Black Widow Spider Antivenin for Patients With Systemic Latrodectism
Condition: Latrodectism
Intervention: Analatro; Saline
Intervention description: 30 mL of lyophilized antivenom, reconstituted in 50 mL saline infused over 10 minutes, up to 2 doses; 50 mL of saline infused over 10 minutes
Phase: Phase 3
Study type: Interventional
Primary purpose: Treatment
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Enrollment: 60.0
Sex: All
Minimum age: 10 Years
Healthy volunteers: No
Keywords: black widow spider; antivenom; latrodectism

Summary:

      The purpose of this study is to test the efficacy and safety of a new antivenom called
      Analatro® for treating black widow spider bites in patients who present to a hospital
      emergency room within 24 hours of symptom onset. This study will be a phase III,
      multi-center, double-blind, randomized controlled study that takes place in emergency
      departments. The primary aim of this study is to determine the proportion of patients in
      which pain control was not achieved by 48 hours post treatment. Secondary aims are as
      follows: 1) a reduction in pain intensity at the end of the treatment phase compared to
      baseline; 2) the proportion of patients with a clinically significant decrease in pain
      intensity at 30 minutes post-treatment; 3) the proportion of patients in which drug-related
      adverse events occurred; and 4) to determine if serious, drug-related adverse events in
      Analatro-treated patients occurred at a rate greater than one in 10 (10%).
    

Eligibility criteria:

        Inclusion Criteria:

          -  Moderate to severe pain intensity measured using the visual analog scale (VAS score ≥
             40mm) at the start of screening phase (VAS 0)

          -  Diagnosis of latrodectism by the Investigator, with concurrence of diagnosis by a
             physician not directly involved with the study

          -  Moderate to severe pain intensity measured using the visual analog scale (VAS score ≥
             40mm) at Baseline (VAS 1)

        Exclusion Criteria:

          -  Less than 10 years of age

          -  Presents to the emergency department of any healthcare facility greater than 24 hours
             after onset of symptoms

          -  Has a known (self-reported) hypersensitivity to fentanyl, morphine, diazepam, or
             equine serum

          -  History of significant cardiac, respiratory, hepatic or renal disease, psychiatric
             disorder or chronic pain syndrome that in the investigator's assessment would confound
             efficacy or safety endpoint assessment (e.g., a bite to the leg of a patient with
             reflex sympathetic dystrophy)

          -  History or suspected history or substance abuse

          -  Pregnant or breast-feeding

          -  Has a distracting injury with acute pain, or is unable to make a reliable self-report
             of pain intensity to pain relief based solely on the condition of interest

          -  Was already treated with Merck Antivenin Latrodectus Mactans for signs/symptoms
             related to the current widow spider bite

          -  Unable to provide a telephone number to be contacted for follow-up interviews on Days
             2, 10, and 17 after discharge from the emergency department