A clinical trial of penta-erythritol tetranitrate, a khellin derivative (recordil), and iproniazid in angina of effort.

That there is room for improvement in the medicinal treatment of angina of effort, no one will dispute. The clinical trial to be described was designed to test the efficacy of a khellin derivative, iproniazid, and the already widely used penta-erythritol tetranitrate, in the relief of anginal pain. THE DRUGS Penta-erythritol tetranitrate (P.E.T.N.) has the chemical formula CH20NO2 CH2ONO2 C CH2ONO2 CH2ONO2 It was first introduced into medical practice in Sweden during the recent war, and has been subjected to a considerable number of clinical trials (Balatre et al. its efficacy have differed widely and this is no doubt largely due to the different criteria and techniques of investigation employed. In some of the recorded trials, the results have been based on exercise tolerance tests, and the cardiographic changes and the onset and severity of pain were taken as the criteria by which to compare the drug either with a placebo or with no treatment at all. In other trials, criteria included the patients' own impressions, and their records of attacks of pain and consumption of nitroglycerine tablets over a period of weeks. In general, the use of controls has not been uniform, nor has a "double-blind" technique been employed as a means of eliminating observer error. Where exercise tolerance tests were used, the results were largely favourable to the drug Riseman et al., 1958), while in other trials, results were less encouraging, particularly where more stringent criteria and use of controls were employed. Weitzman (1953), whose use of controls did not include a "double-blind" technique, found "unquestionable and sustained improvement in one-fifth of the patients tested," while Fife et al. (1958), employing a "double-blind" method, found the superiority of the drug to a placebo "at best marginal." Penta-erythritol tetranitrate is said to be more effective when given before, rather than after food, and in larger, rather than smaller dose, although side effects have been troublesome with the larger amounts