Glossary: GLP-1, Peptide & Telehealth Terms

GLP-1 and weight

GLP-1: Glucagon-like peptide-1, a hormone the gut releases after eating that signals fullness and slows how quickly the stomach empties. The GLP-1 pathway is the basis of the modern generation of weight-management and type 2 diabetes medications. The science of semaglutide
GLP-1 receptor agonist: A medication that activates the GLP-1 receptor to mimic the GLP-1 hormone. Semaglutide is a GLP-1 receptor agonist.
GIP: Glucose-dependent insulinotropic polypeptide, a second gut hormone involved in how the body handles blood sugar and fat. Tirzepatide acts on both the GIP and GLP-1 receptors.
Dual agonist: A medication that activates two receptors at once. Tirzepatide is a dual GIP and GLP-1 receptor agonist. Semaglutide vs tirzepatide
Semaglutide: A GLP-1 receptor agonist used for type 2 diabetes (brand Ozempic) and chronic weight management (brand Wegovy), taken as a once-weekly injection. Also available as a compounded medication, which is not FDA-approved. The science of semaglutide
Tirzepatide: A dual GIP and GLP-1 receptor agonist used for type 2 diabetes (brand Mounjaro) and chronic weight management (brand Zepbound), taken as a once-weekly injection. Also available as a compounded medication, which is not FDA-approved. The science of tirzepatide
Retatrutide: An investigational triple agonist (GLP-1, GIP, and glucagon receptors) being studied for weight management. Retatrutide is not FDA-approved.

Hormones and peptides

Peptide: A short chain of amino acids that acts as a biological messenger, binding to specific receptors to signal the body to do something. Insulin and GLP-1 are peptides. The science
Testosterone replacement therapy (TRT): Provider-supervised treatment that brings testosterone levels back into a healthy range in men with diagnosed low testosterone, guided by bloodwork and monitored over time. How much does TRT cost?
Hypogonadism: A medical condition in which the body produces too little testosterone, diagnosed with bloodwork. It is the condition testosterone therapy is approved to treat.
Growth-hormone secretagogue: A peptide that prompts the pituitary gland to release more of the body's own growth hormone. Sermorelin and CJC-1295/Ipamorelin are examples.
NAD+: Nicotinamide adenine dinucleotide, a coenzyme central to how cells produce energy and repair DNA. Its levels decline with age.
GHK-Cu: A naturally occurring copper-binding peptide studied for its role in skin and tissue support. Sold by some clinics as a compounded peptide; not FDA-approved.
BPC-157: A synthetic peptide studied primarily in laboratory and animal research for tissue repair. It is not FDA-approved, and the human evidence base is limited.
PT-141 (bremelanotide): A peptide FDA-approved as bremelanotide to treat hypoactive sexual desire disorder in premenopausal women. Other uses are off-label.

Pharmacy and regulation

Compounded medication: A medication custom-prepared by a licensed pharmacy for an individual patient on a prescription. Compounded medications are not FDA-approved, meaning the FDA has not reviewed them for safety, effectiveness, or quality before they are dispensed. Compounded vs brand: is it legal?
FDA-approved: A status meaning the FDA has reviewed a specific product for safety and effectiveness for a specific use before it is marketed. Brand medications are FDA-approved; compounded medications are not.
503A pharmacy: A state-licensed pharmacy that compounds medications for individual patients, generally on a prescription, under section 503A of the federal Food, Drug, and Cosmetic Act. Compounded vs brand: is it legal?
503B outsourcing facility: A facility that registers with the FDA to compound medications at larger scale under current good manufacturing practice (CGMP) standards, governed by section 503B of the federal Food, Drug, and Cosmetic Act.
Titration: Gradually increasing a medication's dose over time to a maintenance level. GLP-1 medications are titrated up over weeks under a provider's guidance.
Off-label use: Prescribing an approved medication for a use other than the one the FDA approved. It is a medical decision made by a licensed provider, not something a patient self-selects.
Telehealth: The delivery of medical care remotely, by video or secure messaging, by a licensed provider. Expert Health connects you with US-licensed providers who deliver care this way. How Expert Health works

These definitions are general and educational, not medical advice. Compounded medications are not FDA-approved. Always consult a licensed provider before starting any treatment.

The terms, in plain English.

GLP-1 and weight

Hormones and peptides

Pharmacy and regulation

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