Isosorbide-5-mononitrate--effective monotherapy in chronic stable angina.

Isosorbide-5-mononitrate (ISMN) is not subject to first-pass metabolism and has more predictable blood concentrations than isosorbide dinitrate. In order to evaluate its efficacy as monotherapy in patients with chronic stable angina, 14 patients were studied. All had angiographically proven coronary artery disease and were limited by angina on a treadmill exercise test. After a 2-week placebo period ISMN was administered in a single-blind fashion with the dosage being titrated at 2-week intervals. The dosage increments were 20 mg once daily, 20 mg twice daily, 40 mg once daily and 40 mg twice daily. Patients were assessed subjectively by anginal attack rate and glyceryl trinitrate (GTN) consumption and objectively by treadmill exercise testing at 12 hours post dosage. ISMN increased the exercise ability significantly on all dosage regimes. However, a significant reduction in ST depression occurred only with the twice-daily regime. The increased exercise performance was associated with a significant decrease in anginal attack rate and GTN consumption from the 20 mg b.i.d. increment. ISMN is an effective antianginal agent with a more favourable profile in twice-daily dosage. Whilst no significant differences emerged between 20 mg and 40 mg twice daily, individual variation occurred, indicating a need for dosage flexibility.