4?-hydroxycholesterol correlates with dose but not steady-state concentration of carbamazepine: indication of intestinal CYP3A in biomarker formation?

ABSTRACT:

Aim

4?-hydroxycholesterol (4?OHC) is an endogenous CYP3A(4) biomarker, which is elevated by use of the CYP3A4 inducer carbamazepine. Our aim was to compare to what extent serum concentration of 4?OHC correlates with dose (presystemic exposure) and steady-state concentration (systemic exposure) of carbamazepine.

Methods

The study was based on a therapeutic drug monitoring material, including information about daily doses and steady-state concentrations (Css ) of carbamazepine. 4?OHC concentrations were determined in residual serum samples of 55 randomly selected carbamazepine-treated patients and 54 levetiracetam-treated patients (negative controls) by UPLC-APCI-MS/MS after liquid-liquid extraction. Correlation analyses between 4?OHC concentration and daily dose and Css of carbamazepine, respectively, were performed by Spearman's tests. In addition, 4?OHC concentrations in females vs. males were compared in induced and non-induced patients.

Results

Median 4?OHC concentration was ~10-fold higher in carbamazepine- vs. levetiracetam-treated patients (650 vs. 54 nmol l(-1) , P < 0.0001). There was a significant, positive correlation between carbamazepine dose and 4?OHC concentration (Spearman r = 0.53, 95% confidence interval [CI] 0.27, 0.72, P < 0.001). No significant correlation between carbamazepine Css and 4?OHC concentration was found (Spearman r = 0.14; 95% CI -0.14, 0.40, P = 0.3). Enzyme-induced females had significantly higher 4?OHC concentrations than males (P < 0.001), while no significant gender difference was found in non-induced patients (P = 0.52).

Conclusion

Serum concentrations of 4?OHC correlate with presystemic, but not systemic exposure of the CYP3A4 inducer carbamazepine. This suggests a stronger inductive effect of carbamazepine on presystemic than systemic CYP3A4 phenotype and might indicate a role of the intestine in 4?OHC formation. Moreover, CYP3A4 inducibility seems to be higher in females than males.

SUBMITTER: Gjestad C 

PROVIDER: S-EPMC4833147 | biostudies-literature | 2016 Feb

REPOSITORIES: biostudies-literature