Frequently asked questions

What is semaglutide?

Semaglutide — marketed under the trademarks Ozempic, Wegovy and Rybelsus — is a 31-amino-acid engineered analogue of the human gut hormone GLP-1, sharing roughly 94% of its sequence. Two substitutions in the backbone block the enzyme that would normally break it down, and a C18 fatty di-acid side chain binds it reversibly to serum albumin, protecting it from renal clearance. The result is a molecule that persists for about a week where the natural hormone lasts about two minutes. It is an approved prescription medicine, available both as a once-weekly injection and as a once-daily oral tablet.

The name is a generic name — an international nonproprietary name — and its ending is meaningful: -tide marks a peptide, and -glutide marks the GLP-1 analogue family. The three trademarks name marketed products rather than the compound, which is why one molecule can carry several of them while having exactly one generic name.

What is semaglutide used for?

It is approved across several indications: type 2 diabetes, chronic weight management, reduction of major adverse cardiovascular events in adults with established cardiovascular disease and overweight or obesity, and — added in 2025 — metabolic dysfunction-associated steatohepatitis.

The outcome evidence behind those is substantial. In SELECT, in 17,604 adults with established cardiovascular disease but no diabetes, the composite of cardiovascular death, non-fatal myocardial infarction and non-fatal stroke fell with a hazard ratio of 0.80 (95% CI 0.72-0.90) ^[3]. In FLOW, in 3,533 people with type 2 diabetes and chronic kidney disease, major kidney-disease events fell with a hazard ratio of 0.76 (95% CI 0.66-0.88) ^[2].

How does semaglutide work?

It is a long-acting agonist at the GLP-1 receptor. Activating that receptor potentiates glucose-dependent insulin secretion from pancreatic beta cells, suppresses inappropriate glucagon release from alpha cells, and slows gastric emptying.

"Glucose-dependent" is the load-bearing phrase: the insulin response scales with blood sugar, which is why the drug alone carries a low risk of driving glucose too low. Its receptor targets span the pancreas, hypothalamus, brainstem, gastric smooth muscle and vagal afferents, and cardiovascular and renal tissue.

How does semaglutide work for weight loss?

Mostly through the brain rather than the metabolism. Rodent work showed semaglutide reaching the brainstem, area postrema, hypothalamic arcuate nucleus and parabrachial nucleus, reducing food intake and altering food preference — and doing so without decreasing energy expenditure ^[6]. It changes how much an animal wants to eat rather than how fast it burns fuel.

In humans, the STEP 1 trial found a mean body-weight change of -14.9% at 68 weeks with once-weekly 2.4 mg, against -2.4% with placebo, in 1,961 adults with overweight or obesity and without diabetes ^[4]. Weight regain after stopping is substantial, which frames the treatment as chronic rather than curative.

What is tirzepatide?

Tirzepatide is a linear 39-amino-acid synthetic peptide built on the native GIP sequence, carrying a C20 fatty di-acid arm that binds albumin and permits once-weekly dosing. It is the first approved dual incretin agonist, activating the GIP receptor and the GLP-1 receptor with a single molecule ^[8]. It is an approved prescription medicine.

Its name is worth a second look. It ends in -tide, marking it as a peptide, but not in -glutide — and that gap is accurate, because it is not simply a GLP-1 analogue.

How does tirzepatide work?

By engaging two incretin receptors at once. Activating both the GIP and GLP-1 receptors enhances glucose-dependent insulin secretion, suppresses glucagon, slows gastric emptying, and reduces appetite and food intake ^[8].

Because one molecule engages both arms, the trials cannot separate how much of the additional effect belongs to the GIP receptor specifically. What the evidence establishes is the combined result — which in trials exceeded selective GLP-1 receptor agonism alone ^[8][11].

What does tirzepatide do in the body?

Four things follow from dual receptor activation: more insulin released when glucose is high, less glucagon released inappropriately, slower emptying of the stomach, and reduced appetite ^[8].

Those have knock-on effects that are equally part of the picture. Slowed gastric emptying underlies most of the gastrointestinal side effects, raises a periprocedural question about retained stomach contents under sedation, and can reduce the reliability of oral hormonal contraceptives around dose increases. A meaningful fraction of the weight lost is lean rather than fat mass. These are consequences of the mechanism, not incidental to it.

What is tirzepatide used for?

It was first approved in May 2022 for type 2 diabetes; a second approval in November 2023 covers chronic weight management in adults with obesity, or overweight plus a weight-related condition; and it was subsequently approved for moderate-to-severe obstructive sleep apnoea in adults with obesity ^[8].

