FORMULATION AND IN VIVO EVALUATION OF VETERINARY CHLORPROMAZINE SOLUTIONS FOR INTRAMUSCULAR INJECTION

The purpose of the study was to present the know-how of preparing intramuscular injection forms of chlorpromazine HCl  (CPZ) solutions for use in veterinary medicine. Aqueous solutions of CPZ were prepared aseptically at concentrations of 10 or 25 mg/ml. The CPZ formulations were intended for veterinary use only. The concentrations of CPZ in the solutions were 1 or 2.5% which were formulated mainly with ascorbic acid, benzyl alcohol, sodium chloride, sodium metabisulfite or sodium sulfite and water for injection. The pH values of the solutions were adjusted by HCl or NaOH to be in the range of 5 to 6 before filtration (pore size of 0.2 µm), sterilization and distribution into air tight containers. The aqueous formulations of CPZ were clear, almost colorless to slightly straw-colored solutions, sterile and free from undesirable visible particlulate matters. They were according to the requirements of solutions intended for intramuscular injection. Using the prepared formulations, the acute toxicity (median lethal dose, LD50) of CPZ was close to that of a commercial product. Similarly, the effectiveness of CPZ, as determined by the median effective doses (ED50) using the formulations, was close to that of the commercial product and the chicks manifested signs of tranquilization without any adverse effect or death. Further, the preparations were safe and effective when CPZ was injected intramuscularly at the recommended doses experimentally in chicks (10 mg/kg) and sheep (2.2 mg/kg). In conclusion, we introduced simple and applicable know-how of CPZ aqueous formulations (1 or 2.5%) for veterinary use to be administered by deep intramuscular injection