Case Report: Analytically Confirmed Severe Albenzadole Overdose Presenting with Alopecia and Pancytopenia

Internet-facilitated self-diagnosis and treatment is becoming more prevalent, putting individuals at risk of toxicity when drugs are acquired without medical oversight. We report a patient with delusional parasitosis who consumed veterinary albendazole purchased on the Internet, leading to pancytopenia, transaminase elevation, and alopecia. A 53-year-old man was sent to the emergency department (ED) by his gastroenterologist because of abnormal laboratory results. The patient had chronic abdominal pain and believed he was infected with parasites. He purchased two bottles of veterinary-grade albendazole on the Internet, and over the 3 weeks before his ED visit, he consumed 113.6 g of albendazole (a normal maximal daily dose is 800 mg). Five days before admission, he noticed hair loss and a rash on his face. His examination was notable for significant scalp hair loss and hyperpigmentation along the jaw line. Laboratory studies were remarkable for pancytopenia (most notably a white blood cell count (WBC) of 0.4 × 10³ cells/mm³, with an absolute neutrophil count (ANC) of 0 × 10³ cells/mm³) and transaminase elevation (aspartate aminotransferase [AST] 268 IU/L, alanine aminotransferase [ALT] 89 IU/L). He developed a fever and was treated with antibiotics and colony-stimulating factors for presumed neutropenic bacteremia. Over the course of 1 week, his hepatic function normalized and his ANC increased to 3,000 × 10³ cells/mm³. Serial albendazole and albendazole sulfoxide concentrations were measured in serum and urine by liquid chromatography-quadruple time-of-flight mass spectrometry. On day 2, his serum concentrations were 20.7 ng/mL and 4,257.7 ng/mL for albendazole and albendazole sulfoxide, respectively. A typical peak therapeutic concentration for albendazole sulfoxide occuring at 2-5 hours post-ingestion is 220-1,580 ng/mL. Known adverse effects of albendazole include alopecia, transaminase elevation, and neutropenia. Pancytopenia leading to death from septic shock is reported. In our patient, prolonged use of high-dose albendazole resulted in a significant body burden of albendazole and albendazole sulfoxide, leading to pancytopenia, transaminase elevation, and alopecia. He recovered with supportive therapy.