Peptide Glossary

Bacteriostatic water is sterile water with 0.9% benzyl alcohol added as a preservative. The benzyl alcohol prevents bacterial growth, which is why a reconstituted vial can be safely used for up to 28 days. Plain sterile water has no preservative and would need to be discarded after a single use. BAC water is the standard solvent for almost all peptides.

BDNF (Brain-Derived Neurotrophic Factor) is a protein in the brain that promotes survival of existing neurons and supports the growth of new ones (neurogenesis). Higher BDNF is associated with better learning, memory, and mood. Nootropic peptides like Semax, Selank, P-21, and Cerebrolysin are believed to act in part by upregulating BDNF.

Bioregulator peptides are very short (2-4 amino acid) peptides researched extensively by the Khavinson group in St. Petersburg. The hypothesis is that each bioregulator selectively binds DNA in a specific tissue type and modulates gene expression there. Examples include Epitalon (pineal gland), Thymalin (thymus), Vesugen (vascular endothelium), and Pinealon (CNS).

A cycle is a planned period of peptide administration followed by a break. For receptor-active peptides (especially GH secretagogues like CJC-1295 + Ipamorelin), cycling — for example 8 weeks on, 4 weeks off — helps prevent receptor desensitization and preserves long-term effectiveness. Bioregulators like Epitalon are also typically cycled (one short course every 6-12 months).

DAC (Drug Affinity Complex) is a maleimide group added to a peptide that allows it to bind covalently to albumin in your bloodstream. Albumin is long-lived (about 3 weeks), so the peptide effectively rides along and stays active for days instead of minutes. CJC-1295 with DAC vs. without DAC is the textbook example — same molecule, very different dosing schedules.

Epitalon (Ala-Glu-Asp-Gly) is the most studied bioregulator peptide. Khavinson's group has reported that it activates telomerase and may extend lifespan in animal models. It's typically dosed in short cycles (10-20 days, 1-2x per year) at 5-10 mg per day, often subq or intranasal.

GHRH (Growth Hormone Releasing Hormone) is the natural hypothalamic hormone that tells the anterior pituitary to release growth hormone. Synthetic GHRH analogues like Sermorelin, CJC-1295, and Tesamorelin mimic this signal. They preserve the body's natural pulsatile release of GH instead of overriding it, which is why they're considered gentler than direct HGH injections.

GHRPs (Growth Hormone Releasing Peptides) like Ipamorelin, GHRP-2, GHRP-6, and Hexarelin work on the ghrelin receptor (GHS-R1a) in the pituitary and hypothalamus to stimulate GH release. They are typically combined with a GHRH analogue (e.g. CJC-1295 + Ipamorelin) because the two pathways amplify each other synergistically.

GIP (Glucose-dependent Insulinotropic Peptide) is the other major incretin hormone. On its own, GIP has modest effects, but when combined with GLP-1 activity (as in Tirzepatide) it appears to enhance weight loss and glucose control beyond what GLP-1 alone produces. Retatrutide adds a third axis — glucagon — to push results even further in trials.

GLP-1 (Glucagon-Like Peptide-1) is an incretin hormone released by your gut after eating. It tells your pancreas to release insulin, slows stomach emptying, and reduces appetite signals in the brain. Synthetic GLP-1 receptor agonists — Semaglutide (Ozempic, Wegovy), Liraglutide, and the dual GLP-1/GIP agonist Tirzepatide (Mounjaro, Zepbound) — exploit this for weight loss and diabetes management.

Half-life is the time required for the concentration of a peptide in your bloodstream to fall by 50%. It directly drives how often you need to dose. BPC-157 has a half-life of only minutes (so twice-daily dosing is common), while CJC-1295 with DAC has a half-life of about a week (so weekly dosing works). Half-life also determines whether peptide levels stay steady or come in pulses — important for hormone-mimicking peptides.

IGF-1 (Insulin-like Growth Factor 1) is produced primarily by the liver when stimulated by growth hormone. Most of GH's muscle-building, recovery, and tissue-growth effects are actually mediated by IGF-1 acting on cells. This is why blood IGF-1 levels are the standard way to measure whether GH-stimulating peptides are working. IGF-1 LR3 is a long-acting research analogue used directly.

Incretins are gut-derived hormones released after meals that amplify the insulin response to glucose. The two main ones are GLP-1 and GIP. Most modern weight-loss peptides target one or both of these systems.

