A nonaqueous, single-phase vehicle that is capable of suspending an 
active agent. The nonaqueous, single-phase vehicle includes at least one 
solvent and at least one 
polymer and is formulated to exhibit phase separation upon contact with an aqueous environment. The at least one 
solvent may be selected from the group consisting of 
benzyl benzoate, decanol, ethyl hexyl lactate, and mixtures thereof and the at least one 
polymer may be selected from the group consisting of a 
polyester, pyrrolidone, ester of an unsaturated 
alcohol, 
ether of an unsaturated 
alcohol, polyoxyethylenepolyoxypropylene block 
copolymer, and mixtures thereof. In one embodiment, the at least one 
solvent is 
benzyl benzoate and the at least one 
polymer is 
polyvinylpyrrolidone. A stable, nonaqueous suspension formulation that includes the nonaqueous, single-phase vehicle and an 
active agent, and a method of forming the same, are also disclosed.