In SURMOUNT-1, 2,539 adults with obesity and without diabetes saw mean weight change at 72 weeks of -20.9% at the 15 mg dose against -3.1% with placebo ^[10]. In SURPASS-2, in 1,879 adults with type 2 diabetes, glycated haemoglobin fell by up to 2.30 percentage points ^[11].

What is CJC-1295?

CJC-1295 is a synthetic analogue of growth-hormone-releasing hormone, built on the first 29 residues of human growth-hormone-releasing factor — written hGRF(1-29) — with four amino-acid substitutions that resist enzymatic breakdown. In the DAC variant, an added linker binds covalently to serum albumin, extending the half-life to days.

It is not approved for human use by any regulator. It is sold by research suppliers for laboratory research use only, and it is prohibited in sport at all times. The name is a company development code rather than a generic name, because the original programme was discontinued before the compound could earn one.

What does CJC-1295 do?

It binds the GHRH receptor on anterior-pituitary somatotrophs, stimulating synthesis and pulsatile release of growth hormone, which raises hepatic IGF-1.

The measured effects in healthy volunteers are clear. Single subcutaneous doses of 30 or 60 micrograms per kilogram produced dose-dependent 2- to 10-fold increases in mean plasma growth hormone for six days or more and 1.5- to 3-fold increases in IGF-1 for nine to eleven days, with an estimated half-life of 5.8 to 8.1 days ^[15]. A companion study found trough growth hormone raised roughly 7.5-fold and IGF-1 about 45% a week after a single dose, with the body's own pulsatile rhythm unaltered ^[16].

What those studies do not show is any clinical benefit. They measured hormone levels, not outcomes.

Is CJC-1295 safe?

There is not enough human evidence to answer that. CJC-1295 has never been approved for human use, and the published human record consists of a small number of early pharmacology studies with no large or long-term trials of safety or efficacy in healthy adults ^[15].

Several concerns are on record. Sustained IGF-1 elevation carries a mechanism-based concern for anyone with a personal or family history of cancer, since population data associate higher circulating IGF-1 with modestly increased risk of certain cancers. Growth hormone promotes renal sodium and water retention, which is the likely basis of the fluid retention and carpal-tunnel-like tingling widely reported by users. Growth hormone is glucose-sparing, so sustained stimulation can reduce insulin sensitivity. Immunogenicity was cited in 2024 regulatory briefing materials among the reasons for not recommending the compound for the 503A compounding bulks list ^[12]. And the original development programme was discontinued, with a patient death from that era frequently cited alongside it — a causal link was never established in the public record, so it stands as unresolved history.

How much CJC-1295 should I take?

This site does not answer that question, for anyone, and no answer to it exists in the published literature.

CJC-1295 is not approved for human use anywhere, so there is no labelled dose, no approved indication, and no regulator-reviewed dosing guidance. Most dosing protocols circulating online are not derived from controlled human trials at all.

What the literature does contain is the amounts administered in two early pharmacology studies: single subcutaneous doses of 30 or 60 micrograms per kilogram in healthy adults aged 21 to 61 ^[15], and 60 or 90 micrograms per kilogram in healthy men aged 20 to 40 ^[16]. Those are records of what researchers gave participants under supervision in a study, not recommendations, and they were measuring hormone response rather than establishing a safe or effective dose.

What does BPC-157 do in the body?

In animal models it acts as a cytoprotective and repair-promoting peptide, and the effect most consistently linked to it is angiogenesis — the growth of new blood vessels into injured tissue.

The best-characterised route is through VEGFR2: BPC-157 up-regulates the receptor and promotes its internalisation, activating the downstream VEGFR2-Akt-eNOS pathway, increasing vessel density and accelerating blood-flow recovery in ischaemic muscle ^[20]. Additional reported routes include FAK-paxillin signalling in cell migration, sensitisation of the growth-hormone receptor in tendon fibroblasts, and modulation of the nitric-oxide and several neurotransmitter systems.

The qualifier matters throughout: these are findings in rodents and cell systems. Human data are limited to three small pilot studies ^[18].

Is BPC-157 a growth hormone?

No. BPC-157 is a 15-amino-acid peptide derived from a partial sequence of a human gastric-juice protein. It is not a growth hormone, not a growth-hormone analogue, and not a growth-hormone secretagogue.

The confusion probably has two sources. One is that BPC-157 has been reported to sensitise the growth-hormone receptor in cultured tendon fibroblasts, which is a downstream mechanistic detail rather than a class membership. The other is proximity: compounds like CJC-1295 genuinely do act on the growth-hormone axis, and the two are frequently discussed in the same settings.

This is exactly the kind of error a naming convention would prevent. CJC-1295 is described in the literature as a GHRH analogue and growth-hormone secretagogue; BPC-157 is described as a pentadecapeptide cytoprotective peptide. The class descriptors differ completely, even though neither compound's primary name reveals that.

