Antipyretic effect of the main dipyrone metabolites on febrile response induced by LPS and Tityus serrulatus scorpion venom

• Grant number: 08/09443-4
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: March 01, 2009
• End date: September 30, 2012
• Field of knowledge: Biological Sciences - Pharmacology - General Pharmacology
• Principal Investigator: Glória Emília Petto de Souza
• Grantee: David do Carmo Malvar
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

The prodrug dipyrone is an important antipyretic drug. After its administration, dipyrone is rapidly converted by hydrolysis in 4- methylaminoantipyrine (4-MAA), which is then metabolized to 4- formylaminoantipyrine 4-(4-FAA), 4- aminoantipyrine ( 4-AA) and 4- acetylaminoantipyrine (4-AAA). However, the metabolites of dipyrone with antipyretic activity, as well as the mechanism of action of these active metabolites are still unclear. Some authors propose that the antipyretic mechanism of dipyrone is dependent of PGE2 synthesis inhibition. Corroborating this proposal, ex vivo and in vitro studies showed that only two dipyrone metabolites, 4-MAA and 4-AA, inhibit the synthesis of PGE2, thus being these compounds considered the active metabolites of dipyrone. However, our group demonstrated recently that the antipyretic effect of dipyrone is not related to inhibition of PGE2 synthesis in the hypothalamus of animals injected with LPS and ET-1. In addition, we demonstrate that of Tityus serrulatus venom (Tsv) induces fever independently of PGE2 synthesis and that dipyrone abolish the vTs-induced fever, enhancing the hypothesis that the antipyretic effect of dipyrone is independent of PGE2 synthesis inhibition. Our results demonstrate that after intraperitoneal (i.p.) administration of dipyrone (120 mg kg-1) all metabolites are quickly detected in plasma, CSF and hypothalamus, and also that the antipyretic effect of dipyrone on the LPS-induced febrile response correspond with the time-points of higher concentration of 4-MAA and 4-AA in the three available tissues. However, the antipyretic effect of dipyrone on Tsv-induced fever only correspond with the time-points of higher concentration of 4-MAA in plasma, CSF and hypothalamus. We also demonstrated that i.p. administration with 4-AA (30-120 mg kg-1), but not 4-AAA (120-360 mg kg-1), dose-dependently inhibits the LPS-induced fever (50 mg kg-1), indicating that 4-AA is a antipyretic metabolite of dipyrone and that the acetylation of 4-AA produced by polymorphic N-acetyltransferase enzyme, converting it to 4-AAA, abolishes its antipyretic effect on LPS-induced fever. Additionally, only i.p. treatment with 4-MAA (60-120 mg kg-1) dose-dependently inhibits the febrile response induced by LPS (50 mg kg-1) or Tsv (150 mg kg-1), demonstrating that 4-MAA is another antipyretic metabolite and that it is the responsible for the PGE2 synthesis inhibition- independent antipyretic effect of dipyrone, observed after injection of Tsv. Moreover, the 4-FAA (120-360 mg kg-1, ip) is another metabolite which also has antipyretic effect during LPS-induced febrile response, however the high antipyretic dose and time-curse for this effect suggests that 4-FAA has little or no relevance in the antipyretic effect of dipyrone. Furthermore, our results demonstrate that higher doses of 4-MAA (240-360 mg kg-1), but not higher doses of the other dipyrone metabolites, induce hypothermia, suggesting that 4-MAA is the metabolite responsible for the hypothermic effect of dipyrone. Finally, we demonstrate that intracerebroventricular treatment with dipyrone, 4-MAA or AA-4 inhibited the LPS-induced fever, and the sequence, in terms of antipyretic potency, of these treatments was as follows: 4-MAA > 4-AA > dipyrone. These results indicate that 4-MAA and 4-AA are dipyrone metabolites with central antipyretic effect, however these results do not exclude the possible involvement of peripheral antipyretic mechanisms.

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

AGUIAR, FERNANDO A.; MALVAR, DAVID DO C.; VAZ, ARTUR DE L. L.; CALIXTO, LEANDRO A.; CLOSOSKI, GIULIANO C.; DE GAITANI, CRISTIANE M.; DE SOUZA, GLORIA E. P.; JABOR, VALQUIRIA A. P.. Simultaneous determination of dipyrone metabolites in rat hypothalamus, cerebrospinal fluid and plasma samples by LC-MS/MS. BIOANALYSIS, v. 5, n. 21, p. 2631-2645, NOV 2013. (08/09443-4)

MALVAR, DAVID DO C.; AGUIAR, FERNANDO A.; VAZ, ARTUR DE L. L.; ASSIS, DEBORA C. R.; DE MELO, MIRIAM C. C.; JABOR, VALQUIRIA A. P.; KALAPOTHAKIS, EVANGUEDES; FERREIRA, SERGIO H.; CLOSOSKI, GIULIANO C.; DE SOUZA, GLORIA E. P.. Dipyrone metabolite 4-MAA induces hypothermia and inhibits PGE(2)-dependent and -independent fever while 4-AA only blocks PGE(2)-dependent fever. British Journal of Pharmacology, v. 171, n. 15, p. 3666-3679, AUG 2014. (08/09443-4)

KANASHIRO, ALEXANDRE; FIGUEIREDO, MARIA J.; MALVAR, DAVID DO C.; SOUZA, GLORIA E. P.. Cytokines, but not corticotropin-releasing factor and endothelin-1, participate centrally in the febrile response in zymosan-induced arthritis in rats. Brain Research, v. 1610, p. 12-19, JUN 12 2015. (08/09443-4, 12/04237-2)