With depleted catecholamines, guanethidine can directly depress the myocardium and can cause an increase in the sensitivity of tissues to catecholamines. Slowly excreted due to extensive tissue binding. The use of a thiazide diuretic may increase the effectiveness of guanethidine and reduce the incidence of edema. Also used for renal hypertension, including that secondary to pyelonephritis, renal artery stenosis, and renal amyloidosis. Use with caution in hypertensive clients with renal disease and nitrogen retention or increasing BUN levels.
Fever decreases dosage requirements.
During prolonged therapy, cardiac, renal, and blood tests should be performed. Used with caution in peptic ulcer. Safety and efficacy have not been determined in children. Rarely, fatigue, psychic depression. Less commonly, angina.