Porous silicon embedded in a thermoresponsive hydrogel for intranasal delivery of lipophilic drugs to treat rhinosinusitis.

Intranasal delivery is the most preferred route of drug administration for treatment of a range of nasal conditions including chronic rhinosinusitis (CRS), caused by an infection and inflammation of the nasal mucosa. However, localised delivery of lipophilic drugs for persistent nasal inflammation is a challenge especially with traditional topical nasal sprays. In this study, a composite thermoresponsive hydrogel is developed and tuned to obtain desired rheological and physiochemical properties suitable for intranasal administration of lipophilic drugs. The composite is comprised of drug-loaded porous silicon (pSi) particles embedded in a poloxamer 407 (P407) hydrogel matrix. Mometasone Furoate (MF), a lipophilic corticosteroid (log P of 4.11), is used as the drug, which is loaded onto pSi particles at a loading capacity of 28 wt%. The MF-loaded pSi particles (MF@pSi) are incorporated into the P407-based thermoresponsive hydrogel (HG) matrix to form the composite hydrogel (MF@pSi-HG) with a final drug content ranging between 0.1 wt% to 0.5 wt%. Rheomechanical studies indicate that the MF@pSi component exerts a minimal impact on gelation temperature or strength of the hydrogel host. The in-vitro release of the MF payload from MF@pSi-HG shows a pronounced increase in the amount of drug released over 8 h (4.5 to 21-fold) in comparison to controls consisting of pure MF incorporated in hydrogel (MF@HG), indicating an improvement in kinetic solubility of MF upon loading into pSi. Ex-vivo toxicity studies conducted on human nasal mucosal tissue show no adverse effect from exposure to either pure HG or the MF@pSi-HG formulation, even at the highest drug content of 0.5 wt%. Experiments on human nasal mucosal tissue show the MF@pSi-HG formulation deposits a quantity of MF into the tissues within 8 h that is >19 times greater than the MF@HG control (194 ± 7 µg of MF/g of tissue vs. <10 µg of MF/g of tissue, respectively).