Glossary
Plain-English definitions for terms used across PepStack. No jargon without explanation.
Amino Acid
The building blocks of proteins and peptides. There are 20 standard amino acids that combine in different sequences to form peptides and proteins.
Bioavailability
The percentage of a substance that enters your bloodstream and is available to have an active effect. Different administration routes affect bioavailability.
Clinical Trial
A research study that tests how well new medical approaches work in people. Trials go through phases (I-IV) with increasing numbers of participants.
Compounding Pharmacy
A pharmacy that creates customized medications by mixing ingredients. Some peptides are available through compounding pharmacies with a prescription.
Contraindication
A condition or factor that makes a particular treatment or procedure inadvisable. For example, pregnancy is a contraindication for most peptides.
Evidence Tier
PepStack's rating system (1-5) indicating the strength and quality of scientific evidence supporting a peptide's effects. Tier 1 = FDA approved, Tier 5 = preclinical only.
FDA Approval
Formal authorization by the U.S. Food and Drug Administration for a drug to be marketed and sold for a specific medical use, based on clinical trial evidence.
Half-Life
The time it takes for half of a substance to be eliminated from your body. A longer half-life means the substance stays active longer.
Intramuscular (IM)
An injection administered directly into a muscle. Some peptides are given via intramuscular injection for faster absorption.
Mechanism of Action
How a substance produces its effects in the body --- the specific biochemical interaction through which a drug or peptide works.
Peptide
A short chain of amino acids (typically 2-50). Peptides are smaller than proteins and can act as signaling molecules in the body, triggering specific biological responses.
Phase I Trial
The first stage of clinical testing, focused on safety and dosing in a small group (20-80 people). Tests whether a treatment is safe, not whether it works.
Phase II Trial
Tests whether a treatment works for a specific condition in a larger group (100-300 people). Also continues to evaluate safety.
Phase III Trial
Large-scale trials (1,000-3,000+ people) that confirm effectiveness, monitor side effects, and compare to existing treatments. Required for FDA approval.
PMID
PubMed Identifier --- a unique number assigned to each article in the PubMed database. Used to find and verify specific research papers.
Preclinical
Research conducted before human testing, including laboratory (in-vitro) and animal studies. Preclinical results do not guarantee the same effects in humans.
Protocol
A specific dosing plan including the amount, frequency, route of administration, and duration. Research protocols are from published studies, not medical advice.
Randomized Controlled Trial (RCT)
A study where participants are randomly assigned to receive either the treatment or a placebo. Considered the gold standard for clinical evidence.
Reconstitution
The process of mixing a freeze-dried (lyophilized) peptide powder with sterile water or bacteriostatic water to create an injectable solution.
Subcutaneous (SubQ)
An injection given into the fatty tissue just beneath the skin. The most common administration route for peptides used outside clinical settings.