title: Sequential randomised and double blind trial of promethazine prophylaxis against early anaphylactic reactions to antivenom for bothrops snake bites.
abstract: OBJECTIVE
  To investigate the efficacy of the H1 antihistamine promethazine against early anaphylactic reactions to antivenom.
  
  
  METHODS
  Sequential randomised, double blind, placebo controlled trial.
  
  
  METHODS
  Public hospital in a venom research institute, São Paulo, Brazil.
  
  
  METHODS
  101 patients requiring antivenom treatment after being bitten by bothrops snakes.
  
  
  METHODS
  Intramuscular injection of promethazine (25 mg for adults and 0.5/kg for children) or placebo given 15-20 min before starting intravenous infusion of antivenom.
  
  
  METHODS
  Incidence and severity of anaphylactic reactions occurring within 24 hours after antivenom.
  
  
  RESULTS
  Reactions occurred in 12 of 49 patients treated with promethazine (24%) and in 13 of 52 given placebo (25%); most were mild or moderate. Continuous sequential analysis indicated that the study could be interrupted at the 22nd untied pair, without preference for promethazine or placebo.
  
  
  CONCLUSIONS
  Prophylaxis with promethazine does not prevent early reactions. Patients should be observed carefully during antivenom infusion and the subsequent few hours.
authors.affiliation: Hospital Vital Brazil, Instituto Butantan, Avenue Vital Brazil 1500, 05503-900, São Paulo, Brazil.
authors.forename: H W
authors.initials: HW
authors.lastname: Fan
authors.forename: L F
authors.initials: LF
authors.lastname: Marcopito
authors.forename: J L
authors.initials: JL
authors.lastname: Cardoso
authors.forename: F O
authors.initials: FO
authors.lastname: França
authors.forename: C M
authors.initials: CM
authors.lastname: Malaque
authors.forename: R A
authors.initials: RA
authors.lastname: Ferrari
authors.forename: R D
authors.initials: RD
authors.lastname: Theakston
authors.forename: D A
authors.initials: DA
authors.lastname: Warrell
mesh_terms: D000293:Adolescent; D000328:Adult; D000707:Anaphylaxis / Q000517:prevention & control*; D000818:Animals; D000997:Antivenins / Q000009:adverse effects*; D017837:Bothrops; D002648:Child; D004311:Double-Blind Method; D005260:Female; D006634:Histamine H1 Antagonists / Q000627:therapeutic use*; D006801:Humans; D007262:Infusions, Intravenous; D007273:Injections, Intramuscular; D008297:Male; D011398:Promethazine / Q000627:therapeutic use*; D012909:Snake Bites / Q000188:drug therapy*
chemical_list: D000997:Antivenins; D006634:Histamine H1 Antagonists; D011398:Promethazine