Propranolol versus verapamil for the treatment of essential hypertension

Variability of blood pressure in ambulatory hypertensive patients: effects of verapamil on twice and thrice daily dose regimens

The antihypertensive effects of verapamil over 24 hours were assessed on twice and thrice daily dose regimens on 12 patients (25-65 years of age; mean age 50) with essential hypertension (WHO stages I-II) in a randomised, double-blind, cross-over trial. After a dose titration period starting with either verapamil 80 mg tid or 120 mg bid the patients kept their maintenance dose (240, 360 or 480 mg daily) for 4 weeks before crossing over to the other administration schedule. Repeated ambulatory blood pressure (BP) curves were recorded in 10 patients with a non-invasive portable device (Pressurometer III, Del Mar Avionics). The BP reductions (causal BP values) obtained by 2- and 3-dose regimens were of similar magnitude (from 170 +/- 19/105 +/- 8 on placebo to 140 +/- 17/87 +/- 7 and to 146 +/- 14/88 +/- 8 by 2-and 3-dose respectively). Analyses of BP curves revealed close similarity in profiles on the two dose regimens, although DBP was significantly (p less than 0.05) lower by 3-dose as compared to 2-dose regimen during the period 0.00-2.59 a.m. Long-term (circadian rhythm) and short-term variability did not differ between the regimens. Despite the slight difference in DBP curves after midnight, the overall impression is that verapamil given both twice and thrice daily provides adequate BP control throughout 24 hours.

Calcium channel blockers in systemic hypertension

Alterations in transmembrane flux of calcium ions may be playing a role in the pathophysiology of systemic hypertension. Calcium channel blockers have been shown to be effective antihypertensive drugs with excellent safety profiles. They are efficacious in the long term treatment of systemic hypertension in all population subgroups, and have special applicability for treating patients with hypertensive urgencies and individuals with concomitant diseases such as angina pectoris and arrhythmias.

Drug treatment of hypertension

There are several first choices for the treatment of mild and moderate hypertension. The selection of a drug may be influenced by concomitant pathology, with positive indications for particular drugs, e.g. coexistent angina, indicating use of a beta-receptor blocking drug or calcium antagonist; fluid retention indicating a diuretic; or contraindication e.g. asthma, and beta-adrenoceptor blocking drugs. beta-Adrenoceptor blocking drugs have the advantage of a long history and of possibly being cardioprotective following myocardial infarction, but they have not yet been established as primary preventive agents in hypertensive patients. The alpha-receptor blocking drugs have the advantage of favourably affecting lipid profile and blood pressure. Therefore, there may be advantages in the use of combined alpha- and beta-blockade. The diuretics, which have the advantage of being inexpensive, are widely used but long term metabolic effects, particularly hypokalaemia, cause concern. This is correctable by co-administration of a potassium sparing diuretic and often preventable by using low doses of the diuretic. Diet may be important as hypokalaemia appears to be less of a problem where potassium intake is high. Experience with calcium antagonists is widening but the use of converting enzyme inhibitors is more limited, and some physicians are less ready to use them as first choice in mild hypertension at present. Drugs like methyldopa, clonidine, the adrenergic neurone inhibitory drugs are now used more as reserve agents. More severe cases of hypertension may require drugs from 2 of the 3 major groups: beta-blocking drugs, vasodilators and diuretics. In some cases, drugs from each of these 3 groups will be required.

