Protease inhibitors and anticonvulsants.

Due to adverse interactions, manufacturers of four licensed protease inhibitors are recommending that their products not be used with the three most frequently prescribed anticonvulsants: carbamazepine, phenobarbitol, and phenytoin. These adverse interactions and their causes are discussed, suggesting that concomitant administration of protease inhibitors may induce early viral resistance and possibly accelerate HIV progression. Further, ritonavir and nelfinavir use may raise serum levels of these anticonvulsants into toxic ranges. Although not approved for single-agent use in the United States, two anticonvulsants that are theoretically less prone to interact adversely with protease inhibitors are gabapentin and lamotrigine. Protocols to manage patients on protease inhibitors and anticonvulsants are suggested.