Salivary passage of 5-fluorouracil during continuous infusion

Plasmatic and salivary concentrations of 5-FU were investigated in ten patients given 5-day continuous infusions of 5-fluorouracil (5-FU) (1 g/m2/day). Measurable concentrations of salivary 5-FU were scattered ranging from 6 to 100 ng/ml. Between individual 5-FU concentrations in saliva and plasma the coefficient of correlation was low. The theoretically predicted ratios of 5-FU concentrations in saliva over those in plasma, calculated as a function of salivary pH, did not correlate with the observed ratios, the majority of which ranged between 0.1 and 0.5. Noteworthy, 8 of 10 patients exhibited a more or less pronounced increase in 5-FU salivary excretion during 5-day continuous i.v. infusions.