Compositions may include a pharmaceutical active agent, a high viscosity liquid carrier material (HVLCM), a lactic acid-based polymer, and an organic solvent. Related compositions and methods are also disclosed. For instance, a carrier formulation for controlled release of injectable drugs is disclosed. The formulation may include a non-water soluble high viscosity liquid which may be sucrose acetate isobutyrate, a lactic-acid based polymer which may be a poly(lactic acid)(glycolic acid), and an organic solvent which maintains the composition in a monophasic form at 25° C. in one atmosphere. Drug in the formulation may be released upon administration such that less than 10% (e.g. 2-8%) of drug is released in the first 5 hours; 10% to 80% of the drug is released during a period of 5 hours to 7 days after administration; and 10% to 40% of the drug is released gradually over a period of 7 days to 28 days from initial administration. The drug may be an anti-schizophrenia agent delivered by injection.