Interaction of macrocyclic lactones with the multidrug transporters: the bases of the pharmacokinetics of lipid-like drugs.

Like most drugs, macrocyclic lactone endectocides (MLs) exert their antiparasitic effects within the defined target tissues where parasites are located, and whose drug concentrations correlate with those in the plasma compartment. The process of drug distribution to the active site constitutes the link in the pharmacokinetic/pharmacodynamic relationship. In the past few years it has become evident that transporter proteins play a major role in regulating the distribution, elimination and metabolism of the antiparasitic macrocyclic lactones. The efflux transporter P-glycoprotein (P-gp) has received the most attention with regards to its strong interaction with ivermectin and other MLs. P-gp has been reported to be involved in restricting the absorption of these drugs, in enhancing their intestinal elimination, in the protection against their neurotoxicity and in the ML resistance mechanisms in parasites. This review focuses on the interaction of MLs with P-glycoprotein and with other multidrug resistance transporters. Given the structural and physicochemical diversity of these drugs, they constitute models of interest to study the major molecular determinants for the interaction with transporters. We will discuss the consequences of such interactions on ML pharmacokinetics and the possibility of benefiting from of drug/drug interaction to reverse multidrug resistance in several therapeutic fights such as against parasites and tumors.