[Possibility of developing tolerance to the anti-anginal effect of isosorbide dinitrate and verapamil]

Using exercise tests in 22 patients with stable angina of effort, the authors studied the possibility of the development of tolerance to the antianginal effect of isosorbide dinitrate (ID) and verapamil (VP). Within 6-12 weeks of the regular intake of ID, 5 (26%) patients developed complete tolerance, 6 (32%) partial tolerance to the drug. In 8 (42%) patients the effect of ID remained stable. A six-week administration of VP was accompanied by no signs of tolerance to the drug even in the patients who showed tolerance to ID.