Antivenin Polyvalent

Antivenin (Crotalidae) Polyvalent, is a refined and concentrated preparation of serum globulins obtained by fractionating blood from healthy horses immunized with the following venoms:

• Crotalus adamanteus (Eastern diamond rattlesnake)
• C. atrox (Western diamond rattlesnake)
• C. durissus terrificus (tropical rattlesnake, Cascabel)
• Bothrops atrox (Fer-de-lance).

Antivenin (Crotalidae) Polyvalent belongs to a group of medicines known as immunizing agents which are used to treat envenomation caused by the bites of certain poisonous snakes called pit vipers (crotalids), which are native to Central, North, and South America.

Pit vipers include rattlesnakes, such as the Eastern and the Western diamond rattlesnakes; copperheads and cottonmouth moccasins, including those of Korea and Japan; the fer-de-lance and similar species; the tropical rattler (Cascabel) and similar species; the Cantil; and the bushmaster of Central and South America.

This antivenin is to be used only by or under the supervision of a doctor in a hospital. This product is available in the following dosage form:

• Kit

Before using Antivenin Polyvalent, 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 pit viper envenomation associated with severe tissue damage or fatal envenomation, 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 drug interactions. However, no known drug interactions are well documented regarding this medicinal product.

Proper usage of Antivenin Polyvalent requires strict adherence to your doctor’s orders. This medicinal product should be given by a nurse or other trained health professional under strict medical supervision of a doctor in a hospital setting, and patients should be carefully monitored during and after the administration.

The intravenous route of administration is preferred, and probably should always be used for moderate or severe envenomation. Intravenous administration is mandatory if the venom-induced shock is present. If antivenin is given intramuscularly, it should be given into a large muscle mass, preferably the gluteal area, with care to avoid nerve trunks.

To be most effective, antivenin should be administered within 4 hours of the bite; it is less effective when given after 8 hours and may be of questionable value after 12 hours.

However, it is recommended that antivenin therapy is given in severe poisonings, even if 24 hours have elapsed since the time of the bite. It should be kept in mind that maximum blood levels of antivenin may not be obtained for 8 or more hours after intramuscular administration.

It is important to give as soon as possible the entire initial dose of antivenin as based on the best estimate of the severity of envenomation at the time treatment is begun.

The following initial doses are recommended:

• • Minimal envenomation: 20-40 mL (contents of 2 to 4 vials).
• • Moderate envenomation: 50-90 mL (contents of 5 to 9 vials).
• • Severe envenomation: 100-150 mL or more (contents of 10 to 15 or more vials).

These recommended initial dosage volumes are in general accordance with those of others. The need for additional antivenin must be based on the clinical response to the initial dose and continuing assessment of the severity of poisoning.

If swelling continues to progress or if systemic symptoms or signs of envenomation increase in severity or if new manifestations appear, for example, fall in hematocrit or hypotension, administer an additional 10 to 50 mL (contents of 1 to 5 vials) intravenously.

Before using Antivenin Polyvalent, there are some precautions you must take. 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 intravenous (IV) or intramuscular (IM) antivenin 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 (anaphylaxis) associated with the use of heterologous sera.

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.

Corticosteroids should not be given simultaneously with antivenin on a routine basis or during the acute state of envenomation; however, their use may be necessary to treat immediate allergic reactions to antivenin, and corticosteroids are the agents of choice for treating serious delayed reactions to antivenin.

Shock the following envenomation is treated like shock resulting from hypovolemia from any cause, including administration of whole blood, plasma, albumin, or other plasma expanders, as indicated.

Aspirin or codeine is usually adequate for relieving pain. Sedation with phenobarbital or mild tranquilizers may be used if indicated, but not in the presence of respiratory failure.

The bitten extremity should not be packed in ice, and so-called cryotherapy is contraindicated.

Compartment syndromes may complicate pit viper envenomation, especially caused by bites on the lower extremities. Prompt surgical consultation is indicated whenever a closed compartment syndrome is suspected.

Defibrination and disseminated intravascular coagulation (DIC) syndromes have been associated with envenomation caused by some pit vipers native to the United States, and appropriate therapy may be indicated.

As with many medications, there are several potential side effects associated with Antivenin Polyvalent. 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:

The immediate systemic adverse reaction (shock, 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. 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.