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

Sildenafil, a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5), is a well-tolerated and highly effective treatment for erectile dysfunction. The mechanism of action of sildenafil depends on activation of the nitric oxide (NO)-cGMP pathway during sexual stimulation, which results in corpus cavernosal smooth muscle relaxation and penile erection. Endogenously derived NO is also involved in blood pressure regulation through its effect on basal vascular tone, which is mediated by cGMP levels. Organic nitrates and NO donors exert their therapeutic effects on blood pressure and vascular smooth muscle by the same mechanism as endogenous NO. Since both sildenafil and organic nitrates exert their pharmacologic effects via increases in cGMP concentrations, a double-blind, placebo-controlled, crossover study was undertaken to investigate the effects of sildenafil coadministered with glyceryl trinitrate on blood pressure and heart rate in healthy male subjects. The hemodynamic effects of sildenafil were also evaluated in a second placebo-controlled crossover study in men with hypertension who were taking the calcium antagonist amlodipine, which has a mechanism of action that does not involve the cGMP pathway. In the first crossover study, subjects were treated with oral sildenafil (25 mg, 3 times a day for 4 days) or placebo and then challenged on day 4 with a 40-minute, stepwise, intravenous infusion of glyceryl trinitrate (0.5 mg/mL in 5% dextrose at an initial infusion rate of 2.5 microg/min and doubling every 5 minutes to a maximum rate of 40 microg/min) 1 hour after taking sildenafil or placebo. On day 5, subjects received a sublingual glyceryl trinitrate tablet (500 microg) 1 hour after taking 25 mg of sildenafil or placebo. During sildenafil treatment, the subjects were significantly less tolerant of intravenously administered glyceryl trinitrate than during placebo treatment, based on the occurrence of a >25 mm Hg decrease in blood pressure or the incidence of symptomatic hypotension (p <0.01). When a sublingual glyceryl trinitrate tablet was administered on day 5, a 4-fold greater decrease in systolic blood pressure was observed for the subjects during the sildenafil treatment period than during the placebo treatment period. The changes in heart rate were negligible during both glyceryl trinitrate challenges. In conclusion, sildenafil potentiated the hypotensive effects of glyceryl trinitrate, an organic nitrate. Thus, sildenafil administration to patients who are using organic nitrates, either regularly and/or intermittently, in any form is contraindicated. In the second crossover study, men with hypertension, who were taking 5 or 10 mg/day of amlodipine, received a single oral dose of 100 mg sildenafil or placebo. Coadministration of sildenafil did not significantly affect the pharmacokinetics of amlodipine. In the 4 hours after dosing, differences in the mean maximum change from baseline in supine systolic and diastolic blood pressures between the sildenafil plus amlodipine and the placebo plus amlodipine treatment periods were -8 mm Hg and -7 mm Hg, respectively (p < or =0.002). The mean maximum supine heart rate increased 2.1 beats/min during sildenafil plus amlodipine treatment and decreased 1.5 beats/min during placebo plus amlodipine treatment (p <0.02). The adverse events in this study were predominantly mild or moderate and did not cause discontinuation of treatment. Adverse events considered to be related to sildenafil treatment included headache, nausea, and dyspepsia. In patients with hypertension who were taking amlodipine therapy, sildenafil produced additive, but not synergistic, reductions in blood pressure. The difference in the mean maximum change from baseline in blood pressure between sildenafil plus amlodipine and placebo plus amlodipine was comparable to the decrease in blood pressure reported for healthy men taking sildenafil alone. (ABSTRACT TRUNCATED)
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PMID:Sildenafil citrate and blood-pressure-lowering drugs: results of drug interaction studies with an organic nitrate and a calcium antagonist. 1007 39

Arterial hypertension is associated with structural and functional alterations of the vessel walls. Because vascular endothelium plays a central role in the control of vascular tone, endothelial dysfunction can also cause certain types of erectile dysfunction. Erectile dysfunction is also a common side effect of certain drugs, including many antihypertensive agents. Physicians should be aware of potential sexual side effects of such drugs and take appropriate steps to alleviate persistent problems. Most important, physicians need to ask patients about sexual function and discuss the possibility of erectile dysfunction caused by antihypertensive therapy. Erectile dysfunction can be effectively treated in most patients, and many treatment options are available. Sildenafil therapy has revolutionized the management of this disorder, but this agent should be used with caution in certain patients taking nitrates.
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PMID:What is causing your patient's sexual dysfunction? Uncovering a connection with hypertension and antihypertensive therapy. 1045 46

There has been considerable media attention surrounding the commercialisation of Sildenafil. The advice of cardiologists is often solicited before its prescription because of its potential side effects; the cardiovascular stress due to sexual activity is generally modest, both in normal subjects and coronary patients with, however, important individual variations, the "legitimate" nature of the intercourse seeming to be one of the principal factors. Recent coronary events, poorly controlled hypertension and uncompensated cardiac failure are the main contra-indications; the prescription should be based on the results of maximal exercise stress testing in patients at risk.
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PMID:[The heart and sexual activity]. 1056 3

