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  • CLASSES

    Snake Antivenoms and Immunoglobulins

    DEA CLASS

    Rx

    DESCRIPTION

    Parenteral antivenin from horses immunized against venoms of Bothrops asper (fer-de-lance) and Crotalus durissus (tropical rattlesnake)
    For management of North American rattlesnake bites
    Initial dose consists of 10 vials, but total dose is highly variable

    COMMON BRAND NAMES

    Anavip

    HOW SUPPLIED

    Anavip Intravenous Inj Pwd F/Sol

    DOSAGE & INDICATIONS

    For the management of crotalid snake bite (North American rattlesnake envenomation).
    NOTE: The total dose of antivenin required is highly variable and depends on: venom burden; potency of the venom; and time to health care presentation.
    NOTE: Prior to administration and at regular intervals during therapy, perform laboratory tests (i.e., complete blood count, platelet count, PT, PTT, serum fibrinogen concentration, serum chemistry) to assess response to therapy and need for additional doses.
    Intravenous dosage
    Adults, Adolescents, Children, and Infants

    Initially, 10 vials via IV infusion. The initial infusion must proceed slowly during the first 10 minutes at a rate of 25—50 mL/hr with careful observation for any allergic reaction. The infusion rate may be increased to 250 mL/hr until completion if no reaction occurs. Observe patient for at least 1 hour following completion of the first dose. If initial control is not achieved by the first dose, an additional dose of 10 vials should be administered every hour until initial control of the envenomation syndrome has been achieved; there is no maximum dose. After initial control has been achieved, monitor patient in a health care setting for at least 18 hours. Additional 4-vial doses may be administered during the 18 hour monitoring period to suppress any re-emerging symptoms that may develop.

    MAXIMUM DOSAGE

    Not applicable; dosage must be individualized to the envenomation.

    DOSING CONSIDERATIONS

    Hepatic Impairment

    Specific guidelines for dosage adjustments in hepatic impairment are not available; it appears that no dosage adjustments are needed.

    Renal Impairment

    Specific guidelines for dosage adjustments in renal impairment are not available; it appears that no dosage adjustments are needed.

    STORAGE

    Anavip:
    - Discard product if it contains particulate matter, is cloudy, or discolored
    - Discard reconstituted product if not used within 6 hours
    - Discard unused portion. Do not store for later use.
    - Do not freeze
    - See package insert for detailed storage information
    - Store at 77 degrees F; brief exposure up to 104 degrees F does not adversely affect product
    Antivenin (Crotalidae):
    - Protect from freezing

    CONTRAINDICATIONS / PRECAUTIONS

    Cresol hypersensitivity, equine protein hypersensitivity

    Crotalidae immune F(ab')2 (Anavip) is derived from equine (horse) plasma; thus, this product must be used cautiously in patients with known equine protein hypersensitivity. Caution is also advised when administering to patients with known cresol hypersensitivity, as cresol is used during the manufacturing process and trace amounts are present in the final product. If a hypersensitivity reaction (i.e., urticaria, rash, wheezing, hypertension, chest tightness) develops during treatment, immediately stop the infusion and administer appropriate therapy. In addition, health care providers are advised to monitor patients for signs and symptoms of delayed allergic reactions or serum sickness (i.e., fever, rash, myalgia, arthralgia, pruritus, urticarial rash); administer appropriate treatment, as needed, should a delayed reaction or serum sickness develop.

    Viral infection

    As with other products derived from or purified with blood components, the possibility of transmitting a viral infection exists in patients receiving crotalidae immune F(ab')2. The manufacturing processes (including pepsin digestion, ammonium sulfate precipitation, heat treatment, nanofiltration) are designed to reduce the risk of transmitting viral infection; however, none of the processes are completely effective. There is also the possibility that unknown infectious agents may be present in this product.

    Coagulopathy, hepatic disease, malnutrition, neoplastic disease, vitamin K deficiency

    Coagulation abnormalities may develop following snake envenomation; therefore, close monitoring of laboratory parameters (including platelet count, PT, PTT, serum fibrinogen concentration) is advised for all patients before and during treatment with crotalidae immune F(ab')2. Particular caution is advised when administering the antivenin to patients with a preexisting conditions associated with coagulation defects (such as coagulopathy, neoplastic disease, hepatic disease, malnutrition, and vitamin K deficiency) as these patients may be at increased risk for adverse events.

    Pregnancy

    Crotalidae immune F(ab')2 is classified as FDA pregnancy risk category C. No adequate and well-controlled studies have been conducted in pregnant women, and the ability of the drug to cause fetal harm or to affect reproduction capacity is unknown. According to the manufacturer, the drug should only be administered to pregnant women if clearly needed.

    Breast-feeding

    Data are limited regarding use of crotalidae immune F(ab')2 during breast-feeding and the excretion in breast milk is unknown. The manufacturer recommends caution when administering to lactating women. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally administered drug, health care providers are encouraged to report the adverse effect to the FDA.

    ADVERSE REACTIONS

    Moderate

    peripheral edema / Delayed / 8.0-8.0
    erythema / Early / 4.0-4.0
    dehydration / Delayed / 2.0-2.0
    thrombocytopenia / Delayed / 1.0-1.0
    dyspnea / Early / 1.0-1.0
    wheezing / Rapid / Incidence not known
    hypertension / Early / Incidence not known

    Mild

    pruritus / Rapid / 43.0-43.0
    nausea / Early / 23.0-23.0
    rash / Early / 12.0-12.0
    arthralgia / Delayed / 11.0-11.0
    myalgia / Early / 7.0-7.0
    vomiting / Early / 6.0-6.0
    headache / Early / 6.0-6.0
    fever / Early / 5.0-5.0
    chills / Rapid / 4.0-4.0
    insomnia / Early / 2.0-2.0
    anxiety / Delayed / 2.0-2.0
    urticaria / Rapid / Incidence not known

    DRUG INTERACTIONS

    There are no drug interactions associated with Crotaline Antivenin, Crotalidae products.

    PREGNANCY AND LACTATION

    Pregnancy

    Crotalidae immune F(ab')2 is classified as FDA pregnancy risk category C. No adequate and well-controlled studies have been conducted in pregnant women, and the ability of the drug to cause fetal harm or to affect reproduction capacity is unknown. According to the manufacturer, the drug should only be administered to pregnant women if clearly needed.

    Data are limited regarding use of crotalidae immune F(ab')2 during breast-feeding and the excretion in breast milk is unknown. The manufacturer recommends caution when administering to lactating women. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally administered drug, health care providers are encouraged to report the adverse effect to the FDA.

    MECHANISM OF ACTION

    Crotalidae immune F(ab')2 binds and neutralizes venom toxins, facilitating their redistribution away from target tissues and their elimination from the body. Its administration following envenomation has been shown to prevent or reverse the progression of local tissue damage and coagulopathy.

    PHARMACOKINETICS

    Crotalidae immune F(ab')2 is administered by intravenous infusion. To evaluate the pharmacokinetics of this drug, 13 healthy volunteers were administered a single one-vial dose of antivenin. After the infusion, blood samples were collected from each volunteer at 15 specific time points. Data from these blood samples showed the drug to have a mean steady-state volume of distribution of 3.3 L and a systemic exposure of 4144 mcg x hour/mL. Mean total clearance was 22 mL/h, resulting in an elimination half-life of 133 hours.