Acute Drug Testing with Nitrates: Angina Relief during Treadmill Exercise

Abstract

To evaluate the effect of sublingual nitroglycerin (N) and chewable isosorbide dinitrate (I) in patients with angina pectoris, 12 subjects underwent treadmill exercise to the point of onset of angina. At that juncture, N or I or placebo (P) was administered and walking was continued until moderately severe angina recurred. For those patients who completed the initial 10-minute exercise period, testing was repeated until moderately severe angina recurred or until a total test time of three hours elapsed. Retesting ensured that each patient was tested separately with N, I and P within a two-week period. Within the I group, four patients experienced the onset of angina relief (AR) at 10 minutes (') 6 seconds (*) +/- 3' 4" with a mean recurrence time (RT) of 154' 3" +/- 4' 27" (P less than or equal to 0.05), for a significant difference. Within the N group, six patients had AR of 8' 3" +/- 1' 1" with an RT of 49' 39" +/- 1' 15" (P less than or equal to 0.01), for a significant effect. Within the P group, only one patient experienced AR. For all other patients in each group, testing was terminated because of moderately severe angina in the 5-8' period of the first test. In comparing subgroups for RT during I therapy (4 patients) versus N therapy (6 patients), a significant difference was noted (154' 3" +/- 27" versus 49' 39" +/- 1' 15") (P less than 0.05). The data suggest a possible benefit of I in selected patients. The effect may last as long as three to four hours. There is also an enhanced benefit of N with the patient in the upright position. This effect may last as long as 40-50'. Treadmill testing is recommended with nitrate administration to determine which drug (I or N) is the more suitable for the specific patient.