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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Prazosin or doxazosin, selective alpha 1-adrenergic receptor inhibitors used in the treatment of hypertension, are known from clinical studies to lower plasma lipids. When diets and dosing regimens are carefully controlled, both agents produce similar effects on plasma lipids in rats, i.e., decreases in triglycerides and in the non-high density lipoprotein (non-HDL) fraction of cholesterol. In order to conduct these studies, models of rats partially fasting (PF) and eating a high-sucrose diet were developed. The effects of prazosin 2.3 mg/kg/day and doxazosin 20 mg/kg/day on plasma levels of triglycerides, total and HDL cholesterol, free fatty acids (FFA), ketones, and other metabolites were measured in rats in the fed, fasting, or PF states, at various times after a meal, and with a high-cholesterol diet. The pattern of responses leads to the hypothesis that, under conditions of partial or complete fasting, alpha 1-adrenergic receptor inhibition can alter intrahepatic FFA metabolism, causing increased ketogenesis and diminished triglyceride synthesis, possibly through potentiation of beta-adrenergic or related pathways. If these concepts prove to be valid in humans, they suggest that factors such as the rate of very-low-density lipoprotein (VLDL) production or the state of sympathetic nervous activity may influence the changes in lipids induced by these agents.
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PMID:Effects of alpha 1-inhibition on lipid metabolism in the rat. 244 38

Central and peripheral alpha-adrenoceptors play an important role in cardiovascular regulation, and selective alpha 1-adrenoceptor antagonists and alpha 2-adrenoceptor agonists have an established place in the therapy of hypertension. Prazosin is a selective alpha 1-antagonist that is both effective in lowering blood pressure and well tolerated. However, the more recently developed alpha 1-antagonists doxazosin and terazosin offer the advantage of having longer half-lives, allowing once daily administration. Clonidine is a centrally acting alpha 2-agonist whose clinical use has often been limited by the dose dependent side effects of dry mouth and sedation, and the belief that it should be given three times per day. However, recent studies have shown that it has substantial antihypertensive efficacy with minimal side effects at low doses, and that half-life is long enough to allow twice daily administration. An improved understanding of the pharmacodynamics and pharmacokinetics of drugs acting on alpha-adrenoceptors allows a more rational approach to their clinical application.
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PMID:Comparison of pharmacokinetics and pharmacodynamics of adrenoceptor agonists and antagonists as antihypertensive agents. 245 58

The present experiment was performed in order to evaluate some of the actions of ketanserin, a blocking agent active at the serotonin 2 (S2) receptors. Male rats were divided into: 1. Two kidney-two clip (2K-2C) renal hypertensive: a silver clip (0.25 mm width) was placed in both renal arteries. 2. Sham-operated: a similar operation without placing the clip was performed. Blood pressure (BP), heart rate and pressor responses to tyramine, angiotensin II and norepinephrine (NE), and the hypotensive effect of prazosin (Pz) and ketanserin (Kt) were recorded in the conscious animals 8 weeks later. Results showed that Pz produced a similar decrease in BP in hypertensive and sham animals while Kt lowered BP much more in hypertensive than in normotensive rats. Prazosin abolished the pressor response to tyramine while ketanserin only diminished tyramine effect. Both hypotensive agents shifted the dose-response curve to NE to the right. Present data have shown that ketanserin and prazosin are effective hypotensive agents in 2K - 2C renovascular hypertension in the rat. They also suggest that both hypotensive compounds have an alpha 1-blocking effect, somehow they seem to have some differences in their pattern of pharmacological action.
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PMID:Effect of ketanserin and prazosin on blood pressure and cardiovascular reactivity to vasopressor agents during the development of two kidney-two clip renal hypertension in the conscious rat. 247 91

