Phase 3 Multicenter Comparative Study to Confirm Safety and Effectiveness of the F(ab)2 Antivenom Anavip.

A Comparison of Anavip® and CroFab® in the Treatment of Patients With Crotalinae Envenomation: A Randomized, Prospective, Blinded, Controlled, Comparative, Multicenter Study

Status

Completed

Phases

Phase 3

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT00636116

Enrollment

121

Registered

2008-03-14

Start date

2008-05-31

Completion date

2012-01-31

Last updated

2012-01-10

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Snake Bite

Keywords

snake bite, antivenin treatment

Brief summary

The purpose of this study is to establish if F(ab)2 antivenom (Anavip) is safe for crotalinae envenomation. Confirm its effectiveness in preventing the occurrence of delayed coagulopathies and compare the safety and efficacy with Fab antivenom (CroFab) in patients with Crotalinae envenomation.

Detailed description

Fewer than 200,000 crotaline envenomations occur annually in the US.Crotaline venoms contain a broad variety of toxins, venom variability and injection quantity among individual snakes and across species result in broadly variable patient presentations. Clinical consequences of crotaline envenomation include local and systemic effects, both of which may progress for hours to days.The best studied systemic consequence is coagulopathy, which may in its complexity mimic disseminated intravascular coagulation. Platelet and clotting disorders respond rapidly to administration of polyvalent antivenom. Crotaline viper envenomation in the United States is treated with one of two licensed products: Wyeth Antivenin (Crotalidae) Polyvalent (Polyvalent), or CroFab® (antivenin Crotalidae polyvalent immune Fab, ovine). In recent years, both of these products have been in critically short supply. Use of Wyeth Polyvalent has been associated with a greater than 75% incidence of adverse reactions, including acute type 1 and delayed type 2 immune reactions.These phenomena are an inherent risk in the use of whole immunoglobulin. CroFab´s low molecular weight creates a pharmacokinetic mismatch with crotaline venom which leds to a recurrent venom effects. Anavip is pharmacologically and pharmacokinetically different.Because of the elimination of the Fc portion of the immunoglobulin molecule, Anavip is expected to produce far fewer adverse reactions than seen with whole immunoglobulin antivenoms and unlike Fab molecules, F(ab)2 molecules exceed the size threshold for renal clearance and thus are expected to remain in circulation for a significantly longer time and substantially reduce the incidence of recurrent coagulopathy.

Interventions

BIOLOGICALCrotalinae (pit viper) equine immune F(ab)2

Anavip with Anavip Maintenance Therapy

BIOLOGICALCrotalidae Polyvalent Immune Fab, ovine

CroFab with CroFab Maintenance Therapy

Study design

Allocation

RANDOMIZED

Intervention model

PARALLEL

Primary purpose

TREATMENT

Masking

QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)

Eligibility

Sex/Gender

ALL

Age

2 Years to 80 Years

Healthy volunteers

Inclusion criteria

* Men and women 2 to 80 years of age * Presenting for emergency treatment of pit viper bite * Informed consent document read and signed by patient (or parent/legal guardian)

Exclusion criteria

* Current use of any antivenom, or use within the last month * Current participation in a clinical drug study, or participation within the last month * Positive urine or blood pregnancy test at screening * Breast-feeding * Allergy to horse serum, sheep serum, or papaya * Underlying medical conditions that significantly alter platelet count or fibrinogen; thrombocytopenia, hemophilia, familial dysfibrinogenemia, leukemia * Use of any medication expected to affect platelet count, coagulation factors or fibrinogen: chemotherapeutic agents, warfarin, heparin * No clinical indications of snake bite requiring antivenom for treatment

Design outcomes

Primary

Measure	Time frame
Incidence rate of patients experiencing coagulopathy during the follow-up phase of the study. Absolute Platelet levels < 150,000/mm3. Absolute Fibrinogen levels < 150 mg/dL. Clinical coagulopathy requiring additional antivenom.	Study Day 5 (±/- 1 day), Study Day 8 (±/- 1 day)

Secondary

Measure	Time frame
Comparison between groups of: Percentage of patients who experience venonemia. Absolute platelet level measured Lowest absolute platelet level measured Absolute fibrinogen level Lowest absolute fibrinogen level	Study Day 5 (+/- 1 day) and Study Day 8 (+/- 1 day)

Countries

United States

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026