In this disclosure, methods and systems for drug delivery utilizing high shear are disclosed. In an embodiment, a method comprises (1) subjecting a therapeutic fluid containing a drug to high shear; and (2) obtaining a processed therapeutic fluid, wherein the processed therapeutic fluid contains the drug in nano-size. In an embodiment, a method comprises (1) subjecting a drug carrier and a therapeutic fluid containing a drug to high shear; and (2) obtaining a processed therapeutic fluid, wherein the processed therapeutic fluid contains the drug carrier loaded with the drug. In an embodiment, a method comprises (1) applying high shear to a drug carrier and a therapeutic fluid containing a drug; (2) obtaining a processed therapeutic fluid, wherein the processed therapeutic fluid contains the drug-loaded carrier; and (3) modifying the drug-loaded carrier with a targeting moiety to obtain a modified drug-loaded carrier.