Tablet formulation for the fast and sustained-release of flavonoids: naringin and naringenin

Naringin and its metabolite naringenin are flavonoids, naturally occurring plant products, possessing a variety of biological effects in mammalian cel l systems, used in medicine and characterised by a low water solubility. In vivo, they show slow and irregular absorption and low bioavailability when administered as solid oral dosage forms. Their poor and pH-dependent solub ility is likely to give a low dissolution rate of the drugs from the solid form, which could be the limiting or rate-controlling step for bioabsorptio n. In this work, pharmaceutical dosage forms were set up and optimised to e nhance the therapeutic potential of these flavonoids after oral administrat ion. In order to improve their dissolution rate, naringin and naringenin we re loaded by co-mixing on sodium carboxymethylcellulose as a superdisintegr ant and dissolution rate enhancer. These drug/polymer systems were used for the preparation of both quick release tablets and slow release matrices, t he last one formulated with HPMC of different viscosity grade. The results of the dissolution tests show that an extended release of the drugs for tim es ranging from 6 to 24 h can be obtained depending on the type and viscosi ty of the HPMC used. In the case of the formulations containing HPMC of hig her viscosity, improved and considerably constant drug release rates were a chieved.