Accidental Overdose of Oral Cyclosporine in Haematopoietic Stem Cell Transplantation: A Case Report and Literature Review

A 26-year-old woman developed symptoms of acute toxicity during cyclosporine (CsA) therapy for graft-versus-host disease prophylaxis. The standard regimen included CsA in a dose of 1.5 mg/kg (120 mg) every 12 h, but, as a medication error, she received a high dose of 500 mg of oral CsA. After 2 h, she developed nausea and vomiting and, subsequently, flushing, chest tightness, tremor and vertigo. Laboratory and clinical examinations revealed high blood CsA concentrations (1000 ng/mL after 12 h) with a mild increase in blood pressure. Therefore, the patient was diagnosed with an acute CsA overdose. Before confirmation of the overdose by measurement of drug concentrations, the second dose was administered at its routine time because of uncertainty about the aetiology of the symptoms. The third dose was withheld, and the patient was monitored closely for clinical and laboratory presentations until the time when the abnormalities were relieved. CsA administration was then resumed with the correct prescription. The patient was discharged with successful engraftment and normal biochemical laboratory results after 1 month. Evaluation with the Naranjo assessment score indicated a probable relationship between the patient’s symptoms and overdosage with the suspected drug. Currently, detailed presentations of acute CsA toxicity cases due to overdose are limited in the medical literature. Evaluation of the patient’s medical and laboratory records, with cooperation of all responsible clinical staff, along with a review of the literature, were very helpful in discovery of the toxicity incident. Vigilance of health care providers with regard to medication errors and early detection of toxicity symptoms can decrease CsA-related morbidity and mortality in the future.