Products
Imiquimod is commercially available as a cream in single-use sachets (Aldara 5%). It has been approved in many countries since 1999. Since 2014, a preparation containing 3.75% imiquimod has also been registered in many countries (Zyclara).
Structure and properties
Imiquimod (C14H16N4, Mr = 240.3 g/mol) is an imidazoquinoline amine structurally similar to nucleoside analogs such as aciclovir. It exists as a white crystalline powder that is somewhat soluble in water.
Effects
Imiquimod (ATC D06BB10) has immunomodulatory, antitumor, antiviral, proinflammatory, and proapoptotic properties. It stimulates the immune system by promoting the production of cytokines such as interferons, interleukins, and TNF-α, and activating immune cells such as monocytes and T cells. The effects are mainly due to binding to Toll-like receptor (TLR) 7 and 8 present on immune cells, which activates the transcription factor NF-κB.
Indications
Imiquimod is approved for the local treatment of condylomata acuminata (genital warts), basal cell carcinoma (basal cell carcinoma), and actinic keratosis. Because of its interesting pharmacologic properties, numerous potential off-label indications have been described in the scientific literature, but imiquimod has not been approved by regulatory authorities for these indications.
Dosage
The directions in the package insert should be followed carefully. Wash hands well before and after application. Sachets are intended for single use only. Depending on the indication, the cream is left to act for several hours and then washed off with mild soap and water. The treated skin should be protected from sunlight.
Contraindications
- Hypersensitivity
To minimize absorption into the body, Imiquimod should not be applied to open ulcers, wounds, on injured skin, mucous membrane and not under occlusion. Full precautions can be found in the drug label.
Interactions
Interactions with other drugs have not been reported. Because imiquimod stimulates the immune system, interactions with immunosuppressants are conceivable.
Adverse effects
The most common adverse effects include local skin reactions at the site of administration, such as itching, burning, irritation, rash, inflammation, redness, and necrosis. Occasionally to frequently, systemic reactions such as infectious disease, headache, muscle pain, lymph node swelling, fatigue, and sleep disturbances also occur despite the low absorption into the bloodstream. Similar side effects are also observed with treatment with interferons.
