The present application provides a colloid drug aggregate composition and methods of use and manufacture thereof. While the formation of colloidal aggregates leads to artifacts in early drug discovery, their composition makes them attractive as nanoparticle formulations for targeted drug delivery. The present application provides an acid-responsive composition comprising: a colloidal aggregate of one or more drugs and a stabilizing agent, wherein the colloidal aggregate disrupts, dissolves or disassembles when the acid-responsive composition is in an acid environment having a pH of less than 7.4. The colloidal aggregate of the composition will disassemble upon contact with acid or upon introduction to an acidic environment, such as is found in the endosomes of cells. This approach makes this composition an attractive vehicle for drug delivery to a target site in a subject or to cells.