Toxicology of benzydamine

Abstract

In acute studies, benzydamine produced pharmacologic effects and death at doses far above the human therapeutic levels. Human therapeutic doses are of the order of 0.7-1.0 mg/kg p.o. The LD 50 values (mg/kg) in mice were 33, i.v.; 110, i.p.; 218, s.c.; and 515, p.o.; and in rats, 100 i.p., and 1050 p.o. The general effects of benzydamine were similar in mice, rats, rabbits, and cats, and consisted of muscle relaxation and sedation, while at higher doses, ataxia and convulsions were observed. In dogs the drug produced sedation, but the occurrence of vomiting prevented the study of high dosages. Benzydamine in chronic studies produced lethal effects only in those experimental conditions and doses favorable to the production of acute pharmacodynamic effects. A depression of growth rate and enlargement of the liver were observed in mice and rats medicated with large doses of benzydamine. The latter effect is probably related to enzyme induction. Hematologic parameters, liver function, reproduction, and histologic structure of the major organs were not altered by benzydamine. The observation of helminthic infestation in control dogs, but not in those given benzydamine, suggested an antihelminthic activity of the drug.