Scanning electron microscopy (SEM)
The surface characteristics of samples were examined using a scanning electron microscope (SEM, Jeol Corporation, Japan) operating at 15 Kv. The powder sample was directly sprinkled onto the double-sided adhesive tape which was affixed to aluminum stub and made electrically conductive by coating in a vacuum with thin layer of platinum (approximately 3–5 nm) for 100 s at 30 W. Samples were observed under scanning electron microscope and micrographs were recorded at different magnifications to study the surface characteristics.
In situ gastric absorption studies
Healthy male albino wistar rats (250 to 300 g) were purchased from Mahaveera Enterprises (146-CPCSEA no: 199; Hyderabad, India) and were randomly distributed into groups of six each. Rats were housed for at least one week in a clean room under controlled environmental conditions (temperature of 25±2°C and a relative humidity of 55±5%) with free access to normal laboratory chow diet and drinking water. All the experiments involving animals were conducted with prior review and approval of the experimental protocols by the Institutional Animal Ethical Committee, St. Peter’s Institute of Pharmaceutical Sciences, Hanamkonda. The rats were fasted with free access to drinking water for 24 h before experiment.
In situ gastric absorption studies were performed in triplicate using the method as reported earlier. (29,30). Briefly, rats were anaesthetized by intraperitoneal injection of thiopental sodium (50 mg/kg body weight) and normal body temperature was maintained by placing them on a thermostatic surface at 37oC. Upon confirmation of the loss of pain reflex, about 3 cm long midline longitudinal opening was made in the abdominal region of rats and a small incision was made in the cardia and pylorus regions of the stomach. After complete removal of gastric contents from stomach by passing enzyme free simulated gastric fluid, cardia was ligated using surgical silk suture and 2 ml of the dispersion of pure ketoprofen/ proliposomal formulation (equivalent to 5 mg/ml of ketoprofen) in enzyme free simulated gastric fluid was administered through the pylorus opening into the stomach using oral gavage needle. Then, the pylorus was also ligated using surgical silk suture and the stomach was positioned back into the abdominal cavity after verification for any leakage for 2 h and handled with care to maintain an intact blood supply. The entire incised abdominal area was covered with normal saline wetted cotton to prevent loss of fluid by evaporation.
On completion of the study period, the pylorus end was opened to collect the perfusate remained unabsorbed and is diluted to 10 ml using enzyme free simulated gastric fluid. Likewise, the volume of dispersion samples (untreated samples; 2 ml) was also made to 10 ml using enzyme free simulated gastric fluid. One ml of the resultant solutions were diluted into validated range using methanol, centrifuged (15000 rpm for 10...