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Angiotensin II receptor blockers (ARBs) represent a new class of effective and well tolerated orally active antihypertensive agents. Recent clinical trials have shown the added benefits of ARBs in hypertensive patients (reduction in left ventricular hypertrophy, improvement in diastolic function, decrease in ventricular arrhythmias, reduction in microalbuminuria, and improvement in renal function), and cardioprotective effect in patients with heart failure. Several large long-term studies are in progress to assess the beneficial effects of ARBs on cardiac hypertrophy, renal function, and cardiovascular and cerebrovascular morbidity and mortality in hypertensive patients with or without diabetes mellitus, and the value of these drugs in patients with heart disease and diabetic nephropathy. The ARBs specifically block the interaction of angiotensin II at the AT1 receptor, thereby relaxing smooth muscle, increasing salt and water excretion, reducing plasma volume, and decreasing cellular hypertrophy. These agents exert their blood pressure-lowering effect mainly by reducing peripheral vascular resistance usually without a rise in heart rate. Most of the commercially available ARBs control blood pressure for 24 h after once daily dosing. Sustained efficacy of blood pressure control, without any evidence of tachyphylaxis, has been demonstrated after long-term administration (3 years) of some of the ARBs. The efficacy of ARBs is similar to that of thiazide diuretics, beta-blockers, angiotensin-converting enzyme inhibitors or calcium channel blockers in patients with similar degree of hypertension. Higher daily doses, dietary salt restriction, and concomitant diuretic or ACE inhibitor administration amplify the antihypertensive effect of ARBs. The ARBs have a low incidence of adverse effects (headache, upper respiratory infection, back pain, muscle cramps, fatigue and dizziness), even in the elderly patients. After the approval of losartan, five other ARBs (candesartan cilexetil, eprosartan, irbesartan, telmisartan, and valsartan) and three combinations with hydrochlorothiazide (irbesartan, losartan and valsartan) have been approved as antihypertensive agents, and some 28 compounds are in various stages of development. The ARBs are non-peptide compounds with varied structures; some (candesartan, losartan, irbesartan, and valsartan) have a common tetrazolo-biphenyl structure. Except for irbesartan, all active ARBs have a carboxylic acid group. Candesartan cilexetil is a prodrug, while losartan has a metabolite (EXP3174) which is more active than the parent drug. No other metabolites of ARBs contribute significantly to the antihypertensive effect. The variation in the molecular structure of the ARBs results in differences in the binding affinity to the receptor and pharmacokinetic profiles. The differences observed in lipid solubility, absorption/distribution, plasma protein binding, bioavailability, biotransformation, plasma half-life, and systemic elimination influence the time of onset, duration of action, and efficacy of the ARBs. On the basis of the daily mg dose, the antihypertensive potency of the ARBs follows the sequence: candesartan cilexetil > telmisartan approximately = losartan > irbesartan approximately = valsartan > eprosartan. After oral administration, the ARBs are rapidly absorbed (time for peak plasma levels = 0.5-4 h) but they have a wide range of bioavailability (from a low of 13% for eprosartan to a high of 60-80% for irbesartan); food does not influence the bioavailability, except for valsartan (a reduction of 40-50%) and eprosartan (increase). A limited dose-peak plasma levels/areas under the plasma level-time curve proportionality is observed for some of the ARBs. Most of these drugs have high plasma protein binding (95-100%); irbesartan has the lowest binding among the group (90%). The steady-state volumes of distribution vary from a low of 9 L (candesartan) to a high of 500 L (telmisartan). (ABSTRACT TRUNCATE
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PMID:Clinical pharmacokinetics of angiotensin II (AT1) receptor blockers in hypertension. 1085 85

Amlodipine, a long-acting dihydropyridine calcium channel blocking agent, was administered to 55 children (age: 11.5 +/- 5.4 years) with hypertension, 49 of whom (89%) had secondary hypertension. Efficacy was assessed by comparing pretreatment blood pressure (BP) to follow-up BP obtained in our outpatient Pediatric Nephrology clinic. Thirty-two (58%) patients achieved BP control with amlodipine alone, and 31 (55%) patients received amlodipine twice daily. Eleven patients received amlodipine as a suspension. Mean amlodipine dose was 0.16 +/- 0.12 mg/kg/day; there was an inverse relationship between patient age and amlodipine dose. Follow-up BP were significantly lower than pretreatment BP: systolic BP fell from 129 +/- 12 to 122 +/- 12 mm Hg (P = .004), and diastolic BP fell from 78 +/- 13 to 70 +/- 19 mm Hg (P = .003). A small, clinically insignificant increase in heart rate (from 91 +/- 19 beats/min to 99 +/- 26 beats/min; P = .02) occurred during amlodipine treatment. Adverse effects reported included dizziness (three patients), fatigue (two patients), flushing (two patients), and leg edema (one patient). All improved with dose reduction. We conclude that amlodipine provides effective BP control without significant adverse effects in children with hypertension, and can be used as monotherapy in most children. Young children appear to require significantly higher doses per kilogram of body weight than older children. Twice-daily dosing may be required in many children to achieve BP control. Detailed pharmacokinetic studies are needed to confirm these observations.
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PMID:Treatment of hypertensive children with amlodipine. 1104 Nov 59

