General resorption of intravesically instilled 5-fluorouracil

To evaluate the resorption of intravesically instilled 5-fluorouracil a single dose of 250 or 1,000 mg. was injected into the empty bladder for 3 hours in 17 patients. The concentration of 5-fluorouracil in serum during instillation was recorded. A microbiologic agar plate method was used for the assay. No measurable 5-fluorouracil concentrations were recorded in the systemic blood of patients with undamaged bladder mucosa and low levels (less than 100 ng./ml. serum) of 5-fluorouracil were found in the systemic circulation of patients with mucosal lesions.