Development and Evaluation of Lorazepam Microemulsions for Parenteral Delivery

The objective of this investigation was to develop lorazepam (LZM) microemulsions as an alternative to the conventional cosolvent based formulation. Solubility of LZM in various oils and Tween 80 was determined. The ternary diagram was plotted to identify area of microemulsion existence and a suitable composition was identified to achieve desired LZM concentration. The LZM microemulsions were evaluated for compatibility with parenteral fluids, globule size, in vitro hemolysis and stability of LZM. Capmul MCM demonstrated highest solubilizing potential for LZM and was used as an oily phase. LZM microemulsions were compatible with parenteral dilution fluids and exhibited mean globule size less than 200 nm. The in vitro hemolysis studies indicated that microemulsions were well tolerated by erythrocytes. The LZM microemulsions containing amino acids exhibited good physical and chemical stability when subjected to refrigeration for 6 months

Design and Evaluation of Microemulsions for Improved Parenteral Delivery of Propofol

The objective of this investigation was to evaluate the potential of the microemulsions to improve the parenteral delivery of propofol. Pseudo-ternary phase diagrams were plotted to identify microemulsification region of propofol. The propofol microemulsions were evaluated for globule size, physical and chemical stability, osmolarity, in vitro hemolysis, pain caused by injection using rat paw-lick test and in vivo anesthetic activity. The microemulsions exhibited globule size less than 25 nm and demonstrated good physical and chemical stability. Propofol microemulsions were slightly hypertonic and resulted in less than 1% hemolysis after 2 h of storage with human blood at 37 °C. Rat paw-lick test indicated that propofol microemulsions were significantly less painful as compared to the marketed propofol formulation. The anesthetic activity of the microemulsions was similar to the marketed propofol formulation indicating that they do not compromise the pharmacological action of propofol. The stability studies indicated that the microemulsions were stable for 3 months when stored at 5 ± 3 °C. Thus, microemulsions appeared to be an interesting alternative to the current propofol formulations