fluorouracil + salicylic acid: clinical use

Prescribing considerations

• Confirm grade I or II hyperkeratotic actinic keratosis and immunocompetent adult status.
• Avoid bleeding lesions, mucosal surfaces and large treatment fields.
• Protect treated sites from excessive ultraviolet exposure.
• Evidence for repeated treatment of recurrent lesions has not been formally established.
• Consider closer review on thin epidermis or where another skin disorder affects the treatment site.

Contraindications and cautions

• Hypersensitivity to fluorouracil, salicylic acid or an excipient
• Pregnancy or breastfeeding
• Renal insufficiency
• Concurrent or recent brivudine, sorivudine or related analogues
• Application where contact with eyes or mucous membranes cannot be avoided

Monitoring

• Review local inflammation, erosion, bleeding, swelling and ulceration.
• Closely monitor sites in people with impaired touch, pain or temperature sensation, including some people with diabetes.
• Consider DPD-related toxicity if unexpected systemic fluorouracil toxicity is suspected, although systemic absorption is normally negligible when used as authorised.

Clinical pharmacology

Fluorouracil inhibits DNA and RNA synthesis through antimetabolite activity. Salicylic acid is keratolytic and loosens corneocyte adhesion. The dried film provides an occlusive effect, while dimethyl sulfoxide aids fluorouracil solubilisation and penetration. Systemic fluorouracil exposure after authorised cutaneous use is very low.

Formulation and product differences

• A clear cutaneous solution that dries to a removable white film.
• Supplied with a cap-mounted brush applicator.
• Contains ethanol and is flammable; dimethyl sulfoxide and ethanol may contribute to local irritation or burning.
• Unlike fluorouracil creams, this formulation includes salicylic acid to reduce hyperkeratosis and improve penetration.