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Neutropenia due to low-dose methotrexate therapy for psoriasis and rheumatoid arthritis may be fatal
B Mayall1, G Poggi, J D Parkin
1Repatriation General Hospital, Heidelberg, VIC.
Objective:
To review experience with neutropenia related to low-dose methotrexate therapy in patients with psoriasis and rheumatoid arthritis.
Design:
Retrospective review of medical records.
Setting:
A 509-bed Melbourne teaching hospital.
Patients:
Five patients admitted in 1987 and 1988, with neutrophil counts of less than 1 x 10(9)/L, given low doses of methotrexate for psoriasis or rheumatoid arthritis.
Main Outcome Measures:
Death, or length of hospital admission.
Findings:
Four patients were women, and one a man; three had been treated for psoriasis, and two for rheumatoid arthritis. Ages ranged from 56 to 91 years. The eldest patients, aged 77, 81 and 91 years, died. The other two were discharged after 43 and 48 days. Prior to or shortly after admission, four patients were treated with penicillin antibiotics which may have interfered with methotrexate excretion.
Conclusions:
Methotrexate clearances (related to creatinine clearance rates and presumably low) were probably reduced sufficiently by concomitant therapy to result in neutropenia. Practitioners using methotrexate should be aware of drug interactions resulting in delayed methotrexate excretion. Blood counts should be monitored after changes in therapy, especially in patients with impaired renal function, such as the elderly.
Insights
Low-dose methotrexate can cause neutropenia in patients with psoriasis and rheumatoid arthritis. Drug interactions, especially with penicillin antibiotics, may delay methotrexate excretion, increasing risk, particularly in the elderly.
Area of Science:
- Pharmacology
- Rheumatology
- Dermatology
Background:
- Low-dose methotrexate is used for psoriasis and rheumatoid arthritis.
- Neutropenia is a potential adverse effect of methotrexate therapy.
Purpose of the Study:
- To review neutropenia associated with low-dose methotrexate in psoriasis and rheumatoid arthritis patients.
- To identify risk factors and potential drug interactions contributing to methotrexate-induced neutropenia.
Main Methods:
- Retrospective review of medical records from a teaching hospital.
- Analysis of five patients with severe neutropenia (neutrophil count < 1 x 10(9)/L) treated with low-dose methotrexate.
- Evaluation of patient demographics, diagnoses, treatment, and outcomes.
Main Results:
- Four of five patients were female, with ages ranging from 56 to 91 years.
- Three patients had psoriasis, and two had rheumatoid arthritis.
- Three elderly patients (77, 81, 91 years) died; two were discharged after prolonged hospital stays (43 and 48 days).
- Four patients received penicillin antibiotics prior to or during admission, potentially interfering with methotrexate excretion.
Conclusions:
- Concomitant therapies, such as penicillin antibiotics, likely reduced methotrexate clearance, leading to neutropenia.
- Practitioners must be aware of drug interactions that delay methotrexate excretion.
- Close monitoring of blood counts is crucial after therapy changes, especially in elderly patients or those with impaired renal function.