2.11. Analgesic Activity Test Using Acetic Acid-Induced Writhing Test

The analgesic activity was determined by the acetic acid abdominal constriction test [18, 19]. Twenty-five male mice were randomly divided into 5 groups, where each group consisted of 5 mice. Group 1 was treated with carboxymethyl cellulose (CMC-Na 0.5%) (as negative control). Group 2 was treated with standard drug diclofenac sodium at a dose of 40 mg/kg body weight [2]. Groups 3, 4, and 5 were treated with AS201-01 tablets at a dose equal to 12.5, 25, and 50 mg andrographolide/kg body weight, respectively. All treatments were administered orally. Thirty minutes after administration of all treatments, each mouse was injected with 1% acetic acid at a dose of 10 ml/kg body weight intraperitoneally [20, 21]. At 5, 15, 25, 35, and 45 minutes after acetic acid injection, the number of writhing responses observed during a 5-minute period were counted and recorded [11].

The percentage of analgesic activity was calculated as follows:

where W is the number of writhing, c is the negative control, and t is the test.