CARBAMAZEPINE AND PROTEASE INHIBITORS

Case reports suggest that ritonavir, lopinavir/ritonavir and nelfinavir markedly increases carbamazepine levels resulting in toxicity. Carbamazepine reduces indinavir and tipranavir levels and efficacy, and would also be expected to decrease the levels of other protease inhibitors.
Although the evidence is limited, these interactions seem to be established. It would therefore appear that the combination of carbamazepine and protease inhibitors should be avoided where possible (mainly because of the risk of antiviral treatment failure). If both must be used then extremely close monitoring of both protease inhibitor levels/efficacy and carbamazepine levels/toxicity is warranted. Indicators of carbamazepine toxicity include nausea, vomiting, ataxia and drowsiness. The authors of one report suggest that amitriptyline or gabapentin would be possible alternatives for carbamazepine when used for pain, or valproic acid or lamotrigine for carbamazepine when used for seizures.