Formulation and evaluation of diclofenac sodium using hydrophilic matrices.

Controlled-release tablets (having near zero-order release) of diclofenac sodium, a water-soluble drug, were prepared using hydrophilic polymers like hydroxypropylmethylcellulose (HPMC), sodium carboxymethylcellulose (NaCMC), and Carbopol 934. Tablets were also prepared with mixtures of polymers of NaCMC, HPMC, and Carbopol 934. The optimum ratio of drug: HPMC. NaCMC was found to be 1:2:1. A combination of nonionic polymer HPMC and anionic NaCMC polymer matrix resulted in near zero-order release of diclofenac sodium. The results obtained were in agreement with the earlier reports. It is observed that increasing polymer content produces more sustained effect. A combination of nonionic polymer HPMC and anionic polymer NaCMC as the polymer matrix resulted in near zero-order release of diclofenac sodium. Drug release from the matrix did not follow Fick's law of 'diffusion and exhibited near zero-order release. Results of the bioavailability studies indicated that formulation 4 with drug:HPMC:NaCMC equal to 1:2:1 was similar to the marketed product Dicloran SR and showed better bioavailability than Voveran SR. A statistically significant difference was seen between Voveran SR and the other two products. A good in vitro-in vivo correlation was observed for these products.