Long-term hypotensive effect of atenolol (ICI 66.082), a new beta-adrenergic blocking agent

Long-term clinical experience with atenolol--a new selective beta-1-blocker with few side-effects from the central nervous system

During the last four years we have used a new cardioselective beta-adrenergic blocking substance, ICI 66.082 (atenolol or Tenormin), alone or in combination with other drugs for treatment of hypertension in a total of 104 patients, including 15 with a chronic obstructive lung disease. Fifty-one patients started treatment with atenolol because of side-effects--especially from the central nervous system--during previous treatment with non-selective beta-blockers, mostly propranolol (Inderal). Mean duration of treatment was 16 months (range 8--36) and mean dosage 163 mg/day. In 18 patients treatment with Tenormin was withdrawn, but only in 10 of them could this be referred to side-effects. Of the 51 patients who complained of or showed side-effects from another beta-blocker, 80% were improved after changing to Tenormin. Of the patients with side-effects from the central nervous system, 73% improved, especially those who complained of nightmares, hallucinations, insomnia or mild depression.

Vasospastic phenomena in patients treated with beta-adrenoceptor blocking agents

Twenty-one patients developed Raynaud's phenomenon during treatment with beta-adrenoceptor blocking agents. The vasospastic symptoms were obviously related to the treatment, but their pathogenesis is still controversial. A decrease in cardiac output might explain the phenomenon. According to our very preliminary data an alpha-adrenergic dominance caused by a direct effect on the peripheral circulation seems more probable. Vasospastic symptoms may arise after treatment with both cardioselective and non-selective beta blocking agents. Cautious prescription of beta blocking drugs to patients with preexisting peripheral vascular disease is recommended.

The effects of a beta 1-blocking agent, atenolol, on blood pressure, plasma renin activity and prostaglandin F2 alpha excretion in patients with essential hypertension

The antihypertensive action of beta-blocking agents has been suggested to be associated with the decrease in plasma renin activity (PRA) and can be antagonized by indomethacin, a prostaglandin (PG) synthesis inhibitor. We studied the acute and long-term effects of a beta 1-blocking agent, atenolol (50 mg b.i.d.), on blood pressure (BP), PRA and urinary PGF2 alpha excretion in 12 male patients (40 years old) with essential hypertension. BP was measured by means of a brachial cuff. PRA and PGF2 alpha were estimated radioimmunologically. One day after the initiation of atenolol treatment, BP fell significantly, the supine values from 159/114 to 143/104 mmHg and the erect from 158/118 to 140/106 mmHg. In six weeks BP decreased further to 135/94 and 134/96 mmHg, respectively. After the cessation of atenolol for three weeks BP rose to the pre-atenolol level. When the dose was readjusted (25-150 mg daily for 26 weeks), diastolic BP remained at 100 mmHg or higher in only two patients. During the atenolol treatment PRA declined to one-third of the pre-atenolol level in one day and to one-half in six weeks. The urinary excretion of PGF2 alpha was not affected by atenolol. Our results suggest that 1) the antihypertensive action of atenolol and the reduction of PRA are substantial already in one day, and 2) the decrease in BP or PRA is not associated with PGF2 alpha production.

Drugs in exacerbation of psoriasis

Drugs that have been associated with the precipitation or exacerbation of psoriasis include lithium, beta adrenergic receptor blocking agents, and antimalarials. The withdrawal of corticosteroids has been reported to activate pustular psoriasis. Nonsteroidal anti-inflammatory drugs, such as indomethacin, have recently been reported to exacerbate psoriasis, although additional well-controlled studies are still needed. Drugs used for treatment of psoriasis will sometimes cause a flare because of irritation, phototoxicity, or hypersensitivity reaction resulting in a Koebner phenomenon. Because psoriasis is a very complex disease and its activity is often unpredictable, clinical studies on adverse drug effects on psoriasis have been difficult to conduct. This review evaluates clinical, histologic, and biochemical evidence in the literature for drug-associated onset or exacerbation of psoriasis.

