A synthetic peptide (LY3437943) studied for triple-receptor activation across the GLP-1, GIP, and glucagon pathways simultaneously.

Reported findings: in the Phase 2 trial (Jastreboff et al., NEJM, 2023; n=338), mean body weight change at 48 weeks was −8.7% (1 mg), −17.1% (4 mg), −22.8% (8 mg), and −24.2% (12 mg), compared with −2.1% on placebo. At the 12 mg dose, 83% of participants reached a ≥15% weight reduction. A substudy in participants with fatty liver disease reported liver fat reductions of up to 82% at 24 weeks on the 12 mg dose. Phase 3 trials (the TRIUMPH programme) are ongoing, with one reporting up to 28.7% weight loss at 68 weeks in preliminary results.

A growth-hormone-releasing hormone (GHRH) analogue, studied for its stimulating effect on the pituitary's release of growth hormone.

Reported findings: the two pivotal Phase 3 trials behind its FDA approval (in HIV-associated lipodystrophy) reported visceral fat reductions of approximately 15% at 26 weeks and 18% at 52 weeks versus placebo, with no significant change in subcutaneous fat or overall BMI. The FDA label explicitly notes it is weight-neutral and is not indicated for general weight loss — its studied effect is specific to visceral (deep abdominal) fat redistribution in that patient population, not total body weight.

A selective growth hormone secretagogue studied for stimulating GH release via the ghrelin receptor.

Reported findings: the foundational study (Raun et al., 1998, in swine) reported ipamorelin released GH at potency comparable to GHRP-6, with no significant elevation in ACTH or cortisol even at doses over 200x the effective dose for GH release — a selectivity not seen with earlier secretagogues like GHRP-2 or GHRP-6, which do raise cortisol and ACTH alongside GH. Human data is honestly thin: it's limited to a couple of small pharmacokinetic studies and one Phase II trial (for post-surgical bowel motility) that was discontinued before completion. Most of what's known comes from animal models, not large human trials.

A naturally occurring copper-binding tripeptide first identified in human plasma in the 1970s — one of the longer-studied compounds in this category.

Reported findings: research is concentrated in dermatological, wound-healing, and tissue-remodelling contexts, with proposed mechanisms including stimulating collagen and elastin production and modulating antioxidant pathways. Most published research uses topical application in dermatological studies rather than injectable research contexts.

Also referred to in research literature as Mod GRF 1-29 — a modified GHRH fragment studied for stimulating a pulsatile pattern of GH release intended to mimic the body's natural release rhythm.

Reported findings: studies report a comparatively short research half-life relative to the DAC-modified version, producing a shorter, sharper release pattern rather than a sustained elevation.

The same underlying GHRH analogue, modified with a Drug Affinity Complex (DAC) — a chemical addition that binds to albumin in the bloodstream, extending how long it remains active.

Reported findings: research has explored this version for producing a more sustained elevation in GH and IGF-1 levels over time, in contrast to the pulsatile pattern studied with the non-DAC version above.

Delta Sleep-Inducing Peptide was first isolated in the 1970s from research on rabbits, named for its association with delta-wave (slow-wave) sleep observed in early animal studies.

Reported findings: subsequent research has explored possible roles in stress-hormone regulation (including the ACTH/cortisol pathway) and pain perception, though the precise mechanism remains incompletely understood and reported results have been inconsistent across studies. Human trial data remains limited compared to animal-model research.

A synthetic analogue of tuftsin, a naturally occurring immunomodulatory peptide, developed through Russian pharmacological research.

Reported findings: a 62-patient Russian trial (Zozulya et al.) compared selank against medazepam (a benzodiazepine) in generalized anxiety disorder and neurasthenia, using the Hamilton, Zung, and CGI psychiatric rating scales. The reported anxiolytic effect was similar between the two, with selank additionally showing antiasthenic (anti-fatigue) and mild psychostimulant effects not seen with the benzodiazepine. Selank is approved in Russia for this indication; it has not gone through FDA or MHRA review, and independent replication outside Russian literature is limited.

Derived from a fragment of ACTH (adrenocorticotropic hormone) but modified to remove ACTH's own hormonal activity. Developed in Russia, where it's approved as a prescription medication for certain neurological indications — it is not approved by the MHRA or FDA elsewhere.

Reported findings: a 110-patient Russian stroke-rehabilitation trial (Gusev et al., 2018) reported semax raised plasma BDNF and improved Barthel index and motor-function scores over roughly 5 months, across both early- and late-rehabilitation groups. An earlier 1997 study compared 30 acute stroke patients on semax against 80 on conventional therapy, reporting improved recovery on clinical and EEG measures, though that early study was non-randomised and didn't report numeric effect sizes. Semax has been approved in Russia for acute ischemic stroke since the 1990s on the strength of this literature — but it has never been through a large Western randomised controlled trial, and no Cochrane review includes it. That's a genuinely different evidence standard to compounds like Tesamorelin, worth being clear about.

