62.有關口服digoxin與quinidine併用時產生交互作用之機轉，下列何者正確？
(A)digoxin之腸道吸收增加
(B)digoxin之腎臟排除增加
(C)quinidine之腸道吸收增加
(D)quinidine之腎臟排除增加

♧ P-gp抑制劑例如有verapamil, quinidine, cyclosporine, propafenone, clarithromycin，這些與digoxin併用，會導致digoxin血中濃度上升

P-glycoprotein was first described in tumour cells. These cells had over-expression of P-glycoprotein which reduced the access of cytotoxic drugs. As this made the tumours resistant to various anticancer drugs, P-glycoprotein was also known as multidrug resistance protein. 

P-glycoprotein is also expressed in a variety of normal, non-tumorous tissues with excretory functions (small intestine, liver and kidney)  and at blood-tissue barriers (blood-brain barrier, blood-testis barrier and placenta).

1. P-gp最早在腫瘤細胞發現，會將抗癌藥物打出體外，所以又稱為MDR protein。
2. P-gp在腸道、肝臟、腎臟、BBB都存在。