Centruroides Immune F(ab′)2 (Monograph)
Brand name: Anascorp
Drug class: Antitoxins and Immune Globulins
Introduction
Antivenom; equine IgG F(ab′)2 fragments capable of binding and neutralizing venom toxins of Centruroides scorpions.
Uses for Centruroides Immune F(ab′)2
Scorpion Envenomation
Treatment of clinical signs of scorpion envenomation; designated an orphan drug by FDA for this use.
May shorten time to resolution of envenomation symptoms, possibly eliminating need for treatment in an intensive care unit.
In the US, Centruroides sculpturatus (commonly known as the bark scorpion) is the only scorpion considered potentially dangerous to humans; found mainly in Arizona, but may be found in parts of California, New Mexico, Texas, Nevada, and northern Mexico.
Consider consultation with experts experienced in treating Centruroides envenomation (e.g., Arizona Poison and Drug Information Center in Tucson, Banner Good Samaritan Poison and Drug Information Center in Phoenix).
Centruroides Immune F(ab′)2 Dosage and Administration
General
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Initiate treatment as soon as possible after a scorpion sting in patients who develop clinically important signs of scorpion envenomation (e.g., loss of muscle control, roving or abnormal eye movements, slurred speech, respiratory distress, excessive salivation, frothing at the mouth, vomiting).
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Monitor closely during and for up to 1 hour after completion of IV infusion to confirm resolution of clinically important signs of envenomation.
Administration
IV Administration
Administer by IV infusion.
Reconstitution and Dilution
Reconstitute each vial of lyophilized Centruroides (scorpion) immune F(ab′)2 (equine) with 5 mL of 0.9% sodium chloride; mix using continuous gentle swirling. When multiple vials are indicated (e.g., for initial dose), combine required number of reconstituted vials immediately following reconstitution.
Prior to infusion, dilute total dose (total combined reconstituted vials) to a total volume of 50 mL using 0.9% sodium chloride.
Rate of Administration
Administer by IV infusion over 10 minutes.
Dosage
Dosage expressed in terms of number of vials.
Pediatric Patients
Scorpion Envenomation
IV
Initially, 3 vials.
Give additional 1-vial doses every 30–60 minutes as needed.
Adults
Scorpion Envenomation
IV
Initially, 3 vials.
Give additional 1-vial doses every 30–60 minutes as needed.
Special Populations
No special population dosage recommendations.
Cautions for Centruroides Immune F(ab′)2
Contraindications
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Manufacturer states none.
Warnings/Precautions
Sensitivity Reactions
Hypersensitivity Reactions.
Severe hypersensitivity reactions, including anaphylaxis, may occur.
Patients with known allergies to equine protein are at increased risk for anaphylactic reactions. Patients who previously received Centruroides (scorpion) immune F(ab′)2 (equine) or another equine antivenom or antitoxin may be at increased risk for severe hypersensitivity reactions.
Monitor closely for hypersensitivity during antivenom infusion; IV epinephrine, corticosteroids, and diphenhydramine should be readily available.
If anaphylactic reaction occurs, immediately discontinue antivenom infusion and initiate appropriate emergency medical care.
Delayed Hypersensitivity or Serum Sickness Reactions.
Delayed hypersensitivity or serum sickness reactions may occur. Mild symptoms may include pruritus, nausea, urticaria, low-grade fever, and malaise; severe manifestations include persistent urticaria, vomiting, arthralgia, myalgia, syncope, and angioedema.
Monitor for manifestations of delayed allergic reactions or serum sickness (e.g., rash, fever, myalgia, arthralgia) at follow-up visits. Treat such reactions as necessary; treatment is generally symptomatic (e.g., antihistamines, analgesics, antipyretics, corticosteroids).
Risk of Transmissible Infectious Agents
Prepared from equine plasma; potentially may transmit infectious agents, including viruses. Several steps in manufacturing process (e.g., pepsin digestion, ammonium sulfate precipitation/heat treatment, nanofiltration) reduce risk of transmission of viruses.
Cresol Content
Contains trace amounts of cresol (<0.41 mg per vial) from manufacturing process. Cresol used as an injectable excipient has resulted in localized reactions and generalized myalgia.
Specific Populations
Pregnancy
Category C.
Lactation
Not known whether distributed into milk. Use with caution in nursing women.
Pediatric Use
Efficacy and safety in pediatric patients comparable to that in adults. Has been used in children ranging from younger than 1 month to 18 years of age.
Geriatric Use
Efficacy and safety in geriatric patients not studied specifically; considered comparable to that in overall patient population.
Common Adverse Effects
Vomiting, pyrexia, rash, nausea, pruritus.
Drug Interactions
No formal drug interaction studies to date.
Centruroides Immune F(ab′)2 Pharmacokinetics
Absorption
Onset
Following IV infusion, clinically important manifestations of scorpion envenomation generally resolve within 4 hours.
Elimination
Half-life
Approximately 6.6 days in healthy (nonenvenomed) adults. Additional study needed to determine pharmacokinetics in patients with scorpion envenomation.
Stability
Storage
Parenteral
For Injection, for IV Use
Room temperature (up to 25°C); may be exposed to temperatures up to 40°C. Do not freeze. Discard partially used vials.
Actions
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Centruroides (scorpion) immune F(ab′)2 (equine) is a polyvalent preparation of venom-specific F(ab′)2 fragments of equine IgG that bind and neutralize Centruroides venom toxins, facilitating redistribution of the venom away from target tissues and elimination from the body.
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Manufactured from plasma of horses immunized with venom of C. noxius, C. limpidus limpidus, C. limpidus tecomanus, and C. suffusus suffusus. Although C. sculpturatus venom not used in manufacturing process, in vitro studies demonstrate similar binding affinities and high degree of cross-reactivity among venoms of the various Centruroides species, including C. sculpturatus.
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Standardized by ability to neutralize Centruroides scorpion venom in mice (mouse LD50 neutralizing units). Each commercially available vial will neutralize ≥150 mouse LD50 units of Centruroides venom.
Advice to Patients
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Importance of immediately contacting clinician or seeking emergency treatment if manifestations of delayed allergic reactions or serum sickness (e.g., rash, pruritus, joint pain, arthralgia, fever, lymphadenopathy, malaise) develop within 14 days following hospital discharge. (See Delayed Hypersensitivity or Serum Sickness Reactions under Cautions.)
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Importance of women informing clinicians if they are pregnant or breast-feeding.
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Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as any concomitant illnesses.
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Importance of informing patients of other important precautionary information. (See Cautions.)
Additional Information
The American Society of Health-System Pharmacists, Inc. represents that the information provided in the accompanying monograph was formulated with a reasonable standard of care, and in conformity with professional standards in the field. Readers are advised that decisions regarding use of drugs are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and that the information contained in the monograph is provided for informational purposes only. The manufacturer’s labeling should be consulted for more detailed information. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information contained in the monograph is not a substitute for medical care.
Preparations
Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.
Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.
Routes |
Dosage Forms |
Strengths |
Brand Names |
Manufacturer |
---|---|---|---|---|
Parenteral |
For injection, for IV use |
Anascorp |
Rare Diseases Therapeutics |
AHFS DI Essentials™. © Copyright 2025, Selected Revisions June 10, 2024. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.
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