In Vivo Genotoxicity and Cytotoxicity Kinetics of Trimethoprim Sulfamethoxazole in Well-nourished and Undernourished Young Rats

Undernutrition is a serious health problem prevalent in poor countries, affecting millions of people worldwide, especially young children, pregnant women, and sick elderly individuals. This condition increases vulnerability to infections, leading to widespread use of antibiotic treatments in undernourished populations. The objective of the present study was to determine the in vivo genotoxic and cytotoxic effects of trimethoprim-sulfamethoxazole (TMP-SMX) treatment according to nutritional conditions. The effects of TMP-SMX treatment were measured by analyzing the kinetics of micronucleated reticulocytes (MN-RET) induced in the peripheral blood of young, well-nourished (WN) and undernourished (UN) rats. In the WN group, two distinct peaks of MN-RET were observed, while the UN group had a significantly higher basal frequency of MN-RET compared to the WN group and only a later peak. Reticulocyte (RET) frequency slightly decreased in WN, indicating a poor cytotoxic effect. In contrast, in the UN, the treatment caused a significant increase in RET frequency. The results indicate that SMX's aromaticity index decreases when formed with TMP, suggesting potentially fewer toxic effects. In vivo TMP-SMX produces two MN-RET induction peaks in WN animals, indicating two DNA damage induction mechanisms and consequent micronucleus production. The UN rats did not display the two peaks, indicating that the first MN induction mechanism did not occur in UN, possibly due to pharmacokinetic effects, decreased metabolism or effects on cell proliferation. TMP-SMX has a slight cytotoxic effect on WN. In contrast, in the UN, the antibiotic treatment seems to favor early erythropoiesis.