Size analysis of liposomes
Size analysis of the liposomes formed after hydration of the ketoprofen proliposomal formulations (5 mg) with distilled water (10 ml) by manual agitation for 2 minutes in a glass tube was performed at 25oC using Mastersizer 2000 Ver 5.6 (Malvern Instruments Ltd. Malvern UK). Size of the liposomes formed after hydration was recorded as volume median diameter (VMD, 50% undersize) and polydispersity index (size distribution) was expressed by the term span, which was mathematically expressed as follows (26).
To determine the amount of ketoprofen entrapped in the liposomes, proliposomal powder (5 mg) was reconstituted in 10 ml of distilled water and manually agitated for few minutes to form liposomal suspension. The ketoprofen content in the resulting liposomes was determined by centrifugation method (22). After centrifugation of liposomal suspension, supernatant obtained was collected and assayed for ketoprofen content using UV spectrophotometer. Then the amount of ketoprofen present in the precipitated layer (C) as entrapped drug was calculated from the difference between the amount of ketoprofen in the liposomal suspension before centrifugation (A) and the amount of ketoprofen in the supernatant layer after centrifugation (B) (i.e., C = A-B), and the entrapment efficiency (%) was then calculated using the following expression.
Entrapment efficiency (%) = (C / A)*100
In vitro dissolution study
In vitro dissolution studies of pure ketoprofen and proliposomal powder formulations were conducted in triplicate using USP (XXIV) type II apparatus (Electrolab, Mumbai, India) at the rotational speed of 50 rpm. Simulated gastric fluid (pH 1.2; 900 ml; at 37± 0.5oC) without enzymes was used as dissolution media. Sieved samples of pure ketoprofen and proliposomal formulations of ketoprofen (equivalent to 25 mg) were added into the dissolution media and an aliquot of 5 ml was withdrawn at designated time...