The dissolution profiles of the all developed proliposomal formulations exhibited relatively similar drug release characteristics at the end of 60 min, However initial drug release characteristics showed improved dissolution rate of ketoprofen in the formulation KPL3 at 1:1 ratio of HSPC and cholesterol. Also previous reports suggests that proliposomal formulations composed with lipid and cholesterol at 1:1 ratio produced stable liposomes upon hydration with resistance to degradation by pancreatic lipase and acidic (pH 2) conditions (38). Based on dissolution studies and previous reports KPL3 with equimolar ratios of HSPC and cholesterol was selected as optimized formulation for improved oral delivery of ketoprofen.
Solid state characterization
Fourier transform infrared spectroscopic studies
FTIR studies were performed to know the chemical interactions between drug and components of proliposomes based on characteristic drug peaks absence or shifting. The FTIR spectrum of pure ketoprofen, individual components of proliposomal formulation i.e. cholesterol, HSPC, pearlitol SD 200 and optimized proliposomal formulation (KPL3) were shown in Figure 4A-E, respectively. The spectrum of pure ketoprofen showed intense, well defined characteristic absorption peaks at 1654.2 cm−1, 1694.8 cm−1 (C=O stretching of carboxylic acid and ketone), 1283.69 cm−1, 1227.6 cm−1 (C-O carboxylic acid stretching), 715.31 cm−1, 690 cm−1 (C-H out of plane bending vibrations of aromatics). Cholesterol showed principle absorption peaks at 2930.7 cm−1 (C-H aliphatic stretching), 1464.88 cm−1 (in the plane bending for CH3, OH) and HSPC at 2916.5 cm−1, 2849.61 cm−1 (C-H stretching of alkane), 1735 cm−1 (C=O stretching vibration of carboxylic acid), 1467.41 cm−1 (CH2, CH3 in the plane bending vibrations of alkanes). FTIR spectrum of pearlitol SD 200 showed characteristic peaks at 3282.7 cm−1 (O-H stretching of alcohol), 1077.9 cm−1 and 1018.9 cm−1 (C-O stretching of alcohol), 952.05 cm−1, 927.18 cm−1 and 882.6 cm−1 (C-H out of plane bending). The infrared spectrum of proliposomal formulation showed all the characteristic peaks of ketoprofen and other components of proliposomal formulation. As spectrum of proliposomal formulation showed superimposable pattern of ketoprofen with additive component peaks without any change in peak positions indicates lack of chemical interaction between ketoprofen and components of proliposomal formulation.
Differential scanning calorimetry
DSC thermal profiles of ketoprofen, pearlitol SD 200 and ketoprofen loaded proliposomal powder KPL3 (Figure 5A-C) allows to resolve physical state i.e. crystallinity and thermotropic phase transition behavior of drug in the formulation. The thermal profiles of pure ketoprofen and pearlitol SD 200 used as inert carrier showed sharp phase transition peaks at 97.8°C and 168.24 ºC, corresponding to their melting point temperatures, with a melting enthalpy of 132.4 J/g and 94.50 J/g respectively, concludes existence of...