Store doser calciumfolinat skal undgås, da de kan svække antitumoraktiviteten af methotrexat, specielt i CNS- tumorer hvor calciumfolinat akkumuleres ved gentagne cyklusser.
Excessive calcium folinate doses must be avoided since this might impair the antitumour activity of methotrexate, especially in CNS tumours where calcium folinate accumulates after repeated courses.