Formulation and in vitro Evaluation of Eudragit® Microspheres of Stavudine

• Published in: Tropical journal of pharmaceutical research Vol. 4; no. 1
• Main Author: Sunit Kumar Sahoo, Abdul Arif Mallick, BB Barik and Prakash Ch Senapati
• Format: Journal Article
• Language: English
• Published: Pharmacotherapy Group, Faculty of Pharmacy, University of Benin, Benin City, Nigeria 01-07-2006
• Subjects: stavudine, Eudragit, microspheres, controlled release, polymethacrylate
• ISSN: 1596-5996

Purpose: The aim of this study was to formulate and evaluate
microencapsulated controlled release preparations of a highly
water-soluble drug, stavudine, using Copolymers synthesized from
acrylic and methacrylic acid esters (Eudragit RS 100 and RL 100) as the
retardant material. . Methods: Microspheres were prepared by solvent
evaporation method using an acetone / liquid paraffin system. Magnesium
stearate was used as the droplet stabilizer and n-hexane was added to
harden the microspheres. The prepared microspheres were characterized
for their micromeritic properties and drug loading, as well by fourier
transform infrared spectroscopy (FTIR), differential scanning
calorimetry, x-ray powder diffractometry and scanning electron
microscopy. The in vitro release studies were performed in pH 6.8,
phosphate buffer. Results: The prepared microspheres were white, free
flowing and spherical in shape. The drug-loaded microspheres showed
67-91% of entrapment and release was extended upto 6 to 8 h. The
infrared spectra and differential scanning calorimetry thermographs
showed stable character of stavudine in the drug-loaded microspheres
and revealed the absence of drug-polymer interactions. X-ray
diffraction patterns showed that there was decrease in crystallinity of
the drug. Scanning electron microscopy study revealed that the
microspheres were spherical and porous in nature. Conclusion: The
best-fit release kinetics was achieved with Higuchi plot followed by
zero order and First order. The release of stavudine was influenced by
the drug to polymer ratio and particle size & was found to be
diffusion controlled.