Ricin ● Naturally occuring ○ Seed of castor bean plant ○ Water soluble protein ● Type 2 ribosome inactivating proteins composed ○ A chain ■ Depurinates 28S rRNA ○ B chain ■ Cell surface ■ Binding with receptor ■ Manage endocytosis ● Enters cell through receptor ● Removal of adenine base ○ 28S rRNA ■ 60S subunit ○ Inhibits protein synthesis = cell death ○ cytotoxic = protein shutdown Route Toxicity Level Inhalation Very high Respiratory failure, pulmonary edema Ingestion Moderate–high GI bleeding, liver/kidney damage Injection Extremely high Local necrosis, systemic organ failure Skin contact Low Toxic only if absorbed or injected LD50 ● Human ○ Oral: ~1~20 mg/kg ○ Inhalation: ~1–5 µg/kg ○ Injection: ~1–2 µg/kg Substance Estimated Human Lethal Dose Mechanism Potency Ricin 1–20 mg/kg (oral) Inhibits protein synthesis Very high Fentanyl ~2 mg total (inhaled/injected) Opioid receptor agonist Higher (by mass) Treatment ● There are no antidote ● Supportive care could be given to the patients ○ IV fluid ○ Electrolyte adjustment ● With proper care given, patient can survive ○ >5 days without organ failure