Assessment of 'once daily' verapamil for the treatment of hypertension using ambulatory, intra-arterial blood pressure recording

A new, slow release formulation of verapamil, "verapamil o.d." was administered to 12 patients with essential hypertension. Drug administration was started at a dose of 240 mg and increased to 480 mg after 2 weeks of treatment if the cuff blood pressure response was unsatisfactory. The drug reduced the daytime intra-arterial blood pressure significantly from 180.7/106.8 mm Hg to 157.3/89.4 mm Hg. The daytime heart rate fell from 88.1 to 71.8 beats/min. The night-time blood pressure decreased from 155.7/87.2 mm Hg to 140.5/75.3 mm Hg. The nocturnal heart rate decreased from 62.8 to 57 beats/min. Hourly plots of mean systolic and diastolic pressure showed a significant reduction of systolic pressure for 21 of 24 h and of diastolic pressure for all 24 h following a single morning dose. The drug modified the absolute blood pressure and heart-rate response during both forms of exercise, but did not alter the magnitude or rate of blood pressure change. The tilt-test produced no evidence of postural hypotension. Only one patient experienced any side effects whilst taking the drug. These results indicate good 24-h blood pressure control and reduced exercise blood pressure levels during treatment with this new formulation of verapamil. The reduced frequency of drug administration should improve patient compliance with treatment of hypertension.

Calcium modulators: future agents, future uses

The calcium modulators have been a significant therapeutic advancement for the treatment of angina. Structural analogs of verapamil and nifedipine have been synthesized, as have structurally unique compounds. As the role of calcium in body processes is further elucidated, the efficacy of the calcium modulators is being evaluated for numerous disorders. It is anticipated that the newly synthesized compounds will have specificity toward particular body processes, thus providing efficacy with minimal side effects.

Diltiazem versus propranolol in essential hypertension: responses of rest and exercise blood pressure and effects on exercise capacity

Both beta-blocking and calcium channel-blocking drugs are being used with increasing frequency as initial therapy for essential hypertension. The present study was designed to compare the antihypertensive effects of a beta-blocking drug, propranolol, with a calcium channel-blocking drug, diltiazem, at rest and during upright bicycle exercise and to determine whether exercise capacity is altered by these therapies. Twenty-one patients with uncomplicated systemic hypertension and a diastolic blood pressure (BP) of 95 to 110 mm Hg without medication were randomly assigned to propranolol or diltiazem therapy in a double-blind manner. The total daily dosages were titrated as needed, from 160 to 480 mg of propranolol (mean 371 mg) and 120 to 360 mg of diltiazem (mean 307 mg) over 12 weeks, and the titrated dose was maintained for 4 additional weeks. Both drugs significantly reduced supine BP (from 149 +/- 14/101 +/- 4 to 136 +/- 17/89 +/- 10 mm Hg with propranolol and from 157 +/- 14/103 +/- 4 to 144 +/- 13/93 +/- 8 with diltiazem. Only diltiazem reduced BP during submaximal exercise, but both agents produced significant responses during maximal exercise. Diltiazem had no effect on maximal heart rate, exercise duration or O2 uptake, whereas propranolol reduced maximal VO2 from 27 +/- 6 to 22 +/- 6 ml/min/kg (p less than 0.01) and also shortened duration of exercise. Propranolol, despite its effects on heart rate, maintained the workload VO2 relation at submaximal loads, suggesting an increased oxygen delivery. However, these adaptive mechanisms appear to be insufficient during maximal effort.

Verapamil in essential hypertension: a comparison with atenolol plus hydralazine

The effects of graded doses of verapamil were compared with those of a combination of atenolol and hydralazine in a double-blind, randomised, crossover trial in 16 patients with essential hypertension. During the placebo phase, mean arterial pressure (M.A.P.) was 123 +/- 17 mmHg. Verapamil (dose range 160-480 mg/day) lowered M.A.P. to 109 +/- 7 mmHg (p less than 0.01 vs placebo). The combination of atenolol (50-100 mg/day) and hydralazine (50-200 mg/day) lowered M.A.P. to 100 +/- 11 mmHg (p less than 0.001 vs placebo, p less than 0.05 vs verapamil). Neither regimen produced any deleterious effects on electrocardiographic intervals, echocardiographic indices of left ventricular function or plasma lipids. Verapamil was well tolerated and provided satisfactory alternative therapy in these patients with mild-to-moderate essential hypertension.

