Crotalidae immune FAB (equine) (Rx)

Brand and Other Names:Anavip
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

lyophilized powder for reconstitution

  • Minimum mouse LD-50 neutralizing units per vial
    • Bothrops asper (Terciopelo or fer-de-lance) 780 units
    • Crotalus simus (formerly Crotalus durissus; Central American Rattlesnake) 790 units
    • Crotalus adamanteus (Eastern Diamondback Rattlesnake) 244 units
    • Crotalus atrox (Western Diamondback Rattlesnake) 147 units
    • Crotalus scutulatus (Mohave Rattlesnake) 185 units
    • Agkistrodon contortrix (Copperhead) 28 units
    • Agkistrodon piscivorus (Cottonmouth or Water Moccasin) 61 units

North American Pit Viper Envenomation

Equine-derived antivenin indicated for North American Pit Viper envenomation

Administer as soon as possible after bite in patients who develop any signs of envenomation (eg, local injury, coagulation abnormality, systemic signs of envenomation)

Initial dose: Reconstituted and diluted solution of 10 vials IV over 1 hr

Additional dose(s) to achieve initial control: Administer additional 10-vial doses if needed to arrest progressive symptoms and repeat hourly; there is no known maximum dose

Observation and late dosing: Additional 4-vials doses IV prn; infusion over 1 hr

Dosing Considerations

Amount of antivenin required to treat a snake-bitten patient is highly variable, owing in part to the venom burden, the potency of the venom, and the time to health care presentation

Use supportive measures to treat certain manifestations of envenomation (eg, pain, swelling, hypotension, wound infection)

Contact local poison control center for additional individual treatment advice

Laboratory monitoring

  • Before initiating obtain CBC count, platelet count, PT, PTT, serum fibrinogen level, and routine serum chemistries
  • Repeat testing at regular intervals to gauge response to therapy and anticipate additional dosing

American pit vipers

  • Bothrops asper (Terciopelo or fer-de-lance)
  • Crotalus simus (formerly Crotalus durissus; Central American Rattlesnake)
  • Crotalus adamanteus (Eastern Diamondback Rattlesnake)
  • Crotalus atrox (Western Diamondback Rattlesnake)
  • Crotalus scutulatus (Mohave Rattlesnake)
  • Agkistrodon contortrix (Copperhead)
  • Agkistrodon piscivorus (Cottonmouth or Water Moccasin)

Dosage Forms & Strengths

lyophilized powder for reconstitution

  • Minimum mouse LD-50 neutralizing units per vial
    • Bothrops asper (Terciopelo or fer-de-lance) 780 units
    • Crotalus simus (formerly Crotalus durissus; Central American Rattlesnake) 790 units
    • Crotalus adamanteus (Eastern Diamondback Rattlesnake) 244 units
    • Crotalus atrox (Western Diamondback Rattlesnake) 147 units
    • Crotalus scutulatus (Mohave Rattlesnake) 185 units
    • Agkistrodon contortrix (Copperhead) 28 units
    • Agkistrodon piscivorus (Cottonmouth or Water Moccasin) 61 units

North American Pit Viper Envenomation

Equine-derived antivenin indicated for North American Pit Viper envenomation

Administer as soon as possible after bite in patients who develop any signs of envenomation (eg, local injury, coagulation abnormality, systemic signs of envenomation)

Initial dose: Reconstituted and diluted solution of 10 vials IV over 1 hr

Additional dose(s) to achieve initial control: Administer additional 10-vial doses if needed to arrest progressive symptoms and repeat hourly; there is no known maximum dose

Observation and late dosing: Additional 4-vials doses IV prn; infusion over 1 hr

Dosing Considerations

Amount of antivenin required to treat a snake-bitten patient is highly variable, owing in part to the venom burden, the potency of the venom, and the time to health care presentation

Use supportive measures to treat certain manifestations of envenomation (eg, pain, swelling, hypotension, wound infection)

Contact local poison control center for additional individual treatment advice

Laboratory monitoring

  • Before initiating obtain CBC count, platelet count, PT, PTT, serum fibrinogen level, and routine serum chemistries
  • Repeat testing at regular intervals to gauge response to therapy and anticipate additional dosing

American pit vipers

  • Bothrops asper (Terciopelo or fer-de-lance)
  • Crotalus simus (formerly Crotalus durissus; Central American Rattlesnake)
  • Crotalus adamanteus (Eastern Diamondback Rattlesnake)
  • Crotalus atrox (Western Diamondback Rattlesnake)
  • Crotalus scutulatus (Mohave Rattlesnake)
  • Agkistrodon contortrix (Copperhead)
  • Agkistrodon piscivorus (Cottonmouth or Water Moccasin)
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Adverse Effects