The specific competitive alpha 1-postsynaptic blocking action and haemodynamic effects of prazosin (Minipress) have been summarized. Prazosin causes dilatation of arterioles and veins, reduces total peripheral resistance as well as preload and afterload. Cardiac output does not change at rest, stroke volume and subsequent cardiac output increase during exercise. The changes in heart rate have non-significant. It does not cause sympathetic counter-regulation, plasma renin activity does not increase, aldosterone level decreases, salt- and fluid retention may rarely be observed. It does not provoke angina. The authors report on the results of their examinations with the first dose of prazosin in 61 patients (in 33 cases by the double-blind cross-over method by placebo control), and summarize the observations made with the drug in long-term treatment in Hungary. The authors and other teams used prazosin as a long-term treatment (of approximately 3 months) in combination with other drugs in a total of 344 patients, and as monotherapy in 159 patients. In the course of combination treatment side-effects were observed in 15% of the patients (dizziness, headache, weakness, occasionally palpitation). During monotherapy, side-effects occurred in 12% of the patients (tachycardia, headache, weakness, dizziness). Hungarian results confirm the usefulness of prazosin in all stages of hypertension. It is effective in 30-35% of the cases as a monotherapy (this rate is congruent with the efficacy of beta-blockers, calcium antagonists and antihypertensive drugs of central action). Earlier prazosin had been used as a third agent in combination treatment of hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The mechanism of the action of Minipress. Examinations in hypertension. 257 64

Competitive alpha1-adrenoceptor antagonists are effective in the treatment of both hypertension and cardiac failure. Prazosin has both a short half-life and a short duration of action, but other related quinazoline derivatives, such as doxazosin and terazosin, have pharmacokinetic and pharmacodynamic profiles which make them potentially suitable for once-daily administration. Acute reductions in blood pressure have been correlated with plasma concentrations of prazosin but in most instances, particularly during long term therapy, there is no simple, direct relationship between drug concentration and the fall in blood pressure. Using integrated pharmacokinetic-pharmacodynamic analysis, correlations have been described not only for reductions in blood pressure during short and long term treatment but also for alpha1-adrenoceptor antagonist activity. Furthermore, this integrated approach defines the drug concentration-effect relationship in individual subjects and provides a mathematical description of response that is potentially useful for investigating the factors (both kinetic and dynamic) which influence the inter- and intrasubject variability in antihypertensive effect of alpha-adrenergic blockers. Preliminary data suggest that the long term response to treatment with prazosin and doxazosin is mainly dependent upon the height of the pretreatment blood pressure and the response to the first dose.
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PMID:Pharmacokinetic-pharmacodynamic relationships of alpha-adrenoceptor antagonists. 257 89

Alpha adrenergic receptor-blocking drugs lower the blood pressure but until prazosin, a post synaptic alpha 1 receptor-blocking drug was introduced, they had limited clinical application. Prazosin, terazosin and doxazosin are all effective as single therapy or in combination with other anti-hypertensive drugs. As vasodilators they combine particularly well with beta adrenergic-blocking drugs. The only serious side effect, namely first dose postural hypotension, can be avoided by starting with a small dose and avoiding concomitant salt depletion. The disappointing results of trials in mild hypertension, in terms of prevention of coronary artery disease and its complications, have been attributed in part to the fact that several of the drugs used in these studies have an adverse effect on atherogenic lipids. alpha 1 adrenergic-blocking drugs have a beneficial effect on the lipid profile. Anti-hypertensive therapy usually needs to be continued on a long term, often permanent, basis. For this reason, drugs which have a beneficial effect on atherogenic lipids are preferable as initial therapy and, where possible, single therapy in the treatment of mild hypertension.
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PMID:Alpha 1-blockers, their antihypertensive efficacy and effects on lipids and lipoprotein. 257 78