Calcium channel blockers and treatment of hypertension

Over the past years, research efforts have been focused on the pathophysiologic role of calcium ions, and the implication for the potential role of calcium channel blockers in the management of essential hypertension. Numerous studies have shown that nifedipine and verapamil are effective antihypertensive agents, initial experience with diltiazem is also encouraging. The magnitude of blood pressure reduction with these drugs is related to the pre-treatment blood pressure. In refractory hypertension, combination with other antihypertensive agents provide additive effect. In the elderly population and in patients with ischemic heart disease, supraventricular arrhythmia, bronchospastic disease, peripheral vascular disease or diabetes mellitus, the calcium channel blockers offer potential advantages over other antihypertensive agents. Experimental studies also suggest that these drugs may reverse ventricular hypertrophy. When long-term safety with these drugs is documented from well-controlled clinical trials, the calcium channel blockers may be our first line of therapy for the management of hypertension.

Diltiazem as monotherapy for systemic hypertension: a multicenter, randomized, placebo-controlled trial

A multicenter, randomized, placebo-controlled, parallel group study of diltiazem in essential hypertension was carried out in 77 patients (40 diltiazem, 37 placebo) with stable supine diastolic blood pressure (BP) between 95 and 110 mm Hg. Patients were withdrawn from previous antihypertensive therapy for at least 4 weeks, titrated to the optimal dose, and followed for a total of 12 weeks during therapy. A diltiazem dose of 360 mg/day was required in 85% of the patients. Average BP in all positions was significantly (p less than 0.0001) reduced by diltiazem compared with placebo. With diltiazem, average supine BP fell from 156/100 mm Hg at baseline to 141/87 at end titration and 145/90 mm Hg at week 12, whereas average standing BP fell from 152/101 mm Hg to 136/90 and 143/91 mm Hg, respectively, at those times. There was no significant change in heart rate at week 12. Diltiazem tended to be more effective in older patients, but caused no increase in orthostatic BP drop. There were no statistically significant changes in BP in the placebo group. Two patients receiving placebo and 1 patient receiving diltiazem discontinued therapy as a result of adverse effects, and overall, side effects were only slightly more common with diltiazem treatment. Thus, diltiazem was effective and well tolerated single therapy for mild to moderate systemic hypertension and appears to compare favorably to most agents being used.

Comparative effects of diltiazem and hydrochlorothiazide in blacks with systemic hypertension

The blood pressure-lowering effects of a calcium-entry blocker, diltiazem (240 or 360 mg/day), and a thiazide diuretic, hydrochlorothiazide (50 or 100 mg/day), were studied in 20 black hypertensive patients. Supine blood pressure decreases of -34/-18 mm Hg for diltiazem and -29/-21 mm Hg for hydrochlorothiazide were noted after 14 weeks of therapy. Differences between drugs were not significant. Blood pressures were normalized in all 4 of the monotherapy nonresponders when the 2 drugs were combined. Significant adverse effects were not noted. These data suggest that diltiazem is an effective antihypertensive agent in black patients. As monotherapy, its blood pressure-lowering effect is equivalent to hydrochlorothiazide.

Antihypertensive therapy with calcium-channel blockers: comparison with beta blockers

As a result of concern about the safety and long-term toxicity of diuretics, there is a growing trend toward the use of alternative agents as initial therapy in essential hypertension. Worldwide, beta blockers and vasodilators, especially the calcium-channel blockers, are the most commonly used alternative agents. Several studies comparing these 2 classes of medications are reviewed. These studies indicate that verapamil, nifedipine and diltiazem are all comparable in efficacy to beta blockers. When combined, calcium-channel blockers and beta blockers produce additive responses. These agents may differ in the relation between the magnitude of their antihypertensive effect and patients' pretreatment plasma renin activity and age. Younger persons and those with high plasma renin activity tend to respond better to beta blockers; older subjects and those with low plasma renin activity are more consistently responsive to calcium-channel blockers. The choice of agent should be individualized, based upon accompanying illnesses, adverse-effect profile and demographic factors.