Effect of oral cholestyramine on the elimination of high-dose methotrexate.

The anion exchange resin cholestyramine binds methotrexate (MTX) effectively in vitro. The binding capacity exceeds that of activated charcoal by a factor of 5.4. On two patients undergoing high-dose MTX therapy it is also shown that cholestyramine binds MTX in vivo. This leads to an enhanced non-renal excretion of MTX. Therefore, cholestyramine may be of clinical value in patients who develop renal function impairment whilst undergoing MTX therapy.