitrates decrease the resistance to the emptying of blood from the left ventricle as well as the filling pressure. Nitrates are relatively well tolerated, except for an initial throbbing headache which rapidly resolves as tolerance develops. Nitrates are available in a multitude of forms including sublingual, oral, topical, transmucosal, intravenous, and spray preparations. Oral preparations undergo a first-pass effect in the liver, requiring larger doses. Other forms avoid this problem by direct transdermal absorption or the intravenous route. The latter has the advantage of rapid administration and ease of titration. The choice of nitrate depends upon the clinical situation.
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PMID:Nitrate therapy in angina and congestive heart failure. 390 32


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