Formulation and Evaluation of Lamivudine Sustained Release Matrix Tablets Using Synthetic Polymers

Oral route has been the commonly adopted and most convenient route for the drug delivery. Oral route of administration has been received more attention in the pharmaceutical field, because of the more flexibility in the designing of dosage form than drug delivery design for other routes. The oral drug delivery depends on various factors such as type of delivery system, the disease being treated, the patient, the length of the therapy and the properties of the drug. Most of the oral controlled drug delivery systems (OCDDS) relay on diffusion, dissolution, or combination of both mechanisms, to release the drug in a controlled manner to the gastro intestinal tract (GIT). The physico-chemical properties include crystal nature, solubility, partition coefficient, intrinsic dissolution, etc. dosage form characteristics are controlled and optimized with respect to the physico-chemical properties of the drug and relevant GI environmental factors. Other factors need to be considered are diseased state, the patient compliance & length of therapy. The goal of targeted oral drug delivery systems is to achieve better therapeutic success compared to conventional dosage form of the same drug. This could be achieved by improving the pharmacokinetic profile, patient convenience and compliance in therapy. In the present studies, matrix formulation LF3 containing HPMC K4M were probably showing maximum retardation of drug release and it shows anomalous diffusion mechanism, for these reasons, it was considered that the formulation LF3 as best formulation among all the nine formulations. Based on release exponent (n) values, it was concluded that mechanism of drug release was found to be diffusion coupled with erosion (anomalous transport mechanism). From the stability studies, there was no significance difference in hardness, drug content and in vitro release profile for the best formulation