Encoded by the KISS1 gene, kisspeptin was identified as a key regulator of the hypothalamic-pituitary-gonadal (HPG) axis — the signalling pathway controlling reproductive hormone release.

Reported findings: research has focused heavily on its role triggering GnRH (gonadotropin-releasing hormone) release from the hypothalamus, with studies exploring relevance to puberty onset and fertility research within reproductive endocrinology.

A long-acting analogue of human amylin, a hormone naturally co-secreted with insulin that contributes to satiety signalling.

Reported findings: as a standalone agent in the REDEFINE 1 trial (NEJM, 2025; n=3,417), cagrilintide alone produced a mean body weight change of −11.5% at 68 weeks versus −3.0% on placebo. Combined with semaglutide (as "CagriSema"), the mean change was −20.4%, versus −14.9% for semaglutide alone — 60% of participants on the combination reached ≥20% weight loss and 23% reached ≥30%. This combination approach is an area of active ongoing trial work.

A combination blend of GHK-Cu, BPC-157, TB-500, and KPV. Each component has a separate, independently studied research history:

BPC-157 (derived from a fragment found in gastric juice) is studied in animal models of tissue and gut-lining repair. TB-500 (a fragment of the protein thymosin beta-4) is studied for its proposed role in cell migration during tissue repair. KPV (a tripeptide fragment of alpha-MSH) is studied in anti-inflammatory research contexts. GHK-Cu is covered separately above.

A multi-peptide blend of GHK-Cu, TB-500, BPC-157, and KPV, referenced in recovery-focused and tissue-research literature — see the individual component entries above for each one's separate research background.

Phase 2 data published 2023 (New England Journal of Medicine)

Triple-agonist trials have run in supervised clinical settings over roughly 48-week windows, with Phase 3 trials ongoing. All published dosing was administered and monitored by clinical staff.

FDA-approved 2010 for a specific clinical indication

Clinical trials supporting approval ran over 26–52 week supervised periods. It remains one of the more clinically established compounds in this category.

Mostly preclinical / early-phase data

First synthesized in the 1990s. Published human data is more limited than Tesamorelin's, concentrated in smaller early-phase supervised studies.

Predominantly animal-model literature

Most published research remains at the preclinical (animal-model) stage, with human clinical trial data still limited.

Long research history, mostly topical/dermatological

One of the longer-studied compounds here, though most published literature concerns topical rather than injectable research contexts.

Watching the actual technique is often clearer than reading it. A few general reconstitution walkthroughs worth watching before doing this yourself for the first time:

→ How To Properly Reconstitute Peptides — Michael Nielsen MD

→ Reconstituting Your Peptides — A Tutorial

→ Peptide Reconstitution: Everything You Need to Know

A Certificate of Analysis (COA) is an independent lab's report on a specific batch. The core piece is usually an HPLC (High-Performance Liquid Chromatography) trace — a graph where the sample is compared against a known reference standard. A sharp, isolated peak at the expected retention time indicates the sample is largely the intended compound; extra smaller peaks nearby indicate impurities, and the purity percentage is essentially how much of the total peak area belongs to the main compound.

Purity vs identity: a purity test confirms how clean a sample is, but doesn't by itself prove it's the correct compound at all — some COAs also include a separate identity test (like mass spectrometry) to confirm that.

Red flags: a batch number that doesn't match the vial; a suspiciously round number like exactly 100.00%; a typed percentage with no actual chromatogram image; a testing lab that isn't named or can't be found; a document that's clearly a reused template rather than batch-specific.

Most research peptides ship as a lyophilised (freeze-dried) powder rather than a liquid, because the powder form is far more chemically stable — it can typically be stored for a long time, whereas a liquid solution starts degrading from the moment it's mixed.

Why bacteriostatic water specifically: it contains roughly 0.9% benzyl alcohol as a preservative. Since a reconstituted vial is typically punctured and drawn from multiple times over days or weeks, that preservative keeps bacteria from establishing in the vial between uses. Plain sterile water has no such preservative, so it's generally treated as single-use only, or frozen in individual portions immediately.

Technique matters: water is typically added slowly down the inside wall of the vial rather than directly onto the powder, and the vial is gently swirled or rolled rather than shaken — vigorous agitation can introduce foam and physically stress the peptide bonds, potentially reducing effectiveness. Some people also equalise vial pressure by drawing out an equivalent volume of air before adding water, since a puncture-sealed vial can otherwise build pressure that makes future draws harder to judge accurately.

