Drug interactions linked to transporters

The membrane transfer of drugs that are substrates for a particular transporter will change when that transporter is subject to another drug that induces or inhibits its activity. For example, the action of P-glycoprotein can be inhibited by quinidine, verapamil, erythromycin, clarithromycin and the statins. Inhibition of this transporter can interfere with its ability to keep loperamide out of the brain, resulting in opioid effects in the central nervous system. Similarly, 

The OAT family of transporters can be inhibited by probenecid. If a substrate of this family of transporters, such as penicillin, is administered concomitantly with probenecid, the dmg can have decreased renal secretion, with a resulting increase in the plasma penicillin concentration. Cimetidine is an inhibitor of members of the OAT, organic cation transporter (OCT) and OATP families of transporters This inhibition has been shown to result in a decrease in the renal excretion of substrates such as procainamide and levofloxacin, resulting in increased plasma concentrations of these dmgs. 

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