Peptide
Glossary

"Essentially a Copy"

FDA guidance prohibiting compounded drugs that are essentially copies of commercially available FDA-approved products. A key regulatory constraint on compounding GLP-1 drugs.

177Lu-DOTATATE

A peptide-radioligand therapy (Lutathera) that uses a somatostatin analog to deliver radioactive lutetium-177 directly to neuroendocrine tumor cells.

500 Dalton Rule

The principle that molecules larger than approximately 500 Daltons generally cannot penetrate intact skin effectively. Many cosmetic peptides exceed this threshold, necessitating delivery-enhancing strategies like palmitoylation or nanocarriers.

503A Compounding

A section of the FD&C Act allowing licensed pharmacies to compound patient-specific prescriptions from bulk drug substances, subject to specific requirements including valid prescriptions.

503B Outsourcing Facility

An FDA-registered facility that can compound drugs without patient-specific prescriptions, subject to cGMP requirements and FDA inspection. Distinct from 503A pharmacies.

Acetyl Dipeptide-31 Amide

A peptide with anti-inflammatory and extracellular-matrix-building effects. A 2025 study showed it improved early signs of aging and reduced a skin glycation index over 12 weeks, positioning it for 'pre-aging' skincare applications.

Acetyl Hexapeptide-8 (Argireline)

The best-known neurotransmitter-inhibitor peptide in cosmetics. Proposed to interfere with SNARE-complex-mediated neurotransmitter release to reduce expression lines. Clinical studies suggest improvements in wrinkle depth and elasticity, but low skin penetration remains a major limitation.

Acromegaly

A condition caused by excess growth hormone, typically from a pituitary tumor. Treated with somatostatin analogs like octreotide.

ADSCP6

A preclinical peptide studied for scar modulation. A 2025 study reported reduced collagen I and alpha-SMA in hypertrophic scar fibroblasts, improved wound healing, and less collagen deposition in mice via NF-kB, FAK, STAT3, and SMAD2 pathways.

AgelessRx

A longevity-focused telehealth platform offering NAD+, rapamycin, and other longevity prescriptions. Positioned in the anti-aging medicine space.

Amino Acid

The building blocks of peptides and proteins. There are 20 standard amino acids encoded by DNA, plus non-standard variants used in synthetic peptides.

Amycretin

An investigational oral GLP-1/amylin co-agonist in development, potentially offering oral convenience with dual-mechanism weight loss.

Amylin

A peptide hormone co-secreted with insulin that regulates appetite and gastric emptying. Amylin analogs (pramlintide, cagrilintide) are being combined with GLP-1 drugs.

AOD-9604

Anti-Obesity Drug fragment 9604. A modified fragment of human growth hormone investigated for fat metabolism. Not FDA-approved; gray-market availability.

API (Active Pharmaceutical Ingredient)

The biologically active component of a drug product. In peptide compounding, API characterization and impurity profiling are critical quality considerations.

Bioavailability

The fraction of an administered drug that reaches systemic circulation. Oral peptide bioavailability is typically <2% without enhancement technology.

Biologic

A product derived from living organisms (proteins, antibodies, gene therapies). Biologics are NOT eligible for traditional 503A/503B compounding pathways.

Boxed Warning

The FDA's most serious warning on a drug label, enclosed in a black box. Tirzepatide carries one for thyroid C-cell tumor risk.

BPC-157

Body Protection Compound-157. An investigational peptide with tissue repair and anti-inflammatory claims. Not FDA-approved; commonly sold on the gray market as 'research only.'

Branded vs. Compounded

The distinction between FDA-approved branded drugs (Ozempic, Mounjaro) and pharmacy-compounded versions. Compounded versions are typically cheaper but face regulatory scrutiny.

Bulk Drug Substance

An active pharmaceutical ingredient (API) used in compounding. Under 503A, must have a USP/NF monograph, be a component of an FDA-approved drug, or appear on the FDA's bulks list.

CagriSema

An investigational combination of cagrilintide (amylin analog) and semaglutide being developed for enhanced weight loss beyond semaglutide alone.

Carrier Peptide (Cosmetic)

Peptides designed to shuttle biologically useful ions or cofactors into skin. The best-known example is GHK-Cu (copper tripeptide), which delivers copper ions to support fibroblast activity, collagen synthesis, and wound healing.

