In vivo activities of the new anthelmintic depsipeptide PF 1022A

PF 1022A is a member of a new class of cyclic depsipeptides with antiparasi tic activity. Following in vitro and laboratory animal studies it was teste d for its anthelmintic efficacy in companion and livestock animals against a wide spectrum of intestinal nematodes and lungworms. Studies were carried out in rats, dogs, horses. sheep, and cattle. Animals were either naturall y or experimentally infested. The efficacy of PF 1022A was investigated aga inst the following parasite species: Stronglyoides ratti and Nippostrongylu s brasiliensis rats. Ancylostoma caininum in dogs, small strongyles (cyatho stomes) in horses. Trichostronglyus colubriformis and Haemonchus contortus in sheep, and Dictyocaulus viviparus in cattle. Doses varied from 1 to 10 m g/kg body weight for oral, subcutaneous or intravenous application in compa nion and livestock animals. High degrees of efficacy were found in all the above-cited examinations. and no clinical signs of intolerability were obse rved. (1995) described its activity in the jird against Haemonchus contortu s, Trichostronglyus colubriformis, and Ostertagia ostertagi after oral appl ication. By contrast, they found a significant decrease in the activity of PF 1022A against T. colubriformis and O. ostertagi after parental applicati on. Several in vitro studies revealed that PF 1022A was very active against Trichinella spiralis and Nippostronglyus brasiliensis when it was given at 1 mu g/ml (Martin ct al. 1996) and at 0.1 mu M against H. contortus (Conde r et al, 1995). To provide further insight into the anthelmintic capacity o f PF 1022A we investigated its activity against several important nematodes using different routes of application in rats, dogs, horses, sheep, and ca ttle.