Ketamine-in oil-in-water multiple emulsion for prolonged drug release

A preparation of Ketamine [2-(Chlorophenyl)-2-(methylamino) cyclohexanone, C13H16ClNO, anesthetic agent] in oil in water multiple emulsion for prolong ed drug release was formulated and evaluated. Ketamine, the cyclohexylamine , is used as a short-acting anaesthetic in humans and in some animal specie s [1]. Ketamine is poorly bound to plasma proteins and has a half-life of a pproximately 4 hours following intravenous injection [2]. Ketamine leaves t he blood very rapidly to be distributed into the tissues with a high lipid solubility [2]. The recommended dosage of intravenous Ketamine is 2.5-20mg/ kg [3]. The LD50 injected intraperitoneally in mice and rats is 100 times t he intravenous and 30 times the intramuscular dose used in humans. The objective of this study was to test the concept that a multiple emulsio n could be formulated which has high porosity and lower viscosity at 37 deg rees C consistent with its intended use for sustained drug release and to p rolong the half-life of the anesthesia. The results showed that the Ketamin e (100mg/ml in inner phase) released 8.2% at 10 minutes, 67.0% at 30 minute s, and 95.5% at 60 minutes from the Ketamine/O/W multiple emulsion in a wel l-controlled manner.