Methadone dosing data

The reduction in stavudine levels and the changes in abacavir peak levels with methadone are probably not clinically relevant, but again, further data are required. The reports with abacavir suggest that it would be prudent to monitor methadone dose requirements when this drug is started. Tenofovir does not appear to affect methadone levels. 

The immunotoxic potential of methadone has been studied in rats that were given methadone 20 or 40 mg/kg/ day for 6 weeks (33). The higher dose increased serum IgG concentrations but had no effect on functioning of the immune system. This suggests that methadone is not associated with immunotoxicity, even at dosages that were very high compared with usual clinical doses. The author advised caution in extrapolating animal data to humans. 

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