Abstract:
The HIV epidemic has reached an important threshold in India. India has the World’s second largest burden of HIV-infected persons. The objective of the present study was to formulate and evaluate once-daily sustained release matrix tablets of Stavudine using hydrophilic hydroxypropyl methylcellulose alone, combination of two different viscosity grades of hydroxypropyl methylcellulose and combination of hydroxypropyl methylcellulose with ethyl cellulose. Stavudine (Antiviral agent) has a short half life 1.22 h and usual oral dosage regimen 30mg and 40 mg twice daily. The most commonly used method of modulating the drug release is to include it in a matrix system. The viscosity of hydroxypropyl methylcellulose polymer influences the erosion rate of matrix tablet. The rate of tablet erosion can be adjusted by the choice of hydroxypropyl methylcellulose polymer viscosity or by mixing hydroxypropyl methylcellulose polymer of varying viscosities. The drug release for extended duration using a hydrophilic matrix system is restricted because of rapid diffusion of dissolved drug through the hydrophilic gel network. For such circumstances, hydrophobic polymers are suitable, along with a hydrophilic matrix for developing sustained release dosage forms. Hydrophobic polymers provide several advantages, ranging from good stability at varying pH values and moisture levels to well established safe applications. Therefore, in this study, the hydrophilic polymer (hydroxypropyl methylcellulose) was used as matrix material and hydrophobic polymer (ethyl cellulose) was used to extend the drug release. The results of invitro dissolution study shown that the formulation F8 (HPMC K15M: Ethyl cellulose, 1:1) exhibited satisfactory drug release pattern and total drug release pattern was very close to theoretical release profile. The mechanism of the drug release from sustained release matrix tablet of formulation F8 was fickanian diffusion.

Keywords: Stavudine, Hydrophilic Polymer, Hydrophobic Polymers, Antiviral Agent.