- USES: Class of drugs that are primarily used to treat hypertension and congestive heart failure. Potassium sparing diuretics and carbonic anhydrase inhibitors are covered in separate managements. PHARMACOLOGY: Work in a variety of mechanisms including inhibiting sodium and chloride reabsorption in the distal convoluted tubule (thiazides), inhibiting transport of sodium, potassium, and chloride in the thick ascending limb of the loop of henle (loop), and osmotic agents (mannitol). TOXICOLOGY: Produce hypovolemia and electrolyte deficiencies. EPIDEMIOLOGY: Rare overdose which uncommonly results in significant morbidity or death. MILD TO MODERATE TOXICITY: Mild dehydration, tachycardia, dry mucous membranes, headache, muscle cramps, thirst, and brisk diuresis. Large doses of furosemide or ethacrynic acid can cause ototoxicity. SEVERE TOXICITY: Hypotension, hypochloremic metabolic alkalosis, mental status changes, and electrolyte abnormalities (i.e. hypokalemia, hypomagnesemia, hypochloremia, hypocalcemia) are the most common manifestations of severe poisoning. Rarely muscle spasms, tetany, seizures, coma, or dysrhythmias may develop secondary to severe electrolyte abnormalities. CNS depression has been reported rarely in children with acute ingestion without significant electrolyte abnormalities. ADVERSE EFFECTS: Thiazides are associated with hyperglycemia and hyperlipidemia. Furosemide has been associated with ototoxicity, hyperglycemia, and hypercholesterolemia. Diuretics have a large number of drug interactions as well. Extravasation of mannitol can cause tissue injury and compartment syndrome.
Range of Toxcity:
- TOXICITY: Toxic doses are not well established. Diuresis is expected to result at even therapeutic doses. Toxicity is most common with chronic dosing and acute toxicity is often related to other factors such as comorbid conditions and access to fluid replacement. THERAPEUTIC DOSE: Furosemide is typically dosed at 20 to 80 mg with repeat doses as necessary in adults; pediatric dose is 1 to 2 mg/kg orally. Hydrochlorothiazide is typically dosed at 12.5 to 50 mg daily in adults; pediatric dose is 1 to 3 mg/kg divided twice daily.
- Support: MANAGEMENT OF MILD TO MODERATE TOXICITY: Patients with minor symptoms can be managed with supportive care only. Oral hydration and oral electrolyte supplementation may be sufficient. Severe electrolyte disturbances and/or mental status changes indicate a more severe poisoning. MANAGEMENT OF SEVERE TOXICITY: Severe toxicity is very rare. Treatment should be directed at intravenous correction of volume loss and electrolyte abnormalities.
- Decontamination: PREHOSPITAL: Prehospital decontamination is not indicated as toxicity is rare. HOSPITAL: Activated charcoal is rarely indicated as acute toxicity is rare.
- Airway management: Diuretic poisoning should not produce symptoms mandating airway management.
- Antidote: There is no specific antidote.
- Monitoring of patient: Monitor vital signs and serum electrolytes. Obtain an ECG in patients with significant electrolyte abnormalities.
- Enhanced elimination procedure: Hemodialysis is not expected to be helpful.
- Patient disposition: HOME CRITERIA: Asymptomatic patients with inadvertent ingestion of less than a maximal daily dose can be monitored at home. OBSERVATION CRITERIA: Adults with intentional ingestions or symptomatic children should be referred to a health care facility. Patients who are asymptomatic after 6 hours can be discharged home. ADMISSION CRITERIA: Patients who have severe electrolyte abnormalities or vital sign abnormalities should be admitted. CONSULT CRITERIA: Consult a poison center or medical toxicologist for assistance in managing severe poisonings.