Leflunomide

Teriflunomide may decrease peak INR by approximately 25%. Close monitoring of INR is required with concomitant use.

Exposure to alosetron may be reduced when coadministered with leflunomide. Monitor and adjust dose as required.

For other substrates of BCRP (e.g., mitoxantrone) and drugs in the OATP family (e.g., methotrexate, rifampin), especially HMG-Co reductase inhibitors (e.g., atorvastatin, nateglinide, pravastatin, repaglinide, and simvastatin), consider reducing the dose of these drugs and monitor patients closely for signs and symptoms of increased exposures to the drugs while patients are taking leflunomide [see Clinical Pharmacology (12.3) ].

Exposure to cefaclor may be increased when coadministered with leflunomide. Monitor and adjust dose as required.

Exposure to cimetidine may be increased when coadministered with leflunomide. Monitor and adjust dose as required.

Exposure to ciprofloxacin may be increased when coadministered with leflunomide. Monitor and adjust dose as required.

Exposure to duloxetine may be reduced when coadministered with leflunomide. Monitor and adjust dose as required.

Teriflunomide may increase systemic exposure of ethinylestradiol. Consideration should be given to type or dose of oral contraceptives used with leflunomide.

Exposure to furosemide may be increased when coadministered with leflunomide. Monitor and adjust dose as required.

Exposure to ketoprofen may be increased when coadministered with leflunomide. Monitor and adjust dose as required.

Teriflunomide may increase systemic exposure of levonorgestrel. Consideration should be given to type or dose of oral contraceptives used with leflunomide.

Exposure to methotrexate may be increased when coadministered with leflunomide. Monitor and adjust dose as required.

Exposure to paclitaxel may be increased when coadministered with leflunomide. Monitor and adjust dose as required.

Exposure to penicillin G may be increased when coadministered with leflunomide. Monitor and adjust dose as required.

Exposure to pioglitazone may be increased when coadministered with leflunomide. Monitor and adjust dose as required.

For other substrates of BCRP (e.g., mitoxantrone) and drugs in the OATP family (e.g., methotrexate, rifampin), especially HMG-Co reductase inhibitors (e.g., atorvastatin, nateglinide, pravastatin, repaglinide, and simvastatin), consider reducing the dose of these drugs and monitor patients closely for signs and symptoms of increased exposures to the drugs while patients are taking leflunomide [see Clinical Pharmacology (12.3) ].

Exposure to repaglinide may be increased when coadministered with leflunomide. Monitor and adjust dose as required.

Rifampin increases plasma concentration of teriflunomide (leflunomide's active metabolite) by 40%. Caution recommended due to potential for continued concentration increases with multiple dosing.

Exposure to rosiglitazone may be increased when coadministered with leflunomide. Monitor and adjust dose as required.

Teriflunomide may increase exposure of rosuvastatin. Dose should not exceed 10 mg once daily.

For other substrates of BCRP (e.g., mitoxantrone) and drugs in the OATP family (e.g., methotrexate, rifampin), especially HMG-Co reductase inhibitors (e.g., atorvastatin, nateglinide, pravastatin, repaglinide, and simvastatin), consider reducing the dose of these drugs and monitor patients closely for signs and symptoms of increased exposures to the drugs while patients are taking leflunomide [see Clinical Pharmacology (12.3) ].

7 DRUG INTERACTIONS Following oral administration, leflunomide is metabolized to an active metabolite, teriflunomide, which is responsible for essentially all of leflunomide's in vivo activity. Drug interaction studies have been conducted with both ARAVA (leflunomide) and with its active metabolite, teriflunomide, where the metabolite was directly administered to the test subjects. Drugs metabolized by CYP2C8 and OAT3 transporters: Monitor patients because teriflunomide may increase exposure of these drugs.

Exposure to theophylline may be reduced when coadministered with leflunomide. Monitor and adjust dose as required.

Exposure to tizanidine may be reduced when coadministered with leflunomide. Monitor and adjust dose as required.

Exposure to zidovudine may be increased when coadministered with leflunomide. Monitor and adjust dose as required.

7 DRUG INTERACTIONS Following oral administration, leflunomide is metabolized to an active metabolite, teriflunomide, which is responsible for essentially all of leflunomide's in vivo activity. Drug interaction studies have been conducted with both leflunomide and with its active metabolite, teriflunomide, where the metabolite was directly administered to the test subjects. Effect of potent CYP and transporter inducers Leflunomide is metabolized by CYP450 metabolizing enzymes.

In patients taking leflunomide, exposure of drugs which are OAT3 substrates (e.g., cefaclor, cimetidine, ciprofloxacin, penicillin G, ketoprofen, furosemide, methotrexate, zidovudine) may be increased.