Impact of superdisintegrants on efavirenz release from tablet formulations.

Efavirenz (EFV) tablets of different doses were prepared by a wet granulation process using different superdisintegrants such as crosscarmellose sodium (CCS), sodium starch glycollate (SSG) and crosspovidone (CP) to evaluate the role of different disintegrants on the in vitro release of EFV. Further, the mode of addition of disintegrants on EFV dissolution from tablets containing 600 mg of the drug was evaluated by incorporating the disintegrants extragranularly (EG), intragranularly (IG) or distributing them equally (IG and EG). In vitro dissolution of the prepared tablets was conducted using the recommended medium and a dissolution medium developed in-house, which had the ability to discriminate between the formulations. The t50 and t80 values were indicative of the fact that the drug release was faster from tablet formulations containing CP. CP was able to release the drug faster than the other two disintegrants in both dissolution media and the drug release was unaffected by the mode of CP addition.

Formulation and evaluation of clarithromycin microspheres for eradication of Helicobacter pylori.

The objective of the study was to develop a stomach-specific drug delivery system for controlled release of clarithromycin for eradication of Helicobacter pylori (H. pylori). Floating-bioadhesive microspheres of clarithromycin (FBMC) were prepared by emulsification-solvent evaporation method using ethylcellulose as matrix polymer and Carbopol 934P as mucoadhesive polymer. The prepared microspheres were subjected to evaluation for particle size, incorporation efficiency, in vitro buoyancy, in vitro mucoadhesion and in vitro drug release characteristics. The prepared microspheres showed a strong mucoadhesive property with good buoyancy. The formulation variables like polymer concentration and drug concentration influenced the in vitro drug release significantly in simulated gastric fluid (pH. 2.0). The in vivo H. pylori clearance efficiency of prepared FBMC in reference to clarithromycin suspension following repeated oral administration to H. pylori infected Mongolian gerbils was examined by polymerase chain reaction (PCR) technique and by a microbial culture method. The FBMC showed a significant anti-H. pylori effect in the in vivo gerbil model. It was also noted that the required amount of clarithromycin for eradication of H. pylori was significantly less in FBMC than from corresponding clarithromycin suspension. The results further substantiated that FBMC improved the gastric stability of clarithromycin (due to entrapment within the microsphere) and eradicated H. pylori from the gastrointestinal tract more effectively than clarithromycin suspension because of the prolonged gastrointestinal residence time of the formulation.

In vitro and in vivo evaluation of the Gelrite gellan gum-based ocular delivery system for indomethacin.

The poor bioavailability and therapeutic response exhibited by the conventional ophthalmic solutions due to pre-corneal elimination of the drug may be overcome by the use of in situ gel forming systems, which upon instillation as drops into the eye undergo a sol-gel transition in the cul-de-sac. This may result in better ocular availability of the drug. The purpose of this work was to develop an ophthalmic delivery system of the NSAID indomethacin, based on the concept of ion activated in situ gelation. Gelrite gellan gum, a novel ophthalmic vehicle, which gels in the presence of mono or divalent cations present in the lacrimal fluid, was used as the gelling agent. The developed formulations were therapeutically efficacious (in a uveitis induced rabbit eye model) and provided sustained release of the drug over an 8-hour period in vitro.