Synthesis of thiazolotriazine derivatives and their antinociceptive effects in mice.
Ans raci A series of 2-(4-arylpiperazin-1-yl-methyl)-4-methyl-1-oxo-5,6,8,8a-tetrahydro -thiazolo[3,4-d] [1,2,4]triazines was prepared and tested for antinociceptive activity. The compounds were prepared by the Mannich reaction from the corresponding 2-unsubstituted thiazolotriazines. When administered intraperitoneally most were found to have potent analgesic activity in the mouse during tests of phenylbenzoquinone-induced abdominal constriction; ED50 values (doses resulting in half the maximum effect) ranged from 10 to 87 mg kg(-1). Derivatives with a 3-chloro- or 4-fluorophenylpiperazinylmethyl side-chain in the 2-position of the bicyclic system were, when administered intraperitoneally at doses greater than 25 mg kg(-1), also effective in the hot-plate test without associated sedative effects. The compounds have a large therapeutic index; intraperitoneal LD50 values (doses which result in the death of half the animals) were > 700 mg kg(-1). Naloxone attenuated the analgesic activity of the 3-chloro derivative, suggesting the participation of micro-receptors in the antinociceptive effects of this drug. In addition, a nonopioid mechanism, probably related to enhancement of the release of 5-hydroxytryptamine and noradrenaline, or inhibition of the neuronal re-uptake of these compounds, has been evinced to explain the analgesic properties of the 3-chloro or 4-fluoro derivatives. These results provide evidence for the involvement of noradrenergic and 5-hydroxytryptaminergic pathways in the analgesic activity of 3 and 4. Because of their potential effectiveness, the 3-chloro- or 4-fluorophenylpiperazinylmethyl derivatives might be suitable for treatment of a wide variety of painful conditions and could be attractive reserve agents for patients dissatisfied with opioids.
Groupe de Recherche en Pharmacochimie and Laboratoire de Chimie Thérapeutique, Clermont-Ferrand, France.
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Issartel
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Coudert
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Rubat
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Nhamias
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Couquelet
D018712:Analgesics, Non-Narcotic / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D004347:Drug Interactions; D008297:Male; D051379:Mice; D013844:Thiazoles / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D014227:Triazines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*
D018712:Analgesics, Non-Narcotic; D013844:Thiazoles; D014227:Triazines