Emergency Medicine Resident and MedED Enthusiast. Learning and teaching medicine one doodle at a time!
Case:
A 26-year-old female presents to the ED after an attempted suicide with an intentional ingestion of an unknown amount of castor beans about 1 hour prior to presentation. The patient is immediately attached to continuous cardiac and pulse oximetry monitoring. An IV line is established and initial vitals are: BP 136/76, Pulse 112, Temp 98.9 F, RR 17, and she is satting 100% on room air.
Based on the timing of the ingestion, would this patient benefit from gastrointestinal decontamination? If so, what methods would you consider?
Introduction
Castor bean plants are known to contain ricinus communis (a.k.a. ricin), a potent ribosome inhibitor. There is an excellent review of the mechanism of ricin toxicity published by Audi et al. in JAMA which demonstrates how ricin binds to the cell surface, moving into the cell and inactivating ribosomes by removing an adenine from its position. Ricin is able to inactivate 1500 ribosomes per minute. It also may cause other cytotoxic effects such as apoptosis.
Ricin content in each bean is reported to be up to 5% of the bean (100 mg seed may have a total ricin content of up to 5 mg). Although castor oil is produced from these beans, ricin becomes inactivated during the extraction process and therefore is not expected to result in toxicity associated with castor oil ingestions.
Lethal Dose
The median lethal dose of ricin varies depending on the route of exposure. Ricin’s lethal dose is reported to be 3-5 mcg/kg if inhaled, 5-10 mcg/kg if injected, and 20-30 mcg/kg if ingested orally.
There is variable lethality associated with oral ingestion which may be attributed to how the beans were ingested. In order for ricin to be released from the beans, mastication must occur meaning that if the individual swallows the beans whole it is less likely they will exhibit toxicity. However, if the beans are chewed or crushed, there may be a greater clinical effect. The minimum number of beans associated with death is 2.
Clinical Manifestations
Manifestations may occur within 4 to 10 hours; however, most typically occur within 4 to 6 hours. Inhaled ricin is associated with cough, dyspnea, pulmonary edema, and progressive respiratory decline. Injected ricin is associated with fever, shock and multiorgan failure. Oral ingestion is associated with nausea, vomiting, bloody diarrhea, severe dehydration leading to electrolyte imbalances, liver and kidney damage, and fatality.
Laboratory abnormalities include leukocytosis, elevated transaminases and creatinine kinase, hyperbilirubinemia, renal insufficiency and anemia.
Management
There is no antidote for ricin and treatment is supportive. Gastrointestinal decontamination with activated charcoal or gastric lavage can be considered to prevent systemic absorption into the GI tract. A single dose of activated charcoal 25 grams-100 grams may be considered specifically in non-vomiting, stable patients. If the patient has begun vomiting, gut decontamination is unlikely to be helpful. Gastric lavage may be considered in any scenario, although decontamination should be utilized for patients presenting within 1 hour from ingestion if there are no contraindications (such as loss of protected airway, ingestion of a strong alkali/strong acid, or ingestion of a hydrocarbon). Gastric lavage is performed by inserting a tube through the mouth or nose, with the distal end inside the stomach. Then 250 mL aliquots of room temperature 0.9% sodium chloride is instilled through a funnel or lavage syringe up to several liters. Gastric lavage is complete when there is colorless particulate matter return or the lavage solution is clear. Dialysis will not be effective due to ricin’s large molecular size.
Supportive care by means of fluid hydration, repletion of electrolyte imbalances, bronchodilators, vasopressor therapy, endotracheal intubation, and supplemental positive end-expiratory pressure should be provided as needed.
The Debrief
- Castor beans contain ricin, a ribosome inhibitor and known toxin that may result in death after ingestion of as little as 2 beans.
- Symptoms may occur within 4-6 hours. They may be nonspecific, including vomiting, diarrhea and progress to dehydration, circulatory and respiratory collapse.
- No antidote is available at this time and supportive care is the standard. Gastric decontamination should occur in patients who present to the emergency department within 1 hour of exposure.
- Decontamination includes activated charcoal 25 grams-100 mg as a single dose or gastric lavage. Contact the Poison Control Center for more information: 1- 800- 222- 1222
References
- Audi J, Belson M, Patel M, Schier J, Osterloh J. Ricin poisoning: a comprehensive review. JAMA. 2005;294(18):2342-2351. doi:10.1001/jama.294.18.2342
- Thornton SL, Darracq M, Lo J, Cantrell FL. Castor bean seed ingestions: a state-wide poison control system’s experience. Clin Toxicol (Phila). 2014;52(4):265-268. doi:10.3109/15563650.2014.892124
- Lopez Nunez OF, Pizon AF, Tamama K. Ricin Poisoning after Oral Ingestion of Castor Beans: A Case Report and Review of the Literature and Laboratory Testing. J Emerg Med. 2017;53(5):e67-e71. doi:10.1016/j.jemermed.2017.08.023
- Vale JA, Kulig K; American Academy of Clinical Toxicology; European Association of Poisons Centres and Clinical Toxicologists. Position paper: gastric lavage. J Toxicol Clin Toxicol. 2004;42(7):933-943. doi:10.1081/clt-200045006