Does BPC-157 work immediately?

No controlled human data establish an onset time, because no controlled human efficacy trials exist ^[18].

The pharmacokinetics are known from animals and are notably fast: linear kinetics, an elimination half-life under 30 minutes, and rapid breakdown into small peptide fragments that enter normal amino-acid metabolism ^[19]. That short half-life sits oddly beside the durations users describe, and reconciling the two is an open question in the pharmacology rather than a settled account.

What research-use communities report is anecdotal, not clinical evidence: improvement in tendon, ligament and joint complaints often described over the first one to three weeks, and gut symptom changes often described over one to two weeks. Those are self-reported timelines from uncontrolled use, with no comparison group and no way to separate the compound from healing that would have happened anyway.

Does BPC-157 damage the liver?

There is no human evidence that it does, and there is also very little human evidence of any kind, so the honest answer is that liver safety in people has not been established either way.

The single relevant datapoint is small. A first-in-human intravenous safety pilot gave BPC-157 at up to 20 mg to two healthy adults; it was well tolerated, with no observed adverse events and no measurable changes in cardiac, hepatic, renal, thyroid or glucose biomarkers ^[17]. Two participants cannot establish organ safety.

The broader position from the 2025 review is that rigorous large-scale trials are lacking and the compound should be treated as investigational ^[18]. A separate and more practical concern is that BPC-157 moves through non-regulated channels, so the identity, purity and actual contents of a given product are unverified ^[18] — which means any adverse effect could originate in something other than the peptide.

What is PT-141?

PT-141 is a synthetic cyclic heptapeptide — a ring of seven amino acids — and a lactam analogue of alpha-melanocyte-stimulating hormone. It is a structural relative of melanotan II, differing in that the C-terminal amide is replaced by a carboxylic acid.

The most important fact about it is a naming fact. PT-141, bremelanotide and Vyleesi are the same molecule. Bremelanotide is the generic name and the label under which the compound was approved in June 2019 for one narrowly defined indication; Vyleesi is the trademark under which the approved product is marketed. Material sold as PT-141 research chemical sits outside that approval, with no verification of identity, purity or concentration.

What is PT-141 peptide?

Chemically it is a small cyclic peptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH, closed by a lactam bridge between the aspartate and lysine side chains. Its drug class is melanocortin receptor agonist, acting principally at MC3R and MC4R.

It appears in the literature under several other labels, and each belongs to a different naming system: the systematic description cyclo-[Nle4-Asp5]-alpha-MSH(4-10), which identifies it as a modified fragment of the parent hormone; the abbreviation BMT; and salt forms written bremelanotide acetate or PT-141 acetate, where the counter-ion is named because the material in a vial is a salt of the peptide rather than the free peptide.

At seven residues it is the shortest compound in this hub — semaglutide has 31 and tirzepatide 39.

What does the PT-141 peptide do?

It activates central melanocortin receptors, chiefly MC4R, concentrated in the hypothalamus and limbic system, and is thought to engage dopaminergic pathways governing sexual desire and arousal.

The mechanism is central, not vascular. PDE-5 inhibitors act peripherally on vascular smooth muscle; this compound acts on the neural circuitry of sexual motivation. It does not work through the hypothalamic-pituitary-gonadal axis and does not directly raise testosterone.

Neuroimaging supports that account: in a placebo-controlled crossover fMRI study of 31 premenopausal women, MC4R agonism significantly increased sexual desire for up to 24 hours and altered brain processing of erotic stimuli, including enhanced amygdala-insula connectivity ^[23]. Animal work adds a limit — in female Syrian hamsters, bremelanotide did not enhance sexual reward as measured by conditioned place preference, suggesting it does not act on the ventral tegmental to nucleus accumbens reward circuit ^[22].

Because MC4R also helps regulate appetite, and because related melanocortin receptors drive pigment cells, effects on food intake and on skin darkening are consequences of the same receptor family.

What is PT-141 used for?

As bremelanotide, it is approved in the United States for acquired, generalised hypoactive sexual desire disorder in premenopausal women, and for nothing else. It is not approved for men, for postmenopausal women, or to enhance sexual performance ^[26].

The approval rests on two identical phase 3 trials enrolling 1,267 premenopausal women, in which both co-primary endpoints were met over 24 weeks: sexual desire improved by 0.35 on the integrated FSFI-desire measure and desire-related distress fell by 0.33 on the integrated FSDS-DAO item, both against placebo (P<0.001) ^[24]. A 52-week open-label extension in 684 women found sustained improvement and no new safety signals, with nausea in 40.4%, flushing in 20.6% and headache in 12.0% ^[25].

Critical re-analyses argue those effects, while statistically significant, are small, and question their clinical meaningfulness. Any use beyond the approved indication is off-label and outside the studied population.

