Potential Methadone Interaction?

• In one case series (n=14), nelfinavir shown to decrease methadone levels by 29-47%

  • however, no Sx withdrawal noted in any of subjects

• Clinical significance:

  • expect ? levels within 1-2 weeks after starting ARVs
  • patient already on ARVs for 3 weeks; no signs of methadone withdrawal
  • therefore, may not need to adjust methadone dose

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Methadone is partly metabolized by CYP3A and glucuronyl transferase. While nelfinavir is a CYP3A inhibitor, it also induces the activity of glucuronyl transferase. In clinical practice, 29-47% ? methadone concentrations have been noted when nelfinavir was given to patients on stable methadone dosages. However, no symptoms of methadone withdrawal were observed in these subjects.

• Hsyu et al., CROI 2000, abstract #87

• Beauverie et al. AIDS 1998;12:2510-1.

Monitor for symptoms of methadone withdrawal; adjustment of methadone dosage may be necessary.