BACKGROUND: Omeprazole is a proton pump inhibitor of increasingly wideapplication in the treatment of different gastroenterological diseases. The purpose of the study wasto evaluate the effect of omeprazole (O) on the level of plasma malondialdehyde (MDA).
MATERIAL AND METHODS:Omeprazole was administered intraperitoneally to male Wistar rats twice a day, for 3 days, in two doses:O1-0.57 mg/kg body weight (b.w.), O2-5.71 mg/kg b.w. Twelve hours after the last injection half of theanimals were terminated (I). The remaining rats were kept for the next 6 weeks without any xenobiotics(II). The blood was taken from the still beating heart and then centrifuged. The plasma level of MDAwas determined and compared to the 1 mg of the blood protein.
RESULTS: A significant (p < 0.05) increaseof MDA level was found in the O2II group, as compared with the O2I group. The level of MDA was higherafter 6 weeks' period in relation to the animals that were terminated on the 4th day of the experiment.
CONCLUSION: Three-day omeprazole administration did not change the MDA level in the rat plasma.

Keywords: Malondialdehyde, MDA, omeprazole, Mutagenesis, carcinogenesis, Rat