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Antivenoms have been widely used for more than a century for treating snakebites and other accidents with poisonous animals. Despite their efficacy, the use of heterologous antivenoms involves the possibility of adverse reactions due to activation of the immune system. In this paper, alternatives for antivenom production already in use were evaluated in light of their ability to minimize the occurrence of adverse reactions. These effects were classified according to their molecular mechanism as: anaphylactic reactions mediated by IgE, anaphylactoid reactions caused by complement system activation, and pyrogenic reactions produced mainly by the presence of endotoxins in the final product. In the future, antivenoms may be replaced by humanized antibodies, specific neutralizing compounds or vaccination. Meanwhile, improvements in antivenom quality will be focused on the obtainment of a more purified and specific product in compliance with good manufacturing practices and at an affordable cost.

Dear Editor:In the field of envenomations by poisonous animals, the ability of antivenoms to neutralize the lethal effects of venoms is estimated by a biological assay in which mice are inoculated with a range of venom/antivenom concentrations and the survival/death ratio is recorded. A statistical technique (e.g., Probit) is employed to estimate the amount of antivenom that protects 50% of the animals. This quantity is called median effective dose or effective dose 50 (ED 50 ) and is normally expressed in volume units (i.e., mL or μL). The ED 50 is used in an expression for the assessment of the potency (P) of the antivenom, as follows (1, 2): P = (n -1)LD 50 / ED 50 [1]where "LD 50 " is the median lethal dose (mass of venom that kills 50% of mice), and "n" is the number of LD 50 s used in the assay. "P" is the amount of venom, expressed in mass units or number of median lethal doses, that is completely neutralized per unit volume of antivenom (the expression "(n -1) LD 50 " is used instead of the total amount of venom, nLD 50 , because at the endpoint of the neutralization assay, one LD 50 remains unneutralized and causes the death of 50% of mice). However, in the literature, it is very frequent to find that the same term, ED 50 , is utilized to represent