Physically stable, transparent, biologically compatible, easy to prepare lipid solutions of somatostatin analogue inhibitors of growth hormone release are disclosed; they are suitable for subcutaneous or intramuscular administration and provide a sustained release of the active principle. The processes for the preparation of said formulations is also disclosed. These solutions contain one somatostatin analogue inhibitor of growth hormone release, preferably octreotide; a C 1 -C 8 alcohol, preferably ethanol; a phospholipid, preferably lecithin; and a C 1 -C 4 alkyl fatty acid ester, preferably isopropyl myristate.