Preparation of injectable suspensions having improved injectability

A composition for injection through a needle into a host, consisting of:

• microparticles comprising a peptide and a polymeric binder selected from the group consisting of poly(glycolic acid), poly-d,l-lactic acid, poly-l-lactic acid, copolymers of the foregoing, poly(aliphatic carboxylic acids), copolyoxalates, polycaprolactone, polydioxanone, poly(ortho carbonates), poly(acetals), poly(lactic acid-caprolactone), polyorthoesters, poly(glycolic acid-caprolactone), polyanhydrides, and polyphosphazines;
• and
• an injection vehicle, wherein the injection vehicle consists essentially of a viscosity enhancing agent, a wetting agent, and a tonicity adjusting agent,
• wherein the microparticles are suspended in the injection vehicle at a concentration of more than about 30 mg/ml and up to about 300 mg/ml to form a suspension, wherein a fluid phase of the suspension has a viscosity of greater than 30 cP and less than 600 cP at 20° C., and wherein the viscosity of the fluid phase of the suspension provides injectability of the composition into the host through a needle of medically acceptable size.