Drug Interactions between elacestrant and Symfi Lo

GENERALLY AVOID: Coadministration with potent or moderate inducers of CYP450 3A4 may significantly decrease the plasma concentrations of elacestrant, which is primarily metabolized by the isoenzyme. When elacestrant (345 mg single dose) was administered with rifampin, a potent CYP450 3A4 inducer, elacestrant peak plasma concentration (Cmax) and systemic exposure (AUC) decreased by 73% and 86%, respectively. Concomitant use of efavirenz, a moderate CYP450 3A4 inducer, is predicted to decrease elacestrant (345 mg single dose) Cmax and AUC by 44% to 63% and 55% to 73%, respectively. Reduced effectiveness of elacestrant may result.

MANAGEMENT: Coadministration of elacestrant and potent or moderate CYP450 3A4 inducers should be generally avoided. However, some authorities recommend continuing elacestrant without dose adjustment if a strong or moderate CYP450 3A4 inducer must be used for a short duration of time (i.e. less than or equal to 3 days) or intermittently (i.e. treatment periods less than or equal to 3 days separated by at least 2 weeks or 1 week and 5 half-lives of the CYP450 3A4 inducer, whichever is longer).

MONITOR: Coadministration of efavirenz with other agents known to induce hepatotoxicity may potentiate the risk of liver injury. Efavirenz has been associated with hepatotoxicity during postmarketing use. Among reported cases of hepatic failure, a few occurred in patients with no preexisting hepatic disease or other identifiable risk factors.

MANAGEMENT: The risk of hepatic injury should be considered when efavirenz is used in combination with other agents that are potentially hepatotoxic (e.g., acetaminophen; alcohol; androgens and anabolic steroids; antituberculous agents; azole antifungal agents; ACE inhibitors; cyclosporine (high dosages); disulfiram; endothelin receptor antagonists; interferons; ketolide and macrolide antibiotics; kinase inhibitors; minocycline; nonsteroidal anti-inflammatory agents; other HIV reverse transcriptase inhibitors; proteasome inhibitors; retinoids; sulfonamides; tamoxifen; thiazolidinediones; tolvaptan; vincristine; zileuton; anticonvulsants such as carbamazepine, hydantoins, felbamate, and valproic acid; lipid-lowering medications such as fenofibrate, lomitapide, mipomersen, niacin, and statins; herbals and nutritional supplements such as black cohosh, chaparral, comfrey, DHEA, kava, pennyroyal oil, and red yeast rice). Patients should be advised to seek medical attention if they experience potential signs and symptoms of hepatotoxicity such as fever, rash, itching, anorexia, nausea, vomiting, fatigue, malaise, right upper quadrant pain, dark urine, pale stools, and jaundice. Monitoring of liver function tests should occur before and during treatment, especially in patients with underlying hepatic disease (including hepatitis B or C coinfection) or marked transaminase elevations. The benefit of continued therapy with efavirenz should be considered against the unknown risks of significant liver toxicity in patients who develop persistent elevations of serum transaminases greater than five times the upper limit of normal.

MONITOR: Coadministration of efavirenz with other agents known to induce hepatotoxicity may potentiate the risk of liver injury. Efavirenz has been associated with hepatotoxicity during postmarketing use. Among reported cases of hepatic failure, a few occurred in patients with no preexisting hepatic disease or other identifiable risk factors.

MANAGEMENT: The risk of hepatic injury should be considered when efavirenz is used in combination with other agents that are potentially hepatotoxic (e.g., acetaminophen; alcohol; androgens and anabolic steroids; antituberculous agents; azole antifungal agents; ACE inhibitors; cyclosporine (high dosages); disulfiram; endothelin receptor antagonists; interferons; ketolide and macrolide antibiotics; kinase inhibitors; minocycline; nonsteroidal anti-inflammatory agents; other HIV reverse transcriptase inhibitors; proteasome inhibitors; retinoids; sulfonamides; tamoxifen; thiazolidinediones; tolvaptan; vincristine; zileuton; anticonvulsants such as carbamazepine, hydantoins, felbamate, and valproic acid; lipid-lowering medications such as fenofibrate, lomitapide, mipomersen, niacin, and statins; herbals and nutritional supplements such as black cohosh, chaparral, comfrey, DHEA, kava, pennyroyal oil, and red yeast rice). Patients should be advised to seek medical attention if they experience potential signs and symptoms of hepatotoxicity such as fever, rash, itching, anorexia, nausea, vomiting, fatigue, malaise, right upper quadrant pain, dark urine, pale stools, and jaundice. Monitoring of liver function tests should occur before and during treatment, especially in patients with underlying hepatic disease (including hepatitis B or C coinfection) or marked transaminase elevations. The benefit of continued therapy with efavirenz should be considered against the unknown risks of significant liver toxicity in patients who develop persistent elevations of serum transaminases greater than five times the upper limit of normal.

MONITOR: Coadministration with elacestrant may increase the plasma concentrations of drugs that are substrates of P-glycoprotein (P-gp) and/or breast cancer resistance protein (BCRP). When the P-gp substrate digoxin was administered with elacestrant (345 mg single dose), digoxin peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 1.3-fold and 1.1-fold, respectively. The Cmax and AUC of rosuvastatin, a BCRP substrate, increased by 1.5-fold and 1.2-fold, respectively, when administered with the same dose of elacestrant. Adverse reactions associated with P-gp and BCRP substrates may be increased.

MANAGEMENT: Caution is advised if elacestrant is coadministered with substrates of P-gp and/or BCRP, particularly sensitive substrates or those with a narrow therapeutic range. The prescribing information for concomitant medications should be consulted to assess the benefits versus risks of coadministration and for any dosage adjustments that may be required.