Leucovorin Disease Interactions

The use of leucovorin is inappropriate therapy for patients with undiagnosed anemia. Leucovorin can obscure the diagnosis of pernicious anemia by alleviating the hematologic conditions and allowing progression of neurologic complications.

Leucovorin enhances the toxicity of 5-fluorouracil. When these drugs are administered concurrently in the palliative therapy of advanced colorectal cancer, gastrointestinal toxicities, particularly stomatitis and diarrhea are observed more commonly and may be more severe and of prolonged duration. Therapy with these agents must not be initiated or continued in patients who have symptoms of gastrointestinal toxicity of any severity until those symptoms have completely resolved. Monitor patients experiencing diarrhea and institute appropriate care.

Leucovorin is excreted by the kidney and the risk of toxic reactions to the drug may be greater in patients with impaired renal function. Leucovorin should be used cautiously on these patients, and care should be taken in dose selection. Monitoring of renal function is recommended.

Seizures have occurred rarely during administration of leucovorin, primarily in patients receiving high dose leucovorin or leucovorin in combination with 5-fluorouracil, or in patients with a history of seizures or central nervous system abnormalities (unspecified). Folic acid in large amounts may counter the anticonvulsant effects of phenobarbital, phenytoin, and pimozide. Clinical monitoring of seizure activity is recommended and modification of anticonvulsant therapy may be necessary.