Once daily propranolol in the treatment of mild to moderate hypertension: a dose range finding study

Comparative in vivo evaluation of propranolol hydrochloride after oral and transdermal administration in rabbits

The purpose of this study was the in vivo evaluation of orally and transdermally administered propranolol hydrochloride in rabbits. Transdermal patches of propranolol hydrochloride (PPN) were formulated employing ethyl cellulose and polyvinylpyrrolidone as film formers. The pharmacodynamic (PD) and pharmacokinetic (PK) performance of PPN following transdermal administration was compared with that of oral administration. This study was carried out in a randomized cross-over design in male New Zealand albino rabbits. The PK parameters such as maximum plasma concentration (C(max)), time for peak plasma concentration (t(max)), mean residence time (MRT) and area under the curve (AUC(0-alpha)) were significantly (P<0.01) different following transdermal administration compared to oral administration. The terminal elimination half-life (t(1/2)) of transdermally delivered PPN was found to be similar to that following oral administration. In contrast to oral delivery, a sustained therapeutic activity was observed over a period of 24 h after transdermal administration compared to oral administration. The relative bioavailability of PPN was increased about fivefold to sixfold after transdermal administration as compared to oral delivery. This may be due to the avoidance of first pass effect of PPN. The sustained therapeutic activity was due to the controlled release of drug into systemic circulation following transdermal administration.

Once-daily propranolol for hypertension: a comparison of regular-release, long-acting, and generic formulations

This randomized, single-blind, crossover study compared three formulations of propranolol, each given once daily for hypertension. After an initial titration phase, subjects randomly received regular-release, long-acting, or a generic propranolol formulation. Each drug was given for 4 weeks and each active treatment was separated by a washout phase to allow blood pressure to return to baseline. Twelve subjects received all three active treatments. Systolic and diastolic blood pressures and pulses were significantly reduced from baseline by all formulations. There was no significant difference among drugs. Examination of diastolic blood pressures suggested some loss of antihypertensive control at the end of the dosing interval. These results indicate that it may be possible to administer propranolol once daily for hypertension and that there is no advantage for using the long-acting form.

The effect of cimetidine dose timing on oral propranolol kinetics in adults

Ten healthy male volunteers completed a study to determine the effect of cimetidine dose timing on the oral clearance of propranolol. Propranolol HCl 160 mg as tablets, was administered daily at 8 AM for 4 consecutive days on three occasions. In addition, cimetidine HCl 800 mg as tablets, was administered either simultaneously in the morning with propranolol (8 AM), at bedtime (10 PM), or not at all (control). Each treatment was separated by at least a 3-day washout. Propranolol and cimetidine serum samples were measured over the 24-hour dosing interval after the last propranolol dose. Cimetidine administration at 8 AM and 10 PM was associated with significant mean increases in the propranolol area under the serum concentration-time curve of 26% and 41%, respectively (P less than .002). The mean elimination half-life of propranolol was 6.3 hours during all three treatments. There was no significant difference in area under cimetidine serum concentration time curve between 8 AM and 10 PM dosing. Dosing cimetidine at bedtime 10 hours before propranolol does not diminish the magnitude of interaction.

Beta blockers in hypertension

Beta-adrenoceptor antagonists are effective in the management of patients with mild-to-moderate hypertension. Noncardioselective agents, cardioselective agents and beta blockers with intrinsic sympathomimetic activity (ISA) are equally effective, provided they are used in equipotent doses. Beta blockers can be used as first-line therapy in the management of hypertension and can be safely combined with diuretics, vasodilators, or both, for a better control of blood pressure. The exact mechanism by which beta blockers decrease blood pressure remains speculative, but they all reduce cardiac output during long-term therapy; drugs with ISA lower cardiac output and heart rate less than do drugs without ISA. Pharmacokinetic properties of beta blockers differ widely; drugs metabolized by the liver have shorter plasma half-lives than drugs primarily excreted by the kidneys. Although many of the side effects of various beta blockers are similar, differences in water and lipid solubility account for a higher incidence of central nervous system side effects with lipid-soluble drugs (such as propranolol and metoprolol) than with hydrophilic drugs (such as atenolol and timolol). The incidence of cold extremities has been reported to be less with drugs with ISA, and the incidence of bronchospasm less with cardioselective drugs. In the management of uncomplicated mild-to-moderate hypertension, all beta blockers are equally effective and produce less troublesome side effects than alternative antihypertensive agents. For effective therapy beta blockers can be used in 2 divided daily doses or even once daily.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-acting propranolol (Inderal LA): pharmacokinetics, pharmacodynamics and therapeutic use

Long-acting propranolol (Inderal LA) is a new formulation of propranolol that allows release of the drug in a controlled manner, so that the plasma concentration at 24 hr after dosing is greater with long-acting propranolol than with conventional tablets. A single dose of 160 mg of long-acting propranolol can produce cardiac beta-adrenoceptor blockade throughout a 24 hr period without variability due to multiple peak concentrations. It has been shown that this formulation is as effective in the treatment of angina pectoris, hypertension and hyperthyroidism as the standard formulation. Studies with long-acting propranolol in cardiac dysrhythmias are lacking. This new dosage form would be a means of simplifying dosing regimens and thereby hopefully enhancing patient convenience and compliance.

