What Are Peptides? The Irish Researcher’s Guide (2026)

Peptides are short chains of amino acids, typically between 2 and 50 residues long, that carry out a huge range of signalling roles in biology. Insulin is a peptide. Oxytocin is a peptide. So are BPC-157, TB-500, GHK-Cu, Semaglutide, Tirzepatide, and the growing catalogue of compounds studied for tissue repair, metabolic regulation, cognitive function, and skin biology.

This is Peptides Lab Ireland’s plain-English guide to what peptides are, how they work, why they’ve become one of the most-searched compound categories among Irish researchers in the last three years, and what the HPRA regulatory framework means for anyone sourcing them in Ireland.

The chemistry, quickly

Amino acids are the building blocks of proteins. When two amino acids link through a peptide bond, you get a dipeptide. Three amino acids → tripeptide. Fifty amino acids and under → peptide. More than that and biochemists start calling it a protein, though the boundary is fuzzy.

The specific sequence of amino acids determines how the peptide folds, what receptors it binds, and what biological effect it triggers. BPC-157’s 15-residue sequence targets tissue-repair pathways. Semaglutide’s modified GLP-1 sequence extends its half-life so it survives longer in the bloodstream. Tirzepatide is a dual agonist — it activates two different receptor types (GLP-1 and GIP) because its sequence was engineered to fit both.

The main categories of research peptides

Tissue repair and healing

Recovery & healing peptides like BPC-157, TB-500 (thymosin β-4), and GHK-Cu are studied for their effects on soft-tissue regeneration, tendon and ligament repair, and angiogenesis. See our BPC-157 + TB-500 blend for combined research.

GLP-1 and metabolic peptides

Semaglutide, Tirzepatide, Retatrutide and related compounds mimic incretin hormones. Read our peptide research blog for structured comparisons.

Growth hormone secretagogues

Ipamorelin, GHRP-2, GHRP-6, MK-677 (Ibutamoren), and CJC-1295 stimulate endogenous growth hormone release through different mechanisms. See our hormonal support catalogue.

Cosmetic and skin peptides

GHK-Cu (copper peptide), Argireline, and Matrixyl are studied for effects on collagen synthesis, wound healing, and skin barrier function. See skin & anti-ageing.

Neuropeptides

Semax, Selank, Cerebrolysin, and Dihexa are researched for cognitive and neuroprotective effects. See our neurology catalogue.

The Irish regulatory position

None of the research peptides discussed above hold a medicinal product authorisation from the Health Products Regulatory Authority (HPRA). Under the Medicinal Products Regulations 2007, that means they are not legal to sell or supply for human or veterinary use in Ireland.

What is legal: supplying and possessing these compounds as research chemicals for in-vitro laboratory work. This sits outside the HPRA medicines regime and is where Peptides Lab Ireland operates. Every compound we supply is:

• Labelled for research use only, not for human or veterinary use
• Manufactured to research-grade purity (typically ≥99% HPLC)
• Supplied with per-batch Certificate of Analysis on request
• Backed by our ISO 9001 certified quality management system with UKAS-verified third-party testing

Why researchers buy peptides in Ireland domestically

Ordering peptides from US suppliers means customs risk (Revenue can and does seize suspicious pharmaceutical-adjacent shipments) and 7–14 day delivery. Ordering from EU suppliers avoids the customs step but adds cross-border VAT complexity. Ordering from a domestic Irish supplier means:

• Same-day dispatch, 24–48h delivery to any Irish county
• Irish VAT handled correctly (no customs charge surprises)
• Cold-chain integrity (peptides are heat-sensitive; shorter transit = better)
• Local recourse if anything goes wrong

How peptides are stored and reconstituted for research

All lyophilised peptides need to be stored at ≤-20°C long-term and reconstituted with bacteriostatic water before use in assays. See our bacteriostatic water product and the linked reconstitution guide.

Further reading

• All research peptide guides on the Peptides Lab Ireland blog
• Delivery to Ireland — timelines and cold-chain policy
• Frequently asked questions
• About Peptides Lab Ireland — who we are

Author: Emma Louise, Chief Compliance Officer, Peptides Lab Ireland. This page is research-context information, not medical or clinical advice.