Antivenin

Antivenin (Micrurus fulvius), is a refined, concentrated, and lyophilized preparation of serum globulins obtained by fractionating blood from healthy horses that have been immunized with eastern coral snake venom.

Antivenin (Micrurus fulvius) belongs to a group of medicines known as immunizing agents which are indicated only for the treatment of envenomation caused by bites of North American coral snakes like the Eastern coral snake, the Texas coral snake, and some other related species of coral snakes.

North American coral snake antivenin is to be used only by or under the supervision of a doctor. This product is available in the following dosage forms:

• Kit
• Powder for Solution

Before using Antivenin, you must know all about the risks and complications associated with it. The most suitable drug therapy is chosen by a doctor with the active participation of the patient.

There are some important factors such as drug interactions, the presence of any metabolic impairment, history of hypersensitivity reaction, pregnancy, lactation etc. that may alter the desired therapeutic effects of a medicine.

Sometimes the presence of other health disorders affects the beneficial effects of this medicine and even may cause serious toxic effects. For persons with coral snake envenomation threatening life or limb, there are no contraindications to administration of antivenin.

However, administration to persons known to be allergic to horse serum, either by history or as a result of an appropriate sensitivity test, requires careful monitoring and considerable experience in the use of antivenom of equine origin.

Healthcare providers must be prepared to manage severe, immediate allergic reactions (anaphylaxis) seen with antivenins of equine origin. Further, antivenin should never be administered prophylactically to asymptomatic patients.

In addition, it is always recommended to consult with your doctor if you are in need of some other medications or even any over-the-counter medicine for another health problem in order to avoid unwanted toxic effects which may take place because of the following drug interactions:

• Therapy with beta-adrenergic blockers has been associated with an increased severity of acute anaphylaxis. Anaphylaxis may be prolonged and resistant to conventional treatment in patients receiving beta-adrenergic blockers.
• The therapeutic actions of epinephrine and other adrenergic agents may be altered, and larger than usual doses may be required.
• Morphine or other narcotics that depress respiration are contraindicated.

Proper usage of Antivenin requires strict adherence to your doctor’s orders. For the proper management of the patient, hospitalization is required. Initially, an intravenous drip of 250 to 500 ml of Sodium Chloride Injection, USP is started.

If the results of appropriate tests have indicated the patient is not dangerously hypersensitive to horse serum, and depending on the nature and severity of the signs and symptoms of envenomation, 3 to 5 vials (30 to 50 ml) are administered intravenously by slow injection directly into the intravenous tubing or by adding to the reservoir bottle of the intravenous drip.

In either case, the first 1 or 2 ml should be injected over a 3- to the 5-minute period with careful observation of the patient for evidence of allergic reaction. If no signs or symptoms of anaphylaxis appear, the injection or intravenous infusion is to be continued.

Response to treatment may be rapid and dramatic. However, the patient should be observed carefully and additional antivenin should be administered intravenously if required.

In using Antivenin, you must be careful and take some precautions as advised by your doctor. Before administration of any product prepared from horse serum, appropriate measures must be taken in an effort to detect the presence of dangerous sensitivity: 

A careful review of the patient's history, including any report of asthma, hay fever, or other allergic manifestations upon exposure to horses and prior injections of horse serum.

Patients sensitive to antivenin or horse serum may develop anaphylaxis. Therefore, a suitable test for detection of sensitivity should be performed in every patient prior to administration, regardless of clinical history.

General constant attendance and observation for untoward response are mandatory whenever horse serum is administered intravenously so that, should such occur, the injection may be discontinued and appropriate treatment instituted immediately.

Those responsible for administration and/or monitoring administration of antivenin should be familiar with current recommendations for treatment of severe, immediate, systemic reactions (e.g. anaphylaxis).

Appropriate tetanus prophylaxis is indicated since tetanus spores may be carried into the fang puncture wounds by dirt present on the skin at the time of the bite.

A broad-spectrum antibiotic inadequate dosage is indicated if local tissue damage is evident.

As with many medications, there are several potential side effects associated with Antivenin. These side effects usually go away during the treatment episode as your body adjusts to the medicine. Further, 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 notice any of the following toxic effects, especially:

An immediate systemic reaction (allergic reaction, shock or anaphylaxis) usually occurs within 30 minutes. Symptoms and signs may develop before the needle is withdrawn and may include apprehension, flushing, itching, urticaria, edema of the face, tongue, and throat, a cough, dyspnea, cyanosis, vomiting, and collapse.

Serum sickness usually occurs 5 to 24 days after administration and its frequency may be related to the number of antivenin vials administered. The incubation period may be less than 5 days, especially in those who have received horse-serum-containing preparations in the past. The usual symptoms and signs are malaise, fever, urticaria, lymphadenopathy, edema, arthralgia, nausea, and vomiting.

Occasionally, neurological manifestations develop, such as meningismus or peripheral neuritis. Peripheral neuritis usually involves the shoulders and arms. Pain and muscle weakness are frequently present, and permanent atrophy may develop.