vs : what is the difference?

01

At a glance

The main differences in one list:

• Length: all 44 amino acids of GHRH for ; the first 29 for .
• Added group: a trans-3-hexenoyl chain on the first amino acid of ; none on .
• Reference formula: C221H366N72O67S (about 5,136 g/mol) versus C149H246N44O42S (about 3,358 g/mol).
• Stability: the plasma enzyme DPP-IV cuts the start of ; resisted it in a 2007 study.
• Formats at Prism Labs: both as 10 mg lyophilized vials.

Sources: [2] PubChem · reference structure · [1] PubChem · reference structure · [4] Journal of Clinical Investigation · 1989 · [5] Basic & Clinical Pharmacology & Toxicology · 2007

02

What they share

Both copy the same stretch of the natural hormone: the 29 amino acids of are also the first 29 of , which continues for 15 more.

Both end in an amide, like the natural hormone, and both were among four GHRH analogues in a 2021 anti-doping study.

Sources: [1] PubChem · reference structure · [2] PubChem · reference structure · [5] Basic & Clinical Pharmacology & Toxicology · 2007 · [7] Drug Testing and Analysis · 2021

03

Length versus protection

The natural hormone breaks down quickly in blood. A 1989 study traced the main cut to the enzyme dipeptidyl peptidase IV (DPP-IV), which splits the chain between its second and third amino acids, and found the same cut in the 1–29 amide.

is the hormone made shorter, not sturdier: in 1984 rat pituitary-cell experiments it kept about half the full hormone’s potency, but nothing protects its first two amino acids.

keeps the full length and protects the start: in a 2007 preclinical paper, its hexenoyl group resisted DPP-IV and slowed breakdown in rat, dog and human plasma. Even so, its half-life in dogs was 21 to 45 minutes.

Sources: [4] Journal of Clinical Investigation · 1989 · [3] Biochemical and Biophysical Research Communications · 1984 · [5] Basic & Clinical Pharmacology & Toxicology · 2007

04

Where and fit

took a third route: the 1–29 sequence with four amino acids substituted. The 2005 paper that introduced it also added an albumin-binding group, which kept it in rat plasma beyond 72 hours. Versions with and without this group, called DAC, are separate compounds.

is not a GHRH analogue. A 1998 study showed that this five-residue peptide works through a different receptor; in 1999 that receptor’s natural ligand was identified as ghrelin, a peptide from the stomach.

The blend pairs one of each: without DAC and .

Sources: [6] Endocrinology · 2005 · [7] Drug Testing and Analysis · 2021 · [8] European Journal of Endocrinology · 1998 · [9] Nature · 1999

05

How their research differs

Their literatures overlap less than their sequences:

• : 1980s structure–activity work in rat pituitary cells, and where plasma enzymes cut it.
• : plasma stability and repeat-dose studies in rats, dogs and pigs (2007), then clinical studies covered in its profile.
• Both: urine detection methods (2021).

These are observations in laboratory models. They are not evidence about any use in people.

Sources: [3] Biochemical and Biophysical Research Communications · 1984 · [4] Journal of Clinical Investigation · 1989 · [5] Basic & Clinical Pharmacology & Toxicology · 2007 · [7] Drug Testing and Analysis · 2021

06

Formats and full profiles

Both ship as 10 mg lyophilized vials, reconstituted with bacteriostatic water such as . Each lot has its own certificate of analysis: how to read a peptide COA.

Full profiles: What is ? and What is ?

The secretagogue on its own: What is ?