Cash-Pay Model

A pricing model where patients pay out-of-pocket rather than through insurance. Most compounded peptide and telehealth services operate on cash-pay.

Cell-Penetrating Peptide (CPP)

Short peptides that facilitate the transport of molecules across cell membranes. In cosmetics, CPPs are used as delivery vehicles to help larger peptides or actives penetrate the skin barrier more effectively.

cGMP

Current Good Manufacturing Practice. FDA regulations ensuring drugs are consistently produced and controlled to quality standards. Required for 503B facilities.

CJC-1295

A synthetic GHRH analog with extended half-life, often compounded in combination with ipamorelin. Not FDA-approved; regulatory and safety concerns exist.

Collagen (Cosmetic Context)

The most abundant structural protein in skin, providing firmness and tensile strength. Collagen production declines with age; signal peptides aim to stimulate fibroblasts to produce more collagen, while oral collagen peptides claim to support skin from within.

Compounding Pharmacy

A pharmacy that creates customized medications by combining or altering ingredients. Central to the peptide telehealth ecosystem, operating under 503A or 503B frameworks.

Cosmeceutical

A cosmetic product with biologically active ingredients that have drug-like benefits. Cosmetic peptides fall into this category — more active than basic cosmetics but not regulated as drugs.

Cosmetic Peptide

Short amino-acid sequences used in topical skincare or ingestible nutricosmetic products to influence skin appearance or biology. Grouped into four main classes: signal peptides, carrier peptides, neurotransmitter-inhibitor peptides, and enzyme-inhibitor peptides.

Dasiglucagon

A glucagon analog approved for acute hypoglycemia rescue in diabetes patients. Offers improved stability over native glucagon.

Degarelix

A GnRH antagonist used for advanced prostate cancer. Unlike GnRH agonists, it does not cause an initial testosterone surge.

Depot Injection

A long-acting injectable formulation that slowly releases drug over weeks to months. Octreotide LAR and leuprolide depot are peptide examples.

Dermis

The thick middle layer of skin containing fibroblasts, collagen, elastin, blood vessels, and nerve endings. The target layer for most anti-aging peptide activity, though reaching it through intact skin remains the central delivery challenge.

Desmopressin

A synthetic vasopressin analog used for diabetes insipidus, nocturnal enuresis, and hemophilia A. Available as injection, nasal spray, and oral tablet.

Diabetes Insipidus

A condition characterized by excessive thirst and urination due to insufficient vasopressin (ADH). Treated with desmopressin.

Drug Modality

A class or type of therapeutic agent. Peptides represent a distinct modality between small molecules and large biologics, offering high specificity with moderate molecular weight.

Drug Shortage

When demand for an FDA-approved drug exceeds supply. During shortages, compounding pharmacies may produce copies. The semaglutide shortage drove massive compounding activity.

DSIP

Delta Sleep-Inducing Peptide. A neuropeptide investigated for sleep regulation and stress modulation. Not FDA-approved.

DTC (Direct-to-Consumer)

A business model where companies sell directly to consumers, bypassing traditional healthcare intermediaries. Most GLP-1 telehealth platforms use DTC models.

Elastin

A protein in the dermis that provides skin elasticity and resilience. Like collagen, elastin production declines with age. Several cosmetic peptides claim to stimulate elastin synthesis in fibroblast models.

Enzyme-Inhibitor Peptide

Peptides that inhibit enzymes involved in skin degradation, such as matrix metalloproteinases (MMPs) that break down collagen and elastin. They aim to slow extracellular matrix degradation rather than stimulate new production.

Epithalon

A synthetic tetrapeptide studied for telomerase activation and anti-aging effects. Not FDA-approved; sold as a research peptide.

Expression Lines

Wrinkles formed by repeated facial muscle movements (frown lines, crow's feet). Neurotransmitter-inhibitor peptides target these by attempting to reduce the intensity of muscle contractions that cause them.

Extracellular Matrix (ECM)

The structural network of proteins (collagen, elastin, fibrillin) and glycosaminoglycans that provides skin with structure, hydration, and mechanical support. Peptide anti-aging claims largely revolve around modulating ECM turnover.

