Preparation and characterization of rilpivirine solid dispersions with the application of enhanced solubility and dissolution rate

Rilpivirine (RPV) is a pharmaceutical drug used for the treatment of HIV infection. The drug is characterized with poor aqueous solubility and dissolution rate leading to low bioavailability of the drug. Hence, there is a need for the improvement of the solubility and dissolution of such drugs. In this exertion, enhancement of the solubility and dissolution of the practically water insoluble drug rilpivirine was achieved by solid dispersion (SD) preparation using solvent evaporation method which eventually leads to bioavailability enhancement. SD's were formed using Kollidon VA 64 which is a water-soluble copolymer and varying copolymer ratio to Avicel PH-101, Gelucire 50/13 and lecithin soya. Solubility studies were carried out to establish the solubility-enhancing property of the SD's. To support solubility analysis results, powder dissolution studies were carried out. The SD's were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray powder diffraction studies, scanning electron microscopy. It was found that the SD's formed showed the absence of crystalline nature of the drug and its conversion to amorphous state. The solubility and dissolution of the rilpivirine SD's were enhanced. There is a 14.9 fold increase in solubility for Drug: Kollidan VA 64: Gelucire 50/13 (1:4:1). For Drug: Kollidan VA 64 (1:5), Drug: Kollidan VA 64: Lecithin soya (1:4:1) and Drug: Kollidan VA 64: Avicel PH-101 (1:4:1) it was 5.9, 5.4 and 4.2 respectively. In-vitro drug release kinetics was investigated. This study demonstrates the use of solvent evaporation method for the preparation of SD’S in solubility and dissolution enhancement.