Controlled Release Microbeads of Zidovudine Incorporated with Natural Waxes: Design and Characterization

Zidovudine (AZT) is an antiretroviral drug with activity against Human Immunodeficiency Virus (HIV) Type 1. However, only temporary and limited benefits are observed in HIV infected patients treated with zidovudine alone or in combination with other antiretroviral drugs. Upon oral administration, it exhibits dose dependent toxic effects such as hepatotoxicity, hyperglycemia, hyperlipidemia, lactic acidosis, lipodystropy, osteonecrosis. These side effects often require dosage reduction or even cessation of treatment. Hence, in the present work an attempt is being made to develop a stable drug delivery system for zidovudine in the form of controlled release microbeads incorporated with different types of waxes. Wax incorporated microbeads of Zidovudine were prepared by melt extrusion-ionotropic gellation method. A series of tests have been carried out to characterize the microbeads in vitro, including particle size distribution, SEM analysis, loading parameters, in vitro release studies and stability studies. Compatibility studies proved that there was no interaction between zidovudine and different waxes used. Zidovudine beads were roughly spherical in nature, which was confirmed by Scanning electron microscopy. Zidovudine loaded beads with normal frequency distribution were obtained. A maximum of 74.65% drug entrapment efficiency was obtained. The in-vitro performance of Zidovudine beads showed sustained release up to 24 hrs depending on the wax concentration. Finally it can be concluded that the formulated matrix type microbeads with bees wax were more feasible and effective than carnauba wax beads in encapsulating zidovudine and thereby increasing the effectiveness of the drug.