Ricin

CAS RN: 9009-86-3

Treatment Overview

0.4.2 ORAL/PARENTERAL EXPOSURE
  • A) MANAGEMENT OF MILD TO MODERATE TOXICITY
    • 1) Significant toxicity is not expected after ingestion of intact or whole seeds (ie, castor bean, abrus precatorius seeds). Management of mild to moderate toxicity requires only good supportive care. Treatment may include volume resuscitation for vomiting and diarrhea, and electrolyte restoration for abnormalities.
  • B) MANAGEMENT OF SEVERE TOXICITY
    • 1) Severe toxicity may require more aggressive treatment, including intubation and the use of pressors for hypotension. Treat seizures with benzodiazepines, add propofol or barbiturates, if seizures persist.
  • C) INHALATION EXPOSURE
    • 1) Move patient to fresh air and observe for respiratory distress, and treat symptomatic patients as necessary with supplemental oxygen, inhaled beta adrenergic agonists, or intubation.
  • D) DERMAL EXPOSURE
    • 1) Remove contaminated clothing and wash exposed area thoroughly with soap and water.
  • E) EYE EXPOSURE
    • 1) Irrigate exposed eyes with copious amounts of water or normal saline for at least 15 minutes, removing contact lenses first if the patient wears them. If the patient continues to have irritation, pain, swelling, lacrimation, or photophobia after eye wash, a more detailed ophthalmologic exam should be performed.
  • F) PARENTERAL EXPOSURE
    • 1) Parenteral exposure may be very difficult to detect. Local excision of injected ricin toxin as soon as possible after exposure may prevent or alleviate systemic effects.
  • G) DECONTAMINATION
    • 1) PREHOSPITAL: Decontamination is generally not necessary if the seeds were known to have been swallowed intact without chewing. Prehospital use of activated charcoal should be considered if the patient is not already vomiting and the ingestion is recent (within the last hour), or if there will be a delay in transport to a healthcare facility of an hour or more. Contraindications of activated charcoal include a depressed mental status that might lead to a compromised airway, seizures, or other comorbidities that might be adversely affected by induced emesis.
    • 2) DERMAL or EYE EXPOSURE: Decontaminate by washing the skin or irrigating the eyes.
    • 3) HOSPITAL: Decontamination is generally not necessary if seeds are known to have been swallowed intact without chewing. Administer activated charcoal, if the ingestion is relatively recent (within the past hour) and the patient is able to protect their airway. Gastric lavage may also be considered for a relatively recent or very large ingestion that has occurred within the past hour. There is no evidence for the use of additional doses of activated charcoal. Whole bowel irrigation with polyethylene glycol solution might be considered for ingestions of multiple seeds, especially if the patient presents more than an hour after ingestion, but it has not been studied.
  • H) AIRWAY MANAGEMENT
    • 1) In mild to moderate toxicity, airway management is unlikely to be an issue. However, patients with more severe toxicity may exhibit depressed mental status or other symptoms that may require intubation.
  • I) ANTIDOTE
    • 1) There is no specific antidote available.
  • J) ENHANCED ELIMINATION
    • 1) Due to their large molecular size (ricin: 66 kilodaltons; abrin: 65 kilodaltons), hemodialysis is unlikely to be useful, although charcoal hemoperfusion may adsorb circulating toxalbumins (although there is no reported clinical experience with this method). There is also no evidence for the use of urinary alkalinization or multiple dose activated charcoal to enhance toxin elimination.
  • K) PATIENT DISPOSITION
    • 1) HOME CRITERIA: Asymptomatic patients who have inadvertently ingested intact seeds without chewing can be monitored at home. Patients with deliberate ingestions and those who have chewed the seeds should be referred to a healthcare facility.
    • 2) OBSERVATION CRITERIA: All symptomatic patients those with intentional ingestions, and those who have swallowed chewed or broken seeds (ie, castor bean or abrus precatorius seeds) should be sent to a healthcare facility for observation until they are clearly improved or asymptomatic. Of note, most patients with significant toxicity develop GI effects within 6 to 12 hours, but more severe manifestations may develop for 1 to 5 days. If a patient is asymptomatic after 12 hours, they may be discharged; however, the patient should be instructed to return to the hospital if symptoms develop after that period.
    • 3) ADMISSION CRITERIA: All symptomatic patients should be admitted. Depending on the severity of illness, a patient may require an ICU admission. Criteria for discharge from the hospital should include either resolution of all symptoms or clear improvement from the toxicity.
    • 4) CONSULT CRITERIA: Consult a medical toxicologist or poison center for any patient with symptoms of a significant exposure. Consultation from law enforcement may be needed if there is a history of exposure to purified ricin. For intentional self-harm exposures, a psychiatric consult is necessary.
  • L) PITFALLS
    • 1) The most difficult issue in managing these patients may be in making the diagnosis. Assays for detection for toxalbumin exposure exists, but are not readily available. Thus, a careful initial history and investigation is necessary in making the diagnosis.
  • M) TOXICOKINETICS
    • 1) There is extremely limited data available concerning the toxicokinetics of toxalbumins in humans. Oral absorption is poor. The half-life of ricin was 2 days in one patient. Most patients with significant toxicity develop GI effects within 6 to 12 hours, but more severe manifestations may develop for 1 to 5 days.
  • N) PREDISPOSING CONDITIONS
    • 1) Patients at extremes of age or in poor health may be more sensitive to the toxic effects of toxalbumins.
  • O) DIFFERENTIAL DIAGNOSIS
    • 1) The differential diagnosis can include certain mushroom poisonings, organophosphate toxicity, and other causes of severe gastrointestinal symptoms.
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