Geref® (sermorelin acetate)

Description:

Sermorelin is a synthetic analog of endogenous growth hormonereleasing hormone (GHRH or GRF). Sermorelin is a portion of this polypeptide hormone, specifically consisting of the first 29 of its 44 amino acid structure. As its name states very clearly, the biological activity of GHRH is to stimulate the synthesis of growth hormone, which occurs in the pituitary gland. Studies have shown, however, that the GHRH peptide can be partly truncated without sacrificing its GH stimulating ability.1 Sermorelin (GRF129NH2) was developed based on this research, and shares the full biological activity of GHRH with regard to increasing the endogenous production of growth hormone. Based on its structure and action, sermorelin is classified as a growth hormone releasing factor (GHRF) or GH secretagogue.

Sermorelin, as an acetate salt, is used in clinical medicine for two primary applications. The first is to diagnose pituitary deficiency. The procedure involves measuring the serum growth hormone response over a 1-2 hour window following a single IV infusion of sermorelin acetate.2 An intact hypothalamo-pituitary-growthhormone axis should yield a predictable increase in the GH level. The second common medical application is the treatment of growth hormone deficiency in children. As with recombinant growth hormone medications (rHGH, somatropin), sermorelin acetate can provide the benefits of sustained elevations in GH, including enhanced IGF-1 (Insulin-like Growth Factor) output and increased linear height.3 Sermorelin is a very specific acting drug, and has no effect on prolactin, LH, FSH, insulin, cortisol, glucose, glucagon, or thyroid hormone levels.4 This also lends to its therapeutic potential.

Athletes are interested in sermorelin acetate for the same reasons they use recombinant human growth hormone. Among other things, growth hormone has anabolic and anti-catabolic properties. An elevated GH level may support new muscle tissue growth, and also enhance strength, energy levels, and connective tissues. GH is also a potent modulator of fat loss. The physique- and performance-enhancing properties of growth hormone are widely accepted by the bodybuilding and competitive athletic communities, such that rHGH medications are very popular. Although sermorelin acetate has a much shorter history of use, it is slowly gaining acceptance among the community as a viable alternative to low dose growth hormone injections. It is also presently popular in antiaging medicine, where again it serves as an alternative to growth hormone in the treatment of age-related GH deficiency (‘somatopause’).

When comparing this drug to recombinant human growth hormone, sermorelin acetate does appear to be less effective under normal therapeutic conditions. During clinical studies, fewer patients on average seem to respond favorably to therapy in contrast to somatropin, and for those that do respond the improvements are often less pronounced.5 Still, it would be a mistake to exclude sermorelin acetate as a viable therapeutic option. For example, studies have found that sermorelin acetate can result in significant increases in height velocity in children with GH deficiency.6 Furthermore, these improvements seem to be well sustained after one year of therapy.7 8 Antibodies to GHRH do develop in some patients during extended therapy, and may impair the potency of the drug.9 The full biological relevance of this antibody reaction, however, remains unclear.

Sermorelin is approved in the United States for the treatment of GH deficiency in children only. Prolonged studies treating adults with somatopause are lacking. One investigation looked at the effects of 2 mg sermorelin acetate per day for 6 weeks in a group of eleven healthy elderly men (aged 64 to 76) with low circulating IGF-1 levels.10 Various measures of body composition and performance were recorded at the beginning and end of the study. As a result of treatment, there was a significant increase in nocturnal GH output, area under peak GH release, and GH peak amplitude. This was accompanied by improvements in certain measures of strength and endurance including upright row, shoulder press, and abdominal crunch. Many other measures did not reach statistical significance, however, which may reflect study limitations such as small population sizes and a short duration of intake.

Another investigation looked at the effects of sermorelin acetate in a group of HIV+ men with lipodystrophy.11 HIV lipodystrophy tends to be characterized by the abnormal distribution of fat cells and suppressed levels of growth hormone. During this investigation, 31 men aged 18 to 60 years were given 1 mg of sermorelin acetate or placebo by subcutaneous injection twice daily for 12 weeks. The primary outcome of the study was a significant increase in serum IGF1 in the sermorelin acetate group (104 ng/mL vs 6 ng/mL). This was accompanied by a favorable increase in lean body mass (+.9 kg vs -.3 kg) and decrease in visceral and subcutaneous fat. Sermorelin acetate was well tolerated, and did not result in any change in other health markers including blood pressure, cholesterol, triglycerides, insulin, or hemoglobin. None of the participants discontinued therapy due to side effects.

