Antihypertensive effect of felodipine combined with beta-blockade. A comparison between 2 and 3 daily dosages

Influence of nicardipine and nifedipine on plasma carvedilol disposition after oral administration in rats

The effect of two kinds of 1,4-dihydropyridine calcium-channel blockers, nicardipine hydrochloride and nifedipine, on the disposition of carvedilol, was studied in rats. Blood samples were assayed for carvedilol levels using solid-phase extraction and high-performance liquid chromatography. The plasma carvedilol concentration was found to be significantly higher, and the area under the concentration-time curve up to 24 h (AUC0-->24) was 6.7 and 3.0 times higher after simultaneous oral administration of 20 mg kg(-1) carvedilol with 40 mg kg(-1) nicardipine hydrochloride, or with 40 mg kg(-1) nifedipine, respectively, than after administration of carvedilol alone. The pharmacokinetic interaction between carvedilol and dihydropyridine calcium-channel blockers is thought to be attributable to vasodilator-induced changes in hepatic first-pass metabolism, inhibition in the absorption barrier by P-glycoprotein and in the metabolism of carvedilol.

The efficacy of felodipine ER on regression of left ventricular hypertrophy in patients with primary hypertension

The aim of the study was to evaluate the efficacy over 1 year of of felodipine ER 5 and 10 mg once daily (od) in 12 Caucasian patients with left ventricular hypertrophy secondary to primary hypertension. After a placebo period of 20 days, a physical examination and an echocardiography were performed in each patient. All patients started treatment with felodipine ER 5 mg. In 3 of the 12 patients the dose was increased to 10 mg od to control blood pressure (BP). BP was recorded every 2 weeks during the first 3 months, and at monthly intervals from the 3rd to the 12th months. An echocardiogram was taken at the end of the 3rd, 6th, 9th and 12th months. At the end of the placebo period, the mean SBP/DBP (+/-SD) was 178 +/- 11/104 +/- 5 mmHg. Mean SBP and DBP decreased significantly (p < 0.001) during the first 2 months to 138 +/- 10/86 +/- 3 mmHg and remained at this level until the end of the study. Mean left ventricular mass index (LVMI) decreased from 170 +/- 33 g/m2 after the placebo period to 115 +/- 19 g/m2 after 1 year (p < 0.01). It is concluded that felodipine ER 5 and 10 mg od over 1 year statistically significantly reduced both BP and LVMI.

New calcium antagonists: relevance of vasoselectivity

The calcium antagonists are a heterogeneous class of drugs used to treat a number of cardiovascular disorders. A new generation of calcium antagonists under development have a higher degree of selectivity for vascular smooth muscle and coronary vasculature compared with verapamil, nifedipine, and diltiazem. The clinical relevance of vasoselectivity and its impact on drug selection are discussed. The newer calcium antagonists are important alternatives to older agents and may be associated with improved tolerance and a reduced incidence of adverse effects. Their place in therapy has yet to be defined by comparative studies of efficacy and safety.

Verapamil 240 SR versus verapamil 120 SR in arterial hypertension. A randomized double-blind, placebo-controlled study with 24-hour ambulatory blood pressure monitoring

Fifteen patients (6 males, 9 females), age range 36-70 years, were enrolled in a randomized, double-blind, placebo-controlled study according to a Latin-square design, with the aim of comparing 24-hour blood pressure profiles after three 15-day treatment periods with placebo, verapamil SR 120 mg (V120 SR) given twice daily (bid), and verapamil SR 240 mg (V240 SR) given once daily (od). All of the patients were diagnosed as mild or moderate essential hypertensives on the basis of standard casual recordings. Noninvasive 24-hour ambulatory blood pressure (BP) monitoring was performed with an ICR Spacelab 5200 automatic device. In comparison with placebo, a clinically and statistically significant reduction in both systolic and diastolic BP over 24 hours was obtained with both active treatments. Comparison of the two active treatments shows that V240 SR led to a greater reduction in systolic and diastolic BP than V120 SR. No changes in heart rate were observed. Both treatments were well tolerated. In conclusion, both verapamil regimens proved to be effective and safe in treating essential hypertensives, with V240 SR giving better 24-hour BP control.

Calcium channel antagonists: Part VI: Clinical pharmacokinetics of first and second-generation agents

A survey of the pharmacokinetic properties of the three prototypical calcium antagonist agents shows that they have in common a very high rate of hepatic first-pass metabolism with, in the case of verapamil and diltiazem, the formation of an active metabolite that affects the dose during chronic therapy. Therefore, the major factor altering the pharmacokinetic properties and the dose of the drug required is the capacity of the liver to metabolize the drug, which in turn depends on the hepatic blood flow and the activity of the hepatic metabolizing systems. Hence liver disease, a low cardiac output, and coadministration of certain drugs inducing or inhibiting the hepatic enzymes, all indirectly affect the pharmacokinetic properties of the calcium antagonists. There are also other potential drug interactions of a kinetic or dynamic nature that may arise. In general, renal disease has little effect on the pharmacokinetics of calcium antagonists.