Sildenafil is the first of a series of orally active treatments for MED which has resulted in unprecedented demand for treatment and potentially high cost to the NHS. Further oral therapies are likely to follow in the next year or so. In clinical trials, sildenafil produced an erection (sufficient to achieve intercourse) lasting up to 4 h on around 70% of occasions. This was reduced to 50% in 'high-risk' groups (e.g. diabetics) and a placebo response in as many as 10-20% has been reported. Whether or not sildenafil should be prescribed at NHS expense has been more a matter for political, than clinical, debate. A clearer picture is now emerging with treatment available to those considered the 'most deserving' cases. The bigger picture is of impotence in large numbers of men with hypertension who are on antihypertensive therapy and have obvious small vessel disease. One option is to consign sildenafil to Schedule 10 (Black List) so that it is only available on private prescription. This would allay fears of the cost of treatment for those merely seeking to 'boost' already adequate sexual performance.
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PMID:Sildenafil citrate (Viagra). 1059 58

Sildenafil citrate is the first oral agent approved for the treatment of erectile dysfunction (ED); other oral agents are in the process of development. Because the mechanism of action of many of these agents involves vasodilation, there is a potential for interaction with the cardiovascular system. Sildenafil inhibits phosphodiesterase-5 (PDE-5) which is found in the corpus cavernosum and in the systemic vasculature. Sildenafil causes a mild decrease in systemic arterial pressure ( approximately -8/-5.5 mm Hg); it causes a synergistic and often major decrease in systemic arterial pressure in the presence of organic nitrates (nitric oxide donors). Sildenafil is therefore contraindicated in patients taking organic nitrates. A review was made of clinical trials in populations of men with (1) erectile dysfunction; (2) chronic stable ischemic heart disease and erectile dysfunction; and (3) hypertension and erectile dysfunction. This review showed that sildenafil was effective and not associated with an increase in serious cardiovascular adverse events, myocardial infarction (MI), or death compared with placebo. Although there have been spontaneous reports of death among men using sildenafil, there are limitations to spontaneous-event reporting. In addition. the numbers of such reports are well below the expected numbers of deaths when considering the number of men who have received prescriptions for sildenafil and their age and cardiovascular risk factor profile. Because there is a small but finite risk of having a cardiac event with sexual activity, physicians should discuss with their cardiac patients the risks of sexual activity before prescribing any treatment for ED. In addition, they should evaluate their patients' cardiac status when considering the safety of administering any ED treatment that may have systemic vasodilatory properties and can potentially lower blood pressure. In some cases, exercise treadmill testing may be warranted to determine whether ED patients with coronary artery disease can achieve the physiologic workload (4-6 metabolic equivalents) associated with sexual intercourse.
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PMID:Cardiovascular risk and sildenafil. 1089 81

Oral sildenafil is an effective treatment for erectile dysfunction (ED), which is a common complaint for patients with hypertension and those taking antihypertensive agents. This post hoc subanalysis assessed the efficacy and safety of sildenafil in men with ED who were receiving concomitant antihypertensive medication. Efficacy was assessed in 3414 men (1218 of whom were taking antihypertensive medication) who received sildenafil (5 to 200 mg) or placebo for 6 weeks to 6 months in 10 double-blind, placebo-controlled studies. The significant improvements in erectile function demonstrated by sildenafil-treated patients were comparable in patients taking and those not taking antihypertensive medication. Safety was assessed in 3975 men (1094 of whom were taking one or more antihypertensive agent, classified as a diuretic, beta-blocker, alpha1-blocker, angiotensin converting enzyme inhibitor, or calcium channel blocker), who received sildenafil or placebo in 18 double-blind, placebo-controlled studies. For patients taking sildenafil and antihypertensive medication, the incidence of treatment-related adverse events (34%) was similar to that for sildenafil-treated patients not taking any antihypertensive agent (38%). The incidences of the most common adverse events and of adverse events potentially related to blood pressure decreases (eg, hypotension, dizziness, and syncope) were similar in both sildenafil groups. The number of antihypertensive medications taken from among the five classes had no effect on the adverse event profile of sildenafil. Sildenafil is an effective and well-tolerated treatment for ED in patients taking concomitant antihypertensive medication, including those on multidrug regimens.
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PMID:Effect of sildenafil in patients with erectile dysfunction taking antihypertensive therapy. Sildenafil Study Group. 1120 84

Hypertension is one of several risk factors for erectile dysfunction. Others include the cardiovascular risk factors of low levels of high density lipoprotein, high total cholesterol, smoking, and diabetes. Certain antihypertensive drugs, especially the thiazide diuretics, can contribute to erectile dysfunction. Sildenafil is the first oral agent available for the treatment of erectile dysfunction. It works in patients with psychogenic as well as organic erectile dysfunction, including men with hypertension and men on antihypertensive medicines. Sildenafil alone causes small drops in systolic and diastolic blood pressure. When administered to patients on antihypertensive drugs it was again associated with small drops in arterial pressure and no increase in adverse events compared to patients not taking antihypertensive drugs. When sildenafil is given in the setting of organic nitrates (nitric oxide donors), large falls in blood pressure may occur. Sildenafil is absolutely contraindicated in the setting of organic nitrate use. (c)2000 by Le Jacq Communications, Inc.
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PMID:Hypertension as a Risk for Erectile Dysfunction: Implications for Sildenafil Use. 1141 23

