The issue of bioavailability of oral low dose methotrexate: should we choose only 10 mg of MTX a week in conjunction with anti-TNF therapy?

[...]data from different studies in RA show that the bioavailability of oral MTX is highly variable, decreased in higher oral doses and significantly lower compared with parenteral administration. 3 - 5 After oral administration, MTX is actively absorbed from the proximal jejunum; the active absorption is capacity-limited and consequently decreases with increased oral doses.