Tolerance to sustained isosorbide dinitrate

Duration of action of single oral doses of ISDN or placebo during acute and sustained therapy in 12 patients with stable angina. Compared to placebo, ISDN was associated with an increase in exercise time to angina that persisted for eight hours during acute therapy but was attenuated in degree and lasted for only two hours during sustained therapy. The improvement was dose-dependent up to the 30 mg dose; there was no further improvement with the 60 mg (not shown) and 120 mg doses.