title: Efficacy and safety of scorpion antivenom plus prazosin compared with prazosin alone for venomous scorpion (Mesobuthus tamulus) sting: randomised open label clinical trial.
abstract: OBJECTIVE
  Envenomation by Mesobuthus tamulus scorpion sting can result in serious cardiovascular effects. Scorpion antivenom is a specific treatment for scorpion sting. Evidence for the benefit of scorpion antivenom and its efficacy compared with that of commonly used vasodilators, such as prazosin, is scarce. We assessed the efficacy of prazosin combined with scorpion antivenom, compared with prazosin alone, in individuals with autonomic storm caused by scorpion sting.
  
  
  METHODS
  Prospective, open label randomised controlled trial.
  
  
  METHODS
  General hospital inpatients (Bawaskar Hospital and Research Centre Mahad Dist-Raigad Maharashtra, India).
  
  
  METHODS
  Seventy patients with grade 2 scorpion envenomation, older than six months, with no cardiorespiratory or central nervous system abnormalities.
  
  
  METHODS
  Scorpion antivenom plus prazosin (n=35) or prazosin alone (n=35) assigned by block randomisation. Treatment was not masked. Analysis was by intention to treat.
  
  
  METHODS
  The primary end point was the proportion of patients achieving resolution of the clinical syndrome (sweating, salivation, cool extremities, priapism, hypertension or hypotension, tachycardia) 10 hours after administration of study drugs. Secondary end points were time required for complete resolution of clinical syndrome, prevention of deterioration to higher grade, doses of prazosin required overall and within 10 hours, and adverse events. The study protocol was approved by the independent ethics committee of Mumbai.
  
  
  RESULTS
  Mean (SD) recovery times in hours for the prazosin plus scorpion antivenom group compared with the prazosin alone groups were: sweating 3 (1.1) v 6.6 (2.6); salivation 1.9 (0.9) v 3 (1.9); priapism 4.7 (1.5) v 9.4 (1.5). Mean (SD) doses of prazosin in the groups were 2 (2.3) and 4 (3.5), respectively. 32 patients (91.4%, 95% confidence interval 76.9% to 97.8%) in the prazosin plus antivenom group showed complete resolution of the clinical syndrome within 10 hours of administration of treatment compared with eight patients in the prazosin group (22.9%, 11.8% to 39.3%). Patients from the antivenom plus prazosin group recovered earlier (mean 8 hours, 95% CI 6.5 to 9.5) than those in the control group (17.7 hours, 15.4 to 19.9; mean difference -9.7 hours, -6.9 to -12.4). The number of patients whose condition deteriorated to a higher grade was similar in both groups (antivenom plus prazosin four of 35, prazosin alone five of 35). Hypotension was reported in fewer patients in the antivenom plus prazosin group (12 of 35, 34.3%) than in the prazosin group (19 of 35, 54.3%), but the difference was not statistically significant. No difference was noted in change in blood pressure and pulse rate over time between two groups.
  
  
  CONCLUSIONS
  Recovery from scorpion sting is hastened by simultaneous administration of scorpion antivenom plus prazosin compared with prazosin alone.
  
  
  BACKGROUND
  CTRI/2010/091/000584 (Clinical Trials Registry India).
authors.affiliation: Bawaskar Hospital and Research Centre, Mahad, Dist-Raigad, Maharashtra, India 402301. himmatbawaskar@rediffmail.com
authors.forename: Himmatrao Saluba
authors.initials: HS
authors.lastname: Bawaskar
authors.forename: Pramodini Himmatrao
authors.initials: PH
authors.lastname: Bawaskar
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D058668:Adrenergic alpha-1 Receptor Antagonists / Q000008:administration & dosage* / Q000009:adverse effects; D000328:Adult; D000818:Animals; D000997:Antivenins / Q000008:administration & dosage* / Q000009:adverse effects; D002648:Child; D002675:Child, Preschool; D004338:Drug Combinations; D005260:Female; D006801:Humans; D007155:Immunologic Factors / Q000008:administration & dosage* / Q000009:adverse effects; D007223:Infant; D007262:Infusions, Intravenous; D008297:Male; D011224:Prazosin / Q000008:administration & dosage* / Q000009:adverse effects; D065008:Scorpion Stings / Q000188:drug therapy*; D012604:Scorpion Venoms; D012605:Scorpions; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D058668:Adrenergic alpha-1 Receptor Antagonists; D000997:Antivenins; D004338:Drug Combinations; D007155:Immunologic Factors; D012604:Scorpion Venoms; D011224:Prazosin