What is topical fluorouracil, and how does it work (mechanism of action)?

  • Topical fluorouracil is a drug that is used to treat conditions of the skin in which there is rapid multiplication (division) of cells, for example, skin cancer. In order to multiply or divide, cells must produce DNA for each new cell. The DNA is critical since it is the genetic material that directs the activity of all cells. Production of DNA depends on the production of RNA which serves as a messenger during the production of DNA. Fluorouracil prevents the formation of RNA which, in turn, prevents the formation of DNA. As a result, cells cannot multiply. With continued treatment, the remaining cells also die.
  • The FDA approved fluorouracil in July 1970.

What brand names are available for topical fluorouracil?

Carac, Efudex, Fluoroplex, Tolak

Do I need a prescription for topical fluorouracil?

Yes

What are the uses for topical fluorouracil?

  • Topical fluorouracil is used to treat certain skin conditions in which cells are multiplying rapidly.
  • It is used to treat cancerous or precancerous conditions including solar keratoses, actinic keratosis, superficial basal cell carcinoma, and Bowen's disease (a type of skin cancer).
  • It also is used to treat some noncancerous conditions in which cells are dividing rapidly, including psoriasis, genital warts, and porokeratosis (an unusual inherited skin condition causing dry patches on the arms and legs).
  • Fluorouracil works best on the face and scalp, and is less effective on other areas of the body. It also destroys sun-damaged skin cells making the skin smoother and more youthful-appearing.

What are the side effects of topical fluorouracil?

Common side effects of topical fluorouracil include:

Other side effects include:

  • Ulcer formation
  • Hypo-pigmentation
  • Scarring
  • Bacterial infection

What is the dosage for topical fluorouracil?

  • The cream or solution is applied once or twice daily after washing the area that is to be treated with plain water.
  • The course of treatment continues for at least 2-6 weeks depending on the condition being treated.
  • A tiny amount of the cream should be gently rubbed into all of the treated areas with a fingertip. It is important to apply it to all of the skin and not just visible lesions. Afterward, the finger should be rinsed thoroughly with water. (Alternatively, a glove can be used.)
  • After a few days, the lesion becomes red and may even blister and weep. There may be some soreness.
  • Tretinoin cream (Retin-A and others) enhances the effect of 5-fluorouracil by peeling off the top layer of skin. When fluorouracil is prescribed with tretinoin cream, the combination works best if the tretinoin has been used for at least two weeks prior to starting fluorouracil.

QUESTION

Psoriasis causes the top layer of skin cells to become inflamed and grow too quickly and flake off. See Answer

Which drugs or supplements interact with topical fluorouracil?

There are no known drug interactions with topical fluorouracil.

Is topical fluorouracil safe to take if I'm pregnant or breastfeeding?

  • Although very little fluorouracil is absorbed from normal skin, about 20% can be absorbed into the blood when fluorouracil is applied to damaged skin. Fluorouracil can cause damage to the fetus, and it should not be used by pregnant women.
  • It is not known whether fluorouracil passes into breast milk. Since some amount is absorbed from the skin into the body, nursing mothers should not use fluorouracil.

What else should I know about topical fluorouracil?

What preparations of topical fluorouracil are available?

Cream 0.5, 1 and 5%. Solution 2 and 5%.

How should I keep topical fluorouracil stored?

Cream and solution should be stored at room temperature, between 15 C and 30 C (59 F and 86 F).

Summary

Topical fluorouracil (Carac, Efudex, Fluoroplex, Tolak) is a medication prescribed for the treatment of conditions of the skin such as skin cancer, psoriasis, and keratosis. Review side effects, drug interactions, warnings, and pregnancy and breastfeeding safety information prior to taking this drug.

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Medically Reviewed on 8/7/2019
References
FDA Prescribing Information
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