Sermorelin acetate could be viewed as offering a therapeutic advantage over recombinant growth hormone in some cases, in that it is less likely to result in GH excess. This is due to the fact that it relies on the body’s own hormone synthesis instead of exogenous supplementation. Thus, normal IGF-1 feedback inhibition is likely to help set a natural limit to the growth hormone stimulating effect.12 As such, hormone levels are more easily controlled with sermorelin acetate. Under normal conditions, while sermorelin will produce significant elevations in GH and IGF1, these levels should not exceed the high end of the normal range.13 Given this feature, sermorelin acetate may be a more comfortable option for some patients. Studies seem to support this notion, finding many of the same physical and metabolic benefits of GH injections, without reporting the same issues with insulin resistance, fluid retention, or muscle pain.

History:

Sermorelin acetate was developed during the early 1980s, and approved for prescription sale by the U.S. Food and Drug Administration in 1997. It was introduced to market under the brand name Geref Diagnostic by the international biotechnologies firm Serono. As the name implies, it was primarily developed as a diagnostic tool. It was specifically used for evaluating potential pituitary deficiency in GH production. Given its effect on growth hormone levels, however, the drug was also approved by the FDA for the treatment of GH deficiency in children. Geref was never widely prescribed, however, especially for uses relating to childhood GH deficiency, where it was never able to compete with somatropin. Serono ultimately discontinued the product in October 2008, citing supply issues with the active pharmaceutical ingredient.14 This was the only company manufacturing sermorelin as a commercial product in the United States, thus it is no longer available as a stock pharmacy item. The active material sermorelin acetate is still made by at least one licensed supplier, however, so the drug remains available here as a compounded medicine.

How Supplied:

Geref Diagnostic was supplied in ampules containing dry lyophilized sermorelin acetate, equivalent to 50 mcg of sermorelin. This was reconstituted with a sterile diluent (also supplied) before use. Generic compounded versions of this medication typically contain between 3.0 and 7.5 mg of dry lyophilized sermorelin acetate in a multi-dose vial. Reconstitution before use is also required.

Structural Characteristics:

Sermorelin acetate is the acetate salt of a synthetic 29- amino acid peptide (GRF 1-29 NH 2) that corresponds to the amino-terminal segment of the naturally occurring human growth hormone-releasing hormone (GHRH) with 44 amino acid residues

Warnings:

Sermorelin acetate should be used with care in epileptic patients. Obesity, uncontrolled hypothyroidism, hyperglycemia, or elevated plasma fatty acids may impair the effectiveness of sermorelin. Therapy should be discontinued in patients treated for childhood GH deficiency once the epiphyses have closed

Side Effects:

The most common side effects to sermorelin acetate therapy are injection site reactions such as pain, redness, and swelling. During clinical trials, this occurred in approximately 17% of patients. Less common side effects include difficulty swallowing, itching, dizziness, flushing, headache, nausea, vomiting, altered sense of taste, restlessness, and sleepiness.

Administration:

When used medically for the treatment of idiopathic growth hormone deficiency in prepubertal children with growth failure, sermorelin acetate is administered by subcutaneous injection at a dosage of 0.03 mg per kg of body weight once a day at bedtime. Injection sites should be rotated to avoid irritation or the buildup of scar tissue. When used to evaluate pituitary capacity in adults, a single intravenous infusion of 1.0 mcg/kg body weight is administered in the morning after an overnight fast. This is followed by 60-120 minutes of periodic blood sampling to measure pituitary hormone output

When used for physique- or performance-enhancing purposes, sermorelin acetate is given by subcutaneous injection. It is typically administered at a dosage of 0.2 to 0.5 mg per day (200-500 mcg), which is given before sleep. Studies, however, do suggest that this drug is more effective when given twice daily.15 Therefore, it is often preferred to divide the total daily dosage into two applications, one in the morning and one in the evening. Cycles of sermorelin acetate usually last between 8 and 12 weeks. Some anti-aging practitioners will prescribe the medication for much longer periods of time, however, and cycles lasting 24-48 weeks are not uncommon. The hope is that the extended maintenance of youthful growth hormone levels will yield more significant physiological changes.

