This Page Intentionally Left Blank - Int Medical

severe cramps associated with terrestrial envenomation. 31,38 Though there are
no RCTs comparing calcium and muscle relaxants, case report data in latro-
dectism indicate superiority of diazepam over calcium preparations. 50 There
is no good evidence supporting use of non-benzodiazepine muscle relaxants
(e.g. methocarbamol); these agents are not recommended.
NSAIDs have been reported useful in small case series of bites from spiders
such as brown recluses and tarantulas. 51,52 Preliminary evidence from animal
models and case reports suggests a role for NSAIDs for scorpion envenomation.
39,53 The use of NSAIDs in snakebites is discouraged, since many snake
venoms inhibit the arachidonic acid cascade (NSAID administration can
theoretically worsen bleeding and renal complications). 54 Safety considerations
aside, trials of NSAIDs suggest they provide less-effective snakebite pain
relief than antivenom. 55
Case series evidence supports consideration of injecting local anesthetics
(e.g. lidocaine, mepivacaine) for bites of some spiders, scorpions, and centipedes.
44,56–59 Limited case report evidence supports use of Bier’s block
regional anesthesia for Latrodectus species, but caution is recommended
owing to the risk of worsening toxicity. 60,61
A large randomized double-blind trial demonstrated no utility for corticosteroids
in scorpion envenomation. 62 Case series suggest that corticosteroids
are occasionally useful for some centipede bites, especially in
cases in which Wells’ syndrome (eosinophilic cellulitis) develops. 44,58
n Summary and recommendations
First line: fentanyl (initial dose 50–100 μg IV, then titrate)
Bites and stings – terrestrial 127
Reasonable:
n antihistamines (e.g. diphenhydramine 25–50 mg IV q4–6h)
n morphine (initial dose 4–6 mg IV, then titrate) if antivenom will not be
administered for severe symptoms
n local anesthetic (e.g. bupivacaine 0.25%) injection unless snakebite
Pregnancy:
n fentanyl (initial dose 50–100 μg, then titrate)
n local anesthetic (e.g. bupivacaine 0.25%) injection unless snakebite