Medline ® Abstracts for References 2,3

BACKGROUND: Methotrexate is a folic acid antagonist widely used for the treatment of inflammatory disorders for more than 50 years. Methotrexate is a standard systemic therapy for severe psoriasis and rheumatoid arthritis. Folic acid supplementation has been advocated to limit the toxicity of methotrexate on blood cells, gastrointestinal tract and liver. However, there is still controversy regarding the usefulness of folic acid supplementation.

OBJECTIVES: We sought to assess the evidence for the efficacy of folic acid supplementation in patients treated with methotrexate for inflammatory diseases. We also investigated whether folic acid supplementation may decrease the efficacy of methotrexate.

METHODS: Cochrane and MEDLINE databases were systematically searched. Randomized controlled trials in patients treated with methotrexate for rheumatoid arthritis or psoriasis with or without arthritis were included. Study selection, assessment of methodological quality, data extraction and analysis were carried out by two independent researchers. We selected double-blind randomized placebo-controlled trials. Analysis was performed for each subgroup of side-effects: gastrointestinal, mucocutaneous, haematological and hepatic.

RESULTS: Six randomized controlled trials met the inclusion criteria, with a total sample of 648 patients. There were 257 patients in the placebo group, 198 patients treated with folic acid, and 193 patients treated with folinic acid. The statistical analysis showed a significant reduction of 35.8% of hepatic side-effects induced by methotrexate for patients with supplementation with folic or folinic acid (95% confidence interval -0.467 to -0.248). There was no statistical difference for mucocutaneous and gastrointestinal side-effects although there was a trend in favour of supplementation. The effect of supplementation on haematological side-effects could not be assessed accurately due to a low incidence of these events in the population studied. We were unable to analyse the effect of supplementation on the effectiveness of methotrexate, as markers of activity used in each study were not comparable.

CONCLUSIONS: Supplementation with folic acid is an effective measure to reduce hepatic adverse effects associated with methotrexate treatment. There is no difference between folinic acid and folic acid, but the lower cost of the latter promotes its use.

OBJECTIVE: To study the effect of folates on discontinuation of methotrexate (MTX) as single-drug antirheumatic treatment due to toxicity, to determine which type of adverse events are reduced, to study the effects on the efficacy of MTX, and to compare folic with folinic acid supplementation in a 48-week, randomized, double-blind, placebo-controlled trial.

METHODS: Patients with active RA (n = 434) were randomly assigned to receive MTX plus either placebo, folic acid (1 mg/day), or folinic acid (2.5 mg/week). The initial MTX dosage was 7.5 mg/week; dosage increases were allowed up to a maximum of 25 mg/week for insufficient responses. Folate dosages were doubled once the dosage of MTX reached 15 mg/week. The primary end point was MTX withdrawal because of adverse events. Secondary end points were the MTX dosage and parameters of efficacy and toxicity of MTX.

RESULTS: Toxicity-related discontinuation of MTX occurred in 38% of the placebo group, 17% of the folic acid group, and 12% of the folinic acid group. These between-group differences were explained by a decreased incidence of elevated liver enzyme levels in the folate supplementation groups. No between-group differences were found in the frequency of other adverse events or in the duration of adverse events. Parameters of disease activity improved equally in all groups. Mean dosages of MTX at the end of the study were lower in the placebo group (14.5 mg/week) than in the folic and folinic acid groups (18.0 and 16.4 mg/week, respectively).

CONCLUSION: Both folate supplementation regimens reduced the incidence of elevated liver enzyme levels during MTX therapy, and as a consequence, MTX was discontinued less frequently in these patients. Folates seem to have no effect on the incidence, severity, and duration of other adverse events, including gastrointestinal and mucosal side effects. Slightly higher dosages of MTX were prescribed to obtain similar improvement in disease activity in the folate supplementation groups.