Imiquimod powder for inhalation to stimulate innate immunity

Literature data suggest that toll-like receptor agonists administered by inhalation stimulate innate immunity, providing broad-spectrum, short-term protection against infectious diseases. They are promising also to improve the course of diseases, as adjuvants in allergen immunotherapy, and in association with antigens in inhalation vaccines. Imiquimod, an agonist of toll-like receptors 7 and 8, is currently FDA-approved for topical administration. This work aimed to design an IMQ powder for inhalation to stimulate the immune response in the airways for broad-spectrum, short-term protection against infections, to fight infectious diseases, and/or as adjuvant in allergen immunotherapy, as well as in vaccines for pulmonary administration. Highly respirable and crystalline imiquimod microparticles were produced via spray drying and micronization. The microparticles are suitable for inhalation both alone and in adhesive mixtures with coarse lactose. In vitro studies proved the powders' non-cytotoxicity and ability to induce a controlled production of inflammatory cytokines.