Rat poisoning treatment and organophosphate poisoning and other poisoning cases commonly seen and treatment and drugs with dosage
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Poisoning: Common Cases, Treatment & Drug Dosages
General Approach to Any Poisoning
Before antidote-specific therapy, every poisoning case follows this framework:
- ABC stabilization - airway, breathing, circulation
- Decontamination - remove exposure (skin/eye wash, remove clothing)
- Gut decontamination - activated charcoal if appropriate
- Antidote - where available
- Enhanced elimination - as indicated
- Supportive care - ICU admission for serious cases
Activated Charcoal (First-line gut decontaminant)
- Dose: 1 g/kg body weight (max single dose 100 g)
- Multi-dose: 12.5 g every 4-6 hours for drugs with long half-lives or enterohepatic recirculation
- Works by binding toxin in the gut AND creating a diffusion gradient that draws absorbed toxin back across the intestinal wall
- Safe in pregnancy, breastfeeding, and pediatrics
- NOT useful for: iron, lithium, alcohols, caustics, hydrocarbons
- Contraindicated if airway not protected, bowel obstruction, or ileus
1. Organophosphate (OP) Poisoning
Sources: Pesticides (malathion, parathion, chlorpyrifos), nerve agents (sarin, soman, tabun, Novichok)
Mechanism: Irreversible inhibition of acetylcholinesterase → accumulation of acetylcholine at muscarinic and nicotinic receptors → cholinergic crisis
Clinical Features (SLUDGE + Nicotinic + CNS)
| System | Signs |
|---|---|
| Muscarinic (SLUDGE) | Salivation, Lacrimation, Urination, Defecation, GI cramps, Emesis |
| Muscarinic (DUMBELS) | Diarrhea/Diaphoresis, Urination, Miosis, Bradycardia/Bronchospasm/Bronchorrhea, Emesis, Lacrimation, Salivation |
| Nicotinic | Muscle fasciculations, weakness, paralysis, tachycardia |
| CNS | Anxiety, seizures, coma |
Death occurs from: bronchorrhea + respiratory muscle paralysis + CNS depression
Treatment
Step 1 - Decontamination
- Wear neoprene/nitrile gloves (not latex)
- Remove all clothing, bag as hazardous waste
- Wash with mild detergent (dishwashing liquid) and copious water - including scalp, hair, fingernails, skin folds, conjunctivae
- Treat contaminated runoff as hazardous material
Step 2 - Monitoring & Oxygen
- Cardiac monitor, pulse oximeter
- 100% oxygen via non-rebreather mask
- Suction airway secretions
- Intubate if: coma, seizures, respiratory failure, excessive secretions, severe bronchospasm
Step 3 - Atropine (Muscarinic antagonist)
| Patient | Dose |
|---|---|
| Adults | 1.2-3.0 mg IV initial bolus (depending on severity) |
| Children | 0.05 mg/kg IV initial bolus |
- Double the dose every 5 minutes until adequate atropinization:
- Chest clear on auscultation ✓
- Heart rate >80 bpm ✓
- Systolic BP >80 mmHg ✓
- Maintenance infusion: 10-20% of the total atropinization dose per hour (typically 0.4-4 mg/h IV in adults)
- Endpoint: secretion control, not pupil size or heart rate alone
- Watch for atropine toxicity: absent bowel sounds, hyperthermia, delirium
Step 4 - Pralidoxime (2-PAM) - Oxime/Cholinesterase reactivator
| Parameter | Details |
|---|---|
| Mechanism | Reactivates acetylcholinesterase at neuromuscular junction before "aging" occurs |
| Adult dose | 30 mg/kg IV (up to 1-2 g) in normal saline, infused over 5-10 min |
| Children | 30 mg/kg IV up to 1 g |
| Timing | Give as soon as possible; may still be given 24-48 h after exposure |
| Infusion | Continuous infusion 8 mg/kg/hour for 24-48 h |
| Duration | Continue until no signs/symptoms on withholding; may last weeks |
- Works at nicotinic receptors (muscle weakness) - atropine does NOT cover these
- Less effective once "aging" (irreversible binding) has occurred - more rapid with nerve agents
Step 5 - Seizures: Benzodiazepines IV
Avoid: succinylcholine, ester anesthetics, beta-blockers (potentiate poisoning)
Source: Tintinalli's Emergency Medicine, Table 201-3
2. Rat Poisoning (Rodenticide Poisoning)
A. Anticoagulant Rodenticides (Most Common)
