Sermorelin Sexual Function Impact: What the Evidence Actually Shows

What sermorelin does

Sermorelin is a 29-amino-acid analogue of human growth hormone-releasing hormone, the shortest synthetic peptide with the full biological activity of GHRH [2]. It acts on the pituitary's GHRH receptor to trigger release of the body's own growth hormone. The effect is brief: in a study of 30 healthy men aged 19 to 43 given the peptide intravenously or intranasally, it was rapidly eliminated after an intravenous dose while growth hormone stayed raised for about 3 hours [8].

What the sermorelin studies measured

One physiology study in older men gave 10 healthy men (mean age 68) 0.5 mg and 1 mg of GHRH(1-29) under the skin twice daily for 14 days each, in random order, and compared them with 9 young men (mean age 26). At the high dose, 24-hour growth hormone and IGF-1 rose to levels not significantly different from the young men [4]. It was a short physiology study, not a clinical-benefit trial.

The 1-year pediatric trial enrolled 110 previously untreated children with growth hormone deficiency (86 evaluable) on 30 micrograms per kg once daily at bedtime. Mean height velocity rose from 4.1 cm a year at baseline to 8.0 cm at 6 months and 7.2 cm at 12 months; no adverse changes appeared in general biochemistry or hormone tests, fasting glucose did not change, and IGF-1 was not excessively raised [3].

The nearest human data come from recombinant growth hormone

In a 12-month study of 11 adult men with isolated growth hormone deficiency after pituitary surgery, recombinant growth hormone raised IGF-1 and increased CG-stimulated testosterone from 7.9 ng/mL at baseline to 9.6 ng/mL at 6 months and 9.9 ng/mL at 12 months. Seminal plasma volume rose from 1.7 mL to 2.9 mL, while sperm count, motility and abnormal forms did not change significantly [1].

That study measured hormones and semen, not libido or erections, and the drug was recombinant growth hormone rather than sermorelin. The sermorelin studies above measured growth and hormone endpoints, not sexual ones.

What sermorelin was approved for, and what is sold today

Geref, the brand of sermorelin acetate, held two FDA approvals: a 0.05 mg/ampule product for testing the pituitary's ability to secrete growth hormone, and 0.5 mg and 1 mg vials for treating idiopathic growth hormone deficiency in children with growth failure [5]. Those approved uses did not include adults, anti-aging, weight loss or athletic performance [5]. The manufacturer discontinued it in 2008, FDA withdrew both approvals in 2009, and in 2013 FDA determined it had not been withdrawn for reasons of safety or effectiveness [5].

No sermorelin product is FDA-approved today, so there is no current approved dose. The pediatric program used 30 micrograms per kg once daily under the skin at bedtime, and the older-men study used 0.5 mg or 1 mg twice daily for 14 days; neither is a recommended dose [3][4]. Sermorelin sold in the US today is compounded, and compounded drugs are not FDA-approved: FDA does not review their safety, effectiveness or quality before they are marketed [6].