Trapidil is as effective as isosorbide-dinitrate for treating stable angina pectoris: a multinational, multicenter, double-blind, randomized study.

OBJECTIVE

Nitrates have long been used in the treatment of stable angina pectoris. We set out to show that trapidil, a triazolo-pyrimidine with a mode of action different from that of nitrates, is not inferior to isosorbide-dinitrate (ISDN) in the treatment of this clinical syndrome.

PATIENTS AND METHODS

We studied the efficacy of 200 mg trapidil (t.i.d.) vs. ISDN (20 mg b.i.d.) in patients with chronic stable angina treated for 12 weeks. The therapeutic effect was measured in terms of responder rate as change in total exercise time (TET) by at least 60 seconds using the bicycle ergometer test.

RESULTS

A total of 648 patients were included in the study. Responder rates in the Per- Protocol (PP) population (n = 529) were 50.4% (n = 133) in the trapidil group and 52.5% (n = 139) in the ISDN group (p = 0.233). As the lower non-inferiority limit (-15%) was clearly excluded from the 95% CI (pp: -10.6%, +6.4%; ITT -9.7%, 5.7%), non-inferiority of trapidil compared to ISDN can be concluded. Trapidil 200 mg t.i.d. combined with short-acting NTG prn as rescue medication over 12 weeks in subjects with chronic stable angina pectoris proved to have similar effects on TET and on other clinical endpoints as ISDN 20 mg b.i.d. The secondary efficacy analyses did not reveal any clinically relevant differences between treatment groups, and were not in conflict with the non-inferiority claim. Patients in the ISDN group had significantly more headache (34.1%; n = 110) compared to those taking trapidil (19.3%, n = 62; p <0.0001).

CONCLUSIONS

Overall results of this study show that both drugs are equally effective and safe for the short-term treatment of patients with chronic stable angina pectoris and that trapidil can be considered as therapeutically equivalent to ISDN.