Enhancement of Aqueous Solubility and Oral Bioavailability of Bcs Class II Drug by Dry Emulsion

Abstract

Liquid emulsions have distinct advantages over other dosage forms by improving oral bioavailability as well as by reducing the side effects. On contrary, liquid emulsion exhibit lack of physicochemical stability and compliance issues. To overcome these problems, dry emulsion formulation recommended. Dry emulsions are formulated by spray drying, evaporation and rotary evaporation. The aim of the present investigation is to improve the dissolution and oral bioavailability of poorly water soluble drug Olmesartan medoxomil by preparing dry emulsion. Olmesartan medoxomil is poorly soluble drug used for treatment of high blood pressure, showing absorption window at stomach and upper part of small intestine. Dry emulsion was ready by victimisation purgative during which drug is very soluble, using poloxamer188 as water soluble carrier and aerosil 200 as an adsorbent. The preferred oils were castor oil, olive oil, soybean oil and isopropyl myristate and polymers were PEG400, Eudragit EPO and Poloxamer 188. Dry emulsion was prepared by spray drying. Dry emulsion was evaluated for drug content, percentage moisture content, aqueous solubility, dissolution study and in-vivo bioavailability study. In vitro drug release of dry emulsion was studied by using USP type II paddle dissolution apparatus. The solubility of the drug was increased with surfactant and polymer at 1:1 ratio. Probable mechanisms of improved solubility were characterized by particle size determination, Differential Scanning Calorimetry (DSC), Powder X-ray Diffractometry (PXRD) and Scanning Electron Microscopy (SEM). This study revealed that solid dry emulsion technique could prove promising for improvement of solubility, dissolution rate and oral bioavailability of Olmesartan medoxomil.