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Interventions for preventing reactions to snake antivenom
1Pediatrics, Faculty of Medicine, Chulalongkorn University, Rama IV Road, Bangkok, Thailand, 10330. fmedinp@md2.md.chula.ac.th
Background:
Antivenom is used to neutralise snake bite toxins in people showing evidence of envenomation. It is made from animal sera, and adverse effects, including life threatening anaphylaxis, are common.
Objectives:
To assess the effects of drugs given routinely with snake antivenom to prevent adverse effects.
Search Strategy:
Cochrane controlled trials register; contact with researchers in the field.
Selection Criteria:
Randomised and quasi-randomised trials testing routine adrenaline (epinephrine), antihistamines, or corticosteroids.
Data Collection And Analysis:
The two authors applied the inclusion criteria, assessed trial quality, and extracted the data. We sought additional data from trialists where required.
Main Results:
One trial in Sri Lanka (n = 105) giving adrenaline with polyspecific antivenom showed fewer adverse reactions in the adrenaline group, and this effect was preserved when stratified for severity. One trial in Brazil (n = 101) using three types of Bothrops antivenom showed no benefit of antihistamine drugs.
Reviewer'S Conclusions:
Routine prophylactic adrenaline for polyvalent antivenom known to have high adverse event rates seems sensible, based on this one trial. If clinicians believe local factors do not justify routine adrenaline, then they should test their belief in a randomised trial. Antihistamine appears to be of no obvious benefit in preventing acute reactions from antivenoms.
Insights
Routine adrenaline may reduce adverse reactions to snake antivenom, particularly for polyspecific antivenoms with high adverse event rates. Antihistamines showed no benefit in preventing acute reactions from antivenoms.
Area of Science:
- Pharmacology
- Toxicology
- Clinical Medicine
Background:
- Snake antivenom neutralizes venom toxins but can cause severe adverse effects like anaphylaxis.
- Adverse reactions are a significant concern in antivenom therapy.
Purpose of the Study:
- To evaluate the efficacy of prophylactic drugs administered with snake antivenom to mitigate adverse events.
- Assessing the role of adrenaline, antihistamines, and corticosteroids in preventing antivenom reactions.
Main Methods:
- Systematic review of randomized and quasi-randomized controlled trials.
- Searched the Cochrane Controlled Trials Register and contacted researchers for relevant studies.
- Data extraction and quality assessment performed by two independent reviewers.
Main Results:
- One trial (n=105) in Sri Lanka indicated that adrenaline reduced adverse reactions when given with polyspecific antivenom.
- This protective effect of adrenaline was consistent across different severity strata.
- A separate trial (n=101) in Brazil found no benefit from antihistamine drugs when used with various Bothrops antivenoms.
Conclusions:
- Routine prophylactic use of adrenaline appears reasonable for polyvalent antivenoms with known high rates of adverse events, based on limited evidence.
- Clinicians should consider randomized trials if local factors suggest adrenaline is not warranted.
- Antihistamines do not appear to offer significant benefits in preventing acute antivenom reactions.