The medical treatment of angina pectoris

A risk-benefit assessment of carvedilol in the treatment of cardiovascular disorders

Carvedilol is a nonselective beta-adrenoceptor blocking vasodilator drug that may be a promising new agent in the management of cardiovascular disease. The rationale for the development of agents of this type is that the alpha-blocking component may overcome the direct vasoconstrictor consequence of beta 2-blockade, whilst the beta-blocker component may inhibit the reflex tachycardia that occurs following alpha-blockade. In clinical trials published to date, carvedilol has been demonstrated to be effective as an antihypertensive agent as monotherapy and also as additional therapy in those patients whose blood pressure cannot be controlled on other standard agents. It is also effective in the management of angina. Carvedilol has beneficial haemodynamic effects in patients with congestive heart failure. beta-Blocker vasodilator drugs of this type may be particularly useful in this condition as the vasodilator component of the drug may overcome the initial negative inotropy of the beta-blocker. In addition, carvedilol possess potentially useful pharmacological actions. In particular, the drug has antimitogenic and free radical scavenging effects that may make it a useful therapy in the long term management of atherosclerotic vascular disease. Its metabolic profile is also favourable, presumably on the basis of its alpha-blocking properties. Thus, beta 2-mediated adverse effects on peripheral vascular tone, glycaemic control and lipid status appear to be offset by the alpha-blocking property of the drug. Carvedilol thus far appears to be well tolerated, with postural dizziness the major adverse effect, especially in the elderly. As with nonselective beta-blockers, carvedilol is contraindicated in patients with asthma.

A risk-benefit assessment of celiprolol in the treatment of cardiovascular disease

Celiprolol is a third-generation beta-adrenoceptor blocker with selective beta 1-antagonist, partial beta 2-agonist and mild alpha 2-antagonist actions. It seems to be as effective as other beta-blockers in the treatment of hypertension and angina pectoris. beta-Blockers have many cardioprotective effects and have been shown to reduce the morbidity and mortality from coronary artery disease in a number of trials. However, there is no good clinical evidence that celiprolol itself has specific cardioprotective properties other than those attributable to this class of drugs. Because of its pharmacological profile, celiprolol is less likely to cause bradycardia, deterioration in cardiac function and other adverse effects mainly caused by beta 2-blockade. Unlike most other beta-blockers, celiprolol has no adverse effects on plasma lipids. It seems to be well tolerated in diabetic patients and patients with renal dysfunction.

Efficacy and safety of perhexiline maleate in refractory angina. A double-blind placebo-controlled clinical trial of a novel antianginal agent

Despite large gains in the medical and surgical treatment of angina pectoris in the past two decades, many patients are refractory to conventional medical therapy and are unsuitable for a first or, more commonly, repeat coronary revascularization procedure. We evaluated the efficacy of perhexiline maleate, a drug with an antianginal mechanism of action in humans that is as yet unknown, by using a randomized double-blind placebo-controlled crossover design in 17 patients with refractory angina who continued to receive maximal antianginal therapy, typically including nitrates, a beta-blocker, and a calcium channel antagonist. In view of perhexiline's potential for hepatic and neurological toxicity, plasma drug levels were monitored and maintained in the 150-600 ng/ml range. Sixty-three percent of patients were judged perhexiline responders by objective exercise testing criteria, as compared with 18% of patients on placebo (p less than 0.05). By blinded review of subjective measures of anginal frequency and severity, 65% of patients noted an improvement while on perhexiline, whereas no patient identified the placebo phase with improvement. Side effects observed in 29% of patients were minor and related to transient elevations of blood levels of more than 600 ng/ml; no patient suffered hemodynamic or cardiac conduction abnormalities attributable to perhexiline. With attention to the pharmacokinetics of perhexiline's elimination in individual patients, this novel antianginal agent seems to be safe and effective and deserves further evaluation in patients already receiving maximal antianginal therapy who are not candidates for revascularization procedures.

Perhexilene: effects on hepatic lysosomal function in rats

1. Perhexilene, a long-acting anti-anginal drug, can induce adverse effects on the liver which may be dose-dependent. At high concentrations, perhexilene causes marked morphological changes in hepatocyte lysosomes. The current study examined the effect of 'therapeutic' doses of perhexilene on hepatic lysosomal function, particularly the biliary release of lysosomal enzymes, using an isolated perfused rat liver (IPRL) model. 2. Pharmacokinetic studies demonstrated that clearance of single doses of perhexilene by the perfused rat liver was dose-dependent and established a 'therapeutic' dose of 0.6 mg using the IPRL. A 5 day pretreatment regimen of 20 mg/kg per day was shown to produce 'therapeutic' perhexilene concentrations of 150-210 ng/ml. 3. At perhexilene concentrations equating the 'therapeutic' range in man, the major effect of perhexilene was at the biliary pole of the hepatocyte. In 5 day pretreatment dose studies, lysosomal enzyme excretion into bile was markedly increased. In single dose studies, the increase in biliary lysosomal enzyme output partially reflected an increase in bile water production which was not seen with the 5 day pretreatment regimen. Hepatic and perfusate lysosomal enzyme activities were not affected. 4. This selective effect of perhexilene on hepatocyte-to-bile lysosomal excretion may reflect intracellular lysosomal drug localization.