Ensitrelvir

Co-administration of XOCOVA can alter the plasma concentrations of other drugs, and other drugs may alter the plasma concentrations of XOCOVA. Consider the potential for drug interactions prior to and during XOCOVA use and review concomitant medications during XOCOVA use. ( 4 , 5.2 , 7 , 12.3 )

7.1 Potential for XOCOVA to Affect Other Drugs Ensitrelvir is a strong inhibitor of CYP3A and an inhibitor of P-gp and BCRP. Co-administration of XOCOVA with drugs that are primarily metabolized by CYP3A or are transported by P-gp or BCRP may result in increased plasma concentrations of such drugs and increase the risk of adverse events [see Contraindications (4) , Warnings and Precautions (5.2) , Drug Interactions (7.3) , and Clinical Pharmacology (12.3) ] . For drugs that are CYP3A substrates and contraindicated with XOCOVA, initiation of XOCOVA should be considered only after careful evaluation of relevant clinical and pharmacokinetic factors related to the concomitant medication.

In addition, re-initiation of contraindicated CYP3A substrates should be considered based on an assessment of the duration of CYP3A inhibition and patient‑specific considerations. Refer to individual drug prescribing information for additional information.

7.2 Potential for Other Drugs to Affect XOCOVA Ensitrelvir is a CYP3A substrate; therefore, drugs that induce CYP3A may decrease ensitrelvir plasma concentrations and reduce XOCOVA therapeutic effect [see Drug Interactions (7.3) and Clinical Pharmacology (12.3) ] . Therefore, use of XOCOVA with strong CYP3A4 inducers is contraindicated [see Contraindications (4) ] . No dose adjustment is recommended when XOCOVA is used concomitantly with moderate or weak CYP3A inducers [see Warnings and Precautions (5.2) ] . Refer to individual drug prescribing information for additional information.

7.3 Established and Other Potentially Significant Drug Interactions Table 1 provides examples of drugs that are contraindicated with XOCOVA [see Contraindications (4) and Warnings and Precautions (5.2) ] . Table 1 is provided as a guide and is not a comprehensive list of all possible drugs that may interact with XOCOVA. The healthcare provider should consult other appropriate resources, such as the prescribing information for the interacting drug, for comprehensive information on dosing and monitoring with concomitant use of a strong CYP3A inhibitor, like XOCOVA [see Drug Interactions (7.1) ].

Table 1 Drugs Contraindicated with XOCOVA due to Risk of Potentially Serious or Fatal Interaction [see Contraindications (4) ] Drug Class Drug(s) within Class Effect on Drug Concentration Clinical Comment Antiarrhythmics quinidine ↑ antiarrhythmic Co-administration is contraindicated due to potential for cardiac arrhythmias. Anticancer drugs apalutamide, enzalutamide ↓ ensitrelvir Co-administration is contraindicated due to potential loss of virologic response. Anticonvulsants carbamazepine See Clinical Pharmacology (12.3) , phenytoin ↓ ensitrelvir Co-administration is contraindicated due to potential loss of virologic response.

Antigout agents colchicine ↑ colchicine Co-administration is contraindicated due to potential for serious and/or life-threatening reactions in patients with renal and/or hepatic impairment. Antimycobacterials rifampin ↓ ensitrelvir Co-administration is contraindicated due to potential loss of virologic response. Antipsychotics lurasidone, pimozide ↑ lurasidone, pimozide Co-administration is contraindicated due to serious and/or life-threatening reactions, such as cardiac arrhythmias. Cardiovascular drugs eplerenone, ivabradine ↑ eplerenone, ivabradine Co-administration is contraindicated.

Cystic fibrosis transmembrane conductance regulator potentiators lumacaftor/ivacaftor ↓ ensitrelvir Co-administration is contraindicated due to potential loss of virologic response. Ergot derivatives dihydroergotamine, ergotamine, methylergonovine ↑ dihydroergotamine, ergotamine, methylergonovine Co-administration is contraindicated due to potential for acute ergot toxicity characterized by vasospasm and ischemia of the extremities and other tissues, including the central nervous system. Herbal products (for depression) St. John's wort ↓ ensitrelvir Co-administration is contraindicated due to potential loss of virologic response.

HMG-CoA reductase inhibitors (statins) simvastatin ↑ simvastatin Co-administration is contraindicated. Discontinue use of simvastatin at least 12 hours prior to initiation of XOCOVA. Immunosuppressants voclosporin ↑ voclosporin Co-administration is contraindicated due to potential for acute and/or chronic nephrotoxicity. Microsomal triglyceride transfer protein (MTTP) inhibitors lomitapide ↑ lomitapide Co-administration is contraindicated due to potential for hepatotoxicity and gastrointestinal adverse reactions.

Mineralocorticoid receptor antagonists finerenone ↑ finerenone Co-administration is contraindicated due to potential for serious adverse reactions, including hyperkalemia, hypotension, and hyponatremia. Sedatives triazolam ↑ triazolam Co-administration is contraindicated.

8.1 Pregnancy Risk Summary Based on animal reproduction studies, XOCOVA may cause fetal harm when administered to a pregnant woman. Embryofetal toxicity (including skeletal malformations and embryofetal lethality) was observed in rabbits during the period of organogenesis at ensitrelvir exposures 7 times the human exposures at the recommended human dose (RHD). In rats, fetal growth retardation, low fetal body weight, and skeletal variations were observed during the period of organogenesis at ensitrelvir exposures 9 times the RHD.

In addition, lethality, low body weight, and retardation of morphological development were observed in pre-weaning pups during gestation and lactation at ensitrelvir exposures 9 times the RHD (see Data ) . Advise pregnant women and females of reproductive potential that XOCOVA may cause fetal harm. The available clinical data on the use of XOCOVA during pregnancy are insufficient to identify a drug-associated risk of major birth defects, miscarriage, or other adverse maternal or fetal outcomes. The background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a risk of birth defects, loss, and other adverse outcomes.

In the general population in the United States, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Data Animal Data In an embryofetal development study in pregnant rabbits, ensitrelvir was administered at oral doses of 30, 100, or 300 mg/kg/day on gestation days (GD) 6-19. Embryofetal lethality, skeletal malformations and variations, abortion, and post-implantation loss were observed with maternal toxicity (decreased food consumption and body weight and body weight gain) at doses ≥100 mg/kg/day.

Malformations of the axial skeleton included fused sternebra, branched rib, fused cervical centrum, supernumerary thoracic vertebra, fused thoracic arch, and fused caudal centrum. Skeletal variations included splitting of the thoracic centrum and increased frequencies of full supernumerary rib and/or supernumerary lumbar vertebra. No effects were observed at 30 mg/kg/day, which is estimated to be 3 times the human exposure at the RHD based on the area under the curve (AUC). In a second embryofetal development study in pregnant rabbits, ensitrelvir was administered at 300 mg/kg/day on GD 6-9, 10-12, 13-15, and 16-19.

Similar malformations of the axial skeleton were observed, with most of the abnormalities present in animals dosed on GD 6-9; maternal toxicity (presenting as…