FDA Bulks List

The FDA's list of bulk drug substances that may be used in 503A compounding even without a USP/NF monograph or FDA-approved drug component status.

FDA Interim Policy (2025)

January 2025 FDA policy tightening compounding rules following resolution of the semaglutide shortage. Restricts compounding of certain peptides when commercial supply is adequate.

Fibroblast

The primary cell type in the dermis responsible for producing collagen, elastin, and other extracellular matrix components. Most anti-aging peptide claims center on stimulating fibroblast activity to increase matrix production.

GHK-Cu

A copper-binding tripeptide investigated for wound healing, skin rejuvenation, and anti-aging. Available in gray-market and cosmetic formulations.

GHK-Cu (Copper Tripeptide)

The best-known carrier peptide in cosmetics. Mechanistic literature associates it with fibroblast support, collagen and elastin synthesis, glycosaminoglycan production, angiogenesis, wound healing, antioxidant activity, and anti-inflammatory effects. Clinically less proven as a standalone topical than its reputation suggests.

GHRH (Growth Hormone-Releasing Hormone)

A hypothalamic peptide that stimulates growth hormone release from the pituitary. Sermorelin and tesamorelin are GHRH analogs.

GIP (Glucose-dependent Insulinotropic Polypeptide)

An incretin hormone that enhances insulin secretion. Tirzepatide is the first approved dual GIP/GLP-1 agonist, showing superior efficacy over GLP-1 alone.

GLP-1 Receptor Agonist

A class of drugs that mimic the incretin hormone GLP-1, stimulating insulin secretion, suppressing glucagon, slowing gastric emptying, and reducing appetite. The dominant peptide drug class today.

Glycation Index

A measure of advanced glycation end-products (AGEs) in skin, which contribute to stiffness, discoloration, and accelerated aging. Acetyl dipeptide-31 amide has been shown to reduce skin glycation index in clinical studies.

Glycosaminoglycan (GAG)

Long sugar chains (e.g., hyaluronic acid) in the extracellular matrix that attract and retain water, providing skin hydration and volume. GHK-Cu is associated with increased GAG production.

GnRH (Gonadotropin-Releasing Hormone)

A hypothalamic hormone controlling reproductive function. GnRH agonists and antagonists are used for prostate cancer, endometriosis, and precocious puberty.

Gray-Market Peptide

Peptides sold as 'research only' or 'not for human consumption' to circumvent FDA regulation. Includes BPC-157, AOD-9604, and many others with no FDA approval.

Growth Hormone Secretagogue

A compound that stimulates growth hormone release, either through GHRH receptors or ghrelin receptors. Ipamorelin and CJC-1295 are examples.

Half-Life

The time required for the concentration of a drug in the body to decrease by half. Many natural peptides have very short half-lives (minutes), requiring formulation strategies to extend duration.

Hims & Hers

A major consumer telehealth platform offering compounded GLP-1 and branded peptide products. Known for consumer-friendly branding and ~$199/mo pricing.

Hormone Optimization

A clinical approach to optimizing hormone levels (testosterone, growth hormone, thyroid) often using peptide therapies. Core offering of peptide-focused clinics.

Hormone Replacement

Therapeutic strategy of supplying exogenous hormones (often peptide-based) to compensate for deficient endogenous production, such as insulin for diabetes.

HSDD

Hypoactive Sexual Desire Disorder. PT-141/bremelanotide (Vyleesi) is FDA-approved for HSDD in premenopausal women.

Hyaluronic Acid

A glycosaminoglycan that holds up to 1,000 times its weight in water, providing skin hydration and plumpness. TriHex technology has been shown to increase epidermal hyaluronic-acid signaling.

Hydrophilic

Water-loving; peptides are generally hydrophilic, which limits their ability to cross cell membranes and contributes to poor oral absorption.

IBS-C

Irritable Bowel Syndrome with Constipation. Linaclotide (Linzess) is a locally acting oral peptide approved for this condition.

Immunomodulator

A substance that modifies immune system activity. Thymosin alpha-1 is an immunomodulatory peptide used in hepatitis and immunodeficiency.

Impurity Profiling

Analytical testing to identify and quantify impurities in a drug substance. Critical for compounded peptides where API quality varies between suppliers.