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

Sublingual (SL) apomorphine (2 to 6 mg) has been shown to be effective for treatment of male erectile dysfunction. Many patients with erectile dysfunction are also being treated for systemic hypertension and/or cardiovascular disease. In a double-blind, randomized, placebo-controlled, crossover trial, SL apomorphine 5 mg and placebo were administered on alternate days to 162 men who were on long-term therapy (> or =4 weeks) with angiotensin-converting enzyme inhibitors, beta blockers, diuretics, calcium channel blockers, alpha(1) blockers, or short- or long-acting nitrates. Blood pressure and heart rate were measured before and after dosing; cardiac rhythm was recorded by 4-hour Holter monitoring. The only potentially clinically significant interactions between SL apomorphine and the antihypertensive agents or short-acting nitrates were greater orthostatic decreases in systolic blood pressure in the alpha-blocker and calcium channel blocker groups (-10 and -6 mm Hg vs placebo, respectively). Administration of SL apomorphine after dosing with long-acting nitrates resulted in significant decreases in blood pressure when patients were standing (mean systolic change, -5 to -9 mm Hg 30 to 60 minutes postdose, p <0.05; mean diastolic change, -3 to -4 mm Hg 50 to 60 minutes postdose, p <0.05). The most common adverse events with SL apomorphine were dizziness, nausea, and headache. Syncope occurred in 1 patient in the beta-blocker group; symptomatic hypotension occurred in 2 patients each in the short- and long-acting nitrate groups. Thus, in patients receiving common antihypertensive agents and short-acting nitrates, as well as in most patients receiving long-acting nitrates, SL apomorphine at higher than recommended doses produced no clinically significant changes in heart rate or blood pressure greater than changes seen with SL apomorphine alone.
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PMID:Cardiovascular safety of sublingual apomorphine in patients on stable doses of oral antihypertensive agents and nitrates. 1158 43

In well designed studies in patients with mild to moderate hypertension, combinations of the sustained-release (SR) formulation of the nondihydropyridine calcium channel antagonist verapamil 120 to 240 mg/day and the ACE inhibitor trandolapril 0.5 to 8 mg/day were significantly more effective in reducing sitting systolic blood pressure (SBP) and diastolic blood pressure (DBP) from baseline than placebo. In most randomised studies, combinations of verapamil SR 120 to 240 mg/day and trandolapril 0.5 to 8 mg/day were significantly more effective in lowering sitting DBP and SBP than the corresponding monotherapies administered at the same dosage. Trandolapril/verapamil SR 2/180 mg/day provided significantly more effective 24-hour ambulatory blood pressure (BP) control than of the corresponding monotherapies. Moreover, trandolapril/verapamil SR reduced BP in patients inadequately controlled with either of the corresponding monotherapies. The antihypertensive efficacy of trandolapril/verapamil SR 2/180 mg/day was generally similar to that of other combinations of antihypertensive agents (metoprolol/hydrochlorothiazide, atenolol/chlorthalidone, lisinopril/hydrochlorothiazide, enalapril/hydrochlorothiazide) in patients with hypertension, including those with type 2 diabetes mellitus. Trandolapril/verapamil SR reduced BP in patients with hypertension and type 2 diabetes or primary renal disease, Black patients and elderly patients. Trandolapril/verapamil SR was more effective than the individual components administered as monotherapy in reducing proteinuria in patients with type 2 diabetes or primary renal disease. Trandolapril/verapamil SR had a neutral or beneficial effect on metabolic parameters (glucose, insulin, lipids) in patients with hypertension, including those with type 2 diabetes. Trandolapril/verapamil SR preserved left ventricular function in patients with heart failure. Fewer cardiac events occurred after therapy with trandolapril/verapamil SR than after trandolapril alone in post-myocardial infarction patients with congestive heart failure. The incidence of adverse events in recipients of trandolapril/verapamil SR was similar to that of the individual components, and that of other combination therapies. In placebo-controlled trials conducted in the US, headache, upper respiratory tract infections, cough, constipation, atrioventricular block (first degree) and dizziness were the most commonly reported adverse events in recipients of combinations of verapamil SR (120 to 240 mg/day) and trandolapril (0.5 to 8 mg/day). In conclusion, the fixed-dose combination of trandolapril/verapamil SR is an effective treatment for patients with hypertension, including those with type 2 diabetes. Trandolapril/verapamil SR tended to be more effective than monotherapy with either verapamil SR or trandolapril, and generally showed antihypertensive efficacy similar to that of other combination antihypertensive therapies. Current data support the use of trandolapril/verapamil SR as an alternative treatment when monotherapy with either agent is not effective. Data from large clinical trials currently being conducted will assist in fully defining the role of trandolapril/verapamil SR as a cardio- and renoprotective agent.
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PMID:Fixed combination trandolapril/verapamil sustained-release: a review of its use in essential hypertension. 1242 Nov 12

