FULL PRESCRIBING INFORMATION
1 INDICATIONS AND USAGE
North American Coral Snake Antivenin (Equine) is indicated only for the treatment of envenomation caused by bites of North American coral snakes - Micrurus (including the eastern and Texas varieties).
2 DOSAGE AND ADMINISTRATION
For intravenous use only.
2.1 Dose
- Contents of each reconstituted vial can neutralize approximately 250 mouse (Lethal Dose) LD50 or approximately 2 mg of Micrurus fulvius fulvius (M. f. fulvius) venom.
- In adults and adolescents, the dose may vary from 3 to 5 vials, depending on the response to treatment.
- In small children, the dose may be decreased, depending on the response to treatment.
2.2 Preparation and Administration
Preparation
- Pry off the small metal disc in the cap over the diaphragms of the vials of North American Coral Snake Antivenin (Equine) and remove cap from diluent vials.
- Swab the exposed surface of the rubber diaphragms of both vials with an appropriate germicide.
- Withdraw 10 mL diluent (Sterile Water for Injection, USP) using a sterile syringe and needle, and insert the needle through the stopper of the vacuum-containing vial of North American Coral Snake Antivenin (Equine).
- The vacuum in the North American Coral Snake Antivenin (Equine) vial will pull the diluent out of the syringe into the vial. Allow room air to be pulled into the North American Coral Snake Antivenin (Equine) vial until all vacuum is released.
- Point the needle at the center of the lyophilized pellet of North American Coral Snake Antivenin (Equine) so that the diluent stream will wet the pellet.
- Reconstitute by swirling, not by shaking, for 1 minute, at 5-minute intervals until you observe complete dissolution of the lyophilized North American Coral Snake Antivenin (Equine). Complete reconstitution usually requires at least 30 minutes.
Administration
- Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.
- Start an intravenous infusion of 250 to 500 mL of Sodium Chloride Injection, USP.
- Determine whether the patient has hypersensitivity to horse-serum in order to evaluate treatment decisions, and to prepare for treatment of anaphylaxis if it occurs [see Warnings and Precautions (5.1)].
- After reconstitution of the lyophilized North American Coral Snake Antivenin (Equine) administer the contents of 3 to 5 vials (30 to 50 mL) intravenously by slow injection directly into the intravenous tubing or the reservoir bottle of the intravenous solution. If added to reservoir bottle, mix by gentle swirling – do not shake.
- Administer the first 1 or 2 mL over a 3- to 5-minute period with careful observation of the patient for evidence of an allergic reaction. If no signs or symptoms of anaphylaxis appear, continue the injection or intravenous infusion.
- Adjust the infusion rate by the severity of signs and symptoms of envenomation and tolerance of North American Coral Snake Antivenin (Equine). Administer at the maximum safe rate for intravenous fluids, based on body weight and general condition of the patient.
- For adults, if given by intravenous infusion to a previously healthy adult, allow 250 or 500 mL to run in within 30 minutes;
- For small children, allow the first 100 mL to run in rapidly but then decrease to a rate not to exceed 4 mL per minute. Response to treatment may be rapid and dramatic.
- Observe the patient carefully and administer additional North American Coral Snake Antivenin (Equine) intravenously as required.
3 DOSAGE FORMS AND STRENGTHS
Each package contains one single use vial with lyophilized North American Coral Snake Antivenin (Equine) for dilution with 10 mL of diluent (Sterile Water for Injection, USP). Contents of each reconstituted vial can neutralize approximately 250 mouse (Lethal Dose) LD50 or approximately 2 mg of M. f. fulvius venom.
4 CONTRAINDICATIONS
- Do not administer North American Coral Snake Antivenin (Equine) prophylactically to asymptomatic patients.1
- Do not administer North American Coral Snake Antivenin (Equine) to patients with a known history of hypersensitivity to horse serum unless the benefits outweigh the risks and appropriate management for anaphylactic reactions is readily available.
5 WARNINGS AND PRECAUTIONS
5.1 Hypersensitivity Reactions
Patients sensitive to North American Coral Snake Antivenin (Equine) or horse serum may develop anaphylaxis. Prior to intravenous North American Coral Snake Antivenin (Equine) administration, consider performing a proper skin test and modify therapy if indicated.
Consider the following precautions to manage hypersensitivity reactions:
- Emergency medical care (e.g., epinephrine, intravenous antihistamines and/or albuterol) should be readily available.
- Carefully monitor patients for signs and symptoms of an acute allergic reaction (e.g., urticaria, pruritus, erythema, angioedema, bronchospasm with wheezing or cough, stridor, laryngeal edema, hypotension, tachycardia).
- Follow-up all patients for signs and symptoms of delayed allergic reactions or serum sickness (e.g., rash, fever, myalgia, arthralgia).
Patients who receive a course of treatment with a foreign protein such as North American Coral Snake Antivenin (Equine) may become sensitized to it. Therefore, use caution when administering a repeat course of treatment with North American Coral Snake Antivenin (Equine) for a subsequent envenomation episode.
6 ADVERSE REACTIONS
The most common adverse reactions observed after treatment with North American Coral Snake Antivenin (Equine) were anaphylaxis and serum sickness, vomiting, and abdominal pain. Because these reactions were reported voluntarily from a population of uncertain size, it is not always possible to estimate their frequency reliably or to establish a causal relationship to drug exposure.
8 USE IN SPECIFIC POPULATIONS
8.1 Pregnancy
Risk Summary
There are no available human data that establish developmental toxicity related to the use of North American Coral Snake Antivenin (Equine). There are no available animal data informing the North American Coral Snake Antivenin (Equine)-associated risk. North American Coral Snake Antivenin (Equine) should be given to a pregnant woman only if clearly required. In the US general population, the background risk of major birth defects is 2–4% and of miscarriage is 15–20% in clinically recognized pregnancies.
8.2 Lactation
Risk Summary
Lactation studies have not been conducted with North American Coral Snake Antivenin (Equine). It is not known whether North American Coral Snake Antivenin (Equine) is excreted in human milk. North American Coral Snake Antivenin (Equine) should be administered to lactating women only if clearly indicated. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for North American Coral Snake Antivenin (Equine) and any potential adverse effects on the breastfed child from North American Coral Snake Antivenin (Equine) or from the underlying maternal condition.
8.4 Pediatric Use
Controlled clinical studies of safety and effectiveness in pediatric patients have not been conducted.
Potential cases of Coral Snake envenomation and subsequent treatment with North American Coral Snake Antivenin (Equine) have been reported in pediatric patients;2 adverse reactions included anaphylaxis (wheezing) requiring treatment with epinephrine, vomiting, and abdominal pain.
11 DESCRIPTION
North American Coral Snake Antivenin (Equine) is a sterile lyophilized powder for solution for injection containing serum globulins obtained by fractionating blood from healthy horses that have been immunized with eastern coral snake (Micrurus fulvius fulvius) venom. Prior to lyophilization, the product contains 0.25% phenol.
12 CLINICAL PHARMACOLOGY
12.1 Mechanism of Action
North American Coral Snake Antivenin (Equine) specifically binds to and neutralizes coral snake venom.
12.2 Pharmacodynamics
North American Coral Snake Antivenin (Equine) is standardized for potency in mice in terms of its LD50 neutralizing capacity per milliliter as determined by intravenous injection of a graded series of mixtures of North American Coral Snake Antivenin (Equine) with M. f. fulvius venom. Based on this assay system, the reconstituted contents of each vial (10 mL) will neutralize approximately 250 mouse LD50 or approximately 2 mg of M.f. fulvius venom.
The results of cross-neutralization tests indicate that North American Coral Snake Antivenin (Equine) will neutralize the venom of M. fulvius tenere (Texas coral snake) but will not neutralize the venom of Micruroides euryxanthus (Arizona or Sonoran coral snake).
14 CLINICAL STUDIES
There have been no well-controlled clinical studies of the use of North American Coral Snake Antivenin (Equine) in patients experiencing envenomation by the Eastern Coral Snake, however a retrospective analysis3 has been published of 387 coral snake exposures treated in a healthcare facility in Florida between 1998 and 2010, including 252 patients who were treated with North American Coral Snake Antivenin (Equine). Patients were managed according to different treatment strategies: (a) asymptomatic at ED arrival and treated empirically (n=134); (b) asymptomatic at ED arrival, but treatment withheld until symptoms appeared (n=106; 6 of the 106 received North American Coral Snake Antivenin (Equine) at some point; the remainder were never treated); (c) symptomatic at ED arrival and treated with North American Coral Snake Antivenin (Equine) (n=112); and (d) symptomatic at ED arrival but not treated with North American Coral Snake Antivenin (Equine) (n=35). The average number of vials administered to treated patients was 3.75 (range 1 – 20 vials); the 17 patients who received repeat treatment were administered 8.3 vials, on average. There was no reported usage of foreign antivenom or acetylcholinesterase inhibitors in this case series. The 387 patients were assessed for clinical outcomes, as shown in Table 1. Outcomes codes range from full recovery with no residual effects ("No Effect") to less than full recovery with significant residual effects ("Major"). Empiric treatment of asymptomatic patients resulted in more 'moderate' and 'major' outcomes compared to withholding treatment until symptoms appeared (p<.001), however, the patients were not randomized and selection biases could have affected this result.
| Treatment Strategy | Empiric (N = 134) | Withhold (N = 106) | Symptomatic with AV (N = 112) | Symptomatic without AV (N = 35) |
|---|---|---|---|---|
| ADR, adverse drug reaction; AV, antivenom; Avg, average; LOS, length of stay; ICU, intensive care unit. | ||||
| ||||
| Primary outcome | ||||
| Endotracheal intubation (%) | 3 (2.2) | 1 (0.94) | 7 (6.25) | 0 (0) |
| Secondary outcomes | ||||
| Days intubated Avg. (SD) | 5.67 (2.89) | 24 (N/A) | 8 (6.22) | 0 (0) |
| ICU admission (%)* | 97 (72.39) | 49 (46.23) | 90 (80.36) | 9 (25.71) |
| ICU LOS Avg.(SD) | 1.5 (1.18) | 1.73 (3.28) | 2.25 (3.35) | 1.3 (0.5) |
| Total LOS Avg.(SD) | 1.58 (1.56) | 1.17 (2.94) | 2.47 (3.68) | 0.94 (0.85) |
| Antivenom ADR (%)* | 26 (19.4) | 0 (0) | 20 (17.86) | 0 (0) |
| Outcome code %* | ||||
| No Effect | 4.76 | 29.29 | 0 | 0 |
| Minor | 71.43 | 56.57 | 34.23 | 63.64 |
| Moderate | 20.63 | 13.13 | 54.05 | 36.36 |
| Major | 3.17 | 1.01 | 11.71 | 0 |
Adverse reactions associated with North American Coral Snake Antivenin (Equine) administration were documented in 46 (18.25%) cases. The most common adverse reactions were hives, rash and/or welts (12%); itching (9%); shortness of breath (8%); hypotension (2%) and angioedema (1%). Antihistamines were administered to 46 patients, corticosteroids to 40, and epinephrine to 10 cases to treat these adverse reactions.
15 REFERENCES
- Bowden, C and Krenzelok, E: Clinical applications of commonly used contemporary antidotes, a US perspective. Drug Safety 1997; 16(1):9-47.
- Sasaki, J et al: Coral snake bites and envenomation in children, A case series. Ped Emerg Care 2014; 30(4):262-5.
- Wood A, Schauben J, Thundiyil J, et al. Review of Eastern coral snake (Micrurus fulvius fulvius) exposures managed by the Florida Poison Information Center Network: 1998-2010. Clin Toxicol 2013; 51(8):783-8.
16 HOW SUPPLIED/STORAGE AND HANDLING
North American Coral Snake Antivenin (Equine) is supplied as a sterile lyophilized powder in single use vial (NDC 0008-0423-01) in a carton (NDC 0008-0423-03).
17 PATIENT COUNSELING INFORMATION
Advise patients to contact the physician or emergency department immediately if they experience any signs and symptoms of delayed allergic reactions or serum sickness up to 14 days following hospital discharge. Symptoms include rash, pruritus, joint pain, arthralgia, fever, lymphadenopathy, and malaise.