The first antivenom was prepared by Calmette in 1894. More than a century later, it is still the only specific treatment for envenoming. The methods currently used by almost all antivenom producers worldwide to isolate and concentrate antivenom antibodies and their enzymatically derived fragments are improvements of those originally developed by Pope in 1938. Several new alternatives have been proposed to produce F(ab')2 or Fab antivenoms to improve their purity, neutralizing potency, and safety and to overcome the problems encountered in the production protocols based on ammonium sulfate precipitation of equine immunoglobulin. These include complete or partial modifications in the antivenom production regarding animal producers (ovine, laying hens...), immunization protocols, crude serum preparation and/or purification procedures concerning antibody extraction (PEG, caprylic acid, ion-exchange chromatography or immunoaffinity chromatography), and cleavage conditions (pepsin, papain...). In Tunisia, antivenom has been produced since the 1950's. Constant improvements and standardization of all the steps involved in antivenom production, purification, and quality control have resulted in a pure, safe, and efficient F(ab')2 product with no side effects when used intravenously, and with a high seroneutralization yield, as a result of the high toxin specific F(ab')2 concentration. The real impact of the new or modified procedures is a substantial increase in the cost of an antivenom dose. The quality is similar to that of the old procedure when its production was accurately standardized, optimized, correctly conducted and controlled. In addition, severe side effects have been reported after application of either equine F(ab')2 or ovine Fab antivenoms purified by the new methods (i.e. ion-exchange chromatography and immunoaffinity chromatography). Consequently, the introduction of these methods in developing countries still needs justification.
antivenom; standardization of antivenom; F(ab')2 and Fab antivenoms; anaphylactic reaction; anaphylactoid reaction; snake bite; scorpion sting