Xylazole (Xyl) is an analogue of xylazine (Xyn) synthesized by Lanzhou Institute of Chinese Traditional Veterinary Medicine. The effects of Xyl on heart rate and blood pressure were studied in 5 conscious dogs. Xyl 1 mg/kg iv was similar to Xyn in producing bradycardia and an initial transient hypertension followed by a lasting hypotension which was less significant than Xyn. Yohimbine (0.1 and 0.3 mg/kg), an alpha 2-adrenoreceptor blocking agent, antagonized bradycardia and hypotension induced by Xyl. Tolazoline (3.3 mg/kg), a nonselective alpha-adrenoreceptor blocking agent, reversed the bradycardia and hypotensive effect. Prazosin (1 mg/kg), an alpha 1-adrenoreceptor blocking agent, did not change Xyl-induced bradycardia and hypotension. Atropine (20 micrograms/kg) not only antagonized Xyl-induced bradycardia but also changed from bradycardia to tachycardia, and greatly potentiated Xyl-induced hypertension for more than 30 min. The results suggested that Xyl-induced cardiovascular effects are similar to Xyn that mediated by alpha 2-adrenoreceptor.
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PMID:[Effects of xylazole on heart rate and blood pressure in conscious dogs]. 257 38

The system release of prazosin confirms the good efficacy and tolerance of Alpress in the hypertension treatment. Prazosin has favorable effects on some risk factors, and it therefore seem interesting to conduct a study in a pannel of hypertensive patients, to emphasize the quality of Alpress response, based on these criteria. This experiment demonstrated the efficacy and tolerance levels of Alpress as well as its favorable effect on cholesterol.
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PMID:[Efficacy, tolerance and incidence of risk factors of Alpress in the treatment of arterial hypertension]. 262 5

This study evaluated the effect of prazosin in controlled mild hypertension and evaluated select metabolic changes that occurred with prazosin monotherapy. Various aspects of glucose, insulin, and lipid metabolism were studied before and after approximately 10 weeks of prazosin treatment in 12 patients with mild hypertension. Prazosin was well tolerated and induced a significant decrease (p less than 0.001) in both systolic and diastolic blood pressures, without any change in body weight. Plasma concentrations of glucose, free fatty acid, and lactate, which were measured hourly from 8 A.M. to 4 P.M. following meals consumed at 8 A.M. and noon, did not change with prazosin treatment. However, the plasma insulin response from 8 A.M. to 4 P.M. decreased significantly (p less than 0.001) following prazosin treatment. In addition, fasting plasma triglyceride and cholesterol concentrations were significantly lower (p less than 0.05) in prazosin-treated persons, as were postprandial triglyceride concentrations (p less than 0.001). Lower total plasma triglyceride and cholesterol concentrations were accounted for by decreases in very low-density lipoprotein cholesterol and triglyceride and low-density lipoprotein cholesterol and triglyceride, whereas both high-density lipoprotein triglyceride and high-density lipoprotein cholesterol concentrations increased following prazosin treatment. Finally, although both apolipoprotein A1 and apolipoprotein B concentrations decreased in association with prazosin treatment, the decrease in apolipoprotein B was much greater in magnitude, leading to an increase in the ratio of apolipoprotein A1 to apolipoprotein B. In this study, treatment of mild hypertension with prazosin led to lower blood pressures and changes in insulin and lipoprotein metabolism that are important in this patient population.
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PMID:Effect of prazosin treatment on carbohydrate and lipoprotein metabolism in patients with hypertension. 264 61

The efficacy and safety of prazosin GITS (gastro-intestinal therapeutic system), a new extended-release once-a-day formulation, were assessed both as monotherapy in mild essential hypertension and in combination with a diuretic in moderate essential hypertension in two multicenter, double-blind, placebo-controlled trials. Prazosin GITS (Minipress XL) given once daily in doses of either 10 or 20 mg significantly reduced sitting and standing systolic and diastolic blood pressure compared with placebo in both mild and moderate essential hypertension. There were minimal, clinically insignificant changes in heart rate following prazosin-GITS treatment (2.5, 10, and 20 mg) compared with placebo treatment. Prazosin GITS was well tolerated; the most common adverse experiences reported were headache, dizziness, and fatigue. All adverse experiences in the moderate hypertension group and the majority (91 percent) in the mild hypertension group were mild-to-moderate in severity. The results from these multicenter trials demonstrate the efficacy and safety of this new extended-release once-a-day formulation of prazosin in the treatment of patients with mild and moderate essential hypertension.
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PMID:Efficacy and safety of Minipress XL, a new once-a-day formulation of prazosin. 266 73


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