Acute versus chronic methotrexate poisoning; a cross-sectional study.

Background: Data is limited on comparison of acute and chronic methotrexate (MTX) poisoning. Methotrexate is an anti-folate drug that may be prescribed in some malignant or chronic inflammatory conditions. The aim of the current study was to compare signs and symptoms, complications, treatment and final outcome of acute and chronic MTX toxicity.

Method: In a retrospective study in a referral center between March 2010 and March 2018, all patients who had been referred with the history of MTX poisoning and hospitalized due to acute or chronic poisoning were evaluated and compared.

Results: Of the total 27 patients admitted during the study period, 13 had referred with acute (group 1; consumption of MTX for less than 7 days) and 14 had referred with chronic toxicity (group 2; consumption of MTX for more than 7 days). Mean age was significantly higher in the second group (P < 0.001). Median total dose of MTX was similar between the groups (P = 0.90). Mucosal ulcers and skin lesions (P < 0.001 and 0.02, respectively) were the only symptoms significantly different between the two groups. Leukopenia (P < 0.001), thrombocytopenia (P < 0.001), and anemia (P = 0.04) were significantly more common in the second group. Blood urea nitrogen and creatinine were also significantly higher in the second group of the patients (P < 0.001 and P = 0.048). Median leucovorin administered dose was 200 mg [14, 480] versus 150 mg [75, 187] (P = 0.69) in groups 1 and 2, respectively.

Conclusions: Chronic MTX poisoning is more serious than acute toxicity and accompanies higher dermatologic, hematologic, and hepatic complications necessitating more aggressive treatments including administration of higher doses of leucovorin or bone marrow stimulants such as G-CSF. This may be attributable to the underlying diseases and features (including older ages) which predispose these patients to complications.