Hypertension is an important risk factor for erectile dysfunction (ED). Consequently, there is a high coincidence between hypertension and ED. Oral sildenafil (Viagra) is an effective treatment for ED in patients with treated or untreated hypertension. The most common adverse events of sildenafil (headache, flushing, hypotension) result from its moderate vasodilating properties. The concomitant use of sildenafil and organic nitrates is contraindicated because it may lead to a potentiation of the decreases in blood pressure and thus cause life-threatening hypotension. In contrast, the concomitant use of sildenafil and different classes of antihypertensive agents (beta-blockers, alpha-blockers, diuretics, ACE inhibitors, calcium antagonists) may lead to additive but not to potentiating blood pressure decreases. Thus, this combination is unlikely to cause clinically significant hypotension or an increased incidence of adverse events. Sildenafil is an effective and well-tolerated treatment for ED in patients taking concomitant antihypertensive medication, including those on multidrug regimens.
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PMID:[Interaction between sildenafil and antihypertensive drugs: what is evidence-based?]. 1159 59

Erectile dysfunction (ED) represents an important quality-of-life issue for many ageing men. Low serum testosterone level and other factors may be involved. Sildenafil is effective and well tolerated in patients with ED of various aetiologies, showing an efficacy of about 75%. However, few efficacy and adverse effect studies have focused specially on ageing men. In 150 patients below 65 years and 44 patients over 65 years, sildenafil was used to treat ED. Efficacy in the younger group (89.1%) was greater than in the older group (65.7%; p < 0.01). Mean serum luteinizing hormone (LH) and follicle-stimulating hormone concentrations (11.0 and 18.9 mIU/mL, respectively) in the older group were higher than in younger group (5.2 and 8.7 mIU/mL, respectively; p < 0.01). Serum testosterone and prolactin (PRL) were similar between groups. Older patients showed higher prevalence of diabetes mellitus, hypertension, and benign prostatic hyperplasia. Only diabetes appeared to decrease efficacy of sildenafil in older patients (p=0.019). A high prevalence of diabetes might be one of the many causes of lower efficacy rate of sildenafil in older men, although efficacy in patients even without diabetes in older men was relatively low. Sildenafil can be used safely and it is still effective for ageing male, because nearly two-thirds of our older subjects had a good response to the drug and no adverse effect was specific to older patients.
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PMID:The clinical studies of sildenafil for the ageing male. 1186 74

Sildenafil inhibits cGMP breakdown by phosphodiesterase 5. In vitro, increased cGMP levels inhibit cAMP breakdown by phosphodiesterase 3. It is uncertain, however, whether sildenafil increases biological effects of interventions increasing cAMP levels in vivo. The objective of the present study in 40 healthy male volunteers was to determine the existence and extent of interactions with sildenafil and vasodilators acting via cGMP or cAMP or independently from these mediators on the arterial tone of the human forearm. Forearm blood flow (FBF) responses (plethysmography) to brachial artery infusions of 3 doses each of nitroglycerin, which increases cGMP levels; of isoprenaline and milrinone, which increase cAMP levels; and of verapamil as a control were assessed at baseline and 80 minutes after 50 mg oral sildenafil in 10 volunteers each. Sildenafil increased FBF (2.5+/-0.1 to 3.5+/-0.2 mL/min per 100 mL, P<0.001; n=40). At equipotent vasodilator dosages, sildenafil increased FBF from 7.5+/-1.0 to 9.8+/-1.2 mL/min per 100 mL for nitroglycerin, from 8.3+/-1.0 to 10.4+/-1.4 mL/min per 100 mL for isoprenaline, and from 8.1+/-1.0 to 10.3+/-1.2 mL/min per 100 mL for milrinone and slightly decreased FBF from 7.7+/-1.3 to 7.1+/-1.2 mL/min per 100 mL for verapamil. ANOVA for repeated measures revealed a significant interaction between sildenafil and the type of vasodilator on FBF (P<0.01). The responses of FBF to nitroglycerin, milrinone, and isoprenaline after sildenafil were similarly increased compared with the response to verapamil (P<0.01). Sildenafil markedly enhanced the arterial vasodilator response to nitroglycerin, milrinone, and isoprenaline. The response to milrinone and isoprenaline is compatible with an interaction between cGMP and phosphodiesterase 3 or an enhancement of the NO component of cAMP-mediated vasodilation, and raises the possibility of enhanced biological effects of interventions leading to increases of cAMP in the presence of sildenafil.
Hypertension 2002 Nov
PMID:Interaction of sildenafil with cAMP-mediated vasodilation in vivo. 1262 68


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