Absorption kinetics of sublingually administered propranolol

The absorption of propranolol through the buccal cavity has been investigated in normal healthy male volunteers. Propranolol doses of 10 mg were retained in the mouth for varying lengths of time to investigate the absorption kinetics. Both plasma and oral contents were analyzed. Propranolol was found to be incompletely absorbed (about 40%) from the buccal cavity. The disappearance of propranolol from the oral cavity does not, however, reflect absorption of drug into the blood. Absorption onto or into the buccal mucosa followed first order kinetics with a half life of 1 to 17 minutes, variability being great between subjects. The appearance of drug into the blood was also first order characterized by a half life of 20 to 25 minutes. It was found that uptake from the oral cavity and appearance in the plasma are separate processes with transport into the plasma being the rate limiting step. This data is discussed in terms of previously presented models of buccal absorption.