The Pharmacokinetics of Methadone Following Co‐Administration with a Lamivudine/Zidovudine Combination Tablet in Opiate‐Dependent Subjects

Abstract
Methadone pharmacokinetics were determined in an open‐label, within subject study in 16 methadone‐maintained, non‐HIV‐infected subjects prior to and following administration of one lamivudine 150‐mg/zidovudine 300‐mgcombi‐nation tablet to determine whether this antiretroviral therapy alters methadone serum concentrations. No significant differences in the mean are aunder the serum concentration‐time curve (AUC0‐24h; 8753 ± 4280 vs. 8641 ± 4431 μg‐h/L), oralclearance(CL/F;9.9± 4.9vs.10.3 ± 5.5 L/h), oral volume of distribution (Vd/F; 647 ± 465 vs. 481 ± 305 L), maximum serum concentration (Cmax; 514 ± 223 vs. 5510 ± 237 μg/L), or terminal elimination half‐life (tl/2; 55.3 ± 61.0 vs. 35.0 ± 17.5 h) were detected. These results suggest that methadone dose change is not likely to be necessary for patients treated with lamivudine/zidovudine combination pharmacotherapy.