MECHANISM OF ACTION
Carbamazepine, phenobarbital, and phenytoin may induce
the metabolism of delavirdine(1) and etravirine(2) by CYP P-450.
DISCUSSION
In a study in 8 subjects, administration of various doses of
carbamazepine, phenytoin, and phenobarbital with delavirdine (300-400 mg 3
times daily) decreased the minimum concentration (Cmin) of delavirdine by
90%.(1)
CLINICAL EFFECTS
Concurrent use of delavirdine(1) or etravirine(2) with
carbamazepine, phenobarbital, or phenytoin may result in sub-therapeutic
levels of the non-nucleoside reverse transcriptase inhibitor (NNRTI) and the
development of resistance to NNRTI's.
SEVERITY LEVEL
1-Contraindicated Drug Combination: This drug combination
is contraindicated and generally should not be dispensed or administered to
the same patient.
PATIENT MANAGEMENT
The US manufacturers of delavirdine(1) and etravirine
(2) state that these agents should not be used in combination with
carbamazepine, phenobarbital, or phenytoin.
PREDISPOSING FACTORS
None determined.
REFERENCES