Toxicological evaluation of pidotimod

This paper reports the toxicological evaluation of pidotimod ((R)-3-[(S)-(5-oxo-2-pyrrolidinyl) carbonyl]-thiazolidine-4-carboxylic acid, PGT/1A, CAS 121808-62-6). Its acute toxicity in mice, rats and dogs was very low after oral, i.v., i.m. and i.p. administration. The repeated administration studies in rats were performed for 4 months via the i.p. route and for 12 months via the oral route. Pidotimod did not show toxic effects at dosages up to 200 mg/kg i.p. and 800 mg/kg p.o. These dosages correspond to 32.5 times the maximum dosage intended for clinical use. The repeated administration studies in dogs were performed for 26 weeks via the i.m. route and for 52 weeks via the oral route. Pidotimod did not show toxic effects at dosages up to 300 mg/kg i.m. and 600 mg/kg p.o.. It did not affect male or female rat fertility at dosages up to 600 mg/kg by oral and 500 mg/kg by i.v. route. The compound was not teratogenic in rats (600 mg/kg p.o. and 1000 mg/kg i.v.), with no effects on subsequent embryofoetal development at dosages up to 1000 mg/kg/day, and in rabbits (300 mg/kg p.o. and 500 mg/kg. i.v.). There were no peri- and postnatal toxic effects in rats (600 mg/kg p.o. and 500 mg/kg i.v.). Local tolerability of pidotimod after i.m. administration was very good. In conclusion pidotimod is characterized by a high safety margin in all animal species.