GUANETHIDINE AND BETHANIDINE IN MANAGEMENT OF HYPERTENSION

1. 1. Guanethidine is a potent, orally effective sympathetic-blocking drug which also blocks the cardioaccelerator fibers. It has no direct effect upon parasympathetic nerve transmission. 2. 2. The major effect of guanethidine is produced by: (A) blocking the release of norepinephrine at the sympathetic nerve endings; and (B) partial depletion of norepinephrine stores in the heart and periphery. 3. 3. The clinical effects of the drug in hypertensive patients are arteriolar and venous dilatation, resulting in a fall in cardiac output and blood pressure, especially in the upright position. 4. 4. Side effects include gastrointestinal symptoms and failure of ejaculation. Orthostatic hypotension, weakness, and bradycardia are indications of excessive drug effect. 5. 5. Guanethidine, in combination with diuretics and Rauwolfia drugs, is effective in the treatment of the moderately severe and severely hypertensive patient. The drug should not be used in patients with mild hypertension, or as the sole therapy, because of its potency and occasional difficulty in dosage regulation. Dosage must be adjusted carefully until a blood pressure response or side effects occur. © 1969.