An elevated total plasma homocysteine (tHcy) level is considered to be an independent risk factor for atherosclerosis. It has been reported that lipid-lowering therapy with fibric acid derivatives (fibrates) increases tHcy and total plasma cysteine (tCys) levels. The aim of this study was to determine whether therapy with folic acid, a potent tHcy-lowering agent, could modify the fenofibrate-induced elevation of plasma aminothiols.

Patients with combined hyperlipidemia (n = 37) were randomized to receive 9 weeks of treatment with micronized fenofibrate 200 mg/day (F group) or fenofibrate 200 mg/day plus folic acid 10 mg/every other day (F+F group). tCys and tHcy levels were determined before and after the therapy with high performance liquid chromatography.

The tHcy level increased significantly in the F group by 51.3% and in the F+F group by 14.6% (between-group difference P = .001). Total plasma cysteine (tCys) increased similarly after both treatments (P = .72). The serum creatinine level increased in the F group by 20.7% and in F+F group only by 9.8% (P = .04). The increase of tHcy level in F group correlated with an increase of tCys and creatinine levels (r = 0.74 and 0.64, respectively). The effects on the lipid profile did not differ by treatment group.

Folic acid effectively reduces the fenofibrate-induced elevation of tHcy and creatinine, but it does not affect the elevation of the tCys. Folic acid has neutral effect on the lipid-lowering action of fenofibrate. Clinical efficacy of fenofibrate might be improved by folic acid coadministration.