Emerging advances in P-glycoprotein inhibitory nanomaterials for drug delivery.

INTRODUCTION: P-glycoprotein 1 (P-gp) pumps out many foreign/toxic substances out of the cells, including intracellular drugs, causing multidrug resistance (MDR) and chemotherapy failure. It remains quite a challenge to inhibit P-gp to combat MDR and improve cellular bioavailability since it requires efficient inhibitors along with adequate formulation strategy. Lately, nanocarriers are gaining much attention and form an attractive platform for delivering drugs into cells. Therefore, nanomaterials act as direct inhibitors of P-gp will be an attractive alternative to overcome MDR. AREAS COVERED: This paper reviews the most recent advances on those nanomaterials that are currently in the developmental stage and has proven useful to treat P-gp involved MDR. Also, we emphasize those emerging multifunctional nanomaterials that can construct 'smart' carriers for both tumor targeting and P-gp inhibition. Furthermore, the mechanisms behind P-gp inhibition and the nanoformulation strategies for drug delivery are also discussed. EXPERT OPINION: In light of these updated reports, this review here seeks to suggest an alternative for the chemoresistant cases, and also bring about new thoughts on tackling P-gp concerned drug delivery issues. New advances in nanomaterials with P-gp inhibition are expected to broaden nanopharmaceutics and traditional chemotherapy applications in the coming years.