In vitro studies using human liver microsomes indicate that fenofibrate and fenofibric acid are not inhibitors of cytochrome (CYP) P450 isoforms CYP3A4, CYP2D6, CYP2E1, or CYP1A2. They are weak inhibitors of CYP2C8, CYP2C19 and CYP2A6, and mild-to-moderate inhibitors of CYP2C9 at therapeutic concentrations. 

Potentiation of coumarin-type anticoagulants has been observed with prolongation of the prothrombin time/INR.

Bile acid sequestrants have been shown to bind other drugs given concurrently. Therefore, fenofibrate should be taken at least 1 hour before or 4 to 6 hours after a bile acid binding resin to avoid impeding its absorption. (See WARNINGS and PRECAUTIONS). 

Concomitant administration of a single dose of fenofibrate (administered as 3 X 67 mg fenofibrate micronized capsules) with a single dose of pravastatin (40 mg) in 23 healthy subjects increased the mean C max and mean AUC for pravastatin by 13%. The C max and AUC of fenofibrate decreased by 2% and 1%, respectively, after concomitant administration of fenofibrate and pravastatin. The mean C max and AUC for 3α-hydroxy-iso-pravastatin increased by 29% and 26%, respectively. 

Concomitant administration of a single dose of fenofibrate (equivalent to 145 mg fenofibrate) and a single dose of fluvastatin (40 mg) resulted in a small increase (approximately 15 to 16%) in exposure to (+)3R,5S-fluvastatin, the active enantiomer of fluvastatin.

A single dose of either pravastatin or fluvastatin had no clinically important effect on the pharmacokinetics of fenofibric acid.

Concomitant administration of fenofibrate (equivalent to fenofibrate 200 mg) with atorvastatin (20 mg) once daily for 10 days resulted in approximately 17% decrease (range from 67% decrease to 44% increase) in atorvastatin AUC values in 22 healthy males. The atorvastatin Cmax values were not significantly affected by fenofibrate. The pharmacokinetics of fenofibric acid were not significantly affected by atorvastatin.

Concomitant administration of fenofibrate (equivalent to fenofibrate 200 mg) once daily for 10 days with glimepiride (1 mg tablet) single dose simultaneously with the last dose of fenofibrate resulted in a 35% increase in mean AUC of glimepiride in healthy subjects. Glimepiride C max was not significantly affected by fenofibrate coadministration. There was no statistically significant effect of multiple doses of fenofibrate on glucose nadir or AUC with the baseline glucose concentration as the covariate after glimepiride administration in healthy volunteers. However, glucose concentrations at 24 hours remained statistically significantly lower after pretreatment with fenofibrate than with glimepiride alone. Glimepiride had no significant effect on the pharmacokinetics of fenofibric acid. 

Concomitant administration of fenofibrate (54 mg) and metformin (850 mg) three times a day for 10 days resulted in no significant changes in the pharmacokinetics of fenofibric acid and metformin when compared with the two drugs administered alone in healthy subjects.

Concomitant administration of fenofibrate (equivalent to fenofibrate 200 mg) once daily for 14 days with rosiglitazone tablet (rosiglitazone maleate) (8 mg) once daily for 5 days, Day 10 through Day 14, resulted in no significant changes in the pharmacokinetics of fenofibric acid and rosiglitazone when compared with the two drugs administered alone in healthy subjects.