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The Efficacy and Safety of Aracmyn in Patients With Systemic Latrodectism

This study has been completed.
Rocky Mountain Poison and Drug Center
Information provided by (Responsible Party):
Instituto Bioclon S.A. de C.V. Identifier:
First received: October 28, 2005
Last updated: March 18, 2016
Last verified: March 2016

The purpose of this study is to compare the safety and effectiveness of an investigational antivenom and the current standard of care (pain management with opioid analgesics) for treating patients with a widow spider bite. The working hypotheses are as follows:

  1. the investigational antivenom is more promptly effective at alleviating the pain associated with a widow spider bite than routine management with opioid pain medication
  2. the investigational antivenom is as safe a treatment as opioid pain medication in treating patients with a widow spider bite.

Condition Intervention Phase
Biological: widow spider antivenom
Biological: Placebo
Phase 2

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double Blind (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: The Efficacy and Safety of Aracmyn® [Antivenin Latrodectus (Black Widow)Equine Immune F(ab)2], in Patients With Systemic Latrodectism: A Phase II, Multi-center, Randomized, Double-Blind Trial

Further study details as provided by Instituto Bioclon S.A. de C.V.:

Primary Outcome Measures:
  • between-treatment groups difference in pain intensity (pre- and post-treatment) [ Time Frame: within first two hours ]

Secondary Outcome Measures:
  • between-treatment groups difference in proportion of treatment failures (absence of pain relief or return to hospital) [ Time Frame: within 24 hours after discharge from emergency department ]
  • between-treatment groups difference in incidence of drug-related adverse events. [ Time Frame: onset of adverse events within 21 days ]

Enrollment: 24
Study Start Date: October 2005
Study Completion Date: December 2006
Primary Completion Date: October 2006 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: 1
Patients with moderate or severe pain due to Black Widow envenomation
Biological: widow spider antivenom
3 vials of antivenom capable of neutralizing 600 LD50 of L. mactans
Other Name: Analatro
Placebo Comparator: 2
Patients with moderate to severe pain due to Black Widow envenomation
Biological: Placebo

Detailed Description:
The purpose of this randomized, double-blind, multi-center phase II trial is to examine the safety and efficacy of Aracmyn® [Antivenin Latrodectus (Black Widow) Equine Immune F(ab)2], a new antivenom, for treatment of patients envenomed by the widow spider. Twenty-four subjects will be randomized to receive either the study drug or control (normal saline) through intravenous (IV) infusion. Following infusion, subjects will be monitored for changes in pain and clinical signs during a two-hour observation period. A standard dose of IV fentanyl will be offered to all subjects as pain medication at specific intervals following treatment. Vital signs, blood samples, and pain intensity scores (using a visual analog scale, VAS) will be collected before and after the infusion, as well as during the observation period. This study uses a treatment failure protocol, which involves administration of Merck Antivenin to subjects who do not obtain adequate pain relief from the study drug or control. Primary efficacy and safety endpoints for this 12-month trial will be improvement in pain intensity and clinical signs and incidence of adverse events, respectively.

Ages Eligible for Study:   10 Years and older   (Child, Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • patient presents for treatment within 72 hours from time of symptoms onset
  • clinical diagnosis of widow spider envenomation
  • patient has moderate to severe pain intensity

Exclusion Criteria:

  • history of significant cardiac, respiratory, hepatic, or renal disease
  • distracting injury or chronic pain syndrome that would obscure pain intensity assessment
  • history of asthma or known sensitivity to fentanyl, morphine, diazepam, or equine serum
  • pregnant or lactating
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00247078

United States, Colorado
Denver Health and Hospital Authority
Denver, Colorado, United States, 80204
Sponsors and Collaborators
Instituto Bioclon S.A. de C.V.
Rocky Mountain Poison and Drug Center
Principal Investigator: Richard C Dart, MD PhD Rocky Mountain Poison and Drug Center
Study Director: Walter Garcia, MD Instituto Bioclon S.A. de C.V.
  More Information

Responsible Party: Instituto Bioclon S.A. de C.V. Identifier: NCT00247078     History of Changes
Other Study ID Numbers: AR-03/02
Study First Received: October 28, 2005
Last Updated: March 18, 2016

Keywords provided by Instituto Bioclon S.A. de C.V.:

Additional relevant MeSH terms:
Spider Bites
Bites and Stings
Chemically-Induced Disorders
Wounds and Injuries
Immunologic Factors
Physiological Effects of Drugs processed this record on May 25, 2017