Multiple toxic effects of low-dose methotrexate in a patient treated for psoriasis

Abstract

A patient who erroneously took oral methotrexate daily rather than thrice weekly for psoriasis developed multiple manifestations of methotrexate toxicity.

Acute Severe Methotrexate Toxicity in Patients with Psoriasis: A Case Series and Discussion

“…The most common adverse event is gastrointestinal intolerance, which is a mild adverse event and can be found in around 30% of patients [5,8]. The most common severe adverse event is bone marrow toxicity, which is found in 2.5-10% of patients [5,9]. Psoriatic plaque ulceration is a characteristic but rare adverse event with only 66 cases reported from 1951 to 1996 [10].…”

A case of Severe Low-dose Methotrexate-induced Toxicity

“…While hepatotoxicity has historically been the most feared side effect, pancytopenia is now emphasized as the most serious adverse event. It has been observed in approximately 1.5% of patients taking low-dose MTX (4,6,7). Psoriatic plaque erosion is a rare cutaneous manifestation of low-dose MTX toxicity with unknown prevalence and has been hypothesized that a painful erosion of psoriatic plaque is an early cutaneous sign of pancytopenia (8).…”

“…Age >55, folate deficiency, low serum albumin level, and drug-drug interactions are also common risk factors (Table 2) (5,7,8).…”

“…NSAIDs (drug retention), aspirin sulfonamides, penicillin, and colchicines (decreases MTX clearance), barbiturates, nitrofurantoin (impair folate absorption), trimethoprimsulfamethoxazole, triamterene, pyrimethamine, ethanol (inhibit the enzyme dihydrofolate reductase) phenytoin, probenecid, salicylates, sulfonamides, tetracycline, chloramphenicol, sulfonylureas (displace MTX from albumin), PPIs (the renal excretion of MTX) are the main accused drugs (4,5,7,9). …”

Adherence to National Recommendations for Safe Methotrexate Dispensing in Community Pharmacies

“…9,10 Serious events, including fatal incidents with MTX, have been reported in several countries. 8,9,[11][12][13] Improving patient safety is a priority health policy across the world. Previous research shows that medication errors are a common cause of harm to patients.…”