New GH secretagogues and potential usefulness in thalassemia

Thalassemic patients today undergo intensive transfusion and chelation regi mes that offer them prolonged survival and improved quality of life. Nevert heless, they face the consequences of chronic illness and therapies which a ffect multiple bodily functions. Endocrine derangements involve, among othe rs, the GB-IGF-I axis with consequent impairment of growth. In such cases, GH release, as assessed with stimulation tests, may be normal whereas ultra dian GH secretion seems to be subnormal. New GH secretagogues (GHRs) are ag ents that stimulate pituitary GH release by acting upon different receptors than the endogenous hypothalamic secretagogue, growth hormone-releasing ho rmone (GHRH). Examples are the growth hormone releasing peptides (GHRPs) GH RP-6, GHRP-1, GHRP-2, Hexarelin and the non-peptidyl MK-0677, These can be administered by multiple routes, even per os or intranasally, thus obviatin g the need for injections. Their Ga releasing capacity is more pronounced a nd prolonged than that of GHRH and their use is devoid of serious side effe cts. The most recently developed GHRs seem to be capable of producing susta ined GH release in many cases and can thus be viewed as therapeutic candida tes in cases of reduced GH secretion with intact pituitary, as seems to be the case in a group of thalassemic patients.