Sunil Firangi

It is well known that solid oral dosage forms, particularly tablets, are the most acceptable form of delivering medication. However, some new variations are beginning to emerge such as mini-tablets, which offer formulation flexibility. A multifunctional and multiple unit system for oral use are developed by filling versatile mini-tablets in a hard capsule. Multipulsatile DDS, site-specific DDS, zero-order DDS, slow/quick DDS, and quick/ slow DDS are designed in different ways and are investigated. Mini-tablets are small tablets with a diameter typically equal to or less than 3 mm that are typically filled into a capsule, or occasionally, further compressed into larger tablets. It is possible to incorporate many different mini-tablets, each one formulated individually and programmed to release drug at different sites within the gastrointestinal track, into one capsule. These combinations may include immediate release, delayed release, and/or controlled release mini-tablets. It is also possible to incorporate mini-tablets of different drugs to treat concurrent diseases or combinations of drugs to improve overall therapeutic outcome, while delivering distinct release rates of each according to disease requirements. Mini-tablets combine the advantages of multiparticulate dosage forms with the established manufacturing techniques of tableting. Additional benefits of mini-tablets include excellent size uniformity, regular shape and a smooth surface, thereby offering an excellent substrate for coating with modified release polymeric systems. From this, study it can be concluded that, granules-mini-tablets filled in HPMC capsule systems and coated mini-tablet-in-HPMC capsule system sulphate shows both sustained release as well as immediate release may improve the bioavailability and efficacy of any drugs. Keywords: Mini-tablets, immediate-release, delayed-release, controlled-release, multiparticulate dosage forms.

  The objective of the present study was to prepare and evaluate gastroretentive effervescent floating drug delivery system containing Zidovudine as a model drug. Zidovudine is the first approved compound for the treatment of AIDS; however the main limitation to therapeutic effectiveness of zidovudine is its dose-dependent toxicity, short biological half-life and poor bioavailability. Zidovudine gastroretentive effervescent floating tablets were prepared by direct compression method. Sodium bicarbonate and citric acid were incorporated as gas-generating agents. Drug compatibility with excipients was checked by DSC and FTIR studies revealed that, there was no incompatibility of the drug with the excipients used. The results of in-vitro buoyancy time and lag time study, the values of in-vitro buoyancy time ranges from 180 to 870 min where as floating lag time ranges from 2.11 to 51.36 min. The formulations prepared with carbopol have longer floating lag times. The formulation GREFT-6 shows the lag time 2.11 min and buoyancy time 870 min. The release of Zidovudine from all the formulations ranges from 45.05 - 64.96 % drug released at the end of 6 hrs. The formulations GREFT-1 and GREFT-2 shows 90 % of drug release within 10 hrs. The formulations GREFT-3 to GREFT-7 shows drug release ranges from 86.17 - 96.65 % at the end of 12 hrs. The results were revealed that as the concentration of carbopol increases, there is decrease in the drug release and floating time has been increased. The formulation GREFT-6 containing Carbopol 934P 100 mg showed the controlled drug release when compare to other formulations. The stability study conducted as per the ICH guidelines and the formulations were found to be stable. From the above studies, it has been observed that effervescent based floating drug delivery system is a promising approach to achieve controlled release behavior. Key wards: Zidovudine, HPMC K4M, carbopol, floating tablets, effervescent.