Drug Interactions between Lypqozet and pexidartinib

GENERALLY AVOID: Serious cases of hepatotoxicity, some fatal, have occurred in patients treated with pexidartinib. Concomitant use of other potentially hepatotoxic agents may potentiate the risk of liver injury. The mechanism of hepatotoxicity is unknown, its occurrence cannot be predicted, and it is unknown whether liver injury occurs in the absence of increased transaminases. In one study, 5% of patients who received pexidartinib developed signs of serious liver injury (elevated serum transaminases greater than 3 times the upper limit of normal (ULN) and total bilirubin greater than 2 times ULN). In these patients, peak ALT ranged from 6 to 9 times ULN, peak total bilirubin ranged from 2.5 to 15 times ULN, and ALP was greater than 2 times ULN. Liver transaminases and total bilirubin improved to less than 2 times ULN in these patients 1 to 7 months after discontinuing pexidartinib.

MANAGEMENT: The use of pexidartinib with other potentially hepatotoxic agents should be avoided. Patients treated with pexidartinib should have liver function tests, including AST, ALT, total bilirubin, direct bilirubin, ALP, and gamma-glutamyl transferase (GGT), prior to initiation of pexidartinib, weekly for the first 8 weeks, every 2 weeks for the next month, and every 3 months thereafter. Pexidartinib therapy may require a dosage reduction, to be withheld, or permanently discontinued based on the severity of the hepatotoxicity. A recurrence of increased serum transaminases, bilirubin, or ALP may occur upon rechallenge with a reduced dose of pexidartinib. Liver function tests should be performed weekly for the first month after rechallenge. 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.

MONITOR: Coadministration with ezetimibe may rarely increase the risk of myopathy and serum transaminase elevations associated with HMG-CoA reductase inhibitors (i.e., statins). The mechanism of interaction is unknown. A case report describes two patients whose serum creatine kinase increased after ezetimibe was added to their statin therapy (atorvastatin and fluvastatin, respectively). One of the patients also developed myalgia and tendinopathy, which resolved promptly after withdrawal of both drugs. Statin therapy was subsequently reintroduced at the previous dosage without incident. In the other patient, serum creatine kinase returned to normal within 4 weeks after discontinuation of ezetimibe while the statin was continued. On the contrary, no cases of myopathy or tendinopathy occurred in a study of 33 hypercholesterolemic patients treated with ezetimibe and atorvastatin or simvastatin. There were also no reports of myopathy or significant increases in serum creatine kinase in a study of 32 subjects treated with ezetimibe and fluvastatin. In controlled clinical studies, the incidence of consecutive elevations (greater than 3 times the upper limit of normal) in serum transaminases was 1.3% for patients treated with ezetimibe in combination with a statin versus 0.4% for patients treated with a statin alone. These elevations were generally asymptomatic, not associated with cholestasis, and returned to baseline after discontinuation of therapy or with continued treatment.

MANAGEMENT: Until further information is available, use of a statin in combination with ezetimibe should be approached with caution. Some authorities consider concomitant use to be contraindicated in patients with active liver disease or unexplained persistent elevations in serum transaminases. Patients should be advised to promptly report to their physician any unexplained muscle pain, tenderness, or weakness, particularly if accompanied by malaise or fever. The drugs should be discontinued if creatine kinase is markedly elevated in the absence of strenuous exercise or if myopathy is otherwise suspected or diagnosed. In addition, liver function tests should be performed at initiation of therapy and according to the recommendations of the HMG-CoA reductase inhibitor.

MONITOR: Coadministration with inhibitors of the organic anion transporting polypeptides (OATP) 1B1 and/or 1B3 may increase the plasma concentrations and effects of ezetimibe, which is a substrate of these hepatic uptake transporters. When a single dose of ezetimibe was taken with steady state bempedoic acid, a weak inhibitor of OATP1B1 and 1B3, the systemic exposure (AUC) and maximum plasma concentration (Cmax) of total ezetimibe (ezetimibe and its glucuronide form) increased by 1.6- and 1.8-fold, respectively. These increases were not considered clinically significant. When coadministered in patients on cyclosporine, a stronger OATP1B1 and 1B3 inhibitor, the AUC and Cmax of total ezetimibe increased by approximately 3.4- and 3.9-fold, respectively, compared to the exposure observed in a historical healthy control population. In another study, a renal transplant patient with severe renal dysfunction who was receiving multiple medications, including cyclosporine, demonstrated a 12-fold greater exposure to total ezetimibe compared to healthy subjects. The exact mechanism of the interaction with cyclosporine is unknown, but its ability to inhibit OATP1B1 and 1B3 may play a role. Data are not available for all inhibitors of OATP1B1 and/or 1B3 with ezetimibe.

MANAGEMENT: Caution and additional monitoring may be advisable if ezetimibe is used concurrently with OATP1B1 and/or 1B3 inhibitors. Additional monitoring of liver enzymes and creatine kinase (CK) may be necessary. Patients should also be advised to promptly report unexplained muscle pain, tenderness, or weakness to their healthcare provider.