...Synthesis and Pharmacology of N-(1-Phenylpyrazolyl)-N-(1-phenylalkyl-4-piperidyl)propanamidesBioorganic & Medicinal Chemistry Volume 10, Issue 3 , March 2002, Pages 817-827 Nadine Jagerovica, Carolina Canoa, José Elgueroa, Pilar Goya, Luis F. Calladob, J. Javier Meanab, Rocío Girónc, Raquel Abaloc, David Ruizc, Carlos Goicoecheac and M. Isabel Martínc
Abstract: The synthesis of new fentanyl analogues in which the benzene ring of the propioanilido group has been replaced by phenylpyrazole is described. Antinociceptive activity was evaluated using the writhing and hot plate tests in mice. Two compounds, 3b and 3d, showed interesting analgesic properties, being more potent than morphine and less than fentanyl but with longer duration of action. These compounds inhibited the electrically evoked muscle contraction of guinea pig ileum and mouse vas deferens but not that of rabbit vas deferens and the effects could be reversed by antagonists (naloxone and/or CTOP), thus indicating that the compounds acted as agonists. Finally, the binding data confirmed that the compounds had high affinity and selectivity for the receptor.
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