Current Insights in Nanoformulations for Quercetin Delivery

Quercetin is a naturally occurring polyphenolic flavonoid that has recently attracted considerable interest from the scientific community due to its intriguing biological properties. Quercetin has been extensively investigated for its pharmacological effects, including antioxidant, anti-inflammatory, anticancer, antidiabetic, antihypertensive, antiasthmatic, anti-obesity, and antiproliferative activities both in vitro and in vivo. However, its physicochemical properties, such as low solubility and bioavailability, severely limit its clinical applications. This review explores the potential of various nanoformulations in developing quercetin dosage forms with enhanced bioavailability. Advances in nanotechnology and intelligent delivery systems enable the successful encapsulation of bioactive quercetin, which is often difficult with conventional formulations. Advanced drug delivery nanosystems can target, encapsulate, and release quercetin more effectively. Fabricating quercetin at the nanoscale can address issues such as low bioavailability, in vivo degradation, toxicity, uneven drug distribution, poor intestinal absorption, and non-specific site action. The unique properties of polymer-based nanocarriers can improve the ADME(T) profile (absorption, distribution, metabolism, excretion, and toxicology). Lipid-based nanocarriers, particularly liposomes, solid-lipid nanoparticles, and nanostructured lipid carriers, are widely used to enhance quercetin’s oral absorption and targeting, increase its therapeutic efficacy, and provide sustained release. Quercetin formulations have also employed micelles and hydrogels made from natural or synthetic polymers. Additionally, cyclodextrins, nanoemulsions, and niosomes are proposed as alternative formulations for administration via various routes. This article provides a comprehensive review of the role of advanced drug delivery nanosystems in the formulation and administration of quercetin.