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 780 units
    • Crotalus durissus 790 units

North American Rattlesnake Envenomation

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

Initial dose: 10-vial dose infused 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 rattlesnake envenomation (eg, pain, swelling, hypotension, wound infection)

Contact the local poison control center for additional individual treatment advice

Dosage Forms & Strengths

lyophilized powder for reconstitution

  • Minimum mouse LD-50 neutralizing units per vial
    • Bothrops asper 780 units
    • Crotalus durissus 790 units

North American Rattlesnake Envenomation

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

Initial dose: 10-vial dose infused 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 rattlesnake envenomation (eg, pain, swelling, hypotension, wound infection)

Contact the local poison control center for additional individual treatment advice

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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%)

Thrombocytopenia (1%)

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Warnings

Contraindications

None

Cautions

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

Monitor patients for at least 18 hr following last infusion for allergic reactions

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 myalgias reported with cresol excipients

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Pregnancy & Lactation

Pregnancy category: C

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

Reconstitution time should be <1 minute when using continuous gentle swirling

Inspect resulting solution for particulate matter and discoloration; the solution should be clear to yellow/green and opalescent: do not use if otherwise discolored or turbid

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

IV Administration

Pre-dose laboratory

  • If possible prior to initiating treatment, perform laboratory analyses, including complete blood 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

Administration and monitoring

  • Infuse IV over 60 minutes; give at a rate of 25-50 mL/hr for the 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, the infusion rate may be increased to the full 250 mL/hr until completion
  • Stop infusion if any allergic reaction occurs, and reassess the need to continue infusion
  • Following the completion of infusion, monitor the 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
  • Prepare vials as described above for the initial dose
  • Once initial control has been achieved, observe the patient to determine any need for further dosing

Observation and late dosing

  • Monitor patients in a 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
  • Reconstitute each vial and further dilute as described above (see IV preparation)

Storage

Store at room temperature (up to 25ºC [77ºF]); brief temperature excursions are permitted up to 40ºC (104ºF)

Do not freeze

Discard partially used vials

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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.