Injectable controlled-release formulations of progestogen drugs

An injectable sustained-release formulation, comprising:

• (a) microspheres comprising a progestogen compound and a biodegradable composition comprising one or more poly(lactic-co-glycolic acid) copolymers (PLGA), wherein the progestogen compound can be released in a sustained and controlled manner with a linear or substantially linear cumulative release profile up to at least about 70% of accumulated release within a controlled time period and substantially without an initial burst or a lag phase;
• and
• (b) a diluent solution in which the microspheres are suspended
• wherein the PLGA polymer has a molar ratio of lactide to glycolide between about 90:10 and about 40:60 and a molecular weight in the range between 4 kD and 120 kD;
• wherein the progestogen compound is present in an amount of between about 10% and about 50% by weight of the microspheres;
• and
• the microspheres encapsulating the progestogen compound have a mean diameter of between about 20 μm and about 150 μm.