Storage after mixing: reconstituted solution generally needs refrigeration (commonly cited as roughly 2–8°C), away from light, and is typically considered usable for a period of some weeks rather than indefinitely — this varies by compound, so product-specific guidance takes priority over any general rule. Cloudiness, visible particles, or an unexpected colour change are commonly cited signs a solution shouldn't be used (note that some compounds, like copper peptides, are naturally coloured rather than degraded).

A peptide is a short chain of amino acids joined by peptide bonds — a type of chemical bond formed between the carboxyl group of one amino acid and the amino group of the next. Chains under roughly 50 amino acids are generally called peptides; longer chains that fold into complex 3D shapes are generally called proteins, though the line between the two is somewhat a matter of convention.

Peptides typically act by binding to a specific receptor on a cell's surface, which triggers that cell to do something — release a hormone, change its metabolism, start a repair process. The "fit" between a peptide and its receptor is often described as highly specific, similar to a key and a lock, which is part of why different peptides are studied for very different biological effects despite superficially similar chemistry.

Why injection rather than swallowing: the digestive system exists specifically to break chemical bonds in food into absorbable pieces — stomach acid and digestive enzymes target peptide bonds directly. An orally taken peptide would largely be broken down into individual amino acids before it ever reached the bloodstream intact, which is why injection (bypassing digestion entirely) is the typical route studied for most peptides.

Syringes: graduated in IU (International Units), most commonly on a 100 IU (U-100) or 40 IU (U-40) barrel scale — this calculator defaults to a 100 IU barrel, so always confirm which scale is actually printed on the syringe in front of you before reading it.

Pens: fixed-click pens (like the 60-click pen this calculator's "Clicks on Pen" figure is based on) deliver one set volume per click, rather than a continuously variable draw the way a syringe works — useful for consistency, less flexible for fine adjustment.

Needle gauge: a higher gauge number means a thinner needle (31G is thinner than 27G, for example). It's common to use a larger-gauge (thicker) needle just to draw water into the vial quickly without dulling it, then switch to a smaller-gauge (finer) needle for the injection itself.

Needle length: subcutaneous injection — into the fatty layer beneath the skin rather than muscle — generally uses noticeably shorter needles than an intramuscular injection would.

Syringe "dead space": the small amount of solution that stays trapped in the needle hub after the plunger's fully depressed — this varies between syringe brands and designs and is one reason draw readings can differ slightly between two physically identical-looking syringes.

Lyophilised: freeze-dried into a stable powder form.
Reconstitution: dissolving a freeze-dried powder back into a liquid using a sterile solvent.
Subcutaneous (SubQ): injected into the fatty layer just beneath the skin, rather than into muscle or a vein.
HPLC: High-Performance Liquid Chromatography — a lab method used to measure a substance's purity.
Purity vs potency: purity measures how much of the sample is the actual intended compound (vs impurities); potency measures how biologically active it is — the two aren't always the same thing.
Excipient: an inactive ingredient added to a formulation for stability or bulk, rather than for biological effect.
Analogue: a compound engineered to mimic or modify the action of a naturally occurring one.
Secretagogue: a substance that triggers another gland or cell to release/secrete something — e.g. a GH secretagogue prompts the release of growth hormone.
Peptide bond: the chemical bond linking one amino acid to the next in a chain.
Denaturation: structural breakdown of a peptide or protein, often from heat, agitation, or improper storage, which can reduce or eliminate its activity.
Bioavailability: the proportion of a substance that actually reaches the bloodstream intact and active, rather than being broken down first.
Cold chain: keeping a product within a required temperature range continuously, from manufacture through to storage in the fridge.

Wash hands before handling any vial or syringe. Wipe the vial top and injection site with a fresh alcohol swab each time. Use a new sterile needle and syringe for every draw and every injection — never reuse or share needles, even your own from an earlier session.

Rotate injection sites rather than using the same spot repeatedly — common subcutaneous sites include the abdomen and outer thigh. Repeated use of one spot can cause tissue lumps (lipohypertrophy) and uneven absorption. Avoid any area that's bruised, swollen, broken, or still tender from the last injection.

Lyophilised (powder) vials are generally stable at room temperature until reconstituted, then need refrigeration — check your specific product's guidance. Protect vials from direct light. Don't use a vial that looks cloudy, discoloured, or has anything floating in it. Discard anything past its labelled expiry.

Never put used needles or syringes in household rubbish. Use a proper sharps container (widely available online or from a pharmacy) and find out your local council's sharps disposal or pharmacy take-back scheme.

Spreading redness, warmth, swelling, or pus at an injection site can indicate infection — contact a GP or pharmacist. Facial or throat swelling, difficulty breathing, hives, or dizziness after an injection can indicate an allergic reaction — this is a medical emergency: call 999 (UK) or go to A&E immediately. If in doubt about any reaction, seek medical attention rather than waiting it out.