Incretin

A gut hormone released after eating that stimulates insulin secretion. GLP-1 and GIP are the two main incretins, forming the basis for incretin-based therapies.

Iontophoresis

A technique using mild electrical current to drive charged drug molecules through the skin. Investigated as a non-invasive peptide delivery method.

Ipamorelin

A growth hormone secretagogue that stimulates GH release via the ghrelin receptor. Commonly combined with CJC-1295 in compounded formulations.

Keratinocyte

The predominant cell type in the epidermis. Keratinocyte-fibroblast cross-talk is central to skin repair biology, and some cosmetic peptides aim to modulate this signaling to improve skin appearance.

Kisspeptin-10

A peptide involved in reproductive hormone regulation. Investigational for fertility and hypogonadism applications.

Leuprolide

A GnRH agonist used for prostate cancer, endometriosis, uterine fibroids, and precocious puberty. Marketed as Lupron.

Linaclotide

A locally acting oral peptide approved as Linzess for IBS-C and chronic idiopathic constipation. Acts in the gut lumen with minimal systemic absorption.

Lipodystrophy

Abnormal fat distribution, particularly HIV-associated lipodystrophy characterized by excess visceral fat. Tesamorelin (Egrifta) is FDA-approved for this condition.

Liposome

A spherical vesicle with a lipid bilayer membrane used to encapsulate and deliver active ingredients into skin. One of the most established nanocarrier technologies for improving cosmetic peptide delivery.

Liraglutide

An earlier GLP-1 receptor agonist marketed as Victoza (diabetes) and Saxenda (obesity). Once-daily injection, predecessor to semaglutide.

Longevity Medicine

A medical specialty focused on extending healthspan and lifespan through interventions like NAD+, peptide therapy, hormone optimization, and senolytics.

Lyophilization

Freeze-drying process used to stabilize peptide drugs for storage. Lyophilized peptides are reconstituted with sterile water before injection.

Matrikine

Endogenous peptide fragments released during extracellular matrix turnover that act as biological signals for tissue repair and remodeling. Signal peptides in cosmetics are designed to mimic matrikine activity to stimulate collagen production.

Medullary Thyroid Carcinoma (MTC)

A rare thyroid cancer. GLP-1 receptor agonists like tirzepatide carry a boxed warning for MTC risk based on rodent studies.

Melanocortin Receptor

A family of G protein-coupled receptors involved in skin pigmentation, sexual function, appetite, and inflammation. PT-141 and Melanotan II target these receptors.

Melanotan II

A synthetic melanocortin receptor agonist investigated for tanning and sexual dysfunction. Not FDA-approved; significant safety concerns including cardiovascular effects.

Membership Model

A subscription-based pricing structure common in peptide telehealth, where patients pay monthly fees for medication access, consultations, and monitoring.

Microneedle

Tiny needles (typically <1mm) that painlessly penetrate the outer skin layer to deliver drugs. An emerging delivery technology for peptides.

Mitochondrial Peptide

Peptides that target or are derived from mitochondria. MOTs-C and SS-31 are mitochondrial peptides investigated for metabolic and aging-related conditions.

MMP (Matrix Metalloproteinase)

A family of enzymes that degrade extracellular matrix proteins including collagen and elastin. UV exposure and aging increase MMP activity; enzyme-inhibitor peptides aim to block MMPs to preserve skin structure.

Mochi Health

A direct-to-consumer GLP-1 telehealth platform focused on accessible weight loss medication access.

MOTs-C

A mitochondrial-derived peptide investigated for metabolic regulation, exercise mimetic effects, and longevity. Not FDA-approved.

Mounjaro

Brand name for tirzepatide approved for type 2 diabetes. The first dual GIP/GLP-1 receptor agonist to reach market.

Multi-Receptor Agonist

A drug that activates multiple receptor types simultaneously. Next-gen metabolic drugs like retatrutide (triple GLP-1/GIP/glucagon agonist) represent this approach.

NAD+

Nicotinamide adenine dinucleotide. A coenzyme central to metabolism and cellular energy. NAD+ IV therapy and precursors (NMN, NR) are popular in the longevity space.

