Author(s): Ranga Priya M and Rajendran N N*
Nevirapine is currently administered twice daily in combination with lamivudine and stavudine for the treatment of HIV infection. Previous study suggests that once daily regimen of nevirapine provides a higher peak and lower trough levels compared with twice daily regimen of the same drug and has proved to be equally efficient. Presently extended release formulation of nevirapine is used for HIV infection in clinical practice; however it lacks zero-order characteristics. The present study aimed to design elementary osmotic pump tablet of nevirapine as once daily preparation to achieve zero-order characteristics. The elementary osmotic pump tablets were developed using variable concentration of poly ethylene oxide (polymer) and potassium chloride (osmogen) with variable orifice diameter and evaluated for physico-chemical and release characteristics. The elementary osmotic pump tablets released the drug at a zero-order rate over a period of 24 hours and the release rate of the drug was found to be influenced by the variables employed. The amount of poly ethylene oxide had a significant effect on the release rate and a direct correlation was observed between the concentration of potassium chloride and the drug release rate. It was seen that the formulations showed no remarkable changes in the physico-chemical and release characteristics as well as drug content after the stability studies. The results demonstrate that elementary osmotic pump tablet of nevirapine is beneficial as once daily preparation for effective control of HIV infection.