Influence of concomitant drugs on methadone elimination half-life in patients under a maintenance treatment.
Methadone elimination half-life was determined in 18 patients under maintenance treatments and found to range from 2.05 to 49.6 h. A study of potential correlations between this parameter and the presence of concomitant drugs, inhibitors or inducers of cytochrome P450, revealed an increase or decrease of methadone elimination half-life, respectively. Twenty-four-hour urinary excretion of methadone was determined in three patients, who were found to release 22.3-49.8% of the dose taken. The amount excreted varied with the chemical form (unaltered drug or its main metabolite) in the three cases. No statistically significant correlation was found between urine pH and the elimination half-life (p < 0.50).
Lucas
A. C. S.
AC
Institute of Legal Medicine, Forensic Toxicology Service, Faculty of Medicine, Santiago de Compostela, Spain.
Bermejo
A. M.
AM
Tabernero
M. J.
MJ
Fernández
P.
P
Cámpora
P.
P