Crotalidae antivenin is an anti-venom used to treat a person who has been bitten by a poisonous snake such as a rattlesnake or Water Moccasin.

Antivenin (Crotalidae) polyvalent may also be used for purposes not listed in this medication guide.

If possible before you receive antivenin (Crotalidae) polyvalent, tell your doctor if you are allergic to any foods, animals, or other allergens.

In an emergency situation it may not be possible before you are treated to tell your caregivers about your health conditions or if you are pregnant or breast feeding. Make sure any doctor caring for you afterward knows that you have received this medication.

Treatment with Crotalidae antivenin should be started as soon as possible after the first appearance of symptoms of a snake bite (fang marks in the skin with swelling or redness and pain, blurred vision, sweating, increased salivation, vomiting, uncontrolled bleeding, trouble breathing, weakness, loss of muscle control, or numbness in the face or body).

Crotalidae antivenin is injected into a vein through an IV. A healthcare provider will give you this injection. Crotalidae antivenin must be given slowly, and the IV infusion can take at least 60 minutes to complete.

antivenin (Crotalidae) polyvalent is most effective if given within 6 hours after the snakebite occurred.

You will be watched closely for up to 60 minutes after receiving Crotalidae antivenin, to make sure this medicine is helping your condition.

You may need to receive additional doses if your condition does not improve after the first dose. Once your symptoms are under control, you may be given more doses every 6 hours for up to 18 hours or longer. Your doctor will determine how long to treat you with Crotalidae antivenin.

Venom from a snake bite can increase your risk of bleeding, which can be severe or life-threatening. Contact your doctor or seek emergency medical attention if you have any bleeding that will not stop.

Your doctor will need to check your progress for up to 2 weeks or longer after you are treated with Crotalidae antivenin. You may need to be re-treated with this medicine, or with other drugs that can help your blood to clot.

Usual Adult Dose for Venomous Snake Bite:

Initial dose: 4 to 6 vials, IV, over 60 minutes: at 25 to 50 mL/hour the first 10 minutes - if no allergic reaction, may increase rate to 250 mL/hour

Continue administering 4 to 6 vials, IV, over 60 minutes, every 6 hours for up to 18 hours, until initial control of envenomation is achieved

Maintenance dose (after initial envenomation control is achieved): 2 vials, IV, every 6 hours for up to 18 hours (3 doses); additional 2 vial doses may be given as deemed necessary based on the patient's clinical course

Comments:
-Administer as soon as possible after snakebite in patients with signs of progressive envenomation (e.g. worsening local injury, coagulation abnormality, or systemic envenomation signs).
-Early use (within 6 hours of snakebite) is advised to prevent clinical deterioration and systemic coagulation abnormalities.
-Closely monitor patients for allergic reactions during the infusion.
-Observe the patient for up to 1 hour after the first dose to determine if initial control has been achieved.

Usual Pediatric Dose for Venomous Snake Bite:

Initial dose: 4 to 6 vials, IV, over 60 minutes: at 25 to 50 mL/hour the first 10 minutes - if no allergic reaction, may increase rate to 250 mL/hour

Continue administering 4 to 6 vials, IV, over 60 minutes, every 6 hours for up to 18 hours, until initial control of envenomation is achieved

Maintenance dose (after initial envenomation control is achieved): 2 vials, IV, every 6 hours for up to 18 hours (3 doses); additional 2 vial doses may be given as deemed necessary based on the patient's clinical course

Comments:
-Administer as soon as possible after snakebite in patients with signs of progressive envenomation (e.g. worsening local injury, coagulation abnormality, or systemic envenomation signs).
-Early use (within 6 hours of snakebite) is advised to prevent clinical deterioration and systemic coagulation abnormalities.
-Closely monitor patients for allergic reactions during the infusion.
-Observe the patient for up to 1 hour after the first dose to determine if initial control has been achieved.

If possible before you receive Crotalidae antivenin, tell your doctor if you allergic to any foods, animals, or other allergens. Before treating you with this medicine, your caregivers should know if you are allergic to papaya, papain, pineapples, sheep, horses, dust mites, or latex.

Also tell your doctor if you have:

• a bleeding or blood clotting disorder such as hemophilia;

• cancer;

• congestive heart failure; or

• an overactive thyroid.

Crotalidae antivenin is made from the blood or plasma of healthy horses or sheep. Animal blood or plasma may contain viruses and other infectious agents. Blood and plasma are tested and treated to reduce the risk of it containing infectious agents, but there is still a small possibility it could transmit disease. Talk with your doctor about the risks and benefits of using this medication.

It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant.

It is not known whether Crotalidae antivenin passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

In an emergency situation it may not be possible to tell your caregivers if you are pregnant or breast-feeding. Make sure any doctor caring for your pregnancy or your baby knows you have received this medicine.

Because you will receive Crotalidae antivenin in a clinical setting, you are not likely to miss a dose.

Since antivenin (Crotalidae) polyvalent is given by a healthcare professional in a medical setting, an overdose is unlikely to occur.

After a snakebite, you should avoid activities that may increase your risk of bleeding or injury. Use extra care to prevent bleeding while shaving or brushing your teeth.

Get emergency medical help if you have signs of an allergic reaction: hives, itching, redness; wheezing, trouble breathing; feeling light-headed; swelling of your face, lips, tongue, or throat.

Some side effects may occur during the injection. Tell your caregiver right away if you feel feverish or nauseated, or if you have low back pain or trouble breathing.

Antivenin (Crotalidae) polyvalent may cause serious side effects. Call your doctor at once if you have:

• easy bruising, unusual bleeding (nosebleeds, bleeding gums, bleeding from an injury);

• purple or red pinpoint spots under your skin;

• fever, swollen glands, rash or itching, joint pain, or general ill feeling;

• heavy menstrual bleeding; or

• itching, rash, or skin redness several days after you were treated with Crotalidae antivenin.

Common side effects of antivenin (Crotalidae) polyvalent may include:

• itching;

• rash;

• nausea; or

• back pain.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Other drugs may interact with antivenin (Crotalidae) polyvalent, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.