Co-administration of Fluvastatin and CYP3A4 and CYP2C8 Inhibitors May Increase the Exposure to Fluvastatin in Carriers of CYP2C9 Genetic Variants.

Fluvastatin, which is one of the hydroxymethylglutaryl-CoA (HMG-CoA) reductase inhibitors (statins), is primarily metabolized by CYP2C9 and to a lesser extent by CYP3A4 and CYP2C8. Predictions of drug-drug interactions (DDI) are important for the safety of combination therapies with statins, in particular drugs that are metabolized by CYP3A4. Little information is available regarding drug interactions with fluvastatin. Since CYP2C9 is a polymorphic enzyme, we investigated the effect of DDI via CYP2C9, CYP3A4, and CYP2C8 on fluvastatin pharmacokinetics by using a validated prediction method in relation to CYP2C9 variants. The predicted increases in the area under the concentration-time curve (AUC) ratios of fluvastatin in carriers with CYP2C9*1/*2, CYP2C9*1/*3, CYP2C9*2/*2, CYP2C9*2/*3, and CYP2C9*3/*3 versus that found in carriers with CYP2C9*1/*1 were 1.16, 1.35, 1.37, 1.65, and 2.06, respectively. Our in silico model predicted that administration of fluvastatin in conjunction with the potent inhibitors that completely inhibited CYP3A4 and CYP2C8 in carriers with the CYP2C9*3/*3 variant would cause a 3.23- and 2.60-fold increase in the AUC ratios, respectively, when compared to that for the carriers with the CYP2C9*1/*1 taking fluvastatin alone. We also predicted the effect of telmisartan when coadministered with fluvastatin. Our prediction results showed that the interaction between telmisartan and fluvastatin via CYP enzymes were negligible in clinical situations.

27-Hydroxycholesterol suppresses lipid accumulation by down-regulating lipogenic and adipogenic gene expression in 3T3-L1 cells.

Cholesterol oxidation products (oxycholesterols) are produced from cholesterol by automatic and/or enzymatic oxidation of the steroidal backbone and side-chain. Oxycholesterols are present in plasma and serum, suggesting that oxycholesterols are related to the development and progression of various diseases. However, limited information is available about the absolute amounts of oxycholesterols in organs and tissues, and the physiological significance of oxycholesterols in the body. In the present study, we quantified the levels of 13 oxycholesterols in white adipose tissue (WAT) of mice and then evaluated correlations between each oxycholesterol level and WAT weight. The sum of the levels of 13 oxycholesterols in WAT (white adipose tissue) was 15.9 ± 3.4 µg/g of WAT weight and approximately 1 % of cholesterol level. Among oxycholesterols, the levels of 27-hydroxycholesterol (27-OH), an endogenous oxycholesterol produced by enzymatic oxidation, and the relative WAT weights were significantly negatively correlated. Next, we evaluated the effects of 27-OH on lipogenesis and adipogenesis in 3T3-L1 cells. TO901317 (TO), a potent and selective agonist for LXRα, significantly increased intracellular TAG contents, while 27-OH significantly reduced the contents to half when compared with control (DMSO) and completely abolished the effect of TO. In addition, 27-OH significantly reduced the mRNA levels of lipogenic (LXRα and FAS) and adipogenic genes (PPARγ and aP2) during adipocyte maturation of 3T3-L1 cells. In conclusion, our results indicate that 27-OH suppresses lipid accumulation by down-regulating lipogenic and adipogenic gene expression in 3T3-L1 cells.