Novel drug carriers capable of targeted and/or pH dependent release of biologically active agents into selected pH environments including the gastrointestinal (GI), ophthalmic, urinary, or reproductive tracts. Unexpectedly, carriers including free fatty acids (FFA) are able to deliver biologically active agents to various pH environments. Such targeted delivery is tailorable and useful for active agents that are: (a) injurious to the upper GI tract (esophagus, stomach, and duodenum), (b) acid labile, (c) impermeable/insoluble compounds in GI fluids, (d) susceptible to first pass metabolism, and/or (e) cause stomach irritation, upset, or dyspepsia.
