Sermorelin: A better approach to management of adult-onset growth hormone insufficiency?

Growth hormone replacement therapy (GHRT) using recombinant human growth hormone (rhGH) has been embraced by many age management practitioners as one of the most effective methods for opposing somatic senescence currently available. However, its routine use has been controversial because few clinical studies have been performed to determine the potential risks of long-term therapy. Also, certain medical and legal issues have not been resolved causing some practitioners to restrict their use of the product. Some of these issues include the fact that: • Improper dosing can lead to side effects that may be serious in some patients, • Injection of hGH creates unnatural conditions of exposure to the hormone that may erode normal physiology, • The Code of Federal Regulations specifi cally forbids the use of rhGH in adults except for treatment of AIDS or human growth hormone defi ciency (GHD) diagnosed pursuant to regularly accepted guidelines. While there is a wealth of information showing that long-term administration of rhGH reduces intrinsic disease and extends life in adults suffering pathogenic GHD, consensus on whether extrapolation of those data to the aging condition is justifi ed has not been reached (Perls et al 2005). Most of the major concerns derive from the fact that rhGH is mitogenic and may awaken latent cancers, that improper dose selection may promote metabolic disorders such as diabetes, and perhaps that pharmacological presentation may exacerbate decline of endocrine function by distorting essential hormonal interactions. Of course, all these concerns are speculative and will not be resolved until suffi cient scientifi c evidence for or against GHRT eventually accumulate. In the interim, the value of rhGH in GHRT will continue to be debated; unfortunately based more upon personal prejudice than objective information. Despite the eventual outcome to the " Great Hormone Debate " as it has been titled in media articles (Landsmann 2006), certain negative aspects of GHRT using rhGH cannot be disputed and justify searching for a better alternative. For example, " square wave " or pharmacological presentation of the exogenous hormone cannot be avoided since it is administered as a bolus, subcutaneous injection. Since the amount of rhGH entering the general circulation is not controlled by normal feedback mechanisms, tissue exposure to elevated concentrations is persistent and eventually may lead to tachyphylaxis and reduced effi cacy. Also, because the body cannot modulate tissue exposure to rhGH, the practitioner is required to " best guess " …