Human growth hormone (hGH) is a polypeptide hormone consisting of 121 amino acids. It is produced by the pituitary gland located in the lower part of the brain and promotes growth and development of human body. hGH plays a critical role in the human metabolic system, stimulating synthesis of proteins and the absorption of amino acids at the cellular level. hGH stimulates production of IGF-1 insulin-like growth factor 1 (IGF-1) in the liver, which has growth-stimulatory effects on variety of tissues including muscles and bone tissue. The level of hGH increases through childhood and adolescence. It is present at the most optimum level during the age of 15 years to 30 years but declines with age.
The key function of hGH is growth and is responsible for increasing height. Thus in children and adolescents, deficiency of hGH or Growth Hormone Deficiency (GHD) can thus lead to dwarfism, delay in sexual maturity or growth delay. In adult, shortage in hGH can adversely affect the overall quality of life including reduction in social, mental and physical energy; reduction in muscle mass, increase in body fat, increase in cholesterol level, higher cardiovascular disease rates and lower bone density.
GHD has been attributed to problems of pituitary gland where the gland does not produce enough growth hormone. Patients with GHD are treated with daily injection of growth hormone. While currently available treatments with rhGH have been shown to increase height and improve other symptoms of GHD, current regimen of daily injection poses significant burden and pain on the patients and increases risk of non-compliance. Studies have indicated that missing more than one dose a week can significantly reduce long-term linear growth. Treatment options that can provide convenience, less side-effects and improved compliance will thus increase over all therapeutic outcomes in patients.