#149 Improvement in solubility of poorly soluble Bosentan monohydrate through self micro-emulsifying drug delivery system

Abstract

Self micro-emulsifying drug delivery system (SMEDDS) is a transparent, physically stable micro-emulsion with a droplet size of less than 50 nm. In the presented study, solubility of bosentan monohydrate (BM) was improved by formulating SMEDDS using oils, surfactant, co-surfactant and to improve the stability; the optimized formulation was converted into a solid dosage form. Initially, the saturation solubility of BM in oil (sesame oil, arachis oil, olive oil, soyabean oil), surfactants (Tween80, Tween20), co-surfactant (PEG200, PEG600) was determined, and those indicating the highest solubility of BM were selected. From the solubility studies, a different combination of components of the emulsion was selected as Group A: sesame oil, Tween20 and PEG; Group B: sesame oil, Tween80, PEG200; Group C: arachis oil, Tween80 and PEG200; Group D: arachis oil, Tween20 and PEG600. The surfactant and co-surfactant were blended together (Smix- 1: 1,2:1, 3:1, 4:1 ) and the oil:Smix (9:1, 8:2, 7:3, 6:4, 5:5, 4:4, 3:7, 2:8, 1:9) were titrated with distilled water till a clear solution was obtained. The pseudo ternary phase diagrams were constructed (Chemixsoftwere) to study micro emulsifying capacity and the effect of the drug on phase structure. The optimized batch was converted into solid SMEDDS by physically mixing with Aerosil 200 in variable concentration. The optimized batch was incorporated in capsule dosage form, and a stability study was carried out. The saturation solubility of BM was found to be superior in arachis oil and sesame oil; surfactant Tween80 and Tween20; co-surfactant PEG600 and PEG200. Amongst all the studied formulations, batch S11 containing sesame oil (10%), Tween80 (13.4%), and PEG200 (6.6%) with Smix 2:1 (90%) showed Nephelometric turbidity unit of 19, the droplet size of 35.77 nm, PDI of 0.169, Zeta potential –21.61 and in-vitro drug content of 88.57% and was considered as most suitable and highly efficient SMEDDS. S11 was converted into a solid-state by mixing physically with Aerosil 200. The homogenized batch S-S11 having S11 and Aerosil 200 in 1:1 ratio (batch S-S11) showed good flow properties and released 88.57% BM in 60 min. Batch S-S11 was found stable for three months during stability study at 40±2 °C and 75±5% RH.