Black Widow Spider Antivenin
Black widow spider antivenin is a life-saving biologic used to treat envenomation caused by the black widow spider (*Latrodectus mactans*). **Clinical Pearls:** * **Species Sensitivity:** Cats, camels, and horses are considered to be exquisitely sensitive to black widow venom. * **Toxicity Profile:** The primary toxic signs are driven by potent neurotoxins (specifically alpha-latrotoxin) in the venom, which cause massive neurotransmitter release leading to severe muscle cramping, rigidity, and autonomic instability. * **Availability:** Antivenins for rare species can be difficult for veterinarians to obtain. Availability is often in flux; contacting a poison control center (e.g., ASPCA Animal Poison Control or local human poison centers) is highly recommended for up-to-date procurement and treatment options.
Mecanismo: Antivenins act by directly neutralizing the complex protein venoms in the patient's systemic circulation. * **Mechanism:** The product provides **passive immunization** via concentrated serum globulins obtained from horses previously immunized with black widow spider venom. * **Pharmacodynamic Pathway:** The antibodies bind to **alpha-latrotoxin** → prevents the toxin from forming pores in presynaptic neuronal membranes → halts the massive, uncoordinated influx of calcium and subsequent depletion of neurotransmitter vesicles (like acetylcholine and norepinephrine). * In humans, clinical symptoms typically begin to subside within 1-2 hours after administration.
Dosificación por especie
- Black Widow Spider Envenomation · After reconstituting the antivenin, add to 100 mL of normal saline and administer via slow IV over 30 minutes. Pretreatment with 2-4 mg/kg of diphenhydramine SC may help calm the patient and may possibly protect against allergic reactions from the antivenin. · IV · Single dose · 30 minutes · Monitor inner pinna during infusion for signs of anaphylaxis (hyperemia). If hyperemia occurs, discontinue infusion and give a second dose of diphenhydramine. Benzodiazepines may alleviate muscle cramping.
- Black Widow Spider Envenomation · Dissolve contents of one vial and add to 100-200 mL of warm 0.9% NaCl and infuse over 2-6 hours. Administer diphenhydramine at 0.5-1 mg/kg prior to infusion. · IV · Single dose · 2-6 hours
- Black Widow Spider Envenomation · After reconstituting the antivenin, add to 100 mL of normal saline and administer via slow IV over 30 minutes. Pretreatment with 2-4 mg/kg of diphenhydramine SC may help calm the patient and may possibly protect against allergic reactions from the antivenin. · IV · Single dose · 30 minutes · Monitor inner pinna during infusion for signs of anaphylaxis (hyperemia). If hyperemia occurs, discontinue infusion and give a second dose of diphenhydramine. Benzodiazepines may alleviate muscle cramping.
- Black Widow Spider Envenomation · Dissolve contents of one vial and add to 100-200 mL of warm 0.9% NaCl and infuse over 2-6 hours. Administer diphenhydramine at 0.5-1 mg/kg prior to infusion. · IV · Single dose · 2-6 hours
Las dosis son una referencia clínica para veterinarios colegiados. Confirme siempre con la ficha técnica vigente y el paciente individual.
Vías de administración
Contraindicaciones
- Known severe hypersensitivity to equine serum (relative contraindication in life-threatening envenomation)
Efectos adversos
- Anaphylaxis (incidence <2%)
- Anaphylactoid reactions (nausea, pruritus, hyperemia of the inner pinna)
- Serum sickness (delayed hypersensitivity)
Interacciones farmacológicas
- Beta-blockers · May mask the early signs associated with anaphylaxis
Monitorización
- Signs associated with an allergic response to the antivenin (anaphylaxis, anaphylactoid-reactions, serum sickness)
- Respiratory/cardiac rate
- Blood pressure
- Serum chemistry (blood glucose mandatory)
- CBC
- Urine output; urinalysis
Sobredosis
Specific overdosage information is not provided. However, excessive administration of serum products increases the risk of volume overload and severe hypersensitivity reactions, including anaphylaxis and serum sickness.
La referencia de fármacos de VetSheet está destinada a veterinarios colegiados como apoyo a la decisión clínica, no sustituye el juicio profesional ni la ficha técnica vigente del fabricante.