Horses are exposed to various kinds of medication, however, there are limited determinations of plasma clearance (CL_p) for the drugs used due to the high cost of equine in vivo studies.

Many of the CL_p values generated come from the equine sports industry for determining drug plasma screening limits in the control of medications at the time of competition.

The kinetics of omeprazole metabolism were investigated in freshly isolated and cryopreserved equine hepatocytes and hepatic microsomes (n = 3 horses).

The V_max, K_m and intrinsic clearance (CL_int) of omeprazole were determined via the substrate depletion method as well as K_m values for the formation of three metabolites.

The CL_int values were extrapolated to in vivo hepatic plasma clearance (CL_H) using the well stirred and parallel tube models.

Cl_p for omeprazole was successfully predicted using freshly isolated or cryopreserved equine hepatocytes, while microsomes under-predicted.

Equine microsomes were used to perform a drug-drug interaction (DDI) study between omeprazole and chloramphenicol. The average inhibitor constant K_i, assuming competitive inhibition, was 15.4 ± 5 µM.

To the authors’ knowledge, this is the first report showing the successful extrapolation of drug CL_p in the horse using equine hepatocytes and the prediction of a DDI using microsomes.

马匹接触各种药物，但是，由于马体内研究的高昂成本，所用药物的血浆清除率（CL _p）测定有限。

产生的许多CL _p值来自马匹体育行业，用于在比赛时确定药物控制中的血浆筛选限度。

在新鲜分离和冷冻保存的马肝细胞和肝微粒体（n  = 3马）中研究了奥美拉唑代谢的动力学。

奥美拉唑的V _max，K _m和内在清除率（CL _int）通过底物消耗法以及形成三种代谢物的K _m值确定。

使用充分搅拌的平行管模型将CL _int值外推至体内肝血浆清除率（CL _H）。

使用新鲜分离的或冷冻保存的马肝细胞成功预测了奥美拉唑的Cl _p，而微粒体的预测不足。

马微粒体用于进行奥美拉唑和氯霉素之间的药物相互作用（DDI）研究。假设存在竞争性抑制，平均抑制剂常数K _i为15.4±5 µM。

据作者所知，这是第一个报告，显示使用马肝细胞在马中成功推断出药物CL _p并使用微粒体预测了DDI。