Agents: Warfarin (first generation), Brodifacoum, Bromadiolone, Difenacoum (superwarfarins - second generation, more potent and longer-lasting)
Mechanism: Inhibit Vitamin K epoxide reductase → depletion of Factors II, VII, IX, X → coagulopathy
Features: Bleeding (ecchymosis, haematuria, GI bleed, intracranial haemorrhage), elevated INR/PT
Treatment: Vitamin K (Phytonadione)
| Route | Dose |
|---|---|
| Subcutaneous | 10-25 mg phytonadione (Vitamin K₁) |
| IV (severe/urgent) | 5-10 mg slow IV infusion (risk of anaphylaxis - use with caution) |
| Oral (maintenance) | 25-50 mg/day for superwarfarins (may need weeks to months) |
- Note: This is for rodenticide toxicity - NOT for simply reversing supratherapeutic INR in patients prescribed warfarin therapeutically
- Severe bleeding may also require Fresh Frozen Plasma (FFP) or Prothrombin Complex Concentrate (PCC) for immediate reversal
- Superwarfarin poisoning (brodifacoum) may require months of Vitamin K therapy due to very long half-life
Source: Goldman-Cecil Medicine, Table 96-6 Antidotes
B. Zinc Phosphide / Aluminium Phosphide (Celphos)
Mechanism: Releases phosphine gas on contact with moisture/acid → inhibits cytochrome c oxidase → multi-organ failure
Features: Vomiting, garlic odor, cardiovascular collapse, pulmonary edema, liver failure
Treatment:
- NO specific antidote
- Gastric lavage with potassium permanganate (1:10,000) or sodium bicarbonate (to reduce phosphine release)
- Avoid oils/fats in stomach (enhance absorption)
- Supportive: inotropes, mechanical ventilation, magnesium sulfate (for arrhythmias)
- Coconut oil has been used empirically to coat stomach
C. Yellow Phosphorus (found in older rat pastes)
Features: "Smoking stool" (feces glow in dark), hepatotoxicity, renal failure
Treatment:
- Gastric lavage with KMnO₄
- Activated charcoal
- Supportive (liver support, hydration)
- Avoid fats and oils
3. Other Common Poisoning Cases
Paracetamol (Acetaminophen) Overdose
Most common intentional overdose presenting to emergency
Mechanism: Toxic metabolite NAPQI (when glutathione stores depleted) → hepatic centrilobular necrosis
Stages:
- 0-24h: Nausea, vomiting, malaise
- 24-72h: RUQ pain, liver enzymes rise, may appear to improve
- 72-96h: Fulminant hepatic failure (jaundice, coagulopathy, encephalopathy)
- Recovery or death
Treatment: N-Acetylcysteine (NAC)
| Route | Regimen |
|---|---|
| IV (standard 3-bag) | 150 mg/kg in 200 mL D5W over 60 min, then 50 mg/kg in 500 mL over 4h, then 100 mg/kg in 1000 mL over 16h |
| Oral | 140 mg/kg loading dose, then 70 mg/kg every 4h x 17 doses |
- Use Rumack-Matthew nomogram to determine who needs treatment (based on serum paracetamol level vs time of ingestion)
- Best started within 8-10 hours of ingestion; still beneficial up to 24h
- Replenishes glutathione stores
Salicylate (Aspirin) Overdose
Features: Tinnitus, tachypnea, mixed respiratory alkalosis + metabolic acidosis, hyperthermia, altered consciousness
Treatment:
- Activated charcoal (multi-dose if large ingestion)
- Urinary alkalinization (sodium bicarbonate): IV bolus 1-2 mEq/kg, then 150 mEq in 1L D5W - maintain urine pH 7.5-8.0; monitor serum K (hypokalemia prevents alkalinization)
- Hemodialysis for severe cases (level >100 mg/dL, renal failure, encephalopathy)
Opioid Overdose
Features: Miosis, respiratory depression, coma (classic triad)
Antidote: Naloxone (Narcan)
| Route | Adult Dose |
|---|---|
| IV | 0.4-2 mg IV; repeat every 2-3 min; up to 10 mg total |
| IM/SC | 0.4-0.8 mg |
| Intranasal | 4 mg (2 mg/nostril) |
| Infusion | 2/3 of effective bolus dose per hour (for long-acting opioids) |
- Onset IV: 1-2 min; duration 30-90 min (shorter than most opioids - repeat dosing/infusion often needed)
Benzodiazepine Overdose
Features: Sedation, respiratory depression (usually mild in isolation; severe with co-ingestions)
Antidote: Flumazenil
| Route | Dose |
|---|---|
| IV | 0.2 mg over 30 sec; repeat 0.3 mg at 60 sec; then 0.5 mg every 60 sec (max 3 mg) |
- Caution: Can precipitate withdrawal seizures in benzodiazepine-dependent patients; use selectively
