The acute toxicity of a new antubercular drug, dextran polyaldehyde conjugate with isonicotinic acid hydrazide (dextrazide), has been studied on animals, HepaRG cell line, and FRSN human skin fibroblasts. Average tolerable doses (LD(10), LD(16)), half-lethal doses (LD(50)), and lethal doses (LD(84)) of dextrazide have been determined for intraperitoneal introduction in mice and rats and intravenous injection in rabbits.