Availability Trends:

Given its low financial value on global pharmaceutical markets, sermorelin acetate is subject to limited availability worldwide. The preparations most commonly found diverted for bodybuilding use include those made by private compounding pharmacies in the United States, and those sold by gray market research chemical supply companies.

1 Stimulation of growth hormone secretion with human growth hormone releasing factors (GRF1-44, GRF1-40, GRF1-29) in normal subjects. Losa M, Schopohl J, Müller OA, von Werder K. Klin Wochenschr. 1984 Dec 3;62(23):1140-3.

2 Testing with growth hormone-releasing factor (GRF(1-29)NH2) and somatomedin C measurements for the evaluation of growth hormone deficiency. Ranke MB, Gruhler M, Rosskamp R, Brügmann G, Attanasio A, Blum WF, Bierich JR. Eur J Pediatr. 1986 Dec;145(6):485-92.

3 Once daily subcutaneous growth hormone-releasing hormone therapy accelerates growth in growth hormone-deficient children during the first year of therapy. Geref International Study Group. Thorner M, Rochiccioli P, Colle M, Lanes R, Grunt J, Galazka A, Landy H, Eengrand P, Shah S.J Clin Endocrinol Metab. 1996 Mar;81(3):1189-96.

4 Growth hormone responses to growth hormone-releasing hormone (129)-NH2 and a D-Ala2 analog in normal men. Barron JL, Coy DH, Millar RP. Peptides. 1985 May-Jun;6(3):575-7.

5 A comparative study of growth hormone (GH) and GH-releasing hormone(1-29)-NH2 for stimulation of growth in children with GH deficiency. Chen RG, Shen YN, Yei J, Wang CF, Xie DH, Wang XH, Zhou JD, Chen CY, Wu YL, Gunnarsson R, et al. Acta Paediatr Suppl. 1993 Mar;388:32-5; discussion 36

6 Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency. Prakash A, Goa KL. BioDrugs. 1999 Aug;12(2):139-57

7 Continuous subcutaneous GHRH(1-29)NH2 promotes growth over 1 year in short, slowly growing children. Brain CE, Hindmarsh PC, Brook CG. Clin Endocrinol (Oxf). 1990 Feb;32(2):153-63.

8 Once daily subcutaneous growth hormone-releasing hormone therapy accelerates growth in growth hormone-deficient children during the first year of therapy. Geref International Study Group. Thorner M, Rochiccioli P, Colle M, Lanes R. et al. J Clin Endocrinol Metab. 1996 Mar;81(3):118996.

9 Growth hormone (GH) profiles in response to continuous subcutaneous infusion of GH-releasing hormone(1-29)-NH2 in children with GH deficiency. Tauber MT, Pienkowski C, Pigeon P, Cataldi M, Rochiccioli P. Acta Paediatr Suppl. 1993 Mar;388:28-30; discussion 31

10 Growth response to growth hormone-releasing hormone(1-29)-NH2 compared with growth hormone. Neyzi O, Yordam N et al. Acta Paediatr Suppl. 1993 Mar;388:16-21; discussion 22.

11 Growth Hormone-Releasing Hormone in HIV-Infected Men With Lipodystrophy A Randomized Controlled Trial. Polyxeni Koutkia; Bridget Canavan; Jeff Breu; et al.JAMA, July 14, 2004—Vol 292, No. 2.

12 Somatomedin-C mediates growth hormone negative feedback by effects on both the hypothalamus and the pituitary.Berelowitz M, Szabo M, Frohman LA, Firestone S, Chu L, Hintz RL. Science. 1981 Jun 12;212(4500):1279-81.

13 Sermorelin: a better approach to management of adult-onset growth hormone insufficiency? Walker RF. Clin Interv Aging. 2006;1(4):307-8.

14 EMD Serono, Inc. to Discontinue Geref Diagnostic 8/5/2008

15 Effects of single nightly injections of growth hormone-releasing hormone (GHRH 1-29) in healthy elderly men. Vittone J, Blackman MR, BusbyWhitehead J. et al. Metabolism. 1997 Jan;46(1):89-96.