2,4-D

CAS RN: 94-75-7

Treatment Overview

0.4.2 ORAL EXPOSURE
  • A) MANAGEMENT OF MILD TO MODERATE TOXICITY
    • 1) The mainstay of managing mild to moderate toxicity is removal/decontamination and supportive care.
  • B) MANAGEMENT OF SEVERE TOXICITY
    • 1) For severe toxicity, treatment should be targeted towards symptoms. Hypotensive patients should be given boluses of isotonic fluids and pressors as necessary. Correct electrolyte abnormalities. Treat cardiac dysrhythmias with standard antidysrhythmics including lidocaine and amiodarone. Patients with severe respiratory symptoms may require intubation.
  • C) DECONTAMINATION
    • 1) PREHOSPITAL: Activated charcoal may be considered if the patient is awake, alert, and cooperative. Remove contaminated clothing and wash exposed skin. Irrigate exposed eyes.
    • 2) HOSPITAL: Activated charcoal may be beneficial, if the patient presents early and is alert. Airway protection should be considered prior to giving activated charcoal in large ingestions because of the risk for CNS depression and seizures. Remove contaminated clothing and wash exposed skin. Irrigate exposed eyes.
  • D) AIRWAY MANAGEMENT
    • 1) Early intubation may be indicated in patients who develop respiratory issues or severe CNS depression.
  • E) ANTIDOTE
    • 1) None
  • F) ENHANCED ELIMINATION
    • 1) Alkaline diuresis can increase elimination of chlorophenoxy compounds, but has not been shown to affect outcome. It may be useful if performed early in the course of treatment. Administer 1 to 2 milliequivalent/kilogram of sodium bicarbonate as an intravenous bolus. Add 132 milliequivalents (3 ampules) sodium bicarbonate and 20 to 40 milliequivalents potassium chloride (as needed) to one liter of dextrose 5% in water and infuse at approximately 1.5 times the maintenance fluid rate. In patients with underlying dehydration, additional administration of 0.9% saline may be needed to maintain adequate urine output (1 to 2 mL/kg/hour). Manipulate bicarbonate infusion to maintain a urine pH of at least 7.5. Administer potassium as necessary. Monitor urine pH hourly.
    • 2) Hemodialysis is likely not useful because of the high degree of protein binding. For 2,4-D, hemoperfusion may be useful as volume of distribution is small, but human studies are not available to evaluate efficacy.
  • G) PATIENT DISPOSITION
    • 1) HOME CRITERIA: Patients with unintentional exposures with minimal to no symptoms may be managed at home.
    • 2) OBSERVATION CRITERIA: Patients should be sent to a healthcare facility if their exposure to chlorophenoxy compounds was in a self-harm attempt or if they are symptomatic. They should be observed for 6 to 12 hours (potential for delayed symptoms) and be clearly improving or asymptomatic prior to discharge.
    • 3) ADMISSION CRITERIA: Patients with severe symptoms or getting worse after an observation period of 6 to 12 hours should be admitted to the hospital. Depending on the severity of their symptoms, ICU admission may be warranted (eg, intubated patients). Patients should not be discharged until they are clearly improving or asymptomatic.
    • 4) CONSULT CRITERIA: Physicians who practice occupational medicine may be useful for patients with workplace exposures to chlorophenoxy herbicides.
  • H) PITFALLS
    • 1) Concentrated formulations of 2,4-D-esters may contain petroleum (hydrocarbon) solvents that can contribute to the overall toxicity.
  • I) PHARMACOKINETICS
    • 1) Well absorbed orally, dermal absorption 5% to 10% over 24 to 144 hours. Highly protein bound, volume of distribution of 2,4-D is small (0.1 L/kg). Metabolized by acid hydrolysis to phenoxy acids which are eliminated in urine. These compounds are strongly acidic (pKa 2.
    • 6) and show dose-dependent elimination (plasma half-lives 10 to 20 hours, rising to 80 to 120 hours in larger doses). Half-life is decreased by urine alkalinization. the half-life of 2,4-D is about 18 hours after oral ingestion, 13 hours after IV administration, 39.5 hours after dermal absorption, and 70 to 90 hours in overdose. 2,4-D amine had a half-life in overdose of 39.5 hours without alkaline diuresis and 2.7 hours with a urine pH greater than 7.5. 2,4,5-T has half-lives from 23 to 33 hours while MCPP had a half-life of 17 hours in an overdose case.
  • J) DIFFERENTIAL DIAGNOSIS
    • 1) Other substances that may mimic chlorophenoxy compound exposures include other irritant chemicals or substances.
0.4.3 INHALATION EXPOSURE
  • A) Administer oxygen for respiratory distress. Administer inhaled beta adrenergic agents for bronchospasm.
0.4.4 EYE EXPOSURE
  • A) Eye exposures should be treated with removal of contact lenses and irrigation of eyes with water for at least 15 minutes. Patients with persistent irritation, pain, swelling, lacrimation or photophobia should have a slit lamp examination.
0.4.5 DERMAL EXPOSURE
  • A) OVERVIEW
    • 1) Remove contaminated clothing and jewelry, and wash skin, hair, and nails vigorously with soap and water. Dermal irritation or burns can be treated with standard topical therapy. Hypersensitivity reactions may require treatment with topical or systemic antihistamines and/or corticosteroids.
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