There is evidence that the metabolism of fluorouracil in the anabolic pathway blocks the methylation reaction of deoxyuridylic acid to thymidylic acid. In this manner, fluorouracil interferes with the synthesis of deoxyribonucleic acid (DNA) and to a lesser extent inhibits the formation of ribonucleic acid (RNA). Since DNA and RNA are essential for cell division and growth, the effect of fluorouracil may be to create a thymine deficiency that provokes unbalanced growth and death of the cell. The effects of DNA and RNA deprivation are most marked on those cells that grow more rapidly and take up fluorouracil at a more rapid rate. The contribution to efficacy or safety of individual components of the vehicle has not been established.

Carac is indicated for the topical treatment of multiple actinic or solar keratoses of the face and anterior scalp.

Carac Cream should be applied once a day to the skin where actinic keratosis lesions appear, using enough to cover the entire area with a thin film. Carac Cream should not be applied near the eyes, nostrils, or mouth. Carac Cream should be applied 10 minutes after thoroughly washing, rinsing, and drying the entire area. Carac Cream may be applied using the fingertips. Immediately after application, the hands should be thoroughly washed. Carac Cream should be applied up to 4 weeks as tolerated. Continued treatment up to 4 weeks results in greater lesion reduction. Local irritation is not markedly increased by extending treatment from 2 to 4 weeks, and is generally resolved within 2 weeks of cessation of treatment.

The following were adverse events considered to be drug related and occurring with a frequency of ≥1% with Carac: application site reaction (94.6%), and eye irritation (5.4%). See Full Prescribing Information.

Fluorouracil may cause fetal harm when administered to a pregnant woman. Fluorouracil is contraindicated in women who are or may become pregnant. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to the fetus. (See Full Prescribing Information.)

There is a possibility of increased absorption through ulcerated or inflamed skin.