Comparison of guanadrel and guanethidine efficacy and side effects.

Eighteen patients with essential hypertension uncontrolled by hydrochlorothiazide alone were randomly assigned to receive additional therapy with either guanadrel sulfate or guanethidine sulfate. The frequencies of morning orthostatic faintness, other orthostatic faintness, and diarrhea were twice as high in eight patients treated with guanethidine as in ten patients treated with guanadrel in a six-month comparison. The two drugs reduced blood pressure about equally well. In light of the efficacy without severe side effects, guanadrel may be an agent for step II therapy of hypertension.