Formulation and in vitro Evaluation of Eudragit^® Microspheres of Stavudine

Sunit Kumar Sahoo¹, Abdul Arif Mallick¹, BB Barik¹ and Prakash Ch Senapati²

¹University Department of Pharmaceutical Sciences, Utkal University, Bhubaneswar, Orissa – 751004, India, ²Torrent Pharmaceuticals, Baddi

 

Tropical Journal of Pharmaceutical Research 2005; 4(1): 369-375 

ISSN: 1596-5996

 

Abstract

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.

 Key words:  Stavudine, Eudragit, microspheres, controlled release, polymethacrylate

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