The current prescription patterns for essential hypertension and the efficacy, safety, tolerability and cost-effectiveness of the newer antihypertensive drugs were evaluated in Nigerian patients. The findings were compared with that of a previous study conducted in the same tertiary hospital 10 years earlier. A cross-sectional evaluation of blood pressure (BP) control in a hypertension clinic was undertaken among 150 Nigerian patients aged 61 +/- 12 years (55% females), with a duration of treatment on a particular drug class or combination of 9 +/- 3 months. The initial blood pressure was 176 +/- 20/108 +/- 11 mmHg and 22% of the patient had concurrent diabetes mellitus. Thiazide diuretics (D) alone or in combination remained the most commonly prescribed drugs in 56% of all patients. There were significant increases in the prescriptions of calcium channel blockers (CCBs) (51%), P < 0.0001, and ACE-inhibitors (ACEIs) (24%), P < 0.0001, but a slight reduction in the use of methyldopa, and fixed drug combinations (P < 0.01) compared to the previous study. The fall in systolic blood pressure on D (r = 0.65, P < 0.001) or CCB (r = 0.48, P < 0.02) was significantly correlated with the initial systolic blood pressure, but not age. More patients achieved normotension BP < 140/90 mmHg on CCB monotherapy (71%), than D monotherapy (56%). Combination therapy with ACEIs + D or methyldopa+thiazides normalized BP in 63 and 68%, respectively. Pulse pressure, a surrogate marker for cardiovascular complications and mortality in essential hypertension, was significantly reduced (P < 0.01) equally by all treatments, with 95% confidence intervals ranging from -28 to -1 mmHg. However, hypertensive-diabetic (HT-DM) patients (n = 33) exhibited no significant change in pulse pressure in response to treatment. Adverse drug reactions that occurred in 11% were impotence or postural dizziness with D, headache and pitting oedema with CCB, and dry cough with ACEI. Pharmaco-economic comparison of the drug classes revealed that for every US dollar (dollar) spent per month, the percentage of treated patients attaining normotension was 18.6 for D, 4.73 for CCB, 3.5 for ACEI + D and 13.6 for methyldopa + thiazides. A combination of ACEI + CCB or D was the preferred treatment for hypertensive-diabetic Nigerians, but only 24% attained a BP < 130/85 mmHg. These results demonstrate a shift in trend to a more rational and efficacious treatment of hypertension over a 10 year period. This may be associated, at least in part, with the intensive and continuous education of the prescribers in rational drug use and the introduction of a hospital formulary. Methyldopa is still a highly efficacious and cost-effective drug in this population. Black HT-DM Africans still constitute a subgroup who not only require more and costlier antihypertensive drugs, but whose BP control is suboptimal, and exhibit a poor therapeutic response to other risk factors (pulse pressure) that constitute a continuing risk for cardiovascular mortality.
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PMID:Shifting trends in the pharmacologic treatment of hypertension in a Nigerian tertiary hospital: a real-world evaluation of the efficacy, safety, rationality and pharmaco-economics of old and newer antihypertensive drugs. 1271 73

Gabapentin is a structural analogue of the neurotransmitter gamma-aminobutyric acid (GABA) approved for use in adults with postherpetic neuralgia. Gabapentin does not bind to GABA(A) or GABA(B) receptors. Its mechanism of action in humans is unclear, but may involve binding to alpha2delta calcium channel subunits in animal models. Reductions in the mean daily pain score from baseline to week 7 or 8 of treatment (primary endpoint) were significantly greater with gabapentin 1800-3600 mg/day than placebo therapy in two well designed trials in patients with postherpetic neuralgia. The proportion of responders (patients showing a > or =50% reduction in mean daily pain score at endpoint versus baseline) was significantly greater with gabapentin than placebo. Daily sleep rating scores, the Short Form McGill Pain Questionnaire (total pain scores), Patient and Clinician Global Impression of Change and measures on the Short Form-36 Health Survey (including physical functioning, role-physical, bodily pain, vitality or mental health) improved to a significantly greater extent with gabapentin than placebo. Adverse events associated with gabapentin in patients with postherpetic neuralgia were usually mild to moderate in intensity, with dizziness, somnolence and peripheral oedema being commonly reported.
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PMID:Gabapentin: in postherpetic neuralgia. 1453 49

