New ventures in the genotoxic and cytotoxic effects of macrocyclic lactones, abamectin and ivermectin.

Abamectin and Ivermectin are 2 closely related members of the Avermectin family of 16-membered macrocyclic lactones derived from the actinomycete Streptomyces avermectinius which exhibit extraordinary anthelmintic activity. They are used worldwide in veterinary and human medicine as well as in agriculture. In the present review we summarized the results published so far for estimating the genotoxicity and cytotoxicity exerted by both compounds in several cellular systems. Although both compounds do not induce in vitro and in vivo gene mutations in either bacterial or mammalian cells, there is no concrete evidence of a clear clastogenic effect exerted both in vitro and in vivo in mammalian cells. However, reports indicating that both anthelmintic agents are able to induce single DNA-strand breaks in vitro and inhibit cell growth either in vitro or in in vivo bioassays, are scarce. Taking into account the similarity of the genotoxicity and cytotoxicity exerted by both antibiotics, and that only Abamectin has been classified so far as a class II toxicity pesticide by the EPA, the necessity of reconsideration for a further hazard evaluation of Ivermectin by an international regulatory agency(ies) is strongly recommended.