Acute toxicity study of liposomal antioxidant formulations containing N-acetylcysteine, α-tocopherol, and γ-tocopherol in rats.

Liposomes have been used for the delivery of antioxidants to different tissues and organs for the treatment of oxidative stress-induced injuries. In this study, the acute toxicity of a single dose of intravenously (i.v.) administered liposomal antioxidant formulation, containing N-acetylcysteine (NAC) with or without α-tocopherol (α-T) or γ-tocopherol (γ-T), in rats was examined. Each group consisted of 5 male and 5 female Sprague-Dawley rats, with a control group receiving empty dipalmitoylphosphatidylcholine (DPPC) liposomes (660 mg/kg) and test groups receiving DPPC liposomes (660 mg/kg) entrapped with 1) NAC (200 mg/kg), 2) NAC (200 mg/kg) and α-T (83.3 mg/kg), and 3) NAC (200 mg/kg) and γ-T (71.4 mg/kg). These dose levels were determined from the dose-range-finding study and were considered to be the maximum feasible dose (MFD) levels, based on the volume of 10 mL/kg and physical properties and viscosity of the test articles that could be safely administered to rats by an i.v. injection. Two weeks after treatment (day 15), rats in the control group and three test groups exhibited no clinical signs of toxicity during the dosing period or during the 14-day post-treatment period. Weight gain and food consumption in all animals was appropriate for the age and sex of animals. Clinical pathology findings (e.g., hematology, coagulation, clinical chemistry, and urinalysis) were unremarkable in all rats and in all groups. In conclusion, the results of this study showed no treatment-related toxicity in rats at the MFD level by a single bolus i.v. administration.