A dose ranging study of atenolol in hypertension: fall in blood pressure and plasma renin activity, beta-blockade and steady-state pharmacokinetics

The relationship between the oral dosage and plasma concentration of the long-acting cardioselective beta-adrenoceptor blocker atenolol and the antihypertensive response to the the degree of beta-adrenoceptor blockade and change in plasma renin activity (PRA) was evaluated in patients with mild-to-moderate essential hypertension in a double-blind, randomized, between-patient, dose-ranging (25, 50 or 100 mg once daily for 4 weeks) study. The optimum, or minimum, daily dose of atenolol to treat patients with mild-to-moderate hypertension was not clearly identified in this study. A between-treatment comparison did not demonstrate that all blood pressure falls were always less in the 25 mg group than in the other two groups. Calculation of beta-error or the power for the negative results between doses suggested that a large sample size is required to draw a conclusion that no dose-antihypertensive relationship of atenolol exists in the treatment of mild-to-moderate hypertension. A relatively flat plasma concentration-antihypertensive response relationship was observed. Steady-state plasma concentrations of atenolol were dose-related and renal drug clearance was well correlated with individual creatinine clearance. beta-adrenoceptor blockade was better correlated with plasma atenolol concentration. Correlations which were less strong were between plasma drug concentration and change in various blood pressures and between blood pressure falls and beta-adrenoceptor blockade. There was no relationship between the fall in blood pressure and change in PRA. Atenolol appeared to suppress PRA in an all-or-none fashion.

Ambulatory blood pressure during once-daily randomised double-blind administration of atenolol, metoprolol, pindolol, and slow-release propranolol

Intra-arterial ambulatory blood pressure was measured over 24 hours, in 34 patients with newly diagnosed hypertension, both before and after double-blind randomisation to treatment with atenolol (n=9), metoprolol (n=9), pindolol (n=9), or propranolol in its slow-release form (n=7). The dosage of each drug was adjusted at monthly clinic visits until satisfactory control of blood pressure was achieved (140/90 mm Hg or less by cuff) or the maximum dose in the study protocol was reached. A second intra-arterial recording was made after these drugs had been taken once daily at 0800 for three to eight months (mean 5.0+/-SD 1.4) and was started four hours after the last dose.At the end of the 24-hour recordings blood pressure was significantly lower with all four drugs. The extent to which the drugs reduced blood pressure, however, differed over the 24 hours. Atenolol lowered mean arterial pressure significantly throughout all 24 recorded hours, metoprolol for 12 hours, pindolol for 15 hours, and slow-release propranolol for 22 hours. Neither metoprolol nor pindolol lowered blood pressure during sleep. A significant reduction in heart rate was observed over 20 hours with atenolol, 20 hours with metoprolol, 10 hours with pindolol, and 24 hours with slow-release propranolol. Atenolol, metoprolol, and slow-release propranolol continued to slow the heart rate 24 hours after the last tablet was taken; this effect on heart rate, however, was not sustained throughout the second morning in those patients taking atenolol. Pindolol, the only drug studied that has intrinsic sympathomimetic activity, increased heart rate and did not lower blood pressure during sleep.Atenolol and slow-release propranolol are effective as antihypertensive agents over 24 hours when taken once daily, whereas metoprolol and pindolol may need to be taken more frequently. At times of low sympathetic tone, however, such as during sleep, beta-blockers with intrinsic sympathomimetic activity may raise heart rate and attenuate the fall in blood pressure with treatment.

Comparative pharmacological and pharmacokinetic observations on propranolol (long acting formulation) and bendrofluazide administered separately and concurrently to volunteers

