Anti-inflammatory, antinociceptive and ulcerogenic activity of a zinc-diclofenac complex in rats

We investigated the anti-inflammatory, antinociceptive and ulcerogenic activity of a zinc-diclofenac complex (5.5 or 11 mg/kg) in male Wistar rats (180-300 g, N = 6) and compared it to free diclofenac (5 or 10 mg/kg) and to the combination of diclofenac (5 or 10 mg/kg) and zinc acetate (1.68 or 3.5 mg/kg). The carrageenin-induced paw edema and the cotton pellet-induced granulomatous tissue formation models were used to assess the anti-inflammatory activity, and the Hargreaves model of thermal hyperalgesia was used to assess the antinociceptive activity. To investigate the effect of orally or intraperitoneally (ip) administered drugs on cold-induced gastric lesions, single doses were administered before exposing the animals to a freezer (-18ºC) for 45 min in individual cages. We also evaluated the gastric lesions induced by multiple doses of the drugs. Diclofenac plus zinc complex had the same anti-inflammatory and antinociceptive effects as diclofenac alone. Gastric lesions induced by a single dose administered per os and ip were reduced in the group treated with zinc-diclofenac when compared to the groups treated with free diclofenac or diclofenac plus zinc acetate. In the multiple dose treatment, the complex induced a lower number of the most severe lesions when compared to free diclofenac and diclofenac plus zinc acetate. In conclusion, the present study demonstrates that the zinc-diclofenac complex may represent an important therapeutic alternative for the treatment of rheumatic and inflammatory conditions, as its use may be associated with a reduced incidence of gastric lesions.