A double-blind, randomized trial of intravenous versus intramuscular antivenom for red-back spider envenoming.
OBJECTIVE
To compare the efficacy of intravenous versus intramuscular antivenom (AV) in the treatment of Red-back spider (RBS) envenoming.


METHODS
Randomized, double-dummy, double-blind, multicentre trial of patients with red-back spider envenoming requiring AV treatment recruited from five hospital EDs in Western Australia.


RESULTS
Thirty-five patients were recruited; two were excluded; 33 were available for initial analysis, but two who were unblinded after one ampoule of trial AV and given i.v. AV had limited data; 31 remained in the study and had more complete data. After AV, pain scores for both i.m. and i.v. groups improved rapidly. At 24 h, the i.v. group was better with a 55% absolute difference (76% vs. 21%; 95% CI 25-85% difference) in the proportion pain-free. There were no safety issues.


CONCLUSIONS
Red-back spider antivenom was initially effective by both i.m. and i.v. routes. The study generates the hypothesis that at 24 h, significantly more patients are pain-free with i.v. administration. Definitive recommendations on the optimal route of administration of RBS AV await the results of further studies.
Ellis
Rodney M
RM
Department of Emergency Medicine, Fremantle Hospital.
Sprivulis
Peter C
PC
Jelinek
George A
GA
Banham
Neil D G
ND
Wood
Simon V
SV
Wilkes
Garry J
GJ
Siegmund
Andrew
A
Roberts
Brigit L
BL
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000997:Antivenins / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D007273:Injections, Intramuscular; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology; D010147:Pain Measurement; D001098:Spider Bites / Q000150:complications / Q000188:drug therapy*; D013111:Spider Venoms / Q000009:adverse effects / Q000037:antagonists & inhibitors*; D016896:Treatment Outcome
D000997:Antivenins; D013111:Spider Venoms