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Centruroides Immune F(ab’)2 (Equine)

Medically reviewed by Last updated on Jul 2, 2020.


(sen tra ROY dez i MYUN fab too E kwine)

Index Terms

  • Centruroides Immune FAB2 (Equine)
  • Antivenin
  • Antivenin (Centruroides) Immune F(ab’)2 (Equine)
  • Antivenin Scorpion
  • Antivenom
  • Antivenom (Centruroides) Immune F(ab’)2 (Equine)
  • Antivenom Scorpion
  • Scorpion Antivenin
  • Scorpion Antivenom

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Solution Reconstituted, Intravenous [preservative free]:

Anascorp: (1 ea)

Brand Names: U.S.

  • Anascorp

Pharmacologic Category

  • Antivenin


Contains venom-specific F(ab’)2 fragments of IgG which bind and neutralize venom toxins; thereby helping to remove the toxin from the target tissue and eliminate it from the body.


Vdss: 13.6 L ± 5.4 L

Onset of Action

Time to resolution of symptoms: Adults: 1.91 ± 1.4 hours; Children: 1.28 ± 0.8 hours; >95% of all patients will experience resolution of symptoms within 4 hours

Half-Life Elimination

159 ± 57 hours

Use: Labeled Indications

Scorpion envenomation: Treatment of scorpion envenomation


There are no contraindications listed within the manufacturer’s labeling.

Dosing: Adult

Scorpion envenomation: IV: Note: Initiate therapy as soon as possible after scorpion sting. Initial: 3 vials (containing ≤57 mg total protein and ≥450 LD50 [mouse] neutralizing units); may administer additional vials in 1-vial increments every 30 to 60 minutes as needed. Typical dosage range: 1 to 5 vials (Boyer 2013).

Dosing: Pediatric

Scorpion envenomation: Infants, Children, and Adolescents: IV: Initial: 3 vials (containing ≤57 mg total protein and ≥450 LD50 [mouse] neutralizing units) initiated as soon as possible after scorpion sting in patients who develop clinically important signs of envenomation; may administer additional vials in 1-vial increments every 30 to 60 minutes as needed; typical reported dosage range: 1 to 5 vials (Boyer 2013).


Reconstitute each vial with 5 mL NS; gently swirl to mix. Dilute dose (eg, 1-3 vials) with NS to a total volume of 50 mL. Inspect diluted solution; do not use if it contains particulate matter or is discolored or turbid.


IV: Administer over 10 minutes; monitor for return of symptoms of envenomation and repeat as needed. Medications (eg, epinephrine, corticosteroids, diphenhydramine) and equipment for resuscitation should be readily available in case of hypersensitivity reactions. Avoid IM since the time to peak blood concentration may be prolonged with this route of administration (Turri 2011; Vasquez 2010).


Store unused vials at room temperature of 25°C (77°F); excursions permitted up to 40°C (104°F); do not freeze. Discard partially used vials.

Drug Interactions

There are no known significant interactions.

Adverse Reactions

The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.

1% to 10%:

Central nervous system: Fatigue (2%), headache (2%), lethargy (1%)

Dermatologic: Skin rash (3%), pruritus (2%)

Gastrointestinal: Vomiting (5%), nausea (2%), diarrhea (1%)

Miscellaneous: Fever (4%)

Neuromuscular & skeletal: Myalgia (2%)

Respiratory: Rhinorrhea (2%), cough (1%)

<1%, postmarketing, and/or case reports: Aspiration, ataxia, chest tightness, hypersensitivity, hypoxia, ocular edema, palpitations, pneumonia, respiratory distress, serum sickness (delayed)


Concern related to adverse effects:

• Acute hypersensitivity reactions: Derived from equine (horse) immune globulin F(ab’)2 fragments; anaphylaxis and anaphylactoid reactions are possible, especially in patients with known allergies to horse protein. However, due to the lower protein content, purity, and absence of the immunogenic Fc portion of the immunoglobulin, serious adverse events are uncommon; in a prospective study (n=1,534), the incidence of acute antivenom reactions and type 3 immune reactions was 0.2% (n=3) and 0.5% (n=8), respectively (Boyer 2013). Patients who have had previous treatment with Centruroides immune F(ab’)2 or other equine-derived antivenom/antitoxin may be at a higher risk for hypersensitivity reactions. In patients who develop an anaphylactic reaction, discontinue the infusion and administer emergency care. Immediate treatment (eg, epinephrine 1 mg/mL, corticosteroids, diphenhydramine) should be available.

• Delayed serum sickness: Delayed serum sickness may occur, usually within 2 weeks; monitor patients with follow-up visits for signs and symptoms (eg, arthralgia, fever, myalgia, rash).

Dosage form related issues:

• Cresol: Product may contain small amounts of cresol resulting from the manufacturing process; local reactions and myalgias may occur.

• Disease transmission: Product of equine (horse) plasma; may potentially contain infectious agents (eg, viruses) which could transmit disease.

Monitoring Parameters

Signs and symptoms of envenomation (eg, opsoclonus, involuntary muscle movement, slurred speech, paresthesias, respiratory distress, salivation, frothy sputum, vomiting). Monitor for signs and symptoms of acute antivenom hypersensitivity reactions (eg, urticaria, dyspnea); follow-up visits for signs and symptoms of serum sickness (eg, arthralgia, fever, myalgia, rash).

Pregnancy Risk Factor C Pregnancy Considerations

Animal reproduction studies have not been conducted. In general, medications used as antidotes should take into consideration the health and prognosis of the mother; antidotes should be administered to pregnant women if there is a clear indication for use and should not be withheld because of fears of teratogenicity (Bailey 2003). Pregnant women experiencing symptoms refractory to reasonable doses of opioids or other systemic effects which pose a danger to the patient or fetus should be considered for antivenom therapy (Brown 2013).

Patient Education

What is this drug used for?

• It is used to treat scorpion stings.

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Nausea

• Vomiting

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Muscle pain

• Joint pain

• Severe loss of strength and energy

• Swollen glands

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a limited summary of general information about the medicine's uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.