Rheological Study of Diclofenac Gel Containing Different Concentration of Carbapol 940

Topical gels of Diclofenac were prepared by using varying concentrations of Carbapol 940 as gellingagents. Diclofenac Sodium, a non steroidal anti-inflammatory agent is frequently prescribed for thelong term treatment of rheumatoid arthritis, osteoarthritis and ankylosing spondylitis10. The drugundergoes substantial first pass effect and only 50% of drug is available systemically. Diclofenacsodium via skin offers the potential advantage of bypassing hepatogastrointestinal first pass metabolismassociated with oral administration. Carbapol 940 is used in concentration of 0.5%, 1% and 1.5% w/v.Carbapol solution gelatinized upon addition of alkaline molecules like Triethanolamine (TEA) tonullify the acidic group, allowing the polymer chain to align closer together forming network. Theviscosity of prepared gels was estimated using a Brookfield viscometer having T-bar spindles and ahelipath attachment. . A number of spindles of various geometry including T-bars and a cone-plateconfiguration are available to provide scientific rheological data for empirical measurement of viscosityon paste and other semi-solid material. The viscosity of the gels increased with increase in gellingagent concentrations. Rate of shearing is directly proportional to shearing stress, which shows that theformulation is non-newtonian in nature. When the rate of shear is increased viscosity decrease thatproves that the formulation is shear thinning pseudo-plastic in nature. The Diclofenac gel formulationalso exhibits thixotropic nature