Novel ethyl-5-amino-3-methylthio-1H-pyrazole-4-carboxylates: Synthesis and pharmacological activity

A series of novel ethyl-5-amino-3-methylthio-1H-pyrazole-4-carboxylates 3a–j were synthesized from condensation of various hydrazides 2a–j with ketene dithioacetal. The synthesized compounds were screened for in vivo analgesic and anti-inflammatory activities using acetic acid writhing test in mice and carrageenan-induced paw edema test in rat, respectively. Diclofenac sodium was used as a standard drug for comparison. Compounds 3a, 3c and 3d exhibited significant analgesic and anti-inflammatory activities at a dose of 25 mg/kg and showed quite less ulcerogenic index in the range of 0.9–1.12 whereas diclofenac sodium showed 3.10.