Bioavailability of alcohol following oral ingestion in humans
Friday, September 18, 2015 — Poster Session V
- AM Durrani
- S O'Connor
- MH Plawecki
- VA Ramchandani
There has been extensive research on the pharmacokinetics of alcohol following oral ingestion, but almost no information on the oral bioavailability of alcohol in humans. The objective of this study was estimate the bioavailability of alcohol following oral relative to intravenous (IV) administration in non-dependent drinkers. This was a 2-session study in 44 healthy male and female nondependent drinkers. In the first session, subjects ingested an oral alcohol dose (1 g/L total body water (TBW)), after an overnight fast, to achieve a target peak breath alcohol concentration (BrAC) of 80 mg/dl. In the second session, subjects received an IV alcohol infusion designed to achieve the same BrAC profile as that achieved in the first session. The individualized infusion-rate profile was pre-computed using a physiologically-based pharmacokinetic (PBPK) model for alcohol with individualized model parameters. Bioavailability (F) was calculated as (AUCoral / AUCIV) x (DoseIV / Doseoral). Mean (SD) oral bioavailability for alcohol was 0.95 (0.19). F was significantly lower in females and associated with TBW (R2 = 0.17). There was a positive association between F and oral dose (R2 = 0.14), suggesting saturable first-pass metabolism. There was no significant relationship between F and oral dose normalized per L of TBW, indicating that sex differences in first-pass effects may be related to body size and composition. This is one of the first reports on absolute bioavailability of alcohol in non-dependent drinkers. Results indicate almost complete bioavailability of alcohol following oral ingestion in fasted individuals.