HGH Fragment 176-191

What it is

HGH Fragment 176-191 is a synthetic 16-amino-acid peptide corresponding to the C-terminal fragment of human growth hormone (residues 176–191). The peptide is essentially identical to AOD-9604 in core sequence, with minor differences in N-terminal modification.

The molecule was developed on the same hypothesis as AOD-9604: that the lipolytic effects of growth hormone could be isolated in the C-terminal fragment without the mitogenic and metabolic effects of the full-length hormone. HGH Fragment 176-191 is available through licensed compounding pharmacies but has accumulated less formal clinical research than AOD-9604.

Mechanism of action

The proposed mechanism is identical to AOD-9604: stimulation of lipolysis through β3-adrenergic receptor pathways without binding the GH receptor and without elevating IGF-1. The peptide does not produce the typical GH-related effects on glucose metabolism, IGF-1, or insulin sensitivity in published research.

Clinical evidence

The clinical evidence base for HGH Fragment 176-191 specifically is limited. Most clinical use is informed by the research base on AOD-9604, with the assumption (probably reasonable) that the closely related peptides have similar effects. Independent clinical trial validation of HGH Fragment 176-191 is sparse.

Why we don’t prescribe it at The Tide

We prescribe AOD-9604 when the clinical scenario calls for this class of peptide. AOD-9604 has more formal clinical research (including the 2007 phase IIb trial) and represents the better-characterized version of this molecule class.

For patients seeking the proposed lipolytic effects of GH fragment peptides, AOD-9604 is the preferred choice. We do not see clinical scenarios where HGH Fragment 176-191 would be preferred over AOD-9604, given the latter’s more substantial research base.

Side effects and contraindications

The side effect profile is similar to AOD-9604: generally well-tolerated, with mild injection site reactions being the most common report. No significant systemic effects on glucose metabolism, GH, or IGF-1 in available data. Long-term safety data is limited. Avoided in pregnancy and breastfeeding.