Pharmaceutical composition containing leuprolide and having both immediate and sustained release properties

A method for preparing a pharmaceutical composition, the method comprising the steps of:

• (a) preparing an immediate release part comprising leuprolide as a first active ingredient;
• (b) preparing a sustained release part comprising leuprolide contained in a microsphere as a second active ingredient, wherein the microsphere is prepared by the steps of:
• (i) mixing an inner aqueous phase (W1) containing leuprolide, a thickener and an aqueous solvent with an oil phase (O) containing a polymer and a fat-soluble solvent to obtain a W1/O emulsion;
• (ii) dispersing the W1/O emulsion of step (i) in a polyvinyl alcohol aqueous solution (W2) to obtain a W1/O/W2 emulsion;
• and
• (iii) drying and recovering the W1/O/W2 emulsion prepared in step (ii);
• and
• (c) mixing the immediate release part and the sustained release part in a pharmaceutically acceptable carrier to form a pharmaceutical composition, wherein the immediate release part comprises 0.1% to 20% of a total amount of leuprolide in the pharmaceutical composition and wherein the microsphere of the sustained release part comprises 80% to 99.9% of the total amount of leuprolide in the pharmaceutical composition;
• and wherein the ratio of leuprolide in the immediate release part to leuprolide in the microsphere of the sustained release part is determined to achieve both immediate and sustained release properties.