A thiosemicarbazone that inhibits viral protein production, once used for the prophylaxis of smallpox and the treatment of vaccination complications; N- methylisatin 3-thiosemicarbazone, C ₁₀ H ₁₀ N ₄ OS. [International Nonproprietary Name (1996) and British Approved Name (1998): metisazone.].
1960s; earliest use found in The British Medical Journal. From meth- (in methyl see note s.v. meth-) + is- + -azone.