All mice were transferred to the observation chamber
10 min before the experiment for acclimatization to the
new environment. Mice were divided into five groups
(n= 6). Control group was treated with 1% Tween 80
solution (10 ml/kg, i.p). Test groups received METS 50,100 and 200 mg/kg (i.p). Standard group was treated with
acetylsalicylic acid (100 mg/kg, s.c). After 30 min of the
drug administration, pain was induced in all mice by
injecting 1% formalin solution (20 μl) into the right hind
paw through intraplantar route. Formalin (1%) solutionwas prepared by diluting commercial formalin solution
(10%) with normal saline. The total number of licking the
injected paw were observed during 0-5 min (Neurogenic,
initial phase) and 20-30 min (Inflammatory, late phase)
after formalin injection. Special measures were taken in
order to avoid any possible disturbance during experments that may affect the animal’s response