The Growth Hormone Axis

CJC-1295 is a modified form of GHRH. It is built to attach to albumin, a common protein in the blood. That stretches its half-life, the time it takes for half of a dose to clear, from minutes to about 6 to 8 days^[14][10]. In healthy adults, one injection raised GH for 6 days or more and IGF-1 for 9 to 11 days, and GH still came out in pulses^[14][10]. It is not FDA approved. FDA has reported serious adverse events with CJC-1295, including a fast heart rate and a reaction in which blood vessels widen throughout the body^[11].

Ipamorelin copies ghrelin and acts on the same receptor to trigger a GH pulse^[15][16]. In animal studies, it raised GH without raising the stress hormones ACTH and cortisol, even at doses more than 200 times higher than needed for GH release. Older peptides of its type did raise them^[15]. In pigs, it also did not change prolactin or several other pituitary hormones^[15]. Human data are limited. A phase 2 trial tested it by IV (into a vein) after bowel surgery^[16]. FDA notes that a published study reported serious adverse events, including a death, when ipamorelin was given by IV for gut motility^[11]. It is not FDA approved.

Sermorelin is a lab-made copy of the first 29 amino acids of natural GHRH^[9][17][18]. FDA approved sermorelin in 1990 as a test of pituitary function and in 1997 to treat children with GH deficiency. The maker stopped selling it in 2008, and FDA later found it was not withdrawn for safety or effectiveness reasons^[19]. Because it works through the pituitary, the body's brake, somatostatin, still limits how much GH is released^[9]. In small studies of older men, sermorelin raised GH levels^[17][18], and one also raised IGF-1^[17].

Tesamorelin is the full 44-amino-acid human GHRH chain with a small chemical group added to one end, which makes it more stable^[20]. Unlike most peptides on this page, it is FDA approved. Its approved use is to reduce excess belly fat in adults with HIV who have lipodystrophy, a condition that changes where the body stores fat^[20]. The label says it is not a weight-loss drug^[20].

In a 26-week trial of 412 people with HIV, daily tesamorelin cut deep belly (visceral) fat by about 15%, while it rose 5% with placebo. Triglycerides fell and IGF-1 rose^[21]. In a 20-week trial of older adults, including some with mild memory problems, tesamorelin improved executive function (planning and focus skills) compared with placebo^[22].