The systemic use of non-steroidal anti-inflammatory drugs (NSAIDs) which act by inhibiting cyclooxygenase (COX) is severely hampered by gastric and peptic ulcers. The topical delivery of NSAIDs has the advantages of avoiding gastric and peptic ulcers and delivering the drug to the inflammation site. Importance of aceclofenac as a new generational NSAID has inspired the development of topical dosage forms. This mode of administration may help to avoid typical side effects of NSAIDs associated with oral and systemic administration such as gastric irritation, particularly diarrhoea, nausea, abdominal pain and flatulence. The aim of this study was to formulate topical gel containing 1% of aceclofenac in carbopol and PEG base and to evaluate it for analgesic and antiinflammatory activity using carrageenan-induced thermal hyperalgesia and paw oedema in rats. Carrageenan administration into the hind paw produced a significant inflammation associated with hyperalgesia as shown by decreased rat paw withdrawal latency in response to a thermal stimulus (47+/-0.5 degrees C) 4 h after carrageenan injection. Topical application of AF1 significantly attenuated the development of hypersensitivity to thermal stimulus as compared to control (P<0.05) and other formulation treated groups (P<0.05). All the AF semisolid formulations, when applied topically 2 h before carrageenan administration, inhibited paw edema in a timedependent manner with maximum percent edema inhibition of 80.33+/-2.52 achieved with AF1 after 5 h of carrageenan administration However, topical application of AF2 markedly prevented the development of edema as compared to other formulation (AF2 and AF3) treated groups (P<0.05). Among all the semisolid formulations, Carbopol gel base was found to be most suitable dermatological base for aceclofenac.
Painful neuropathy, a common complication of diabetes mellitus is characterized by allodynia and hyperalgesia. Recent studies emphasized on the role of non-neuronal cells, particularly microglia in the development of neuronal hypersensitivity. The purpose of the present study is to evaluate the effect of minocyline, a selective inhibitor of microglial activation to define the role of neuroimmune activation in experimental diabetic neuropathy. Cold allodynia and thermal and chemical hyperalgesia were assessed and the markers of inflammation and oxidative and nitrosative stress were estimated in streptozotocin-induced diabetic rats. Chronic administration of minocycline (40 and 80 mg/kg, i.p.) for 2 weeks started 2 weeks after diabetes induction attenuated the development of diabetic neuropathy as compared to diabetic control animals. In addition, minocyline treatment reduced the levels of interleukin-1β and tumor necrosis factor-α, lipid peroxidation, nitrite and also improved antioxidant defense in spinal cords of diabetic rats as compared to diabetic control animals. In contrast, minocycline (80 mg/kg, per se) had no effect on any of these behavioral and biochemical parameters assessed in age-matched control animals. The results of the present study strongly suggest that activated microglia are involved in the development of experimental diabetic neuropathy and minocycline exerted its effect probably by inhibition of neuroimmune activation of microglia. In addition, the beneficial effects of minocycline are partly mediated by its anti-inflammatory effect by reducing the levels of proinflammatory cytokines and in part by modulating oxidative and nitrosative stress in the spinal cord that might be involved in attenuating the development of behavioral hypersensitivity in diabetic rats.