Pralidoxime
Pralidoxime is an oxime antidote.
Group
Oxime antidote
Mechanism of Action
Reactivates organophosphate-inhibited acetylcholinesterase by dephosphorylation before irreversible aging.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Organophosphate poisoning | 20–50 mg/kg | IM, IV | Every 8–12 h | Slow initial IV administration; individualize to recurrence of clinical signs. |
| Organophosphate poisoning — Initial | 20 mg/kg | IM, IV | Once | Slow IV; subsequent doses may use IM or SC. |
| Organophosphate poisoning — Maintenance | 20 mg/kg | IM, SC | Every 8–12 h | |
| Organophosphate poisoning | 10–15 mg/kg | IM, SC | Every 8–12 h | Alternative at least 36-hour course. |
| Organophosphate poisoning | 50 mg/kg | IV | Every 8 h | Give over 30 minutes; may repeat once after 1 hour if signs persist, then every 8 hours for 24-48 hours. |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Organophosphate poisoning | 20–50 mg/kg | IM, IV | Every 8–12 h | Slow initial IV administration; individualize to recurrence of clinical signs. |
| Organophosphate poisoning — Initial | 20 mg/kg | IM, IV | Once | Slow IV; subsequent doses may use IM or SC. |
| Organophosphate poisoning — Maintenance | 20 mg/kg | IM, SC | Every 8–12 h | |
| Organophosphate poisoning | 10–15 mg/kg | IM, SC | Every 8–12 h | Alternative at least 36-hour course. |
| Organophosphate poisoning | 20 mg/kg | IM, IV | Every 6–8 h | Early treatment within 24 hours; slow IV. |
Cattle
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Organophosphate poisoning | 20–50 mg/kg | IM, IV | Every 8 h | Reported large-animal regimen uses a 10% solution; slow IV infusion or repeat based on signs. |
| Organophosphate poisoning | 30 mg/kg | IM | Every 8 h | |
| Organophosphate poisoning | 25–50 mg/kg | IV | 20% solution infused over 6 minutes. |
Sheep
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Organophosphate poisoning | 20–50 mg/kg | IM, IV | Every 8 h | Reported large-animal regimen uses a 10% solution; slow IV infusion or repeat based on signs. |
Pigs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Organophosphate poisoning | 20–50 mg/kg | IM, IV | Every 8 h | Reported large-animal regimen uses a 10% solution; slow IV infusion or repeat based on signs. |
Horses
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Organophosphate poisoning | 20–35 mg/kg | IV | Every 4–6 h |
Birds
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Organophosphate poisoning | 10–100 mg/kg | IM | Every 24–48 h | Separate report allows one repeat after 6 hours. |
Indications
- Organophosphate poisoning
- Selected anticholinesterase overdoses
Contraindications
- Carbamate intoxication: reported advises against treatment.
- Avoid rapid IV administration.
Interactions
- Avoid aminoglycosides, barbiturates, phenothiazines and neuromuscular blockers during organophosphate poisoning when possible.
Adverse effects
- Pain with IM injection; rapid IV use can cause muscle spasm and cardiorespiratory problems.
Toxicity
High exposure can itself cause cholinergic-type weakness, ataxia, vomiting, hyperventilation, seizures or respiratory arrest.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Pralidoxime chloride 1 g vial | Injection | 1000 mg / vial | IV, IM |
| Pralidoxime chloride reconstituted 50 mg/mL Reported confirms 1 g reconstituted to 20 mL; discard after 3 hours. | Injection | 50 mg / mL | IV, IM |
Monitoring and Administration
Treat promptly with atropine as part of the antidotal plan; reported regimen describes atropine 0.1 mg/kg without a specified route here. Monitor rhythm, ventilation, recurrent cholinergic signs and available cholinesterase testing.
Dilute in glucose solution for slow IV infusion. Protect reconstituted solution from light below 25 C and discard after 3 hours.
One severe-poisoning protocol gives atropine 0.1 mg/kg IV then 0.3 mg/kg IM before pralidoxime 50 mg/kg in 10% glucose slowly IV; repeat at 1 hour if weakness persists. Renal failure requires reduction. A ruminant infusion maximum 100 mg/kg/day and bird route-unspecified 10-20 mg/kg every 8-12 hours are not generic bolus regimens.