Nanocarrier (Cosmetic)

Nanoscale delivery systems (liposomes, nanoparticles, nanoemulsions) used to encapsulate peptides and improve their stability, skin penetration, and controlled release in topical formulations.

Neuroendocrine Tumor

A tumor arising from neuroendocrine cells. Treated with somatostatin analogs (octreotide) and peptide-radioligand therapy (177Lu-DOTATATE).

Neurotransmitter-Inhibitor Peptide

The 'Botox-like peptide' category. These peptides interfere with SNARE-complex-mediated neurotransmitter release to soften expression lines. Acetyl hexapeptide-8 (Argireline) is the best-known example, though true topical neuromuscular blockade through intact skin remains scientifically contested.

Noom

A behavior-change platform that integrated GLP-1 prescribing into its weight management program, combining medication with coaching.

Nootropic

A substance claimed to enhance cognitive function. Semax and Selank are peptide nootropics investigated for neuroprotection and cognitive enhancement.

Nutricosmetic

An ingestible product (supplement, functional food) marketed for beauty or skin health benefits. Oral collagen peptides are the most prominent peptide-based nutricosmetic category.

Octreotide

A somatostatin analog used for acromegaly and neuroendocrine tumors. Available as Sandostatin (short-acting) and Sandostatin LAR (long-acting depot).

Oral Collagen Peptides

Ingestible collagen hydrolysates (nutricosmetics) that are distinct from topical cosmetic peptides. Meta-analyses show improvements in hydration, elasticity, and wrinkles, but a 2025 analysis found benefits were not significant in non-industry-funded studies.

Oral Peptide Delivery

The challenge of delivering peptides via oral route despite protease degradation and poor absorption. Rybelsus (oral semaglutide) uses SNAC technology to achieve this.

OS-01 Peptide

A proprietary peptide used in eye formulations. A 2025 study reported improvements in transepidermal water loss, hydration, firmness, elasticity, fine lines, and under-eye appearance after 12 weeks of use.

Osteoporosis

A condition of weakened bones with increased fracture risk. Teriparatide (Forteo) is an anabolic peptide therapy that stimulates new bone formation.

Ozempic

Brand name for injectable semaglutide approved for type 2 diabetes. Widely used off-label for weight loss before Wegovy's approval.

Palmitoyl Pentapeptide-4 (Pal-KTTKS / Matrixyl)

The classic signal peptide in cosmetics, based on the KTTKS sequence. In a double-blind, placebo-controlled, split-face study of 93 women over 12 weeks, it improved fine lines and wrinkles versus control — one of the cleaner ingredient-specific clinical data points in the category.

Palmitoyl Tetrapeptide-7

A peptide with anti-inflammatory properties often paired with palmitoyl tripeptide-1 in cosmetic formulations. A 2024 clinical study showed the combination improved hydration, elasticity, and ultrasound-measured collagen density over 12 weeks.

Palmitoyl Tripeptide-1

A signal peptide used in anti-aging eye creams and serums. In fibroblast models, it increased collagen and elastin markers. Often combined with palmitoyl tetrapeptide-7 in multi-active formulations for synergistic effects.

Palmitoylation

The attachment of a palmitic acid (fatty acid) chain to a peptide to increase its lipophilicity and improve skin penetration. Used in cosmetic peptides like palmitoyl pentapeptide-4 (Matrixyl) and palmitoyl tripeptide-1.

PEGylation

The attachment of polyethylene glycol (PEG) chains to a peptide to increase its size, reduce renal clearance, and extend its half-life in circulation.

Peptide

A short chain of amino acids (typically 2–50) linked by peptide bonds. Over 80 peptide drugs are in clinical use today as a distinct drug modality.

Peptide Bond

The covalent chemical bond formed between the carboxyl group of one amino acid and the amino group of another during peptide synthesis.

Peptide-Drug Conjugate

A therapeutic strategy using peptides as targeting vehicles to deliver drug payloads to specific cells or tissues, similar to antibody-drug conjugates.

Permeation Enhancer

A substance that increases the absorption of drugs across biological membranes. Critical technology for oral peptide delivery to overcome the gut barrier.

Petrelintide

An investigational amylin analog being studied for obesity treatment, designed to complement GLP-1 receptor agonist therapy.