1 The effect of long-acting (LA) propranolol, LA propranolol and bendrofluazide, and a new combined formulation of LA propranolol/bendrofluazide (Inderex) on exercise tachycardia was studied in ten normal volunteers. 2 The preparations were given in random order, double-blind, on three separate study weeks. Observations were made 0, 1, 3, 6, 8, 24, 33 and 48 h after drug administration. 3 The three preparations produced a significant reduction in exercise tachycardia up to 48 h after drug administration, and the effects of the three preparations were not significantly different from each other. 4 Following LA propranolol, LA propranolol and bendrofluazide, and the combined formulation the mean reductions in exercise heart rate 24 h after drug administration were 16.7 +/- 2.1%, 13.0 +/- 1.8% and 16.2 +/- 1.7% respectively. 5 Plasma levels of propranolol and bendrofluazide were measured at 0, 1, 2, 3, 6, 8, 10, 12, 24, 33 and 48 h after dose administration. 6 There was no significant difference in plasma propranolol levels, Cmax propranolol or AUCo-x following the three preparations. The mean apparent t1/2 beta of propranolol after LA propranolol alone was significantly shorter than following the other two preparations (P less than 0.05), but this was not associated with a different pharmacodynamic response. 7 There was no significant difference in the pharmacokinetic parameters of bendrofluazide following the two preparations containing bendrofluazide. No bendrofluazide was detected in plasma after LA propranolol alone. 8 The new combined formulation produces similar pharmacodynamic and pharmacokinetic responses to LA propranolol and bendrofluazide given separately, and to LA propranolol given alone, and so may be of value in the treatment of hypertension.

Single dose administration of propranolol in hypertension: a comparison of two formulations using clinic and home blood pressure measurements

The effect of once daily conventional or long acting propranolol on blood pressure was examined in a double-blind crossover trial in 15 patients with moderate hypertension previously responsive to beta-blocking drugs. After a washout period, patients were randomly allocated to receive either conventional or long acting propranolol (160 or 320 mg once daily) and matching placebo for four weeks. Each treatment period was followed by two weeks during which only placebo was given. Clinic and home blood pressure measurements, taken 24 hours after dosing, indicated adequate and similar control during the two treatment periods. The onset of the antihypertensive action was of similar duration and no "rebound" effect was observed after withdrawing treatment. There was a similar reduction in exercise tachycardia 24 hours after dosing. No difference in the incidence of side effects was detected. These results demonstrate satisfactory blood pressure control with propranolol administered once daily, but do not support any therapeutic advantage of long acting over the conventional formulation of the drug.

Pindolol: a review of its pharmacology, pharmacokinetics, clinical uses, and adverse effects

Pindolol is a new noncardioselective beta adrenergic blocking agent with intrinsic sympathomimetic activity. In the treatment of mild to moderate hypertension, pindolol provides effective control of blood pressure in a large majority of patients when administered alone or, more commonly, when combined with a thiazide diuretic. Pindolol is approximately as effective as propranolol in the therapy of hypertension, but in some crossover trials central nervous system side effects were more frequent with pindolol. A "ceiling effect" may be observed as dosages are titrated upward above approximately 20 to 30 mg per day, such that further blood pressure reductions may not be achievable. Some patients will exhibit a paradoxical increase in blood pressure with an increase in dosage. In patients who respond to modest doses of pindolol, twice or even once daily dosing is often adequate. This prolonged duration of hypotensive activity, while not suggested by the kinetics of this or similar drugs, is probably common to most beta blockers. Investigations in small numbers of patients with angina pectoris have reported variable but generally beneficial results with pindolol.

Comparison of the beta-adrenoceptor blocking activity of oxprenolol, slow release oxprenolol and a combined oxprenolol diuretic preparation

1 Observations were made in five healthy subjects who exercised before and 2, 3, 6, 8 and 24 h after the oral administration on separate occasions of 160 mg oxprenolol, 160 mg slow release oxprenolol, 160 mg slow release oxprenolol with 0.25 mg cyclopenthiazide and placebo. Blood samples were obtained before and at 1, 2, 3, 6, 8, 12 and 24 h after drug administration and assayed for oxprenolol concentration. 2 The three formulations produced maximum reductions of 29% in the exercise tachycardia 3 to 6 h after drug administration. At 24 h the effects of the three preparations were not significantly different from placebo. 3 There were no significant differences in the plasma concentrations produced by the three formulations during the 24 h period. 4 These observations suggest that the slow release formulations of oxprenolol should be given twice daily to maintain cardiac beta-adrenoceptor blockade throughout a period of 24 h.

Observation on the efficacy and pharmacokinetics of betaxolol (SL 75212), a cardioselective beta-adrenoceptor blocking drug

