What is the treatment for zinc phosphide (rat poison) ingestion?

Zinc Phosphide Poisoning Treatment

Immediately activate emergency medical services (EMS) if the patient exhibits any life-threatening symptoms (sleepiness, seizures, difficulty breathing, vomiting), ensure adequate ventilation of the treatment area to prevent phosphine gas accumulation, and provide aggressive supportive care with airway management and circulatory support—there is no antidote for zinc phosphide poisoning. 1, 2, 3

Immediate Actions and Healthcare Worker Safety

Protect Medical Personnel First

• Ensure adequate ventilation of the treatment area immediately to prevent phosphine gas accumulation and secondary exposure to staff. 2
• Use appropriate personal protective equipment including organic vapor filters for air-purifying respirators when managing these patients. 2
• Avoid direct contact with emesis and gastric contents without proper protection to minimize the risk of secondary phosphine gas exposure. 2

Activate Emergency Services

• Call EMS immediately (or Poison Control at 800-222-1222 in the US) for any patient with signs of life-threatening conditions after zinc phosphide ingestion. 1

Decontamination Strategy

What NOT to Do

• Do not induce vomiting, as this may worsen the clinical condition. 2
• Do not administer anything by mouth (water, milk, or other substances) unless specifically advised by poison control, as this may cause emesis and aspiration. 1
• Do not administer activated charcoal unless specifically advised by poison control or emergency medical personnel—it has not been shown to be beneficial and may cause harm. 1
• Do not administer syrup of ipecac for zinc phosphide ingestion. 1

Decontamination Approach

• Consider polyethylene glycol for whole bowel irrigation if radiopaque material is visible on abdominal X-ray and the patient presents early. 2
• This is one of the few interventions that may help remove unabsorbed zinc phosphide from the gastrointestinal tract before it converts to phosphine gas. 2

Pathophysiology Understanding

Zinc phosphide reacts with gastric hydrochloric acid to produce highly toxic phosphine gas, which is absorbed through the stomach and intestines. 3, 4, 5 Phosphine causes cellular hypoxia via mitochondrial toxicity by inhibiting the cytochrome C oxidase system, resulting in multiple organ dysfunction. 4, 6

Clinical Manifestations to Monitor

Immediate Toxicity (First 24 Hours)

• Profuse vomiting (100% of cases), abdominal pain (100%), palpitations and sweating (80%), dyspnea and tachypnea (75%). 7
• Metabolic acidosis (60%), shock (40%), hypotension (40%). 7
• Circulatory collapse, acute pulmonary edema, and congestive heart failure. 3, 5
• The majority of deaths occur in the first 12-24 hours due to refractory hypotension and arrhythmias. 6

Delayed Effects (Beyond 24 Hours)

• Liver failure with elevated enzymes and hyperbilirubinemia. 6
• Acute kidney injury with acute tubular necrosis and tubulointerstitial nephritis requiring hemodialysis. 6
• Myocarditis and pericarditis. 3, 5, 6
• Acute pancreatitis. 6
• Adult respiratory distress syndrome. 6
• Late deaths are commonly due to multiorgan failure. 6

Supportive Treatment Protocol

Airway and Respiratory Management

• Aggressive airway management is critical to successful outcome. 3
• Monitor for acute pulmonary edema and provide respiratory support as needed. 3, 5

Circulatory Support

• Aggressive circulatory support is critical to successful outcome. 3
• Treat hypotension and shock with inotropic support. 5, 6
• Monitor for arrhythmias and myocarditis. 5, 6

Metabolic Management

• Correct metabolic acidosis. 7
• Monitor and manage electrolyte abnormalities. 4

Organ-Specific Support

• Prepare for renal replacement therapy (hemodialysis) if acute kidney injury develops. 6
• Monitor liver function and provide hepatic support as needed. 6
• Monitor for pancreatitis and provide appropriate management. 6

Prognostic Indicators

Poor outcomes are associated with:

• Delayed presentation to medical care. 6
• Development of coagulopathy. 6
• Hyperglycemia. 6
• Multiorgan failure with elevated liver enzymes. 6
• Mortality rate is approximately 25% in case series. 7

Key Clinical Pitfall

There is no antidote or specific treatment for zinc phosphide toxicity—treatment is entirely symptomatic and supportive. 3, 4 Success depends on early recognition, immediate EMS activation, proper healthcare worker protection from phosphine gas exposure, and aggressive supportive care focusing on airway management and circulatory support. 2, 3