Pharmacokinetics (PK)

The study of how the body absorbs, distributes, metabolizes, and excretes a drug. Peptide PK is dominated by rapid protease degradation and renal clearance.

Phase 3 Clinical Trial

The final stage of clinical testing before FDA approval, involving large patient populations to confirm efficacy and safety. Retatrutide and survodutide are in Phase 3.

Photoaging

Premature skin aging caused by chronic UV exposure, characterized by wrinkles, pigmentation changes, and loss of elasticity. A 2024 review concluded that peptide evidence is among the stronger in the cosmeceutical space for addressing photoaging.

Post-Procedure Recovery (Peptides)

The use of peptide formulations to accelerate healing after dermatological procedures (laser, microneedling, chemical peels). One of the strongest evidence areas for cosmetic peptides, as the disrupted skin barrier allows better peptide penetration.

Protease

An enzyme that breaks down peptides and proteins by cleaving peptide bonds. Protease degradation is a major challenge for peptide drug stability and oral bioavailability.

PT-141 / Bremelanotide

A melanocortin receptor agonist FDA-approved as Vyleesi for hypoactive sexual desire disorder (HSDD) in premenopausal women.

Q-Peptide

A peptide regimen studied in post-procedure recovery. A 2025 randomized split-face study after radiofrequency microneedling found it reduced edema, erythema, and purpura and improved early recovery versus peptide-free control.

Radioligand Therapy

A targeted cancer treatment that uses a ligand (often a peptide) to deliver a radioactive isotope directly to tumor cells expressing the target receptor.

Receptor Agonist

A substance that binds to a receptor and activates it, producing a biological response. Many peptide drugs (e.g., GLP-1 agonists) work by mimicking natural hormones.

Receptor Antagonist

A substance that binds to a receptor and blocks its activation, preventing the natural ligand from producing its effect. Degarelix is a GnRH antagonist example.

Retatrutide

An investigational triple agonist (GLP-1/GIP/glucagon receptor) in Phase 3 trials showing unprecedented weight loss efficacy.

Ro

A mass-market telehealth platform focused on FDA-approved branded medications (Wegovy, Zepbound) with a pharmacy network and insurance navigation.

Rybelsus

Brand name for oral semaglutide, the first GLP-1 receptor agonist available in pill form. Uses SNAC absorption enhancer technology.

Scar Remodeling

The process of reorganizing scar tissue to improve appearance and function. Some peptides (Argireline, ADSCP6) show preliminary evidence for scar improvement, but the evidence base remains thin — mostly preclinical or small case series.

Selank

A synthetic peptide derived from tuftsin, investigated for anxiolytic and nootropic effects. Not FDA-approved; available as a research peptide.

Semaglutide

A GLP-1 receptor agonist marketed as Ozempic (diabetes), Wegovy (obesity), and Rybelsus (oral). The most commercially significant peptide drug, driving the GLP-1 telehealth boom.

Semax

A synthetic peptide derived from ACTH, investigated for neuroprotective and cognitive-enhancing effects. Approved in Russia but not by the FDA.

Senolytic

A compound that selectively eliminates senescent (aged, non-dividing) cells. An emerging area in longevity medicine, sometimes combined with peptide therapies.

Sensitive Skin (Peptide Context)

A skin condition characterized by heightened reactivity, redness, and discomfort. Anti-inflammatory peptides and TRPV1-modulating peptides show promise for calming inflammatory tone and improving tolerance in sensitive skin.

Sermorelin

A GHRH (growth hormone-releasing hormone) analog historically FDA-approved for GH deficiency diagnostics under the brand name Geref. Now primarily compounded.

Signal Peptide (Cosmetic)

Peptides designed to mimic endogenous peptide fragments or matrikines that signal skin to initiate repair. They nudge fibroblasts toward producing more collagen, elastin, fibrillin, and related extracellular-matrix components. The most studied class in anti-aging peptide science.

Skin Penetration

The ability of a topical ingredient to pass through the skin barrier to reach target cells. The central limitation of cosmetic peptides — many are too large, hydrophilic, and enzymatically fragile to penetrate effectively without delivery enhancement.

SNAC

Sodium N-[8-(2-hydroxybenzoyl)amino]caprylate. An absorption enhancer used in Rybelsus to enable oral delivery of semaglutide by transiently increasing gastric permeability.

