Polymer-based Sustained Release Systems of Human Growth Hormone

Human Growth Hormone (hGH) is a 191 amino acid polypeptide chain which is secretedin pituitary gland and by absorption in the liver leads to secretion of the insulin-likegrowth factor (IGF-1). IGF-1 increases muscles and bones growth, so the growth hormonedeficiency in the body leads to serious and unpleasant injuries. Approved indications forhGH therapy include treatment of growth hormone deficiency (in children and in adults),Turner syndrome, Prader–Willi syndrome, chronic renal insufficiency and more recently,idiopathic short stature in children, AIDS-related wasting and fat accumulation associatedwith lip dystrophy in adults. Patients’ dissatisfaction, short half-life, renal toxicity createdin daily injections and frequent injections are factors that have compelled researchers toinvestigate the sustained release systems in different forms of this protein. New polymerdrug delivery systems are one of the most effective ways to reduce the frequency ofinjections of daily drugs. In situ forming systems (ISIs), microspheres and hydrogels arethe most important and effectively used methods to deliver drugs to the body. The process,types and properties of the polymer, solvent and additives that are used for such purposesare very important and affect the speed and amount of final release of the drug.