Antivenom therapy: efficacy of premedication for the prevention of adverse reactions

Antivenoms or antitoxins have been effectively used for more than a century. During this time, these products have always proven to be highly effective in the treatment of infections and envenomations. However, antivenoms did not exhibit good safety results in their initial applications. After many improvements, antivenoms have substantially better safety profiles but still have some side effects. Due to the occurrence of adverse reactions, the practice of using premedication with the intent to decrease side effects has become accepted or mandatory in many countries. The drugs used for premedication belong to the histamine H1 antagonist, glucocorticoid and catecholamine groups. Currently, this practice is being questioned due to low or controversial efficacies in clinical assays. In this article, we discuss the causes of adverse reactions, the mechanisms of drugs that block the undesired effects and the results obtained in clinical trials. Although these three families of drugs could have positive effects on reducing adverse reactions, only adrenaline has demonstrated positive results in clinical assays.(AU)

Bilateral Acute Anterior Uveitis and Optic Disc Edema Following a Snake Bite

The authors wish to report a case of bilateral acute anterior uveitis and optic disc edema following a hemotoxic snake bite, in order to highlight the concomitant occurrence of these conditions and the potential adverse effects of anti-snake venom (ASV). A 35-year-old male was bitten by a viper at seventeen thirty hours, and was started on ASV. Two days following treatment he experienced sudden onset redness and painful diminution of vision in both eyes (OU). On examination, the patient's visual acuity (VA) in OU was 20/200. Examination revealed fresh keratic precipitates, cells, and flare in the anterior chamber (AC), posterior synechiae, sluggish and ill-sustained pupillary reaction, and hyperemic, edematous disc with blurred margins in OU. He was started on topical steroids, cycloplegics and intravenous methylprednisolone. Following treatment, the patient showed improvement and was continued on topical medications and oral prednisolone tapered over 3 weeks, after which VA OU improved, the AC showed no cells and flare and disc edema resolved. Uveitis and optic disc edema in snake bite can either be due to the direct toxic effects of the venom or the effect of ASV. Steroids have a beneficial role in the management of these symptoms.

Use of antivenoms for the treatment of envenomation by Elapidae snakes in Guinea, Sub-Saharan Africa

Background In Guinea Elapids are responsible for 20% of envenomations. The associated case fatality rate (CFR) ranged 15-27%, irrespective of treatment. Results We studied 77 neurotoxic envenomations divided in 3 groups: a set of patients that received only traditional or symptomatic treatments, and two other groups that received either 2 or 4 initial vials of Antivipmyn® Africa renewed as necessary. CFR was 27.3%, 15.4% and 17.6%, respectively. Although antivenom treatment was likely to reduce CFR, it didn’t seem to have an obvious clinical benefit for the patients, suggesting a low treatment efficacy. Mean delay to treatment or clinical stages were not significantly different between the patients who recovered and the patients who died, or between groups. Interpretation of these results is complicated by the lack of systematic studies under comparable conditions. Of particular importance is the absence of assisted ventilation, available to patients in all the other clinical studies of neurotoxic envenomation. Conclusion The apparent lack of clinical benefit may have several causes. The hypothesis of a limited therapeutic window, i.e. an insufficient formation of antigen-antibody complexes once toxins are bound to their targets and/or distributed beyond the reach of antivenom, should be explored. .

Snake antivenoms: adverse reactions and production technology: [review]

Antivenoms have been widely used for more than a century for treating snakebites and other accidents with poisonous animais. 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: aused by complement system activation, and pyrogenic reactions produced mainly by the presence of endotoxins in the final product. ln 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 more purified and specific product in compliance with good manufacturing practices and at an affordable cost

Safety of subcutaneous adrenaline as prophylaxis against acute adverse reactions to anti-venom serum in snakebite.

OBJECTIVES: To study the safety of low dose subcutaneous adrenaline given as prophylaxis against acute adverse reactions to anti-venom serum (AVS) in patients bitten by snakes. METHODS: Patients admitted with snakebite envenoming who satisfied inclusion criteria were given 0.25 ml of 1:1000 adrenaline subcutaneously immediately before administration of AVS. They were observed for adverse effects, and pulse and blood pressure (BP) were monitored. RESULTS: 51 patients [35 males, mean age 34.8 years (SD 14)] were included in the study. Adverse reactions to AVS occurred in 15 (29.4%) patients. There was one death from suspected cerebral haemorrhage, and 3 (5.9%) patients developed small haematomas at the subcutaneous injection site. There were no significant changes in mean pulse or BP following administration of subcutaneous adrenaline. CONCLUSIONS: Low dose subcutaneous adrenaline did not cause significant changes in pulse rate or BP. Although the death was unlikely to be directly related to subcutaneous adrenaline, we suggest further studies on the safety of this prophylactic treatment before its routine use.

Acute pulmonary edema as a complication of anti-snake venom therapy.

Polyvalent Anti-snake Venom (ASV) is a life-saving antivenin for severe envenomation due to snake bite in India. ASV infusion is occasionally associated with severe allergic reactions, i.e. anaphylaxis and death. We report a rare instance of non-cardiogenic pulmonary edema due to ASV infusion in an eleven years old boy.

Reações de hipersensibilidade imediatas apos uso intravenoso de soros antivenenos: valor prognostico dos testes de sensibilidade intradermicos / Immediate hypersensitivity reactions after intravenous use of antivenin sera: prognostic value of intradermal sensitivity tests

Foram admitidos no Hospital das Clinicas da FMRPUSP, durante os anos de 1983 a 1988, 494 pacientes vitimas de acidentes ofidicos e escorpionicos que receberam soro antiveneno (SAV) e nos quais foi avaliada a frequencia e tipo das manifestacoes imediatas, bem como o valor prognostico do teste de sensibilidade. Do total de pacientes vitimas de ofidismo, 82 (25,6 por cento) apresentaram reacoes imediatas, das quais as mais comuns foram as cutaneas, isoladas (40 por cento) ou associadas com sintomas respiratorios (19 por cento), seguidas de manifestacoes gastrintestinais (17 por cento). Choque anafilatico foi detectado em 10 pacientes (12 por cento). Em relacao aos acidentes escorpionicos, reacoes imediatas foram observadas em 13 pacientes (7,5 por cento), tambem com predominio de lesoes cutaneas. Sintomatologia cardiocirculatoria foi detectada em apenas 1 paciente. Devido ao baixo valor preditivo positivo (31,8 por cento) e a baixa sensibilidade (54,6 por cento), propomos que o teste de sesibilidade intradermico seja abolido da rotina de atendimento de urgencia aos pacientes vitimas de acidentes por animais peconhentos. Anti-histaminicos (bloqueadores dos receptores "H IND. 1" e "H IND. 2") e corticosteroides devem ser administrados por via parenteral anteriormente a soroterapia, no sentido de prevenir...

Primer caso de enfermedad del suero por suero antiofidico en dosis mínima / First case of serum sichness by snake antivenins at minimun dosages

Presentamos un caso de "enfermedad del suero", por suero antifídico en dosis mínima de 1 frasco indicado para una forma clínica "leve", en un paciente picado por un ofidio Bothrops neuwiedri diporus, que no había sido tratado en ninguna oportunidad con sueros heterólogos, por lo que estamos ante el primer caso documentado de dicha patología