Drug Interactions between fosphenytoin and seladelpar

MONITOR: Concurrent use with CYP450 2C9 inducers that are also able to induce CYP450 2C8 and/or 3A4 may reduce the systemic exposure and clinical effects of seladelpar, which is primarily metabolized via CYP450 2C9 and to a lesser extent by CYP450 2C8 and 3A4. Coadministration of the weak CYP450 3A4 and potent CYP450 2C9 inducer, carbamazepine (titrated to 300 mg twice daily x 8 days) decreased the systemic exposure (AUC) and maximum plasma concentration (Cmax) of a single dose of seladelpar (10 mg) by approximately 44% and 24%, respectively. Clinical data with agents also capable of CYP450 2C8 induction, or differing strengths of CYP450 2C9 and/or 3A4 induction are not available.

MANAGEMENT: The potential for diminished pharmacologic effects of seladelpar should be considered if coadministration with agents capable of inducing CYP450 2C9, as well as CYP450 2C8 and/or 3A4 is clinically necessary. Additional monitoring of the patient's biochemical response (e.g., alkaline phosphatase (ALP) and bilirubin) to seladelpar may be advisable.