ANTI-VENOMS: CURRENT USE AND PERSPECTIVES.

THE ROLE OF LYOPHILIZATED SERUM

FRANÇA, F.O.(1)

(1)Hospital Vital Brazil do Instituto Butantan, Hospital das Clínicas da USP

The accidents caused by poisonous animals are one of the most neglected health problems mainly in the developing countries. Chippaux estimates more than 100,000 deaths per year caused by snake bites. Brazil has at least 28.000 snake bites with more than 100 deaths per year. The perspective to produce more effective and safe antivenoms, with acceptable cost, immediate and easy administration are essential to diminish the morbidity and lethality of these accidents.  Nevertheless there are a lot of limitations to achieve these objectives. Besides the antivenom produced in Brazil has high quality, we need to overcome some obstacles to avoid complications and deaths. The first problem is the geographic distance between the place where the accidents frequently occurr and the health care centers. Almost 70% of deaths in Brazil has occurred in patients who received the antivenom 6 or more hours after the accident. The National Program to Control Poisonous Animal Accidents, developed since 1966, made possible the decentralization of the distribution of antivenom serum and has promoted training to hundreds of health workers to diminish the interval between the accident and the treatment. Many authors suggest the immediate administration of intramuscular antivenom where the accident occurred to neutralize the venom quickly, others have proposed the use of  lyophilizated antivenom to avoid the necessity of constant temperature to maintain the neutralizant power of liquid antivenom. Nowadays snake antivenom is basically composed of horse Ig G polyclonal immunoglobulins  and the production of homologous antivenom will permit the administration of antivenom without risk of anaphylaxis reactions. There are researchers that are working to improve the capacity of neutralization of snake venoms. The use of  pepsin-digested  antibodies antivenom is compared with the whole IgG antivenoms in order to verify which of them are more efficient. Another possibility is the production of monoclonal antibodies that are able to recognize antigenic determinants and theoretically could have a major role in the treatment of snake bites accidents. The discovery of the components that causes abnormalities in patients can lead the production of antivenoms that neutralize only the toxins that has a role in the human accidents. These objectives are not easy to achieve because antibodies derived from animal sera are one of the most misunderstood and undervalued pharmaceutical products. Another obstacle is the complexity of the envenoming. There are variations in venoms of snakes belonged to the same genus, and differences in venoms of snakes belonged to the same species or subspecies (It is common some variation in the venom constitution of snakes belonged to the same species but with different ages and from different geographic origins). The verification of this different approaches are extremely difficult in human accidents because it’s almost impossible to control the variables that influence the evolution of snake bites. Aspects related with the snakes like species, age, length; with the patients like age, weight, the time between the accident and the treatment, the use of tourniquet and aspects related to the snake bite like the quantity of venom inoculated, the region of the body and the site of venom deposition (subcutaneous, muscle or direct in a blood vessel).