The paper presents the toxicological characteristics of 198 cases of acute parenteral heroin intoxication in the whole range of concentrations of their metabolites, which are encountered in practice. An attempt was made to estimate the risk of death within possible blood morphine concentrations in acute heroin intoxication, by taking into account gender- and age-related differences. The median lethal morphine concentration (LD50) has been found to greatly differ in males (0.78 μg/ml) and females (0.98 μg/ml) and in those aged under (0.39 μg/ml) and above (1.50 μg/ml) 25 years. At the age under 25 years, most victims show nearly the same response in the narrow range of concentrations (LD50 = 0.39 μg/ml; LD100 = 1.57 μg/ml); in persons above 25 years of age, there are great individual differences in their sensitivity to the concentration of a toxic substance (LD50 = 1.50 μg/ml; LD100 = 3.90 μg/ml).

        Key words: morphine – morphine concentration – opiate intoxication – toxicity criteria