Microsomal prostaglandin E synthase-1 (mPGES-1) catalyzes the terminal step of prostaglandin E2 (PGE2) production, which plays an important role in the regulation of febrile response. In our previous work, ligand-based pharmacophore models, built with mPGES-1 inhibitors, were employed to identify a novel series of compounds that reduce the febrile response in rats. The study aimed to evaluate the mechanism of action of the most active compound (1). For in vivo assays, rats were pretreated with the antipyretic compounds 1-8, 30 min before LPS injection. For in vitro assays, RAW 264.7 macrophage cells were incubated with the antipyretic compounds 1-8 for 1 hour before LPS stimulus. After 16 h, quantitative real-time PCR was carried out. Additionally, the PGE2 concentration in the hypothalamus was quantified by ELISA and the inhibitory effect of N-cyclopentyl-N'-[3-(3-cyclopropyl-1H-1,2,4-triazol- 5-yl)phenyl]ethanediamide (1) over human COX-2 enzymatic activity was determined with a COX Colorimetric Inhibitor Screening Assay Kit. Compound 1 and CAY10526 showed comparable efficacy to reduce the febrile response when injected i.v. (compound 1: 63.10%, CAY10526: 70.20%). Moreover, compound 1 significantly reduced the mPGES-1 mRNA levels, in RAW264.7 cells, under inflammatory conditions. A chemically-similar compound (8-) also significantly reduced the mRNA levels of the gene target. On the other hand, compounds 6 and 7, which are also somewhat similar to compound 1, did not significantly impact mPGES-1 mRNA levels. PGE2 concentration reduction in the hypothalamus, due to compound 1 central injection, is related to decreased mPGES-1 mRNA levels but not to COX-2 inhibition (IC50> 50 μM). Therefore, compound 1 is a promising lead for innovative antipyretic drug development.