Formulation and evaluation of zidovudine sustained release matrix tablets
ABSTRACT The objective of the study was to design oral sustained release matrix tablets of zidovudine using Hydroxy Propyl Methyl Cellulose (HPMC) K4M, Guar Gum and Ethyl Cellulose as the retardant polymers and study the effect of various formulation factors such as polymer proportion, polymer type and effect of filler type on the in vitro release of the drug. Matrix tablets were prepared by wet granulation method and prepared tablets were evaluated for weight variation percentage friability, hardness thickness and in vitro dissolution studies. All the granules and formulations showed compliance with pharmacopieal standards .In vitro release studies revealed that the release rate decreased with increase polymer proportion and hydrophobic polymers retard the drug release more than hydrophilic polymers .The formulations F2 and F8 sustained release of drug for 12 hrs with 96%, 98% release but F5 (15% of HPMC) using MCC as diluent drug releases 10 hours only. Because of swelling property of MCC increased the drug release profile to a small extent due to change in swelling at the tablet surface. The kinetic treatment showed that the mechanism of drug release non-Fickian for HPMC and Ficikian–Diffusion process for guar gum. The developed sustained release matrix tablets of zidovudine with good initial release for first 2hrs(20-25%) and extended the release up to 12hrs can over come the disadvantages of conventional zidovudine tablets.
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ABSTRACT: T he present work aims at the formulation of novel anti‑human immunodeficiency virus vaginal compactable inserts to enhance the pharmacological effects of zidovudine (AZT). Attempt was taken to design a dosage form, which provides sustained release of the drug at the site of action so as to minimize the overall dose and dosing frequency that can reduce the risk of side‑effects. Different formulations of the vaginal compacts of AZT were prepared employing wet granulation method, utilizing several mucoadhesive polymers such as hydroxypropyl methyl cellulose (HPMC 5, 15, 50, 3000 cps) and methyl cellulose (MC) at 20%, 30% and 40% concentrations. The formulations were evaluated and post‑compression parameters including drug content, swelling study, in vitro diffusion, dissolution and drug release kinetic studies. Instrumental analysis like differential scanning calorimetry as well as Fourier transform infrared spectroscopy were performed to find the change in thermal properties and the possible interactions between drug‑polymer, respectively. X‑ray diffraction study was also done to reveal the modification of crystalline nature of drug in the formulation. The compacts prepared by HPMC 50 cps (40%) exhibited the better results in terms of swelling with sustained drug release through the gelled layer. Regardless of good physicochemical parameters, MC did not display a good polymer of choice due to accumulation of spongy gelled blanket around the compact, which is not homogenous but stiff and brittle.