Introduction
rheumatoid arthritis
RHEUMATOID ARTHRITIS
Methotrexate (MTX) was introduced in the late 1950s and quickly replaced its congener aminopterin as the preferred antifolate drug [Apart from superior efficacy and long-term continuation rates, LD-MTX also has an excellent safety profile, and these features have led to its widespread use in rheumatology for a variety of indications, most common being rheumatoid arthritis [Leucovorin or folinic acid (initially called citrovorum factor) was discovered in 1948 as a growth factor for the bacterium At our tertiary care referral center, we had been treating severe LD-MTX toxicity with leucovorin at a dose of 15 mg every 6 h but found significantly high mortality (unpublished). We speculated that a higher dose of leucovorin may lead to faster hematological recovery and consequently improve outcomes. Thus, we planned this study to compare two different doses of leucovorin, usual (15 mg) or high-dose (25 mg), given intravenously every 6-h.