Sirolimus is known to be a substrate for both cytochrome P-450 3A4 (CYP3A4) and p‑glycoprotein (P-gp). Inducers of CYP3A4 and P-gp may decrease sirolimus concentrations whereas inhibitors of CYP3A4 and P-gp may increase sirolimus concentrations.
Use with Cyclosporine
Cyclosporine, a substrate and inhibitor of CYP3A4 and P-gp, was demonstrated to increase sirolimus concentrations when co-administered with sirolimus. In order to diminish the effect of this interaction with cyclosporine, it is recommended that Rapamune be taken 4 hours after administration of cyclosporine oral solution (MODIFIED) and/or cyclosporine capsules (MODIFIED). If cyclosporine is withdrawn from combination therapy with Rapamune, higher doses of Rapamune are needed to maintain the recommended sirolimus trough concentration ranges [see Dosage and Administration (2.1), Clinical Pharmacology (12.3) ].
Strong Inducers and Strong Inhibitors of CYP3A4 and P-gp
Avoid concomitant use of sirolimus with strong inducers (e.g., rifampin, rifabutin ) and strong inhibitors (e.g., ketoconazole, voriconazole, itraconazole, erythromycin, telithromycin, clarithromycin) of CYP3A4 and P-gp. Alternative agents with lesser interaction potential with sirolimus should be considered [see Warnings and Precautions (5.16), Clinical Pharmacology (12.3) ].
Because grapefruit juice inhibits the CYP3A4-mediated metabolism of sirolimus, it must not be taken with or be used for dilution of Rapamune [see Dosage and Administration (2.7), Drug Interactions (7.3), Clinical Pharmacology (12.3) ].
Inducers or Inhibitors of CYP3A4 and P-gp
Exercise caution when using sirolimus with drugs or agents that are modulators of CYP3A4 and P-gp. The dosage of Rapamune and/or the co-administered drug may need to be adjusted [see Clinical Pharmacology (12.3) ].
- Drugs that could increase sirolimus blood concentrations:
Bromocriptione, cimetidine, cisapride, clotrimazole, danazol, diltiazem, fluconazole, HIV-protease inhibitors (e.g., ritonavir, indinavir), metoclopramide, nicardipine, troleandomycin, verapamil
- Drugs and other agents that could decrease sirolimus concentrations:
Carbamazepine, phenobarbital, phenytoin, rifapentine, St. John's Wort (Hypericum perforatum)
- Drugs with concentrations that could increase when given with Rapamune:
Immunosuppressants may affect response to vaccination. Therefore, during treatment with Rapamune, vaccination may be less effective. The use of live vaccines should be avoided; live vaccines may include, but are not limited to, the following: measles, mumps, rubella, oral polio, BCG, yellow fever, varicella, and TY21a typhoid.
Reports of overdose with Rapamune have been received; however, experience has been limited.In general, the adverse effects of overdose are consistent with those listed in the adverse reactions section [see Adverse Reactions (6) ].
General supportive measures should be followed in all cases of overdose. Based on the low aqueous solubility and high erythrocyte and plasma protein binding of sirolimus, it is anticipated that sirolimus is not dialyzable to any significant extent. In mice and rats, the acute oral LD50 was greater than 800 mg/kg.