Interactive effect of ethanol administration on blood propranolol levels in rats.

Effect of ethanol administration on blood propranolol concentration (BPC) was investigated with rats. By oral administration of 20 mg/kg propranolol hydrochloride together with 1.5 g/kg of ethanol, it was suggested that there might be an increase in blood 4-hydroxypropranolol concentration (BHPC) though BPC did not increase. By oral administration of propranolol 3 hours after oral administration of 1.0 g/kg ethanol, it was suggested that both BPC and BHPC might increase. It was considered that the main mechanisms of increases in BPC and BHPC by ethanol were a rise of intestinal permeability to propranolol and an inhibition of 4-hydroxypropranolol metabolism in hepatic microsomes, respectively.