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Toxicology – Salicylate Toxicity
Source
Salicylates are present in many over-the-counter and prescription medications used for pain, fever, and inflammation. Common sources include aspirin, methyl salicylate (oil of wintergreen), combination cold remedies, topical analgesics, bismuth subsalicylate (e.g., Pepto-Bismol), and effervescent formulations like Alka-Seltzer.
Typical Presentation
Toxicity may occur acutely after a large ingestion or chronically from repeated high dosing, especially in elderly patients. Acute cases often present with gastrointestinal and auditory symptoms, whereas chronic toxicity may present more subtly.
Clinical Features
Acute Toxicity
Patients commonly develop nausea, vomiting, abdominal pain, rapid breathing (tachypnea), ringing in the ears (tinnitus), and confusion. Severe cases may progress to hypoglycemia, seizures, pulmonary edema, and coma. A classic finding is a mixed acid–base disorder: respiratory alkalosis combined with metabolic acidosis.
Chronic Toxicity
Typically seen in older individuals, presenting with confusion, dehydration, and metabolic acidosis. Symptoms are often nonspecific and can mimic other illnesses, making diagnosis more challenging.
Mechanism of Action
Salicylates stimulate the respiratory center in the brain, causing hyperventilation and respiratory alkalosis. They also uncouple oxidative phosphorylation, leading to increased acid production and metabolic acidosis. Additionally, they irreversibly inhibit cyclooxygenase (COX) enzymes.
Management
Treatment is supportive and includes careful monitoring. If intubation is required, maintaining adequate hyperventilation is critical to prevent worsening acidosis. Sodium bicarbonate is administered to alkalinize the blood (target pH ≥7.4) and urine (target pH 7.5–8.5), which enhances salicylate elimination.
Gastrointestinal decontamination with multiple-dose activated charcoal or whole bowel irrigation may be considered. Hemodialysis is indicated in severe toxicity, particularly with high salicylate levels or significant clinical deterioration. Patients should also be monitored for complications such as pulmonary edema.
Key Points
Source
Salicylates are present in many over-the-counter and prescription medications used for pain, fever, and inflammation. Common sources include aspirin, methyl salicylate (oil of wintergreen), combination cold remedies, topical analgesics, bismuth subsalicylate (e.g., Pepto-Bismol), and effervescent formulations like Alka-Seltzer.
Typical Presentation
Toxicity may occur acutely after a large ingestion or chronically from repeated high dosing, especially in elderly patients. Acute cases often present with gastrointestinal and auditory symptoms, whereas chronic toxicity may present more subtly.
Clinical Features
Acute Toxicity
Patients commonly develop nausea, vomiting, abdominal pain, rapid breathing (tachypnea), ringing in the ears (tinnitus), and confusion. Severe cases may progress to hypoglycemia, seizures, pulmonary edema, and coma. A classic finding is a mixed acid–base disorder: respiratory alkalosis combined with metabolic acidosis.
Chronic Toxicity
Typically seen in older individuals, presenting with confusion, dehydration, and metabolic acidosis. Symptoms are often nonspecific and can mimic other illnesses, making diagnosis more challenging.
Mechanism of Action
Salicylates stimulate the respiratory center in the brain, causing hyperventilation and respiratory alkalosis. They also uncouple oxidative phosphorylation, leading to increased acid production and metabolic acidosis. Additionally, they irreversibly inhibit cyclooxygenase (COX) enzymes.
Management
Treatment is supportive and includes careful monitoring. If intubation is required, maintaining adequate hyperventilation is critical to prevent worsening acidosis. Sodium bicarbonate is administered to alkalinize the blood (target pH ≥7.4) and urine (target pH 7.5–8.5), which enhances salicylate elimination.
Gastrointestinal decontamination with multiple-dose activated charcoal or whole bowel irrigation may be considered. Hemodialysis is indicated in severe toxicity, particularly with high salicylate levels or significant clinical deterioration. Patients should also be monitored for complications such as pulmonary edema.
Key Points
- Chronic toxicity is often missed due to nonspecific symptoms.
- Mixed respiratory alkalosis and metabolic acidosis is a hallmark finding.
- Oil of wintergreen is highly concentrated and potentially lethal, especially in children.
- Chronic toxicity generally carries a worse prognosis than acute overdose.
- Adequate ventilation must be maintained in intubated patients.
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