Skip to Content
Looking to save on your medications?  Find out how 

Centruroides Immune F(ab’)2 (Equine)

Generic name: antivenom (centruroides scorpion) systemic

Brand names: Anascorp

Dosage Forms

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

Solution Reconstituted, Intravenous [preservative free]:

Anascorp: (1 ea)


Mechanism of Action

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.

Dosage and Administration

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

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


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

  • Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)
  • Patient may experience nausea or vomiting. Have patient report immediately to prescriber muscle pain, joint pain, severe loss of strength and energy, or swollen glands (HCAHPS).
  • Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.

Source: Wolters Kluwer Health. Last updated June 12, 2019.