Pralidoxime
Pralidoxime (often referred to as 2-PAM) is a specific antidote used in veterinary medicine to treat **organophosphate (OP)** toxicity. It is used to reverse the neuromuscular paralysis associated with OP poisoning. > **Warning:** Pralidoxime is generally contraindicated for carbamate toxicity as it may worsen the clinical picture or provide no benefit. **Clinical Pearl:** Pralidoxime does not cross the blood-brain barrier well; therefore, it primarily relieves peripheral nicotinic signs (muscle tremors, weakness, paralysis) but not central nervous system signs. It must always be used in conjunction with **atropine**, which addresses the life-threatening muscarinic signs (bradycardia, bronchoconstriction, and SLUDGE: salivation, lacrimation, urination, defecation, GI upset, emesis). To be effective, pralidoxime must be administered early, before the OP-enzyme complex undergoes 'aging' (permanent irreversible binding), which typically occurs within 24-48 hours of exposure.
Mecanismo: Pralidoxime works by reactivating the **acetylcholinesterase (AChE)** enzyme that has been inactivated by organophosphate binding. It binds to the OP-AChE complex → cleaves the phosphate bond → releases the OP → restores the enzyme's ability to break down **acetylcholine** at the synaptic cleft. Additionally, it directly detoxifies certain unbound OP molecules through chemical inactivation and retards the 'aging' of phosphorylated cholinesterase into a non-reactive, permanently damaged form.
Dosificación por especie
- Organophosphate toxicity · 10-20 mg/kg · IV/IM/SC · bid to tid · Until nicotinic signs resolve (usually 1-2 days) · Administer IV very slowly over 15-30 minutes. Can also be given as a continuous rate infusion (CRI). Must be given in conjunction with atropine.
- Organophosphate toxicity · 10-20 mg/kg · IV/IM/SC · bid to tid · Until nicotinic signs resolve (usually 1-2 days) · Administer IV very slowly over 15-30 minutes. Must be given in conjunction with atropine.
Las dosis son una referencia clínica para veterinarios colegiados. Confirme siempre con la ficha técnica vigente y el paciente individual.
Vías de administración
Contraindicaciones
- Carbamate toxicity (can exacerbate toxicity)
- Poisoning by non-anticholinesterase compounds
- Hypersensitivity to pralidoxime
Efectos adversos
- Tachycardia
- Muscle rigidity
- Transient neuromuscular blockade (if given too rapidly IV)
- Hypertension
- Hyperventilation
Interacciones farmacológicas
- Phenothiazines · May exacerbate organophosphate toxicity · major
- Succinylcholine · Prolonged neuromuscular blockade due to cholinesterase inhibition · major
- Morphine · May exacerbate respiratory depression in OP toxicity · moderate
- Aminophylline · May exacerbate toxicity · moderate
Monitorización
- Heart rate and rhythm (ECG)
- Respiratory rate and effort
- Resolution of muscle fasciculations and weakness
- Blood pressure
- Renal function (urine output)
Sobredosis
Overdose can cause paradoxical neuromuscular blockade, muscle rigidity, tachycardia, and worsening of cholinergic signs. Treatment is supportive, including artificial ventilation if respiratory paralysis occurs.
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.