Dose-response effect of sublingual captopril in hypertensive crises

Forty-one patients, presenting in the Emergency Service of the Hospital General y Clinico, Tenerife, with symptoms of hypertensive crisis and supine diastolic blood pressure (DBP) greater than 120 mm Hg, were studied. They received 12.5 mg of sublingual captopril and 30 minutes later, if diastolic blood pressure (DBP) was not 100 mm Hg or less, the same dose was repeated by the same route. Supine systolic blood pressure (SBP), DBP and heart rate (HR) were monitored at 0, 5, 10, 15, 30, 45, 60, and 120 minutes after each administration of captopril. In 27 patients (66%) had a satisfactory response (DBP less than or equal to 100 mm Hg), after a single dose, less than 30 minutes after administration, which persisted at 120 minutes. In 14, a second administration was necessary after 30 minutes, and a satisfactory response to the second dose, defined again as DBP reaching values of 100 mm Hg or less, was achieved in 12 of them (29% of the total group). In two patients (5% of total) no full response was obtained. The observed pattern of response suggests that a sublingual dose of 25 mg of captopril is the minimum effective dose, but it is also possible that administration of 12.5 mg of sublingual captopril at 10 to 15 minute intervals, perhaps up to a maximum dose of 37.5 mg, might be considered as an alternative treatment in hypertensive crises.