Safety Profile

A safety profile you can count on1

Since 2001, safety data have been collected on CroFab® Crotalidae Polyvalent Immune Fab (Ovine) in the treatment of North American pit viper envenomation.

In a recent meta-analysis, the incidence of immediate hypersensitivity reactions and serum sickness was 8% (95% CI = 5% to 11%) and 13% (95% CI = 7% to 21%), respectively.*

  • Sensitivity analysis excluding 2 premarketing trials, one with potential Fc contamination, reduced the estimated serum sickness to 8% (95% CI = 4% to 16%)
  • To learn more, see Important Safety Information

*Meta-analysis of CroFab® studies from January 1997 (prior to FDA approval in 2000) to September 2010.


Incidence of clinical adverse reactions in studies of CroFab®

Adverse Reactions Number of Adverse Reactions(N=42)*
Body as a Whole 4  Back pain (2), allergic reactions (1), serum sickness (1)
Skin and Appendages 13  Urticaria (7), rash (3), pruritus (2), subcutaneous nodule (1)
Respiratory System 1  Cough (1)
Digestive System 4  Nausea (3), anorexia (1)
Hematologic System 2  Coagulation disorder (1), ecchymosis (1)
Musculoskeletal 1  Myalgia
Nervous System 1  Nervousness (1)
Early Serum Reactions 7  Urticaria (5), cough (1), allergic reactions (1)
Late Serum Reactions 5  Rash (2); pruritus (1), urticaria (1), serum sickness § (1)

*Of the 42 patients receiving CroFab® in the clinical studies, 19 experienced an adverse reaction. A total of 26 adverse reactions were experienced by these 19 patients.

Six of 42 patients experienced an adverse reaction associated with an early serum reaction, and 4 experienced an adverse reaction associated with a late serum reaction. Two additional patients were considered to have a late serum reaction by the investigator, although no associated adverse reaction was reported.

Allergic reactions consisted of urticaria, dyspnea, and wheezing in 1 patient.

§Serum sickness consisted of severe rash and pruritus in 1 patient.

A retrospective study of postmarketing use of CroFab® reported 36 immediate adverse drug reactions in 6.1% (15/247) of patients, including:

  • 11 immediate serious adverse reactions related to CroFab® in 4 patients: 2 episodes each of hypotension and tongue swelling, and 1 episode each of chest discomfort, angioedema, bronchospasm, wheezing, tracheal edema, dyspnea, and lip swelling.
  • 22 immediate nonserious adverse reactions related to CroFab® in 12 patients: 4 episodes each of rash and pruritus, 3 of urticaria, and 1 each of tachycardia, tachypnea, erythema, swelling, hyperhidrosis, dizziness, headache, musculoskeletal chest pain, chills, feeling cold, and nervousness
  • 2 patients reported delayed hypersensitivity reactions

In a nonconcurrent, observational, cohort study of 93 patients with North American rattlesnake bites treated with CroFab®: 5 patients (5%) had acute hypersensitivity reactions, 4 (4%) developed a mild, easily treated reaction and could finish the full course of antivenom, and only 1 patient developed a reaction that prevented further antivenom administration.10