Peripheal blood toxicity of topical 5-fluorouracil on the Syrian hamster cheek pouch

Toxicological studies on the peripheral blood after topical application of 5-fluorouracil to the buccal pouch of the Suriam hamster showed that a daily application of 10 mul (9.5 mg) was the maximum ideal dose for this animal. This dose did not depress to a significant degree the white blood cell count, red blood cell count, hemoglobin leve., hematocrit value, or the peripheral differential blood counts after 14 daily applications. Doses of increased concentration either daily or periodically were less effective and toxic.