Why do so many peptide names end in -tide?

Because generic naming uses shared word-parts, or stems, to signal what kind of molecule something is. The ending -tide marks a peptide, and it is visible across this hub: semaglutide, tirzepatide and bremelanotide all carry it.

Longer stems narrow the classification further. -glutide marks the GLP-1 analogue family, which is why semaglutide carries it and tirzepatide — built on the GIP sequence and engaging two receptors — does not.

Stems can also sit inside a word rather than at the end. Bremelanotide contains melano, pointing at the melanocortin system it acts on. A reader who decodes only that fragment already knows the receptor family.

The practical value is that the system compresses a pharmacological claim into a few letters, which makes the claim checkable — and makes a deviation from the expected pattern worth investigating.

What is the difference between a research code and a generic name?

A research or development code is assigned inside an organisation: letters identifying the originating company or laboratory, digits identifying the compound. LY3298176, NNC0113-0217, NN9535, PL 14736 and CJC-1295 are all of this type. A code encodes no pharmacology whatsoever — it is an inventory label.

A generic name is assigned by a standards process to compounds moving through regulatory review, and it is built from the stem system described above, so it does carry pharmacological information.

The practical consequence is the useful part. A compound still going by its code as its primary name has usually not completed the path that confers a generic name — and that same path is what produces regulatory dossiers, approved labels, characterised pharmacokinetics and post-market monitoring. So a code standing where a generic name would be expected is a reasonable prompt to ask how far the compound actually got. CJC-1295 is this hub's clearest example: no generic name, because the development programme was discontinued.

What is the difference between a brand name and a generic name?

A generic name identifies a molecule. A brand name, or trademark, identifies a marketed product — one formulation, at set strengths, licensed for set indications, sold by one company in one set of jurisdictions.

The cleanest demonstration in this hub is semaglutide, which carries one generic name and three trademarks: Ozempic, Wegovy and Rybelsus. Nothing about the chemistry differs between them; what differs is the product each names. That asymmetry is the whole distinction in miniature — a molecule can support as many trademarks as its manufacturer has products, but it gets exactly one generic name.

PT-141 shows the same structure from the other direction: the research code PT-141, the generic name bremelanotide, and the trademark Vyleesi all denote a single compound, and the choice among them signals which regulatory world a source is describing.

Three properties make the generic name the more useful one for a reference like this. It is unique per molecule rather than per product. It is stable across manufacturers, formulations and countries, and it outlives patents. And because it is built from stems, it is partly decodable — -tide for a peptide, -glutide for the GLP-1 family, melano for the melanocortin system — whereas a trademark is chosen to be memorable and encodes nothing about pharmacology at all.

One compound in this hub is deliberately handled differently. Tirzepatide is marketed under trademarks that this site does not name, because its signed source record directs that it be described by the international nonproprietary name alone. The omission is noted on its page rather than passed over quietly.

Are PT-141 and bremelanotide the same thing?

They are the same molecule, and they are not the same situation. A third name, the trademark Vyleesi, belongs to the same compound as well.

Chemically there is nothing to separate: bremelanotide is the generic name for the compound also known by the research code PT-141, and marketed as Vyleesi. But bremelanotide names an approved prescription medicine with a specified indication, a labelled dose and dosing ceiling, characterised pharmacokinetics and a warning list ^[26]. Material sold as PT-141 research chemical sits outside that approval framework, and its identity, purity and concentration are unverified.

So the honest answer is that the names are chemically synonymous and practically divergent. Which name a source uses is a reliable clue to which supply chain and which evidence base it is talking about — and this is the reason the PT-141 page treats the compound as the single sharpest naming case in this hub.

What is the difference between CJC-1295 DAC and no-DAC?

Duration, and it is a very large difference hiding behind four characters of text.

Both forms share the same four amino-acid substitutions on the hGRF(1-29) backbone. The DAC form — DAC standing for Drug Affinity Complex — adds a linker that binds covalently to cysteine 34 of circulating serum albumin, stretching the plasma half-life toward that of albumin itself, so it stays active for days. The no-DAC form, also sold as Modified GRF 1-29 or Mod GRF 1-29, keeps the substitutions but has no albumin-binding moiety and is short-acting, lasting minutes to hours.

The safety literature for this compound flags directly that marketing and forums routinely treat the two as interchangeable when they are pharmacokinetically very different, and that the confusion matters — the sustained duration of the DAC form is what drives more prolonged fluid retention, blood-sugar effects and IGF-1 exposure. Community reports bear this out, though as anecdotal, not clinical evidence: users describe water retention as more pronounced with the DAC form, and post-injection flushing as more associated with the short-acting form.

Establishing which form is in question is a precondition for interpreting any reported effect at all.