Calcium channel antagonism and beta blockade in combination--a therapeutic alternative in cardiovascular disorders. A review

Calcium-channel antagonists and beta-adrenergic blocking agents have become important modalities in the cardiovascular therapeutic armamentarium. These drugs are often administered as monotherapy to a wide range of cardiological patients with angina pectoris, hypertension, arrhythmias, congestive heart failure, and other diseases. Since within each class these drugs exhibit pharmacologic differences, it follows that their effectiveness varies in different disease states and that they exhibit a wide variety of side effects. In an attempt to optimize therapy, the individual drugs from these two classes can be combined; and the efficaciousness and side-effect profile of various combinations between calcium-channel antagonists and beta blockers are discussed in this review. Recommendations as to which patients may benefit from a combination and as to which patients may be harmed by the combination therapy will be made. Very few studies have compared the safety and efficacy of a single agent with the combination and with placebo in a controlled randomized fashion. To determine which therapy is superior and to determine which combination one should recommend under what circumstances, such placebo-controlled, randomized trials are a necessity, and will hopefully be performed although the complexity is enormous.

Haemodynamic effects and pharmacokinetics of felodipine at rest and during exercise in hypertensive patients treated with metoprolol or atenolol

A study has been performed in thirteen patients with essential hypertension, WHO Class I-II, and a diastolic blood pressure greater than or equal to 95 mmHg, on beta-blocker (metoprolol or atenolol) monotherapy, who were also given felodipine 10 mg b.d. for 28 days. The acute and steady state blood pressure response at rest and during exercise, and the pharmacokinetics of felodipine and metoprolol, were examined. Felodipine in combination with the beta-blocker reduced the systolic and diastolic blood pressures acutely and at steady-state. The duration of the effect was longer at steady-state. There was a significant correlation between the plasma concentration of felodipine and the change in blood pressure. The increase in systolic blood pressure during exercise was of the same magnitude before and after felodipine administration. No change in resting supine heart rate was found after the administration of felodipine. There was no significant differences in the pharmacokinetics of felodipine during long-term treatment, except for the trough plasma concentration, which was increased at steady-state, even though cumulation of felodipine and its metabolite did not occur. There was a significant decrease in the maximal plasma concentration and AUC of metoprolol after 28 days of treatment with felodipine, but its elimination half-life was not changed. The adverse reactions reported during this study were those generally seen after dihydropyridines and, except for two patients who were withdrawn after the first study day, the effects were well tolerated.

Calcium channel antagonists. Part V: Second-generation agents

Second-generation agents include new dihydropyridines, such as amlodipine, felodipine, isradipine, nicardipine, nimodipine, nisoldipine, and nitrendipine. Verapamil-like agents include tiapamil, gallopamil, and anipamil. Among the diphenylalkylamines, bepridil is of special interest. New preparations of existing agents include slow-release formulations of nifedipine, verapamil, and diltiazem. From all these agents will be selected those that are longer-acting and provide higher vascular selectivity.

Pharmacokinetic interactions between felodipine and metoprolol

This double-blind, cross-over study in healthy male subjects evaluated the pharmacokinetics of felodipine and metoprolol given both separately and in combination. During three, five-day study periods, felodipine 10 mg b.d., metoprolol 100 mg b.d. and a combination of the two, were given in random order. There was at least a 7-day washout period between each pharmacokinetic study day. Plasma levels of unchanged felodipine and metoprolol were measured for 24 h after the last dose, on the 5th day of each treatment period. Eight subjects, aged 19-22 years, completed the study. Both felodipine and metoprolol, given alone and in combination, were well tolerated. None of the felodipine pharmacokinetic variables (tmax, Cmax, Cmin, AUC (0-12) and t1/2) changed significantly when felodipine and metoprolol were given in combination. Cmax and AUC (0-12) for metoprolol increased significantly when metoprolol and felodipine were combined, although tmax, Cmin and t1/2 for metoprolol remained unchanged. The changes in metoprolol pharmacokinetics induced by felodipine are small and unlikely to be clinically important.

Felodipine, blood pressure, and cardiovascular reflexes in hypertensive humans

The influence of acute and chronic treatment with felodipine on ambulatory intra-arterial blood pressure, certain cardiac reflexes, and plasma renin activity was studied in nine patients with essential hypertension. Acute oral administration of the drug caused a significant reduction in blood pressure associated with an increase in heart rate mediated by the sinoaortic baroreceptor-heart rate reflex. After 1 week of treatment reflex resetting had occurred, returning heart rate to normal despite continuing blood pressure reduction. This effect was maintained throughout 6 weeks of treatment. Withdrawal of treatment was followed by return of the blood pressure to control levels associated with significant bradycardia caused by reflex reactivation at its reset level. No change was observed in response to tilting or Valsalva's maneuver or in plasma renin activity. Ambulatory intra-arterial data suggested that the clinically useful antihypertensive action of felodipine persists for 9 hours.

Treatment of essential hypertension with felodipine in combination with a diuretic

In a double-blind cross-over study, the effect on blood pressure (BP), heart rate (HR) and plasma noradrenaline concentration (pNA) of placebo or felodipine given in addition to hydrochlorothiazide was studied in 12 male patients with essential hypertension, not satisfactorily controlled with the diuretic alone. The first dose of felodipine decreased BP and increased HR for about 6 h. After 4 weeks of treatment with felodipine, BP was reduced for 24 h, whereas HR was only transiently increased. The elimination half-life of felodipine was about 23 h. The plasma noradrenaline concentration increased after felodipine and serum uric acid decreased. Side-effects were few and usually mild.