Antihypertensive Drugs Evaluated in a Controlled Double-Blind Study

Abstract

Chlorothiazide caused a significant decrease in the systolic and diastolic blood pressure for 6 weeks as compared to a decrease obtained with an oral placebo. A comparable decrease occurred with the administration of hydrochlorothiazide. The combination of hydrochlorothiazide and reserpine maintained a decrease in systolic and diastolic blood pressure for a period of 12 weeks. Whether this effect is a result of the hydrochlorothiazide alone cannot be answered at this phase of the study. The omission of reserpine from the combination of hydrochlorothiazide and reserpine caused an elevation of blood pressure and a return to the pressure of week 0 in each of the 12 patients during periods varying from 2 to 60 weeks. Hydrochlorothiazide and the ergot alkaloids, when given in combination, caused a significant decrease in the systolic and diastolic blood pressure as compared to the blood pressure obtained after giving oral placebo. The decrease in the systolic and diastolic blood pressure following the administration of guanethidine was not significantly different from the following the administration of oral place -bo to those patients with a blood pressure greater than 200/120 mm Hg. Whether or not true pharmacologic effect will continue after placebo effect disappears is currently being studied. The administration of alpha-methyldopa caused a significant decrease throughout the study in the systolic blood pressure but irregularly in the diastolic blood pressure. The administration of an oral placebo to a group of patients whose blood pressure was greater than 150/100 mm Hg but less than 200/120 mm Hg caused no significant decrease in systolic or diastolic blood pressure. By contrast, a significant decrease occurred in the systolic and diastolic blood pressure following the administration of an oral placebo to a group of patients whose blood pressure exceeded 200/ 120 mm Hg. In the group receiving intramuscular injections, a placebo caused a significant decrease in the systolic blood pressure for 139 weeks and in the diastolic blood pressure for 179 weeks. In those receiving the ergot alkaloids, there was a decrease in the systolic blood pressure for 55 weeks and in the diastolic blood pressure for 169 weeks. The establishment of base lines for a placebo effect on blood pressure whether parenterally or orally, is providing standards with which various agents can be compared as to their hypotensive effect.