A little help
with the words.

Words you may meet.

Peptide

A short chain of amino acids, the building blocks of proteins. The word identifies a kind of substance. It does not establish that a product is safe, approved or appropriate for a person.

Receptor

A part of a cell that receives a signal. When a guide says a medicine acts at a receptor, it is describing a target in the body, rather than an expected result for every person.

GLP-1 and GIP

Gut hormones involved in the body’s response to food. Semaglutide acts at GLP-1 receptors; tirzepatide acts at both GIP and GLP-1 receptors. The initials describe signals, not a ranking of treatments.

Compounded medicine

A medicine prepared to meet a particular patient’s needs. Compounded medicines are not FDA-approved. A provider’s prescription and a pharmacy’s decision about lawful preparation are separate steps.

FDA approval

A decision by the U.S. Food and Drug Administration about a specific medicine and its uses. It does not follow an ingredient name into all products that contain it. Approved semaglutide and tirzepatide products exist; compounded versions are not FDA-approved.

Topical

Placed on the skin. A topical cream and an injection are different forms. Evidence for one cannot establish what the other does. This distinction matters in the GHK-Cu guide.

Placebo

A comparison treatment with no active ingredient. Comparing groups can help researchers separate the effect of the substance being tested from changes that might have happened anyway.

Animal or cell study

Work in an animal model or cells in a laboratory. It can suggest a question for further research. It cannot establish a human treatment result or tell someone what to expect from taking a substance.

Nominated but withdrawn

A term on the FDA’s compounding safety page, current as of April 22, 2026. A request for consideration was withdrawn. That is not FDA clearance or approval, and the FDA’s safety concerns remain.

Licensed provider

A health professional authorized to make care decisions within their scope of practice. At Promise Peptides, a licensed U.S. provider reviews each request and decides whether to prescribe. Not everyone qualifies.