1 What is Anascorp?

Brand: Anascorp

Generic: Scorpion (Centruroides) Immune F(Ab)2 (Intravenous Route)

Scorpion (Centruroides) immune F(Ab)2 injection is an antivenom made from horse proteins that have been immunized with the scorpion’s venom. This medicine is designated as an orphan drug by the Food and Drug Administration (FDA or USFDA) for the treatment of clinical signs of scorpion envenomation, possibly eliminating the necessity of treatment in an intensive care unit.

Since this antivenom shortens the time of resolution of envenomation symptoms, it is preferably used to treat scorpion stings.

A scorpion sting may cause

  • loss of muscle control,
  • slurred speech,
  • troubled breathing,
  • abnormal eye movements,
  • excessive salivation,
  • frothing at the mouth and vomiting.

In the US, Centruroides sculpturatus found mainly in Arizona is the only scorpion considered potentially dangerous to humans. But this bark scorpion may be found in parts of California, New Mexico, Nevada, and Texas.

This medicine is recommended to be given only by or under the direct supervision of a healthcare professional.

This product is available in powder form which is later used to make a solution at the time of administration.

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2 What to Know Before Using

This medicine is prepared from equine (horse) blood and there is increased risk of serious hypersensitivity reactions. In addition, certain infectious agents including viruses may transmit through horse blood products to the people who have received them.

Although the risk transmission of viruses has been greatly diminished in recent years because of several processes in manufacturing system, you should talk with your doctor about this concern if you are about to start a drug therapy. The risk-benefit ratio of taking the drug should be considered carefully.

This is a decision that your doctor will make with your active participation.

Further, this antivenom may cause serious types of allergic reactions, including anaphylaxis.

Anaphylaxis can be life-threatening and requires immediate medical attention.

For this reason, you should consult with your doctor immediately if you have developed

  • rashes,
  • itching,
  • hoarseness,
  • respiratory distress,
  • difficulty in swallowing,
  • edema while you are undergoing this antivenom therapy.

However, studies performed with such medications in pregnant and lactating women have failed to demonstrate a risk to the fetus and the nursing baby respectively. Thus, this medicine can be used during pregnancy and lactation if clearly needed.

3 Proper Usage

The treatment should be initiated with this drug as soon as possible after scorpion sting in patients who develop clinically important signs of scorpion envenomation, including but not limited to

  • loss of muscle control,
  • slurred speech,
  • respiratory distress,
  • roving or abnormal eye movements,
  • excessive salivation,
  • frothing at the mouth and vomiting.

This medicine is intended for intravenous use only. It is usually given to the patients by a nurse or other trained health professional in a hospital. The therapeutic dose and the duration of drug therapy may vary with the severity of the patient’s condition.

Usual therapeutic dose for venomous scorpion bite is given below:

  • The initial dose is 3 vials in case of both adults and children.
  • 5 ml sterile normal saline is mixed by continuous gentle swirling with the contents of each vial.
  • Further, the contents of the reconstituted vials are diluted to a total volume of 50 ml with sterile normal saline.
  • It is advised to inspect the solution visually for particulate matters and discoloration prior to administration. You should not use any turbid vial.
  • Then, the solution should be infused intravenously over 10 minutes.
  • Close monitoring of the patient is recommended during and up to 60 minutes following the completion of infusion to determine if clinically important signs of envenomation have resolved.
  • Partially used vials should be discarded.
  • Additional one-vial doses should be infused over 10 minutes at an interval of 30-60 minutes as needed.

4 Precautions to Take

Firstly, regular visits to your doctor are recommended to check that this medicine is working properly or not.

In addition, the following guidelines should be followed while you are using such medications:

  • Severe hypersensitivity reactions, including anaphylaxis, may occur with such antivenom therapy. Close patient monitoring for hypersensitivity reactions and readiness with intravenous therapy using epinephrine, corticosteroids, and diphenhydramine hydrochloride is recommended while you are receiving this infusion.
  • If an anaphylactic reaction occurs during the infusion, you should discontinue the antivenom infusion and initiate proper emergency healthcare. Patients with known allergies to horse protein are particularly at risk for an anaphylactic reaction.
  • Delayed hypersensitivity or serum sickness reactions may occur which may include mild symptoms such as pruritus, nausea, urticaria, low-grade fever, and malaise. Severe manifestations include persistent urticaria, arthralgia, myalgia, vomiting, syncope, and angioedema. Thus, you should check for manifestations of delayed allergic reactions or serum sickness. Treatment of such reactions is generally symptomatic including antihistamines, analgesics, antipyretics, and corticosteroids.

5 Potential Side Effects

There are some unwanted side-effects associated with each drug that usually do not need medical attention. The most common adverse reactions observed in the clinical studies with this antivenom (in ≥ 2% of patients) include

  • vomiting,
  • pyrexia,
  • rash,
  • nausea,
  • pruritus.

These side-effects usually go away during the treatment episode as your body adjusts to the medicine. Your healthcare professional may advise you about the ways how to prevent or reduce those unwanted side-effects.

Sometimes you may need to consult with the doctor if you feel any of the following toxic effects: