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black widow antivenin (lactrodectus mactans) (equine)
Classes
Spider Antivenoms and Immunoglobulins
Administration
For storage information, see product information within the How Supplied section.
Antivenin is administered intramuscularly or intravenously.
Sensitivity testing should be performed in all patients prior to administration of antivenin (Antivenin Latrodectus mactans, Equine from Merck). A 1 mL vial of normal horse serum is supplied in the antivenin kit for sensitivity testing.
Appropriate medications and equipment to treat anaphylaxis should be available when administering the sensitivity test and antivenin.
Visually inspect parenteral products for particulate matter and discoloration prior to administration whenever solution and container permit. The color of antivenin ranges from light (straw) to very dark (iced tea); color has no effect on potency.
Intravenous route of administration is preferred for children < 12 years old or in adults with severe cases or who are in shock.
Remove 2.5 mL of Sterile Diluent (provided) and inject into vial of antivenin. With the needle still in the rubber stopper, shake vial to dissolve contents. Further dilute in 10—50 mL normal saline.
Administer IV over 15 minutes.
Remove 2.5 mL of Sterile Diluent (provided) and inject into vial of antivenin. With the needle still in the rubber stopper, shake vial to dissolve contents.
Inject entire vial intramuscularly in the region of the anterolateral thigh (in case a tourniquet needs to be applied in the event of an event of a systemic reaction).
Subcutaneous administration is for desensitization purposes only.
Intradermal Administration
Intradermal administration is for sensitivity testing only prior to administration of the antivenin, using the provided normal horse serum.
Adverse Reactions
anaphylactoid reactions / Rapid / Incidence not known
bronchospasm / Rapid / Incidence not known
anaphylactic shock / Rapid / Incidence not known
serum sickness / Delayed / Incidence not known
lymphadenopathy / Delayed / Incidence not known
dyspnea / Early / Incidence not known
arthralgia / Delayed / Incidence not known
urticaria / Rapid / Incidence not known
fever / Early / Incidence not known
muscle cramps / Delayed / Incidence not known
Dea Class
Rx
Description
Antivenin, specific for the Black widow spider (Latrodectus mactans antivenin)
Used to neutralize the symptomatic toxic effects of the black widow spider bite.
Due to the possibility for hypersensitivity reactions, supportive therapy without antivenin use is typically preferred for otherwise healthy patients between the ages of 16 and 60 years.
Dosage And Indications
NOTE: Patients should be observed for serum sickness for an average of 8—12 days following administration of antivenin.
NOTE: Black widow spider antivenin is prepared from horse serum; skin or conjunctival sensitivity testing should be performed in all patients prior to treatment. For all sensitivity testing, Epinephrine and other emergency measures should be available in case of a severe reaction.
Inject intradermally (not under the skin) no more than 0.02 mL of the test material (1:10 dilution of normal horse serum in normal saline). Evaluate site in 10 minutes. A positive reaction is an urticarial wheal surrounded by erythema. A control test of normal saline for injection should also be used to aid in interpretation.]
Instil 1 drop of a 1:10 dilution of horse serum diluted in normal saline into the conjunctival sac. Itching of the eye and reddening of the conjunctiva indicate a positive reaction within 10 minutes.
Instill 1 drop of a 1:100 of horse serum diluted in normal saline into the conjunctival sac. Itching of the eye and reddening of the conjunctiva indicate a positive reaction within 10 minutes.
NOTE: If possible, the patient should be hospitalized.
NOTE: Due to the risk of anaphylactic reactions, the use of antivenin may be deferred in otherwise healthy patients between the ages of 16 and 60 years.
NOTE: Symptomatic treatment (e.g., calcium gluconate, warm baths, morphine) in otherwise healthy individuals may be sufficient. Applying a tourniquet or attempting to remove the venom by incision and suction provides no clinical benefit.
2.5 mL IM in the region of the anterolateral thigh, in case a tourniquet needs to be applied in the event of a systemic reaction. Symptoms usually reside within 1—3 hours. Although one dose is usually adequate, a second dose may be necessary.
Safety and efficacy of IM dosing have not been established in controlled clinical trials. Intravenous dosing is recommended in children < 12 years.
The intravenous route is preferred when a child is < 12 years, or for any person with severe envenomation or shock. Give 2.5 mL antivenin in 10—50 mL of normal saline and administer IV over 15 minutes. One vial is usually sufficient; however, a second dose is necessary in some cases.]
In separate vials or syringes prepare 1:10 or 1:100 dilutions of antivenin in 0.9% NaCl for injection. Using a tuberculin syringe, inject subcutaneous 0.1 mL, 0.2 mL, and 0. 5 mL of the 1:100 solution every 30 minutes (should wait a minimum of 15 minutes between doses). Proceed with the next dose only if no reaction occurs with the previous dose. Repeat with 1:10 dilution, and finally the undiluted antivenin. If there is any reaction after any of the injections, place a tourniquet proximal to the sites of injection and administer epinephrine, 1:1000 (0.3—1 mL subcutaneous or 0.05—0.1 mL IV) proximal to the tourniquet or into another extremity. Wait at least 30 minutes before giving another injection of the antivenin, the amount of which should be the same as the last one not evoking a reaction. If no reaction occurs after giving 0.5 mL of the undiluted antivenin, it is probably safe to continue the dose at 15-minute intervals until the entire dose has been given.
Dosing Considerations
Specific guidelines for dosage adjustments in hepatic impairment are not available; it appears that no dosage adjustments are needed.
Specific guidelines for dosage adjustments in renal impairment are not available; it appears that no dosage adjustments are needed.
Drug Interactions
There are no drug interactions associated with Black Widow Spider Antivenin products.
How Supplied
Black Widow Antivenin (Lactrodectus Mactans) (Equine) Intramuscular Inj Pwd F/Sol: 6000U
Black Widow Antivenin (Lactrodectus Mactans) (Equine) Intravenous Inj Pwd F/Sol: 6000U
Maximum Dosage
2 reconstituted vials (5 mL) IM or IV; although, 1 vial (2.5 mL) is usually adequate for treatment of most cases.
2 reconstituted vials (5 mL) IM or IV; although, 1 vial (2.5 mL) is usually adequate for treatment of most cases.
2 reconstituted vials (5 mL) IM or IV; although, 1 vial (2.5 mL) is usually adequate for treatment of most cases.
2 reconstituted vials (5 mL) IV; although, 1 vial (2.5 mL) is usually adequate for treatment of most cases.
Safety and efficacy have not been established. However, treatment with antivenin is supported in expert medical literature. 1 vial (2.5 mL) IV is usually adequate for treatment of most cases.
Safety and efficacy have not been established.
Mechanism Of Action
The neurotoxic venom (alpha-latroxin) is likely responsible for the signs and symptoms of black widow spider bites and is thought to exert its activity through calcium-mediated release of neurotransmitters from nerve terminals. Local muscle cramps begin from 15 minutes to several hours after the bite. Muscles most frequently affected first are those of the thigh, shoulder, and back. The pain becomes more severe and intractable, spreading to the abdomen, followed by weakness and tremor. Respirations become thoracic, and the patient is restless and anxious. Other symptoms include urinary retention, nausea and vomiting, headache, restlessness, anxiety, fatigue, insomnia, cyanosis, and shock. Small children may experience convulsions. Temperature may be normal or elevated. Most cases of black widow bites do not require hospitalization and symptoms increase in severity for several hours to a day, and then slowly become less severe, subsiding in about 2 days; however, symptoms can last several days in some cases. Treatment is usually symptomatic with analgesics, muscle relaxants, and intravenous calcium gluconate. Patients treated with the antivenin recover rapidly (within 1—2 days); however, non-specific symptoms (e.g., fatigue, weakness) may persist for weeks to months. Black widow spider antivenin blocks the binding of venom to pre-synaptic membranes.
Pharmacokinetics
Black widow spider antivenin is administered intravenously or intramuscularly. Pharmacokinetic data for black widow spider antivenin are unavailable. Symptoms of black widow spider bite usually subside in 1—3 hours after administration of antivenin.
Pregnancy And Lactation
Black widow spider antivenin is classified as FDA pregnancy category C. No adequate and well-controlled studies have been conducted in pregnant women, and its' ability to cause fetal harm or affect reproductive capacity is unknown. Effects of the antivenin on labor and delivery are also unknown. Administer during pregnancy only if clearly needed.
Data are limited regarding use of the black widow spider antivenin during breast-feeding and its' excretion in human breast milk is unknown. The manufacturer advises caution when administering to a nursing woman. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally administered drug, health care providers are encouraged to report the adverse effect to the FDA.