Imiquimod hydrochloride (R 837 hydrochloride) is a small-molecule immune response modifier, a potent and selective agonist of toll like receptor 7 (TLR7), an antagonist of adenosine A₂A receptor with a Ki of 2.16 μM, and an inhibitor of adenylyl cyclase activity, inducing antiviral proteins like cystatin A. It exhibits strong antitumoral and antiviral efficacy, making it effective for conditions such as COVID 19, HPV warts, molluscum contagiosum, actinic keratosis, basal and squamous cell carcinoma, Bowen’s disease, and vulvar intraepithelial neoplasia.