- Short acting (half-life ~1h) - resedation common
Tricyclic Antidepressant (TCA) Overdose
Features: QRS widening, hypotension, seizures, anticholinergic signs, ventricular arrhythmias
Treatment:
- Sodium bicarbonate 1-2 mEq/kg IV bolus - narrows QRS, treats arrhythmias and hypotension (alkalinization reduces protein binding)
- Target blood pH 7.45-7.55
- Avoid physostigmine, flumazenil, physostigmine, beta-blockers
- Benzodiazepines for seizures
- Intubation and ICU if QRS >100 ms
Iron Poisoning
Features: GI hemorrhage, metabolic acidosis, cardiovascular collapse, hepatotoxicity
Antidote: Deferoxamine
| Route | Dose |
|---|---|
| IV (preferred) | 15 mg/kg/hour infusion (max 80 mg/kg/day) |
| IM | 90 mg/kg IM (max 1 g per site) |
- Chelates free iron - urine turns "vin rosé" (orange-pink) indicating active chelation
- Continue until clinical improvement and urine color normalizes
Cyanide Poisoning
Sources: Smoke inhalation, industrial exposure, amygdalin (fruit seeds)
Features: Rapid loss of consciousness, metabolic acidosis (high lactate), "bitter almond" odor, cherry-red skin
Antidotes:
| Drug | Dose | Mechanism |
|---|---|---|
| Hydroxocobalamin | 5 g IV over 15 min (adults); 70 mg/kg in children | Binds cyanide → cyanocobalamin excreted in urine |
| Sodium thiosulfate | 12.5 g IV (50 mL of 25% solution) | Provides sulfur for rhodanese enzyme to detoxify cyanide |
| Sodium nitrite | 300 mg IV (10 mL of 3% solution) | Induces methemoglobin (cyanide scavenger) - AVOID in smoke inhalation |
- Hydroxocobalamin is first-line, especially in smoke inhalation (does not impair oxygen carrying capacity)
Carbon Monoxide Poisoning
Features: Headache, nausea, cherry-red skin (unreliable), altered consciousness, elevated COHb on co-oximetry
Treatment:
| Severity | Treatment |
|---|---|
| Mild-moderate | 100% O₂ via non-rebreather mask (reduces COHb half-life from 5h to 90 min) |
| Severe (coma, seizures, COHb >25%, cardiac involvement, pregnancy) | Hyperbaric oxygen (HBO) - further reduces half-life to ~30 min |
Methanol / Ethylene Glycol Poisoning
Features: Methanol - visual disturbance ("snowfield"), high anion gap acidosis; Ethylene glycol - oxalate crystals in urine, renal failure
Treatment:
- Fomepizole (4-MP): 15 mg/kg IV loading, then 10 mg/kg IV every 12 h x 4 doses (first-line competitive inhibitor of alcohol dehydrogenase)
- Ethanol (if fomepizole unavailable): target serum ethanol 100-150 mg/dL
- Sodium bicarbonate for acidosis
- Hemodialysis for severe cases (high levels, renal failure, visual changes)
Summary Antidote Table
| Poison | Antidote | Key Dose |
|---|---|---|
| Organophosphates | Atropine + Pralidoxime | Atropine: 1.2-3 mg IV (double q5min); Pralidoxime: 30 mg/kg IV |
| Anticoagulant rodenticides | Vitamin K₁ (Phytonadione) | 10-25 mg SC/IV; oral for maintenance |
| Paracetamol | N-Acetylcysteine | 150 mg/kg IV loading |
| Opioids | Naloxone | 0.4-2 mg IV, repeat PRN |
| Benzodiazepines | Flumazenil | 0.2 mg IV, up to 3 mg |
| TCAs | Sodium bicarbonate | 1-2 mEq/kg IV |
| Iron | Deferoxamine | 15 mg/kg/h IV |
| Cyanide | Hydroxocobalamin | 5 g IV |
| Carbon monoxide | 100% O₂ / HBO | - |
| Methanol/Ethylene glycol | Fomepizole | 15 mg/kg IV |
| Salicylates | Sodium bicarbonate + Dialysis | Urine pH 7.5-8.0 |
Sources:
- Tintinalli's Emergency Medicine, Treatment Table 201-3 for organophosphates
- Goldman-Cecil Medicine, Table 96-6: Antidotes and Indications
- Lippincott Illustrated Reviews: Pharmacology - cholinergic crisis mechanisms
- Pfenninger and Fowler's Procedures for Primary Care - activated charcoal protocols
- Morgan and Mikhail's Clinical Anesthesiology - atropine in OP poisoning
Clinical note: Always contact your regional Poison Control Center (in India: 1800-116-117; in the US: 1-800-222-1222) for real-time guidance on any serious poisoning case. Drug doses may need adjustment for pediatric patients, hepatic/renal impairment, and pregnancy.
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