OPIOIDS AND PROTEASE INHIBITORS - ALFENTANIL AND FENTANYL

Ritonavir markedly increases the levels of fentanyl, and markedly increases alfentanil- induced miosis. Other protease inhibitors may also be expected to interact similarly but there seems little documented about these effects in practice. Care should also be taken if ritonavir is used with other protease inhibitors as a pharmacokinetic enhancer.
Concurrent use should be monitored. Dose reductions of fentanyl (given by any route) or alfentanil may be required, particularly with long-term use.