Abstract
Background:
Ketoprofen (KP) is a nonsteroidal antiinflammatory drug that treats musculoskeletal injuries, osteoarthritis, and acute gouty arthritis. However, its use has been linked to certain detrimental effects on the stomach, liver, and renal function.

Aim:
This study investigated the ameliorative effects of omeprazole and quercetin on the negative effects of KP in rats.

Methods:
The experimental rats were randomly divided into four groups: Group I consisted of negative control rats. Rats were treated with ketoprofen in Group II (50 mg/kg b.wt.), omeprazole in Group III (20 mg/kg b.wt.), and quercetin in Group IV 1 h before ketoprofen (50 mg/kg b.wt.). Gastric juice volume and pH, gastric ulcer, ulcer score and curative ratio, serum biochemical analysis (liver function and kidney function), and evaluation of gastric, hepatic, and renal oxidant/oxidant status were all evaluated.

Results:
The obtained results showed significant ameliorative effects of omeprazole and quercetin against the induced alterations in the liver and kidney function tests compared with those in nontreated rats. In addition, KP caused significant oxidative damage, which was significantly improved upon omeprazole and quercetin administration.

Conclusion:
Therefore, it is highly recommended that either omeprazole and/or quercetin be used during the treatment course by KP to decrease its induced adverse effects.

Key words: Ketoprofen; Omeprazole; Quercetin; Oxidative damage; Rats.