Fixed combinations of calcium channel blockers and angiotensin converting enzyme inhibitors represent an alternative to diuretic-based combination therapy. The aim of the present study was to compare the antihypertensive efficacy of the combination enalapril 10 mg/nitrendipine 20 mg (E/N) vs losartan 50 mg/hydrochlorothiazide 12.5 mg (L/H), assessed by 24-h ambulatory blood pressure monitoring. This multicentre, double-blind, parallel study included 97 hypertensive patients (office diastolic blood pressure (DBP) 90-109 mmHg and daytime DBP > 85 mmHg). After a 2- to 3-week period of single-blind placebo, they were randomized to receive double-blind treatment with E/N (n = 48) or L/H (n = 49) for a 4-week period. The primary outcome measure was the difference in 24-h DBP reduction between treatments from randomization to the end of the double-blind period. Secondary efficacy variables included differences in 24-h systolic (S) BP reduction, daytime, night-time and office SBP and DBP reduction, proportion of responders and controlled patients, trough-to-peak ratio and smoothness indexes. Safety was assessed by the proportion of patients with adverse events and the detection of laboratory abnormalities. No significant differences were observed in the primary outcome measure. The group receiving E/N tended to show greater reductions in most measures (24 h, daytime and office SBP and DBP) and higher BP control rates, but only the difference in the rate of office SBP control (< 140 mmHg) reached statistical significance (42.2 vs 22.4%; P = 0.048). The trough-to-peak ratios and smoothness indexes were similar in both groups. The incidence of adverse events related to the treatment was 27.1% (95% CI 14.5-39.6%) in E/N-treated patients and 14.3% (95% CI 4.5-45.8%) in the L/H group, but differences were not significant. The kind of event more frequently observed were flushing and headache in E/N, and dizziness and asthenia in L/H; all observed adverse events were mild. We conclude that E/N and L/H have a similar antihypertensive efficacy, assessed by office or ambulatory blood pressure monitoring. E/N achieved a significantly higher office SBP control rate, but this was accompanied by an apparently higher proportion of mild adverse events.
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PMID:Comparison of the antihypertensive effects of the fixed dose combination enalapril 10 mg/nitrendipine 20 mg vs losartan 50 mg/hydrochlorothiazide 12.5 mg, assessed by 24-h ambulatory blood pressure monitoring, in essential hypertensive patients. 1497 17

Twenty-one elderly patients with chronic brain failure received a single 30 mg oral dose of the calcium channel blocker nimodipine followed by two weeks of 30 mg three times a day (t.i.d.) administration. The aim of this study was to assess if drug accumulation occurred in our frail elderly subjects under this dose regimen. Plasma concentrations of nimodipine and three main metabolites were determined by gas chromatography. During the 2-week period we did not find significant changes in peak plasma concentrations and corresponding areas under the plasma concentration-time curves. Trough nimodipine plasma concentrations before administration of the morning dose were similar on days 7 and 14. Therefore, no evidence of drug accumulation was found. Blood pressure and heart rate remained stable throughout the study period and no adverse effects were observed. During the study period, there was a decline in the proportion of patients who complained about dizziness and insomnia. Overall, our data suggest that there is no need to alter the usual adult dose of nimodipine if this drug is administered to multimorbid frail elderly patients suffering from chronic brain failure.
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PMID:Pharmacokinetics of nimodipine in multimorbid elderly patients with chronic brain failure. 1537 94

Zonisamide is an antiepilepsy drug (AED) with both sodium and calcium channel-blocking properties. This dual mechanism may predict efficacy in some refractory patients, and a broad spectrum of action against different seizure types. Zonisamide has been commercially available in Japan since 1989, and became available in the United States for treatment of adults over the age of 12 with partial-onset seizures in March 2000. Several multicenter clinical trials have been conducted in the United States over the past 15 years. These have included three double-blind, placebo-controlled trials as well as long-term open-label studies. Zonisamide was characterized in these studies as a safe and effective adjunctive treatment for partial-onset seizures. Zonisamide has not yet been studied in the United States as an initial monotherapy, but in one long-term study, some patients were able to discontinue other AEDs and successfully transition to monotherapy. The most frequently reported adverse events were somnolence, dizziness, and anorexia. Current United States labeling states that 12 patients with epilepsy receiving zonisamide had symptomatic kidney stones; however, after more than a dozen years of zonisamide use in Japan, the incidence of kidney stones associated with zonisamide remains low.
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PMID:Review of United States and European clinical trials of zonisamide in the treatment of refractory partial-onset seizures. 1551 95


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