An insulin syringe is a small (typically 0.3-1 mL) syringe with a thin, short needle (usually 29-31 gauge, 5/16 inch). The barrel is marked in 'units' rather than mL — 100 units = 1 mL on a U-100 syringe (the standard). They are ideal for peptides because the markings allow precise small-volume dosing and the thin needle is nearly painless for subq injection.

Intramuscular (IM) injection places the peptide directly into a muscle, typically the deltoid or glute. Absorption is faster and the depot effect is shorter than subq. A few peptides — most notably TB-500 in some protocols — are sometimes given IM near the site of injury.

IU (International Units) measures biological potency rather than mass. It's used when a substance's effect varies between manufacturers or batches. HGH is dosed in IU (typically 1-4 IU per day for research), and oxytocin is sometimes dosed in IU. IU does not directly convert to mg — the conversion depends on the specific compound.

Lyophilization removes water from a frozen peptide solution under vacuum, leaving a stable powder that can be stored at room temperature for shipping and at refrigerator temperatures for long-term storage. Once reconstituted, peptides become much less stable and should be refrigerated.

1 mg = 1,000 mcg. Most peptide doses are written in mcg because the active amounts are small. A typical BPC-157 dose of 250 mcg is 0.25 mg. Always double-check whether a protocol is written in mcg or mg before drawing — a 1000x error is easy to make.

Vial sizes are almost always labeled in mg (e.g. a '5 mg vial' contains 5 mg of peptide powder before reconstitution). Doses, on the other hand, are typically expressed in mcg. Knowing the conversion (1 mg = 1000 mcg) is essential for using the calculator correctly.

Neurogenesis is the formation of new neurons, primarily in the hippocampus in adults. It's driven in large part by BDNF and is linked to learning, memory, and resilience to depression. Several research peptides (Cerebrolysin, P-21, Dihexa) appear to promote neurogenesis or synaptogenesis.

A nootropic is any substance taken to enhance cognitive function. Peptide nootropics include Semax (focus, BDNF), Selank (anti-anxiety, mental clarity), Cerebrolysin (neuroprotection), Dihexa (synaptogenesis), and others. Most are delivered via nasal spray to bypass the blood-brain barrier.

A pleiotropic compound has multiple, independent effects across different systems. BPC-157 is the classic example: it affects nitric oxide signaling, growth hormone receptors, dopamine, and tissue repair pathways simultaneously. This makes it harder to study (no single mechanism) but explains its broad reported effects.

Growth hormone is naturally released in pulses, mostly during deep sleep and after exercise. Steady, around-the-clock GH levels (as caused by long-acting modifications) can desensitize receptors and increase side effects. This is why short-acting GHRH analogues (like Sermorelin or CJC-1295 without DAC) are often preferred — they preserve the natural pulsatile pattern.

Peptides ship as a freeze-dried (lyophilized) powder for stability. Reconstitution is the process of dissolving that powder with bacteriostatic water so it can be drawn into a syringe. The amount of water you add determines the concentration — more water means each unit on the syringe contains less peptide. Always inject the water down the side of the vial, not directly onto the powder, to avoid damaging the peptide.

A secretagogue is a substance that causes another substance to be secreted. Growth hormone secretagogues (GHS) include both GHRH analogues and GHRPs — they don't supply hormone, they tell your body to produce more of its own. This preserves natural feedback loops and reduces some of the side effects associated with exogenous hormone replacement.

Sterile means completely free of bacteria, viruses, fungi, and spores. Anything injected into your body must be sterile to avoid infection or sepsis. This means using sealed sterile vials, fresh insulin syringes, alcohol-wiping every cap before puncturing, and never re-using needles.

Subcutaneous (SC, subq) injection delivers the peptide into the fatty layer just below the skin, typically into the abdomen, thigh, or upper arm. Absorption is slower and steadier than intramuscular, and it's almost painless because there are few nerve endings in fat. Most peptides — including all GH secretagogues, BPC-157, and GLP-1s — are dosed subq.

Telomeres are repeating DNA sequences at the ends of your chromosomes. Every time a cell divides, telomeres get a tiny bit shorter — when they get too short, the cell stops dividing (senescence) or dies. Telomere length is one of the better-studied biomarkers of biological aging. Telomerase is the enzyme that can rebuild telomeres; some peptides (notably Epitalon) are thought to upregulate it.