1 Observations were made in five subjects who exercised before and at 2, 3, 6, 8, 24, 33 and 48 h after the oral administration of placebo and 5, 10, 20 and 40 mg betaxolol. 2 The exercise heart rate remained constant at all times after the placebo. All doses of betaxolol significantly reduced the exercise tachycardia at all times. The maximum effect (34.4 +/- 2.2%) occurred after 40 mg. 3 There was a small decline in effect from the peak to 24 h when 40 mg produced a 23.3 +/- 2.7% reduction and a further decline to 48 h when there was a 14.6 +/- 1.8% reduction. 4 Plasma levels of betaxolol were measured in these studies. The peak plasma concentration occurred between 3 and 8 h with different doses. The plasma elimination half-lives after 10, 20 and 40 mg were 11.4 +/- 2.5, 15.9 +/- 4.9 and 15.1 +/- 3.1 h. 5 The effects of 40 mg betaxolol, 200 mg atenolol, 160 mg propranolol, 160 mg oxprenolol, 400 mg sotalol and placebo on an exercise tachycardia were compared in five subjects who received all treatments in random order. 6 There was no significant difference in the maximum reduction produced in an exercise tachycardia by the different drugs. 7 The effect of all drugs decreased with time. The effect of oxprenolol had worn off at 24 h but at 48 h only atenolol and betaxolol produced significant reductions in the exercise tachycardia. 8 Plasma concentrations of the different drugs were measured and plasma elimination half-lives determined. The half-life for betaxolol was 24.5 h which was longer than that for any of the other drugs. 9 These observations show that betaxolol is a potent beta-adrenoceptor antagonist with a long duration of effect on an exercise tachycardia and a long plasma elimination half-life.

Time-course of the anti-hypertensive action of atenolol: comparison of response to first dose and to maintained oral administration

To show whether repeated administration of atenolol for several days would influence its pharmacokinetic parameters and the extent and duration of the pharmacologic responses, the plasma level of atenolol and changes in heart rate, blood pressure and plasma renin activity were measured in 12 hypertensive patients at various times of day (9 a. m., 12 noon, 3 p. m. and 7 p. m.) after oral administration of the first dose of atenolol 100 mg, again during the 7th and 14th days of continued once-daily administration of the same dose, and finally during the three days following withdrawal of the drug. The peak plasma concentration of atenolol (about 600 ng/ml) was found 3 h after administration of the first dose, and measurable amounts (50-70 ng/ml) were found after 24 h. None of the pharmacokinetic characteristics were changed by administration of a single daily dose for two weeks. After withdrawal of the drug, detectable amounts of atenolol were found in plasma for at least 48 h. The first dose of atenolol caused prompt (3 h) and prolonged (up to 24 h) lowering of supine and standing systolic and diastolic blood pressures, slowing of supine and standing heart rate, reduction of the blood pressure and heart rate responses to dynamic exercise, and a decrease in plasma renin activity. The extent and time-course of all these responses were not influenced by repeated once-daily administration of the 100 mg dose for two weeks. Most of the effects continued during the withdrawal days, the lowering of blood pressure being somewhat more prolonged than the slowing of heart rate. It is concluded that a once-daily dose of atenolol 100 mg decreases blood pressure and heart rate throughout the following 24 h, without excessive daily fluctuation in its effects, and without signs of tolerance or accumulation.

Comparison of the efficacy and pharmacokinetics of conventional propranolol and a long acting preparation of propranolol

1 Plasma levels of propranolol were measured at intervals after the oral administration of 160 mg propranolol and 160 mg L.A. propranolol in ten subjects who received both drugs on separate occasions.

2 Mean peak plasma concentration of propranolol occurred 2 h after propranolol and 10 h after the L.A. formulation; the peak concentration with the former was four times that with the latter. At 24 h the plasma level was significantly higher after L.A. propranolol.

3 Observations were made in nine healthy volunteers who exercised before and at intervals after the oral administration of 160 mg propranolol and 160 mg L.A. propranolol.

4 Propranolol produced a maximum reduction (27.84 ± 2.4%) in the exercise tachycardia at 3 h and L.A. propranolol a maximum reduction (22.00 ± 1.73%) at 6 h. The effects at 24 h were 9.24 ± 1.55 and 16.79 ± 2.16% respectively.

5 Five subjects were given 160 mg propranolol as a single dose daily for 8 days and on a separate occasion similar treatment with L.A. propranolol. Subjects were exercised and blood samples were taken before and 3 h after each dose on days 1 to 5 and on day 8.

6 The reduction in the exercise tachycardia 3 h after propranolol ranged from 33.0 to 36.9% and 24 h after propranolol from 12.2 to 20.8%. The corresponding values after L.A. propranolol were 26.8 and 31.4 (3 h values) and 20.4 and 25.0 (trough values).

7 The trough plasma levels of propranolol during administration of propranolol ranged from 10.2 to 19.4 ng/ml and peak values from 202.2 to 245.0 ng/ml. The corresponding values after L.A. propranolol were 12.5 to 17.5 (trough values) and 18.4 to 50.0 (peak values) ng/ml.

8 These observations show that the new long acting formulation of propranolol produces a significant reduction of an exercise tachycardia throughout a 24 h period without a very high initial effect during single and multiple dosing. This formulation should be suitable for once a day administration.