BICALUTAMIDE Drug Interactions: What You Need to Know

7.

Drug Interactions

Clinical studies have not shown any drug interactions between bicalutamide and LHRH analogs (goserelin or leuprolide). There is no evidence that bicalutamide induces hepatic enzymes. In vitro studies have shown that R-bicalutamide is an inhibitor of CYP 3A4 with lesser inhibitory effects on CYP 2C9, 2C19 and 2D6 activity. Clinical studies have shown that with co-administration of bicalutamide, mean midazolam (a CYP 3A4 substrate) levels may be increased 1.5-fold (for C max ) and 1.9-fold (for AUC). Hence, caution should be exercised when bicalutamide is co-administered with CYP 3A4 substrates. In vitro protein-binding studies have shown that bicalutamide can displace coumarin anticoagulants from binding sites. PT/INR should be closely monitored in patients concomitantly receiving coumarin anticoagulants and bicalutamide. Adjustment of the anticoagulant dose may be necessary. [see Warnings and Precautions (5.2) and Adverse reaction (6.2) ]

• R-bicalutamide is an inhibitor of CYP 3A4; therefore, caution should be used when bicalutamide is co-administered with CYP 3A4 substrates. ( 7 )
• PT/INR should be closely monitored in patients already receiving coumarin anticoagulants who are started on bicalutamide. ( 7 )

4.

Contraindications

Bicalutamide tablets are contraindicated in:

• Hypersensitivity Bicalutamide tablets are contraindicated in any patient who has shown a hypersensitivity reaction to the drug or any of the tablet’s components. Hypersensitivity reactions including angioneurotic edema and urticaria have been reported.
• Women Bicalutamide tablets have no indication for women, and should not be used in this population.
• Pregnancy Bicalutamide tablets can cause fetal harm when administered to a pregnant woman [see Use in Specific Populations (8.1) ] .
• Hypersensitivity (4)
• Women (4)
• Pregnancy ( 4 , 8.1 )

5. WARNINGS AND PRECAUTIONS

• Severe hepatic injury and fatal hepatic failure have been observed. Monitor serum transaminase levels prior to starting treatment with bicalutamide, at regular intervals for the first four months of treatment and periodically thereafter, and for symptoms or signs suggestive of hepatic dysfunction. Use bicalutamide with caution in patients with hepatic impairment. (5.1)
• Hemorrhage with Concomitant Use of Coumarin Anticoagulant. Closely monitor the Prothrombin Time (PT) and International Normalized Ratio (INR), and adjust the anticoagulant dose as needed. (5.2)
• Gynecomastia and breast pain have been reported during treatment with bicalutamide 150 mg when used as a single agent. (5.3)
• Bicalutamide is used in combination with an LHRH agonist. LHRH agonists have been shown to cause a reduction in glucose tolerance in males. Consideration should be given to monitoring blood glucose in patients receiving bicalutamide in combination with LHRH agonists. (5.4)
• Monitoring Prostate Specific Antigen (PSA) is recommended. Evaluate for clinical progression if PSA increases. (5.5) 5.1.

Hepatitis

Cases of death or hospitalization due to severe liver injury (hepatic failure) have been reported postmarketing in association with the use of bicalutamide tablets. Hepatotoxicity in these reports generally occurred within the first three to four months of treatment. Hepatitis or marked increases in liver enzymes leading to drug discontinuation occurred in approximately 1% of bicalutamide tablet patients in controlled clinical trials. Serum transaminase levels should be measured prior to starting treatment with bicalutamide tablets, at regular intervals for the first four months of treatment, and periodically thereafter. If clinical symptoms or signs suggestive of liver dysfunction occur (e.g., nausea, vomiting, abdominal pain, fatigue, anorexia, “flu-like” symptoms, dark urine, jaundice, or right upper quadrant tenderness), the serum transaminases, in particular the serum ALT, should be measured immediately. If at any time a patient has jaundice, or their ALT rises above two times the upper limit of normal, bicalutamide tablets should be immediately discontinued with close follow-up of liver function. 5.2. Hemorrhage with Concomitant Use of Coumarin Anticoagulant In the postmarketing setting, there have been reports of excessive prolongation of the prothrombin time (PT) and International Normalized Ratio (INR) days to weeks after the introduction of bicalutamide in patients who were previously stable on coumarin anticoagulants. Some patients had serious bleeding including intracranial, retroperitoneal, and gastrointestinal requiring blood transfusion and/or administration of vitamin K. Closely monitor the PT/INR, and adjust the anticoagulant dose as needed [see Drug Interactions (7) and Adverse Reactions (6.2) ]. 5.3. Gynecomastia and Breast Pain In clinical trials with bicalutamide 150 mg as a single agent for prostate cancer, gynecomastia and breast pain have been reported in up to 38% and 39% of patients, respectively. 5.4.

Glucose

Tolerance A reduction in glucose tolerance has been observed in males receiving LHRH agonists. This may manifest as diabetes or loss of glycemic control in those with pre-existing diabetes. Consideration should therefore be given to monitoring blood glucose in patients receiving bicalutamide in combination with LHRH agonists. 5.5.

Laboratory Tests

Regular assessments of serum Prostate Specific Antigen (PSA) may be helpful in monitoring the patient’s response. If PSA levels rise during bicalutamide therapy, the patient should be evaluated for clinical progression. For patients who have objective progression of disease together with an elevated PSA, a treatment-free period of antiandrogen, while continuing the LHRH analog, may be considered.