PHARMACEUTICAL COMPOSITION WITH IMPROVED STABILITY

The present invention provides an injectable composition for controlled release drug delivery and the process of making the same, where the composition comprises: a lactate-based polymer having a weight average molecular weight between 5,000 and 50,000 dalton, an acid number of less than 3 mgKOH/g and the content of residual lactide monomers in the lactate-based polymer of less than about 0.3% by weight; a pharmaceutically acceptable organic solvent; and a bioactive substance or a salt thereof that contains an amino acid serine in the molecular structure that is capable of reacting with lactide monomer to form a conjugate; and where the composition reduces the formation of the conjugate.