Atazanavir + Methadone = Unknown or no reaction

Effect on Concentration

Atazanavir
No change
Applies within class?
No
Methadone
No change
Applies within class?
No

Pharmacologic Effects

Atazanavir
Effect
N/A
Applies within class?
No
Methadone
Effect
N/A
Applies within class?
No

Interaction History

N/A

Last Updated 30-Jul-2018

Summary

Sources

Atazanavir versus Methadone ^

Study Design

Methadone pharmacokinetic parameters were measured in 16 patients on chronic methadone therapy prior to and after 14 days of daily administration of atazanavir. Steady-state pharmacokinetic values for total, (R)- (active) and (S)- (inactive) isomers of methadone were derived from plasma concentrations versus time data. Symptoms of opiate withdrawal and excess were monitored.

Study Results

For the active isomer (R)-methadone, the ratio of geometric means for coadministration with atazanavir relative to methadone alone were 1.03 [90% confidence interval (CI), 0.95-1.10] for the area under the concentration-time curve (AUC), 0.91 (90% CI, 0.84-1.00) for plasma maximal concentration and 1.11 (90% CI, 1.02-1.20) for plasma trough concentration. Confidence intervals for all three were within the no-effect or bioequivalence range of 0.80-1.25 for (R)-methadone. Inactive (S)-methadone was modestly reduced during atazanavir coadministration. Clinically relevant symptoms of opiate withdrawal or excess were not detected. Exposures to atazanavir were within range of previously reported values.

Study Conclusions

Co-administration of atazanavir with methadone did not result in either a statistically or clinically significant change in the exposure to the active (R)-methadone isomer. Clinically relevant symptoms of opiate withdrawal or excess were not detected in the 16 patients receiving methadone for chronic opiate addiction. Methadone was not found to have any significant effects on atazanavir concentrations.

References

Friedland G, et al.. Lack of an effect of atazanavir on steady-state pharmacokinetics of methadone in patients chronically treated for opiate addiction. Aids. 2005; : 1635-1641.