Central nervous system side-effects with hydrophilic and lipophilic beta-blockers

Previous investigations have suggested that hydrophilic beta-blockers, which appear at low concentrations in brain tissue, are less likely to produce CNS-related side-effects than are lipophilic beta-blockers, which occur at higher concentrations in the brain. The validity of this hypothesis was tested in a double-blind crossover study in which the hydrophilic beta-blocker atenolol was compared with the lipophilic agents metoprolol and propranolol, in 14 patients with a previous history of nightmares or hallucinations when treated with lipophilic beta-blockers. Nightmares or hallucinations were reported by all patients receiving lipophilic beta-blockers but by only three patients receiving atenolol. The total number of episodes was significantly lower (p less than 0.01) for patients receiving atenolol (8) than for those receiving lipophilic beta-blockers (54). It is concluded that atenolol is significantly less likely to provoke nightmares and hallucinations than are the lipophilic beta-blockers, metoprolol and propranolol. It seems likely that this finding is due to the differences in hydrophilicity amongst these drugs.

Beta-adrenoceptor-blocking agents: are pharmacologic differences relevant?

beta-Adrenoceptor-blocking agents constitute a heterogeneous group of compounds. Membrane- stabilizing (quinidine-like) effects can be demonstrated pharmacologically with most compounds, but only at relatively high concentrations. There is no evidence to suggest that this property is of clinical relevance. Some compounds have a certain selectivity for receptors of the beta 1-type, whereas others possess beta-adrenoceptor stimulant activity (partial agonism). The clinical importance of these latter properties remains controversial. The selectivity for beta 1-adrenoceptors, which can be demonstrated pharmacologically for atenolol, metoprolol, and practolol, appears quite broad. Nevertheless a clear advantage over nonselective compounds with respect to their effects on lung function and vascular resistance in patients has not been established. There are two possible explanations. The first is that the doses used therapeutically may lie outside the selective range; the second is that most tissues appear to possess and mixed population of beta 1- and beta 2-adrenoceptors. According to our present understanding, even absolute specificity for a given subtype cannot provide organ or tissue specificity. Partial agonists provide a constant stimulation of beta-adrenoceptors while at the same time preventing access of catecholamines to the receptor they occupy. With some compounds (e.g., pindolol), stimulant activity may be sufficient to counterbalance the myocardial depression normally resulting from blockade of basal sympathetic tone. Heart rate and cardiac output are thus maintained within normal limits and compensatory increases in vasomotor tone (seen with antagonists lacking intrinsic activity) do not occur. Pindolol has been shown to dilate blood vessels at very low doses and to produce significant relaxation of isolated tracheal smooth muscle at concentrations within the range of therapeutic plasma levels found in humans. These effects may underly the relatively low incidence of bronchopulmonary and vascular side effects reported for this compound.

Clinical evaluation of atenolol in hypertensive patients

Atenolol, a cardioselective beta-adrenergic blocking agent, was given as the sole hypotensive drug for 8-12 weeks to 20 patients with hypertension of varying degrees of severity. Initial systolic blood pressure ranged from 162-238 mm Hg (mean +/- SEM 196 +/- 5.5 mm Hg) and diastolic blood pressure ranged from 105-143 mm Hg (118 +/- 2.5 mm Hg). Three patients had accelerated hypertension, six had cardiomegaly with recent exertional dyspnea and three were diabetics. Atenolol, 100-300 mg once daily, controlled both the supine and standing blood pressure and markedly attenuated the initial hypertensive response to severe exercise. In 17 patients (85%), atenolol therapy reduced blood pressure more than 20/10 mm Hg; however, adequate blood pressure control was not achieved in severe hypertension. A significant hypotensive action developed within 2 weeks of treatment, and control of hypertension was maintained for 2 weeks after sudden interruption of therapy. No patient had postural or postexercise hypotension. The drug appeared to exert its maximum hypotensive effect at the 100-mg dosage. The magnitude of the hypotensive response was related to the initial systolic blood pressure (r = 0.77, p less than 0.01) and the degree of inhibition of exercise tachycardia (r = 0.66, p less than 0.01). The atenolol plasma level and its hypotensive action were not related. Except for impairment of glucose tolerance in diabetic patients, atenolol had minimal side effects.

A comparison of the antihypertensive effect of atenolol (ICI 66 082) and propranolol

Propranolol was given to 30 patients with essential hypertension following randomised, double-blind administration of either placebo or a new cardioselective beta-adrenergic receptor antagonist, atenolol (Tenormin, ICI 66 082). Both atenolol and propranolol caused statistically significant reduction of recumbent and erect blood pressure and heart rate. There were no important differences between these variables on comparison of atenolol and propranolol.