Development and Evaluation of Self-Microemulsifying Drug Delivery System for Improving Oral Absorption of Poorly Water-soluble Olaparib

The purpose of this study is to develop and evaluate a self-microemulsifying drug delivery system (SMEDDS) to improve the oral absorption of poorly water-soluble Olaparib. Through the solubility test of Olaparib in various oils, surfactants and co-surfactants, pharmaceutical excipients for use in SMEDDS manufacturing were selected. Self-emulsifying regions were identified by mixing the selected materials at various ratios, and a pseudoternary phase diagram was constructed by synthesizing these results. Various physicochemical properties of microemulsion incorporating Olaparib were confirmed by investigating the particle morphology, particle size, zeta potential, drug content and stability. In addition, the improved dissolution and oral absorption of Olaparib were also confirmed through a dissolution test and a pharmacokinetic study. An optimal microemulsion was generated in the formulation of Capmul MCM EP/NF 10%, Labrasol 80% and PEG 400 10%. Fabricated nano-sized microemulsions were well-dispersed in aqueous solutions, and it was also confirmed that it was maintained well without any problems of either physical or chemical stability. The 5 min initial dissolution of Olaparib in fabricated formulations was improved by 10.6 times (pH1.2), 14.8 times (pH6.8) and 14.8 times (distilled water) compared to the values of Olaparib powder. The dissolution at 120min was 45.4±4.0%(pH1.2), 53.5±1.1% (pH6.8) and 58.1±1.00% (distilled water) in Olaparib powder but has been significantly improved by 1.7 times (74.8±1.9%), 1.6 times (84.2±0.3%) and 1.5 times (81.2±0.7%) in SMEDDS. Associated with the high dissolutions of Olaparib in fabricated microemulsions, the pharmacokinetic parameters were also greatly improved. The Cmax and AUCinf of Olaparib in the prepared microemulsion were increased 4.2- and 3.2-fold, respectively, compared to powder. Taken together with the results mentioned above, the microemulsion system could be an effective tool as an oral delivery formulation for Olaparib. Additionally, our results demonstrate that the SMEDDS systems comprising Capmul MCM, Labrasol and PEG 400 could be a useful option for improvement of several other poorly water-soluble drugs with physico-chemical properties similar to Olaparib.