Formulation and Evaluation of Diclofenac Sodium Gels Using Sodium Carboxymethyl Hydroxypropyl Guar and Hydroxypropyl Methylcellulose

Abstract:

In this investigation, Diclofenac sodium gels were formulated employing Sodium carboxymethyl hydroxypropyl guar and Hydroxypropyl methylcellulose as gelling agents. Hydroxypropyl methylcellulose (K4M) was employed at 5 % w/w strength whereas, Sodium carboxymethyl hydroxypropyl guar formed a gel at 2.5 % w/w strength, gels were subjected for various evaluation tests such as pH measurement, assay, stability study, rheological evaluation, and invitro release studies across hairless albino rat skin. Gels formulated using Sodium carboxymethyl hydroxypropyl guar displayed a pH value of 7.48, whereas Hydroxypropyl methylcellulose gels revealed a pH value of 7.26. Stability studies revealed good physical stability and assay values did not show much variation from the initial drug content in both the cases with formulations stored at 25⁰C, 60% RH and 40⁰C, 70% RH for six months. Hydroxypropyl methylcellulose at 5% w/w strength revealed shear-thinning property, whereas Sodium carboxymethyl hydroxypropyl guar at 2.5 % w/w strength revealed both pseudoplastic and thixotropic property. The rheological data were fitted into Martin and Co’-worker equation to obtain a linear relationship and from the linear curve fittings, the 'N'- values; the possible flow indices for pseudoplasticity were arrived at. A 'N' value of 4.65 was obtained for Sodium carboxymethyl hydroxypropyl guar gels in contrast to a 'N' value of 1.52 in case of Hydroxypropyl methylcellulose gels. When subjected to In-vitro release studies across hairless albino rat skin, Sodium carboxymethyl hydroxypropyl guar based gels revealed a % cumulative drug release of 25.66 in contrast to a % cumulative drug release of 20.80 in case of Hydroxypropyl methylcellulose based gels at the end of 6 hours. From the above observations, Sodium carboxymethyl hydroxypropyl guar seems to be a promising pharmaceutical adjuvant in the formulation of Diclofenac sodium gels.

Key words: Diclofenac sodium gels, Sodium carboxymethyl hydroxypropyl guar, Hydroxypropyl methylcellulose, Rheological evaluation, Pseudoplasticity index