Enhancement of Dissolution rate and stability study of Ofloxacin Solid dispersion

In case of relatively insoluble drugs i.e., the drugs having solubility less than 1%, the rate of dissolution is usually the rate determining step in the overall absorption process to become bioavailable. However for relatively soluble drugs i.e., the drugs having intrinsic dissolution rate more than 1mg/cm2/min, the permeability of the drug may become the rate determining step. Poor solubility causing potential bioabsorption problems unless the dosage forms are specially designed. Solid dispersion is the dispersion of the drug in a biologically inert matrix. The objective of the present study was to enhance the dissolution rate of Ofloxacin by making a molecular dispersion of drug in the polymeric matrix of Polyethylene Glycol-6000. Solid dispersion of Ofloxacin was prepared following fusion and solvent evaporation techniques. The drug polymer interaction was studied by Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR), which revealed the absence of major interactions in both the methods. Dissolution study of the solid dispersions shows the enhancement of dissolution rate of Ofloxacin. After 15 minutes of study only 65% of the pure drug is dissolved in the aqueous medium whereas at the same time 98% dissolution was observed with the formulation of solid dispersion in presence of a surfactant. Among the two methods; considering the absence of interaction and higher rate of dissolution the solvent evaporation technique is found most suitable to enhance the dissolution rate and consequently the bioavailability of the drug. The stability study of the formulations as per ICH guideline Q1A in stability chamber both at intermediate and accelerated conditions ascertained that the formulations are stable at wide range of storage conditions.

Author(s): Pintu K De, Basudev Sahana and Soumen Rakshit

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