SNARE Complex

A protein complex that mediates neurotransmitter release at nerve endings. Neurotransmitter-inhibitor peptides like Argireline are proposed to interfere with SNARE assembly to reduce muscle contraction and expression lines.

Somatostatin

A peptide hormone that inhibits growth hormone, insulin, and glucagon release. Octreotide is a synthetic somatostatin analog with clinical applications.

Split-Face Study

A clinical trial design where one side of a participant's face receives the active treatment and the other side receives a control. Considered a strong design for cosmetic studies as each person serves as their own control.

SS-31 / Elamipretide

A mitochondria-targeted peptide investigated for mitochondrial dysfunction, heart failure, and rare diseases. In clinical trials.

Sterile Compounding

Preparation of medications in a sterile environment, required for injectable peptides. Subject to USP <797> standards for contamination prevention.

Stratum Corneum

The outermost layer of the skin that acts as the primary barrier to topical drug delivery. The classic '500 Dalton rule' states that molecules larger than ~500 Da struggle to penetrate it, which is the central challenge for cosmetic peptide efficacy.

Subcutaneous Injection

Injection into the fatty tissue beneath the skin. The dominant route of administration for peptide therapeutics due to reliable absorption and patient self-administration.

Survodutide

An investigational dual GLP-1/glucagon receptor agonist in clinical development for obesity and metabolic liver disease.

Target Specificity

The ability of a peptide drug to selectively bind its intended receptor with minimal off-target effects, a key advantage of peptide therapeutics over small molecules.

Telehealth

Remote healthcare delivery via digital platforms. GLP-1 telehealth platforms (Hims, Ro, Noom) have driven massive growth in peptide prescribing.

Telomerase

An enzyme that maintains telomere length, associated with cellular aging. Epithalon is investigated for telomerase activation as an anti-aging strategy.

Teriparatide

A parathyroid hormone analog (PTH 1-34) marketed as Forteo for severe osteoporosis. Stimulates new bone formation rather than just preventing resorption.

Tesamorelin

An FDA-approved GHRH analog marketed as Egrifta for HIV-associated lipodystrophy. Stimulates endogenous growth hormone release.

Thymosin Alpha-1

An immune-modulating peptide with applications in hepatitis and immunodeficiency. Approved in some countries but not FDA-approved in the U.S.

Thymosin Beta-4

A peptide involved in tissue repair and wound healing. Investigational status; commonly found in gray-market peptide offerings.

Thymosin Beta-4 (Cosmetic Context)

A regenerative peptide with accelerated dermal healing evidence in animal models and Phase 2 trial signals in chronic wounds. Closer to true regenerative medicine than ordinary cosmeceuticals, with effects on cell migration, stem-cell mobilization, and inflammation.

Tirzepatide

A dual GIP/GLP-1 receptor agonist marketed as Mounjaro (diabetes) and Zepbound (obesity). Carries a boxed warning for medullary thyroid carcinoma risk.

Transdermal Delivery

Drug delivery through the skin. Generally challenging for peptides due to their size and hydrophilicity, though microneedle patches show promise.

TriHex Technology

A proprietary peptide complex with evidence in post-laser recovery. A 2025 study reported improvements in facial skin quality after 12 weeks, with histologic evidence of new dermal collagen and elastin fibers and increased epidermal hyaluronic-acid signaling.

TRPV1 Modulation

Targeting the TRPV1 receptor (transient receptor potential vanilloid 1) in skin to reduce sensitivity and inflammation. A 2025 study showed peptide-based TRPV1 modulation improved texture, elasticity, and reduced erythema in sensitive skin after 4 weeks.

USP/NF Monograph

United States Pharmacopeia / National Formulary monograph. Official standards for drug substance identity, purity, strength, and quality. Required pathway for 503A compounding eligibility.

Wegovy

Brand name for higher-dose injectable semaglutide approved specifically for chronic weight management in adults with obesity.

WeightWatchers / Sequence

WeightWatchers acquired Sequence to add clinical weight management with GLP-1 prescribing to its traditional behavioral program.

Zepbound

Brand name for tirzepatide approved for chronic weight management. Eli Lilly's obesity-specific formulation of the dual agonist.