Crofab (antivenin,crotalidae Fab(ovin))

Dosage of Crotalidae polyvalent immune Fab (ovine) is expressed in terms of the number of vials of the antivenin.

For the management of envenomation following snakebites involving North American Crotalinae (pit vipers, crotalines), the initial dose (number of vials) of Crotalidae polyvalent immune Fab (ovine), need for additional initial doses to achieve envenomation control, and number of subsequent doses required to sustain control should be based on individual patient response. Age-related dosage adjustments are not indicated. (See Pediatric Use under Warnings/Precautions: Specific Populations, in Cautions.)

The recommended initial dose of Crotalidae polyvalent immune Fab (ovine) in adults or children is 4-6 vials. The manufacturer states that initial doses may vary from a minimum of 4 vials to a maximum of 12 vials based on clinical judgment and severity of envenomation. For patients with life-threatening symptoms (e.g., shock, serious active bleeding), some experts suggest that an initial dose of 8-12 vials should be considered in consultation with experts experienced in treating snakebites.

Patients should be monitored closely for up to 1 hour after completion of the initial infusion to determine if initial control of envenomation has been achieved (i.e., local manifestations arrested and not progressing, systemic symptoms resolved, and coagulation abnormalities normalized or trending towards normalization).

If initial control of envenomation is not achieved after the initial dose, additional 4- to 6-vial doses of Crotalidae polyvalent immune Fab (ovine) should be given until envenomation is controlled.

After initial control of envenomation has been established, additional 2-vial doses of Crotalidae polyvalent immune Fab (ovine) are recommended every 6 hours for up to 18 hours to maintain a response. The manufacturer states that such a scheduled dosage regimen may provide the best control of envenomation symptoms, especially coagulopathies, that may result from continued venom release from depot sites.

After the initial 18-hour scheduled maintenance dosage regimen, additional 2-vial doses of Crotalidae polyvalent immune Fab (ovine) may be given if considered necessary based on the patient's clinical course; however, the optimum dosing schedule for patients who require additional doses after receiving 2-vial doses every 6 hours for 18 hours has not been established.

The maximum dose of Crotalidae polyvalent immune Fab (ovine) that can be administered safely in single or multiple IV infusions is not known; patients in clinical studies have received a total dosage of up to 18 vials without toxic effects.

Crotalidae polyvalent immune Fab (ovine) is administered by IV infusion.

No dosing information is available for this tab.

No dosing information is available for this tab.

No formal drug interaction studies have been performed using Crotalidae polyvalent immune Fab (ovine).

There are no contraindication interactions for this drug.

There are no severe interactions for this drug.

There are no moderate interactions for this drug.

Crotalidae polyvalent immune Fab (ovine) is contraindicated in patients with known hypersensitivity to papaya or papain, unless benefits outweigh risks and appropriate drugs and equipment for management of anaphylactic reactions are readily available. (See Papain Hypersensitivity under Warnings/Precautions: Sensitivity Reactions, in Cautions.)

There are no contraindication contraindications for this drug.

There are no severe contraindications for this drug.

• No disease contraindications

Adverse effects reported in 5% or more of patients receiving Crotalidae polyvalent immune Fab (ovine) include urticaria, rash, pruritus, nausea, coagulation disorder, and back pain.

More Frequent

• Pruritus of skin
• Urticaria

Less Frequent

• Angioedema
• Asthma
• Bronchospastic pulmonary disease
• Chest pain
• Cough
• Ecchymosis
• Erythema
• Hypotension
• Laryngeal edema
• Serum sickness
• Stridor
• Tachycardia
• Wheezing

More Frequent

• Nausea
• Skin rash

Less Frequent

• Anorexia
• Back pain
• Chills
• Increased sputum
• Myalgia
• Nervousness
• Paresthesia
• Subcutaneous nodules

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Efficacy and safety of Crotalidae polyvalent immune Fab (ovine) in pediatric patients are similar to that in adults. Data from a postmarketing retrospective study indicate that 32% (78/247) of patients who received the antivenin were 16 years of age or younger (median age: 8.5 years). Crotalidae polyvalent immune Fab (ovine) has been used in children as young as 14 months of age without unusual adverse effects.

Age-related dosage adjustments of Crotalidae polyvalent immune Fab (ovine) are not indicated since the venom dose following snakebite is expected to be similar in children and adults. However, to avoid fluid overload, some clinicians suggest that the fluid volume used to dilute the antivenin may need to be adjusted in children weighing less than 10 kg. (See Reconstitution and Dilution under Dosage and Administration: Administration.)

Crotalidae polyvalent immune Fab (ovine) should be used in pregnant women only if clearly needed.

It is not known whether Crotalidae polyvalent immune Fab (ovine) can cause fetal harm if administered to a pregnant woman or whether it can affect reproduction capacity. Animal reproduction studies have not been conducted with the antivenin.

It is not known whether Crotalidae polyvalent immune Fab (ovine) is distributed into milk.

The manufacturer states that the antivenin should be used with caution in nursing women.

Efficacy and safety of Crotalidae polyvalent immune Fab (ovine) in geriatric patients appears comparable to that in the overall patient population. Data from a postmarketing retrospective study indicate that 5% (13/247) of patients who received Crotalidae polyvalent immune Fab (ovine) were older than 65 years of age (median age: 72 years).