STUDIES ON METABOLISM OF GUANETHIDINE IN HYPERTENSIVE PATIENTS

The urinary excretion of guanethidine (G) and its metabolites was studied in seven subjects with essential hypertension after a single oral dose of 14C-G and after long-term treatment with oral doses ranging from 10 to 141 mg daily. One metabolite (M1) could be adsorbed on and eluted from cationic exchange resin in the same way as G itself. However, G was extractable into ether from alkaline solutions, whereas M1 remained in the aqueous phase. Both G and M1 were measured by a specific fluorometric method and by radioassay. The urine of patients treated with 14C-G contained more radioactivity than could be accounted for by G and M1, indicating the presence of at least one more metabolite of the drug. © 1969.