Solubility and dissolution rate are two fundamental criteria that portray the drug performance in-vivo. Olmesartan medoxomil (OM) is an orally active angiotensin II type 1 receptor antagonist approved by FDA for the treatment of hypertension. Being classified as BCS class II; OM suffers from poor solubility and low bioavailability. Nanosuspension is a submicron colloidal dispersion of drug particles that are stabilized by ionic or polymeric stabilizers or mixture of both. This work aimed to the formulation of OM nanosuspensions using full factorial design and studying the effect of nanosizing on OM solubility and dissolution rate. Two factors (independent variables) were evaluated: type of stabilizer and drug to stabilizer ratio. The dependent responses measured were: particle size and size distribution (span value). OM nanosuspensions were prepared by simple bottom up method (antisolvent precipitation ultrasonication). The highest desirability value was observed for formula F1. The particle size, span value and zeta potential of optimized formula (F1) were 153.00±0.58 nm, 4.35±0.0036 and -22.75±0.845 mV, respectively. Optimum formulation was further characterized in-vitro regarding its saturation solubility, dissolution rate, transmission electron microscopy and differential scanning calorimetry. Saturation solubility and the %OM dissolved within 8 minutes were enhanced by about 4 and 3 folds, respectively compared to drug alone as a result of size reduction, efficient stabilization with HPMC which were confirmed by transmission electron microscopy. Decrease of crystallinity was revealed by thermal analysis. In summary, the highlighted results confirmed the efficacy of nanosuspensions in enhancing the saturation solubility and dissolution rate of OM.
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