Generic Name and Formulations:
Enzalutamide 40mg; soft gelatin caps.
Astellas Pharma US, Inc.
Indications for XTANDI:
Treatment of castration-resistant prostate cancer.
Swallow whole. 160mg once daily. Give concurrent GnRH analog or patient should have had bilateral orchiectomy. Dose modifications: ≥Grade 3 toxicity or intolerable side effect: withhold dose for 1 week or until improvement to ≤Grade 2, then resume at same or reduced dose (120mg or 80mg), if warranted. Concomitant strong CYP2C8 inhibitors: avoid if possible; if co-administration necessary, reduce enzalutamide dose to 80mg once daily. Concomitant strong CYP3A4 inducers: avoid if possible; if co-administration necessary, increase enzalutamide dose to 240mg once daily. When CYP2C8 inhibitor or CYP3A4 inducer is discontinued, return enzalutamide dose to the dose used prior to initiation of the inhibitor or inducer.
Risk of seizure; permanently discontinue if occurs. Discontinue if posterior reversible encephalopathy syndrome (PRES) develops. Monitor for signs/symptoms of ischemic heart disease; discontinue if Grade 3 or 4 develops. Manage CV risk factors (eg, hypertension, diabetes, dyslipidemia). Evaluate for fall and fracture risk; monitor and manage as per established guidelines. Severe renal impairment or ESRD. Embryo-fetal toxicity. Males with female partners of reproductive potential should use effective contraception during treatment and for 3 months after final dose.
Androgen receptor inhibitor.
Avoid concomitant strong CYP2C8 inhibitors (eg, gemfibrozil) if possible; if co-admin unavoidable, reduce dose (see Adult). Avoid concomitant strong CYP3A4 inducers (eg, carbamazepine, phenobarbital, phenytoin, rifabutin, rifampin, rifapentine, St. John’s Wort); if unavoidable, increase dose (see Adult). Antagonizes midazolam (CYP3A4 substrate) and omeprazole (CYP2C19 substrate). May antagonize concomitant drugs with narrow therapeutic indexes metabolized by CYP3A4 (eg, alfentanil, cyclosporine, ergots, fentanyl, pimozide, quinidine, sirolimus, tacrolimus), CYP2C9 (eg, phenytoin, warfarin), CYP2C19 (eg, S-mephenytoin, clopidogrel); avoid. Conduct more INR monitoring if concomitant warfarin cannot be avoided. Caution with concomitant drugs that may lower the seizure threshold.
Asthenia/fatigue, decreased appetite, hot flush, arthralgia, dizziness/vertigo, hypertension, headache, weight decreased; seizure, PRES, ischemic heart disease, falls, fractures, hypersensitivity reactions (permanently discontinue if severe).
Hepatic (CYP2C8, 3A4); 97–98% protein bound.