Glossary
This market runs on terms that sound like they mean one thing and legally mean another. "Off Category 2" is not permission. "Research use only" is not a quality standard. Here is every term we use, defined so you can check us.
How compounding actually works
503A pharmacy
A pharmacy that compounds a medicine for one named patient at a time, against a prescription.
Named for the section of federal law that exempts it from new-drug approval, adequate-directions labelling and manufacturing rules — but only if it meets every condition attached, including that the active ingredient comes from an FDA-registered establishment with a valid certificate of analysis. Licensed by a state board, not the FDA.
503B outsourcing facility
A compounder that can make batches for office stock without patient-specific prescriptions.
Registers with the FDA, is inspected on a risk-based schedule, and must follow current good manufacturing practice. There are 97 of them. Being registered is not the same as being inspected — 42% never have been.
Bulk drug substance
The raw active ingredient a pharmacy compounds with, as opposed to a finished approved drug.
The regulatory question is always whether a given bulk substance is eligible to be compounded at all, which is what the 503A Bulks List settles.
503A Bulks List
The binding federal list of bulk substances a 503A pharmacy may compound with when no monograph or approved-drug route exists.
Codified at 21 C.F.R. 216.23. It currently contains six substances and has never included a peptide. Adding anything requires notice-and-comment rulemaking, which historically takes years.
Category 1 / 2 / 3
FDA's interim triage of nominated substances while it decides. Non-binding guidance, not the binding list.
Category 1 carries enforcement discretion — FDA says it does not intend to act. Category 2 means identified safety risks and no discretion. Category 3 means insufficient information. Critically, a substance on no list at all also gets no discretion, so removal from Category 2 is not permission.
PCAC
The Pharmacy Compounding Advisory Committee. It advises; the FDA decides.
Its recommendations are non-binding and have gone against FDA's own scientific reviewers — in July 2026 it backed six of seven peptides that FDA staff had recommended against, several by a single vote.
Research use only (RUO)
A label asserting a substance is a laboratory reagent rather than a medicine.
It makes no claim about purity, sterility or dosing accuracy. The rule it borrows from governs in-vitro diagnostic devices and has never applied to peptide drug products. One state pharmacy board has stated plainly that a clinic possessing RUO product is in violation regardless of patient consent.
Certificate of analysis (COA)
A lab report on a specific batch of a substance.
Only as good as its provenance. An independent third-party lab is meaningful; a vendor's in-house sheet is marketing. A COA for a different lot tells you nothing about the vial you were sent, and sterility and endotoxin testing — the tests that matter for anything injected — are frequently absent.
Drug Master File (DMF)
A confidential filing by a company that supplies an active ingredient to the US market.
The FDA publishes the list of who has filed, which is how it is possible to say that 56 of 71 active semaglutide ingredient filings are held by Chinese firms.
What you actually pay
True monthly cost
Medication plus every fee you cannot avoid, on the cadence you are actually billed.
The number this site ranks on. A $199 medication with a required $149 membership is $348, and a $30 plan billed $90 quarterly is a $90 charge.
Listed price
A price published on the provider's own page on a stated date.
One of the three status labels we use. It means we read it at the source, not that we completed a checkout.
Reported price
A price from concordant published sources where the provider's own page blocks verification.
Weaker than a listed price and labelled differently, because several providers gate pricing behind an intake flow.
Checkout-verified
A price someone confirmed by going through the actual purchase flow.
The strongest label we apply, and the rarest, because it requires a human to walk the flow.
Direct-pay / cash-pay
Buying without insurance, at a price the seller sets.
For GLP-1s the manufacturer-run channels are the reference cash prices, and telehealth brands often resell the same product with a membership on top.
Most-favoured-nation (MFN) pricing
A commitment to sell in the US at no more than the price charged in comparable countries.
Both GLP-1 manufacturers signed such agreements with the White House in November 2025; the TrumpRx channel followed in February 2026.
NADAC
The federal survey of what US pharmacies actually pay for drugs on invoice.
Not a list price and not an estimate — a weekly survey of acquisition cost. It is why we can say a month of generic finasteride costs a pharmacy $1.28 while a single Viagra tablet costs $83.63.
Titration
Stepping a dose up gradually to the target.
It matters to cost because several channels price by dose tier, so the cheap starting month is not what year one costs.
Reading evidence without being fooled
Surrogate endpoint
A measurement that stands in for the outcome you actually care about.
Blood NAD+ is a surrogate; living longer is the endpoint. Drugs that reliably moved surrogates have repeatedly failed to improve outcomes, which is why a moved number is a reason to run the trial rather than a substitute for having run it.
Estimand
The precise question a trial's headline number answers.
The same trial can report different figures depending on how it handles people who stop taking the drug. Orforglipron reports −11.2% under one estimand and −12.4% under another; both are real and they are not interchangeable across trials.
Head-to-head trial
A trial that compares two drugs directly, in the same population, at the same time.
Worth far more than comparing numbers from separate trials, which differ in population, duration and analysis before the drugs differ at all. SURMOUNT-5 is the only head-to-head between the two leading GLP-1s.
Confidence interval
The range a result is compatible with.
If it crosses zero, the trial did not show a statistically significant effect. The most-cited BPC-157 result has an interval running from −4.84 to 1.62, which is how a widely repeated 'successful trial' turns out not to have shown benefit.
Form 483
A list of an FDA investigator's observations at the end of an inspection.
Observations, not final findings, and facilities routinely correct them. Still worth reading: 49 of the 97 registered outsourcing facilities have one from their most recent inspection.
Trust signals and what they are worth
LegitScript certification
A third-party certification that an online pharmacy meets a defined standard.
We verify it against the certifying body's own seal server rather than trusting a badge image on a merchant's site, because a badge is just a picture.
Corporate transparency
Whether a company names its legal entity, address, leadership and ownership.
A disclosure test, not a quality test. What weak disclosure costs you is recourse: if you cannot name the entity, you cannot easily dispute a charge, file with a regulator, or join a claim.
Paid newswire release
A press release the subject paid to distribute, which then appears on news-looking sites.
Some are written in the voice of an independent review. The test is whether any named journalist at any outlet wrote about it, or whether every result is a syndication of the same release.
Medical director
A clinician named as overseeing a clinic or platform.
Three Ohio boards jointly stated that naming a clinician who never evaluates the patient does not create the prescriber relationship required before prescribed drugs are administered. The useful question is who actually reviewed your intake, by name.
Terms we deliberately avoid
- "FDA-approved" for anything compounded. Compounded medicines are not FDA-approved, whatever the molecule inside them is. Saying otherwise is the single most common error in this category's marketing.
- "Generic Ozempic" or "generic Wegovy." No generic semaglutide exists in the US. A compounded version is a different regulatory object, not a generic.
- "Clinically proven" without naming the trial, the endpoint and the sample size — all three, or the phrase means nothing.
- "Verified" for a price we only read on a page. That one is listed, and we label it that way.
Definitions written for clarity, not as legal or medical advice. Where a term has a precise regulatory meaning we have linked the page that carries the primary sources. If one of these is wrong, tell us — the correction lands in our public corrections log.