What is Aldara (Imiquimod)?
Aldara is the brand name for imiquimod 5% cream, a topical immune response modifier that works by stimulating the production of interferon-alpha and other cytokines to trigger the immune system to recognize and eradicate viral infections and tumors. 1
Mechanism of Action
- Imiquimod is a heterocyclic imidazoquinoline amide that acts as an agonist for toll-like receptor 7 (TLR-7), inducing cytokines such as interferon-alpha, interleukin-12, and tumor necrosis factor-alpha 2, 3
- The drug exhibits indirect antiviral and antitumor effects by enhancing cell-mediated cytolytic activity, but does not have direct antiviral effects in vitro 3, 4
- It stimulates both the innate immune response and the cellular arm of acquired immunity 5
FDA-Approved Indications
Aldara is FDA-approved for three primary conditions: 1, 6
External Genital and Perianal Warts
- Applied 3 times per week (e.g., Monday, Wednesday, Friday) for up to 16 weeks until total clearance 7, 1
- Applied at bedtime and left on for 6-10 hours, then washed off with mild soap and water 7, 8
- Complete clearance rates of 37-50% in immunocompetent patients, with partial clearance (≥50% reduction) in 76% 4
- Recurrence rates of 13-19% after complete clearance 4
Superficial Basal Cell Carcinoma
- Applied 5 times per week for 6 weeks (maximum 36 packets for treatment period) 1
- Composite clearance rate of 75% with 2-year sustained clearance of 79% 9
- Topical imiquimod appears effective for primary small superficial BCC (Strength of recommendation A, quality of evidence I) 7
- May have a role in primary nodular BCC, though evidence is weaker (Strength of recommendation C, quality of evidence I) 7
Actinic Keratoses
- Applied 3 times per week for 4 weeks (can be repeated for another 4 weeks if needed) 7
- Applied at night and washed off after 8 hours 7
- Complete clearance rate of approximately 50% in meta-analysis of five RCTs 7
- 76% of patients maintained clearance at 12 months in one three-armed RCT 7
Off-Label Uses (Evidence-Based)
Bowen's Disease
- 73% histologically proven resolution when applied once daily for 16 weeks (Strength of recommendation B, Quality of evidence I) 7
- One open study showed 93% clinical and pathological resolution in patients with lower leg lesions 7
- May be useful for large facial lesions and erythroplasia of Queyrat 7
Other Conditions with Preliminary Evidence
- Molluscum contagiosum 3, 5
- Lentigo maligna 2
- Extramammary Paget's disease 2
- Vulvar intraepithelial neoplasia 3
- Keloid prevention after surgery 5
Formulation and Composition
- Each gram contains 50 mg of imiquimod (5% concentration) in an off-white oil-in-water vanishing cream base 1
- Molecular formula: C14H16N4, molecular weight: 240.3 1
- Packaged in single-use packets; partially-used packets should be discarded and not reused 1
Common Side Effects and Management
- Local skin reactions are common and expected, including erythema, itching, and burning (occurring in ≤67% of patients) 1, 4
- These reactions are usually mild to moderate 7
- A rest period of several days may be taken if required by patient discomfort or severity of local skin reaction 1
- Systemic adverse events occur at rates similar to vehicle cream 4
- Persistent hypopigmentation or hyperpigmentation can occur with treatment 7
Critical Safety Considerations
The safety of imiquimod during pregnancy has not been established 7, 8
- Non-occlusive dressings such as cotton gauze or cotton underwear may be used to manage skin reactions 1
- Treatment should not be occluded 1
- Patients should wash hands before and after application 1
Key Clinical Advantages
- Self-administered therapy offering a noninvasive, tissue-sparing alternative to ablative treatments 6
- Superior cosmetic outcomes compared to cryotherapy for some indications 7
- Lower recurrence rates compared to some traditional therapies (e.g., 76% maintained clearance at 12 months vs. 1% for cryosurgery in one AK study) 7
- Does not require office visits for administration, unlike provider-administered therapies 7