Type 2 diabetes mellitus decreases systemic exposure of clopidogrel active metabolite through upregulation of P-glycoprotein in rats.

Patients with diabetic mellitus tend to have a poor response to clopidogrel (Clop) due to reduced generation of active metabolite (Clop-AM). However, the underlying mechanism is not elucidated. A type 2 diabetic mellitus (T2DM) rat model was established by combining high-fat diet feeding and low-dose streptozotocin (STZ) injection. The reduced Clop-AM exposure was observed in T2DM rats after oral administration of Clop. However, in vitro liver microsomes incubated with Clop exhibited increased Clop-AM levels in T2DM rats due to a significant decrease in carboxylesterase (CES)1 expression and activity and a significant increase in the expression or activity of CYP1A2 and CYP3A. Interestingly, different from oral administration, the significantly increased Cmax of Clop-AM was observed in T2DM rats after intravenous injection, with no difference in AUC0-t and t1/2 values between the two strains. Meanwhile, in situ single -pass intestinal perfusion study showed lower absorption rate constant (Ka) and effective apparent permeability values (Peff) of Clop in T2DM rats than in control rats. It is explained by the increased expression or function of P-glycoprotein (P-gp) and pregnane X receptor (PXR) in duodenum and jejunum of T2DM rats. Moreover, the decreased Clop-AM level in T2DM rats was eliminated by the pretreatment of cyclosporin A, a P-gp inhibitor. It suggests that intestinal absorption, not hepatic metabolism is responsible for the reduced Clop-AM exposure in T2DM rats. P-gp might be the key factor causing the reduction of Clop absorption, consequently making less Clop available for Clop-AM formation.