Premium
Codeine kinetics as determined by radioimmunoassay
Author(s) -
Findlay John W. A.,
Butz Robert F.,
Welch Richard M.
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/cpt1977224439
Subject(s) - codeine , pharmacokinetics , bioavailability , radioimmunoassay , crossover study , oral administration , pharmacology , intramuscular injection , analgesic , phenacetin , medicine , chemistry , anesthesia , morphine , placebo , alternative medicine , pathology
Radioimmunoassay (RIA) was used to determine several pharmacokinetic parameters of codeine in man, including the relative bioavailability after oral and intramuscular administration. The study followed a crossover design in 6 healthy, young (18 to 21 yr), male volunteers. Three subjects received 65 mg codeine phosphate orally in an analgesic mixture which also contained aspirin, phenacetin, and caffeine. At the same time a similar group received an equivalent dose of codeine phosphate in a single intramuscular injection. Two weeks later the study was repeated so that each group received the alternate treatment. Plasma samples were collected at various times after drug administration, and codeine concentrations were determined by a specific RIA procedure. The procedure can detect less than 50 pg of codeine. Following intramuscular administration, peak plasma concentrations (194 to 340 nglm!) were observed between 0.25 to 1 hr; after oral dosing, peak codeine plasma concentrations (102 to 140 nglmt) appeared within 0.75 to I hr. The mean plasma t1;2 and volume of distribution of codeine following intramuscular injection were 3.32 hr and 5. I Llkg, respectively. Oral, relative to intramuscular, bioavailability qf codeine, based on areas under the codeine plasma curves, was 42% to 71% (mean, 53%).