IMIQUAD CREAM

Indications

• External genital warts
• Perianal warts
• Actinic keratosis
• Superficial basal cell carcinoma

Dosage

Adults: For external genital and perianal warts, apply 3 times a week until lesions resolve (maximum 16 weeks). For superficial basal cell carcinoma

Mechanism of action

Imiquimod acts as a toll-like receptor (TLR) 7 agonist, stimulating innate and acquired immune responses. This results in the infiltration of inflammatory cells at the application site and subsequent apoptosis of diseased tissue. It induces the production of various cytokines, including interferon-alpha and interleukins (IL-6, IL-8), enhancing immune response against skin lesions. In the context of basal cell carcinoma, it enhances the infiltration of lymphocytes, dendritic cells, and macrophages into tumor lesions, promoting an antitumor effect.

Pharmacodynamics

As an immune response modifier, Imiquimod is effective against skin lesions by promoting an inflammatory response without directly targeting the viruses causing warts. It is utilized for its capabilities in treating warts, actinic keratosis, and certain skin cancers. The drug helps to relieve wart production but does not provide a permanent cure, as new warts may develop during treatment. Its topical application is particularly advantageous in sensitive areas like the face and lower extremities.

Pharmacokinetics

Imiquimod is administered topically, leading to localized effects with minimal systemic absorption. The pharmacokinetics of Imiquimod indicate that it reaches peak concentrations at the site of application, where it exerts its therapeutic effects. The drug's metabolism and elimination pathways have not been thoroughly detailed, but it is known to be metabolized in the liver. The duration of action is contingent upon the frequency of application as outlined in dosing recommendations.

Contra-indications

• Autoimmune diseases
• Impaired peripheral circulation
• Application to broken skin
• Pregnant women (unless benefit outweighs risk)
• Patients with severe cutaneous adverse reactions

Adverse effects

• Skin reactions
• Local erythema
• Erosion
• Ulceration
• Itching
• Pain
• Flu-like symptoms
• Headache
• Nausea
• Decreased appetite
• Arthralgia

Interactions

• None specifically documented; however, caution is advised when used with other topical agents that may irritate the skin.

Precautions

• Avoid contact with eyes and lips
• Avoid application to large areas of the skin
• Use caution in patients with diabetes
• Not suitable for application in the anogenital region in uncircumcised males

Pregnancy

Imiquimod should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Consult with a healthcare provider for guidance.

Breast-feeding

It is unknown whether imiquimod is excreted in human milk. Use with caution and consult a healthcare provider.

Storage

Store at room temperature, away from moisture and heat. Keep the tube tightly closed when not in use.

Formulations

• Imiquimod cream (Aldara®)
• Imiquimod cream (Zyclara®)

Mechanism of action

Imiquimod's mechanism of action is via stimulation of innate and acquired immune responses, which ultimately leads to inflammatory cell infiltration within the field of drug application followed by apoptosis of diseased tissue. Imiquimod does not have direct antiviral activity. Studies of mice show that imiquimod may induce cytokines, including interferon-alpha (IFNA) as well as several IFNA genes (IFNA1, IFNA2, IFNA5, IFNA6, and IFNA8) as well as the IFNB gene. Imiquimod also induced the expression of interleukin (IL)-6, IL-8, and tumor necrosis factor alpha genes. In the treatment of basal cell carcinoma, Imiquimod appears to act as a toll-like receptor-7 agonist, and is thought to exert its anti-tumor effect via modification of the immune response and stimulation of apoptosis in BCC cells. In treating basal cell carcinoma it may increase the infiltration of lymphocytes, dendritic cells, and macrophages into the tumor lesion. Imiquimod and resiquimod represent Toll-like receptor (TLR) 7 and 8 agonists, which emerged as attractive candidates for tumor therapy. To elucidate immune cells, which mainly contribute to TLR7/8-mediated antitumoral activity, /the researchers/ investigated the impact of imiquimod and resiquimod on native human 6-sulfo LacNAc (slan) dendritic cells (DCs). /The researchers/ found that both TLR7/8 agonists significantly improve the release of various proinflammatory cytokines by slanDCs and promote their tumor-directed cytotoxic activity. Furthermore, resiquimod efficiently augmented the ability of slanDCs to stimulate T cells and natural killer cells. These results indicate that imiquimod and resiquimod trigger various immunostimulatory properties of slanDCs, which may contribute to their antitumor effects. Aldara is a cream used for topical treatment of non-melanoma skin cancer, and is thought to act through stimulation of anti-tumour immunity. The active ingredient, imiquimod, has been shown to stimulate toll-like receptor 7. Aldara also induces psoriasis-like lesions when applied to naive murine skin, and as such is used as a mouse model for psoriasis. Here we find that in naive murine skin, Aldara induces inflammation largely independently of toll-like receptor 7. Surprisingly, inflammasome activation, keratinocyte death and interleukin 1 release also occur in response to the vehicle cream in the absence of imiquimod. We show that isostearic acid, a major component of the vehicle, promotes inflammasome activation in cultured keratinocytes, and so may contribute to the observed effects of Aldara on murine skin. Aldara therefore stimulates at least two immune pathways independently, and both imiquimod and vehicle are required for a full inflammatory response. Although it remains to be tested, it is possible that imiquimod-independent effects also contribute to the therapeutic efficacy of Aldara. Imiquimod is recognized as an agonist for Toll-like receptor 7 (TLR7) in immunocompetent cells. TLR7, as well as TLR3 and TLR8, triggers the immune responses, such as the production of type I interferons (IFNs) and proinflammatory cytokines via recognition of viral nucleic acids in the infected cells. In this study, /the reseachers/ proposed that imiquimod has an IFN-independent antiviral effect in nonimmune cells. Imiquimod, but not resiquimod, suppressed replication of human herpes simplex virus 1 (HSV-1) in FL cells. We analyzed alternation of gene expression by treatment with imiquimod using microarray analysis. Neither type I IFNs, nor TLRs, nor IFN-inducible antiviral genes were induced in imiquimod-treated FL cells. Cystatin A, a host cysteine protease inhibitor, was strongly upregulated by imiquimod and took a major part in the anti-HSV-1 activity deduced by the suppression experiment using its small interfering RNA. Upregulation of cystatin A was suggested to be mediated by antagonizing adenosine receptor A(1) and activating the protein kinase A pathway. Imiquimod, but not resiquimod, was shown to int

Pharmacodynamics

Imiquimod is an immune response modifier that acts as a toll-like receptor 7 agonist. Imiquimod is commonly used topically to treat warts on the skin of the genital and anal areas. Imiquimod does not cure warts, and new warts may appear during treatment. Imiquimod does not fight the viruses that cause warts directly, however, it does help to relieve and control wart production. It is not used on warts inside the vagina, penis, or rectum. Imiquimod is also used to treat a skin condition of the face and scalp called actinic keratoses. Imiquimod can also be used to treat certain types of skin cancer called superficial basal cell carcinoma. Imiquimod is particularly useful on areas where surgery or other treatments may be difficult, complicated or otherwise undesirable, especially the face and lower legs.