Effects of vitamin D supplementation in atorvastatin-treated patients: a new drug interaction with an unexpected consequence.

The objective of this study was to determine vitamin D supplementation effects on concentrations of atorvastatin and cholesterol in patients. Sixteen patients (8 men, 8 women; 10 Caucasians, 4 African Americans, 1 Hispanic, 1 Asian), aged 63 +/- 11 years (mean +/- SD, weight 92 +/- 31 kg) on atorvastatin (45 +/- 33 mg/day) were studied with and without supplemental vitamin D (800 IU/day for 6 weeks). Levels of vitamin D (1,25-dihydroxy(OH) and 25 OH-metabolites), atorvastatin (parent, OH-acid metabolites, lactone, and lactone metabolites), and cholesterol (total, low-density lipoprotein (LDL) cholesterol, and high-density lipoprotein (HDL) cholesterol) were determined at 0.5, 3, and 10 h after dosing. Vitamin D supplementation increased vitamin D-25-OH metabolites (P < 0.0001) without increased 1,25-dihydroxy vitamin D. Atorvastatin and active metabolite concentrations (P < 0.001) as well as LDL-cholesterol and total-cholesterol levels (97 +/- 28 mg/dl vs. 83 +/- 30 and 169 +/- 35 mg/dl vs. 157 +/- 37, P < 0.005) were lower during vitamin D supplementation. The conclusion of the study is that vitamin D supplementation lowers atorvastatin and active metabolite concentrations yet has synergistic effects on cholesterol concentrations.