>10%

Pruritus (43%)

Nausea (23%)

Rash (12%)

Arthralgia (11%)

1-10%

Peripheral edema (8%)

Myalgia (7%)

Pain in extremity (6%)

Vomiting (6%)

Headache (6%)

Skin blister (5%)

Erythema (4%)

Chills (4%)

Pyrexia (5%)

Anxiety (2%)

Insomnia (2%)

Dehydration (2%)

Dyspnea (1%)

Thrombocytopenia (1%)

Postmarketing Reports

Chest pain/discomfort

Flushing

Hypersensitivity

Late thrombocytopenia

Necrosis

Prolonged prothrombin time

Tachycardia

Treatment failure resulting in death

Urticaria

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Warnings

Contraindications

None

Cautions

Risk of viral transmission; antivenin is made from equine (horse) plasma

Trace amounts of cresol from the manufacturing process are contained in the antivenin; localized reactions and generalized myalgias reported with cresol excipients

Hypersensitivity

  • May cause allergic reactions; patients with known allergies to horse protein are particularly at risk
  • Monitor for signs and symptoms of anaphylaxis or hypersensitivity (eg, urticaria, rash, tightness of chest, wheezing, hypotension); discontinue IV if these symptoms emerge and initiate appropriate treatment

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Pregnancy & Lactation

Pregnancy

Unknown if antivenin can cause fetal harm when administered to pregnant females or can affect reproduction capacity

Animal reproduction studies have not been conducted

Lactation

Unknown if distributed in human breast milk; use caution

Pregnancy Categories

A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA: Information not available.

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Pharmacology

Mechanism of Action

Contains venom-specific F(ab’)2 fragments of immunoglobulin G (IgG) that bind and neutralize venom toxins, facilitating redistribution away from target tissues and elimination from the body

Pharmacokinetics

AUC: 4144 mcg·hr/mL

Vd: 3.3 L

Mean residence time: 157 hr

Half-life: 133 hr

Total clearance: 22 mL/hr

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Administration

IV Preparation

Reconstitute each vial with 10 mL of sterile 0.9% NaCl

Average reconstitution time per vial is 11.8 seconds (range 8-26 seconds) when using continuous gentle swirling

Inspect resulting solution for particulate matter and discoloration; solution should be clear to yellow/green and opalescent: discard if otherwise discolored or turbid

Combine contents of reconstituted vials promptly and further dilute to total volume of 250 mL with 0.9% NaCl (adjust fluid volume for very small children or infants)

IV Administration

Administration and monitoring

  • Infuse IV over 60 minutes; give at a rate of 25-50 mL/hr for first 10 minutes and monitor for allergic/anaphylactic reactions
  • Discontinue if any allergic reaction occurs, treat reaction, and then reassess risk-to-benefit ratio before continuing
  • If no reaction occurs, infusion rate may be increased to 250 mL/hr until completion
  • Stop infusion if any allergic reaction occurs, and reassess need to continue infusion
  • Following completion, monitor patient for at least 60 minutes for any allergic reaction and to determine that local signs of envenomation are not progressing (leading edge of local injury not progressing), systemic symptoms are resolved, and coagulation parameters have normalized or are trending toward normal
  • Discard partially or unused reconstituted and diluted product

Additional doses to achieve initial control

  • Administer additional 10 vial doses if needed to arrest the progressive symptoms and repeat every hour
  • There is no known maximum dose
  • Repeat above steps for initial dose as many times as needed until local signs of envenomation are not progressing, systemic symptoms are resolved, and coagulation parameters have normalized or are trending toward normal
  • Once initial control has been achieved, observe patient to determine any need for further dosing

Observation and late dosing

  • Monitor patients in healthcare setting for at least 18 hr following initial control of signs and symptoms
  • Reemerging symptoms, including coagulopathies, may be suppressed with additional 4-vial doses of as needed

Storage

Unopened vials

  • Store at room temperature (up to 25ºC [77ºF]); brief temperature excursions are permitted up to 40ºC (104ºF)
  • Do not freeze

Reconstituted or diluted product

  • Use within 6 hr
  • Discard partially used vials
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Images

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Patient Handout

A Patient Handout is not currently available for this monograph.
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Formulary

FormularyPatient Discounts

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The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

Tier Description
1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
NC NOT COVERED – Drugs that are not covered by the plan.
Code Definition
PA Prior Authorization
Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
QL Quantity Limits
Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
ST Step Therapy
Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
OR Other Restrictions
Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
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Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.