Premium
Bioavailability and first‐pass metabolism of oral pentazocine in man
Author(s) -
Ehrnebo Mats,
Boreus Lars O.,
Lonroth Ulla
Publication year - 1977
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1002/cpt1977226888
Subject(s) - bioavailability , pentazocine , oral administration , pharmacology , volume of distribution , pharmacokinetics , medicine , first pass effect , anesthesia , analgesic
The bioavailability of oral pentazocine was studied in 5 healthy volunteers. Plasma concentrations were determined from 30 min up to 6 hr following oral administration (two 50‐mg tablets) and, at other occasions, after intravenous injection of 30 mg pentazocine. The average bioavailability was found to be 18.4 ± 7.8% (SD, n = 5). It is shown that this low bioavailability depend almost entirely on the first‐pass metabolism of pentazocine following oral administration by application of intravenous clearance concepts. The average beta‐phase half‐life was about the same following intravenous administration, 203 ± 71 (SD, n = 5) min as following oral administration, 177 ± 34 (SD, n = 5) min, with a total volume of distribution of 5.56 ± 1.63 (SD, n = 5) Llkg. It is suggested that the variations in bioavailability of orally administered pentazocine have the potential to contribute to variations in pharmacologic effects in patients.