Drug survival and reasons for discontinuation of intramuscular methotrexate: a study of 212 consecutive patients switching from oral methotrexate

OBJECTIVES: To assess the drug survival and reasons for discontinuation of intramuscular methotrexate (imMTX) in rheumatological patients who had switched to imMTX from oral methotrexate (oMTX). METHODS: Data from 212 consecutive patients who switched from oMTX to imMTX therapy at our outpatient clinic between April 1997 and January 2004 were collected retrospectively through survey of case records. Data included reason for discontinuation of oMTX, disease activity parameters, duration of imMTX therapy, and, in patients who withdrew, the reason for discontinuation of imMTX. RESULTS: The main reasons for switching from oMTX to imMTX were lack of efficacy (66%) and adverse events (28%). After 6 months, 114 patients (54%) were still receiving imMTX therapy, and their median serum C-reactive protein (CRP) and the percentage of patients who had received glucocorticoids during the previous 6 weeks had decreased (p<0.001). The median survival of imMTX therapy was 7.5 months (interquartile range 3-17). Twenty per cent of the patients received imMTX for more than 24 months. Of the 212 patients, 41% and 9% stopped imMTX therapy because of lack of efficacy and adverse events, respectively. Of the patients who had stopped oMTX because of adverse events, 22% also withdrew from imMTX because of adverse events. CONCLUSION: Half of the patients benefited from switching from oral to intramuscular methotrexate for at least 6 months, but only a minority adhered to the treatment for years. Lack of efficacy was the most frequent reason for discontinuation, while adverse events were rare.