Drug Interactions for ABIRATAJ

Prostate and other male cancers

Drugs That Inhibit Or Induce CYP3A4 Enzymes

Based on in vitro data, Abirataj is a substrate of CYP3A4.

In a dedicated drug interaction trial, co-administration of rifampin, a strong CYP3A4 inducer, decreased exposure of abiraterone by 55%. Avoid concomitant strong CYP3A4 inducers during Abirataj treatment. If a strong CYP3A4 inducer must be co-administered, increase the Abirataj dosing frequency [see DOSAGE AND ADMINISTRATION and CLINICAL PHARMACOLOGY].

In a dedicated drug interaction trial, co-administration of ketoconazole, a strong inhibitor of CYP3A4, had no clinically meaningful effect on the pharmacokinetics of abiraterone [see CLINICAL PHARMACOLOGY].

Effects Of Abiraterone On Drug Metabolizing Enzymes

Abirataj is an inhibitor of the hepatic drug-metabolizing enzymes CYP2D6 and CYP2C8. In a CYP2D6 drug-drug interaction trial, the Cmax and AUC of dextromethorphan (CYP2D6 substrate) were increased 2.8- and 2.9-fold, respectively, when dextromethorphan was given with abiraterone acetate 1,000 mg daily and prednisone 5 mg twice daily. Avoid co-administration of abiraterone acetate with substrates of CYP2D6 with a narrow therapeutic index (e.g., thioridazine). If alternative treatments cannot be used, consider a dose reduction of the concomitant CYP2D6 substrate drug [see CLINICAL PHARMACOLOGY].

In a CYP2C8 drug-drug interaction trial in healthy subjects, the AUC of pioglitazone (CYP2C8 substrate) was increased by 46% when pioglitazone was given together with a single dose of 1,000 mg abiraterone acetate. Therefore, patients should be monitored closely for signs of toxicity related to a CYP2C8 substrate with a narrow therapeutic index if used concomitantly with Abirataj [see CLINICAL PHARMACOLOGY].