Low Dose Aspirin Like Analgesic and Anti-inflammatory Activities of Mono-hydroxybenzoic Acids in Stressed Rodents

Aims: To compare analgesic and anti-inflammatory activities of aspirin and mono-hydroxybenzoic acids after their daily oral doses.

Main Methods: Efficacies of repeated daily stress response suppressing low oral doses (20mg/kg) of aspirin and 2-, 3-, and 4-hydroxybenzoic acids in mice hot plate test for centrally acting analgesics, and in acetic acid induced writing test were compared. Effects of their same daily doses and treatment regimen in cotton pellet granuloma and carrageenan edema test for anti-inflammatory drugs in stressed rats were compared in a second experiment. Effects of treatments on body weights, basal rectal temperatures, organ weights and plasma glucose, insulin and cortisol levels in stressed animals were compared also.

Key Findings: Although stress response suppressing effects of aspirin and all the three hydroxybenzoic acids in both mice and rats were almost equal, effectiveness of 3- and 4-hydroxybenzoic acids as analgesic and anti-inflammatory agents were lower than those of aspirin or salicylic acid.

Significance: Observations made after single oral doses of aspirin or of mono-hydroxybenzoic acids are not very reliable predictors of their pharmacologically interesting bioactivity profiles and efficacies. Prostaglandin synthesis inhibition is not involved in low dose anti-inflammatory activities of 3- and 4-hydroxybenzoic acids. After their repeated daily low oral doses they are almost as potent stress response desensitizers as aspirin or salicylic acid.