503A and 503B are both FDA- and state-regulated. Research-chemical vendors are not. Know which regulatory regime the product you are buying falls under — it dictates labeling, what you can tell patients, and your downstream liability.

US-based manufacturing does not guarantee quality, but it places the product inside FDA jurisdiction and generally correlates with more rigorous process controls.

Verify directly with the state board of pharmacy and, for 503B, the FDA registration list. Do not rely on the supplier's own marketing claim.

A legitimate COA is lot-specific and includes identity, purity (by HPLC), mass-spec identity confirmation, endotoxin testing, and manufacture/retest dates. A generic COA that repeats across shipments is a red flag.

Third-party testing is a stronger quality signal. For higher-risk products, ask for both.

Clinical-grade peptides should typically be ≥ 98% purity. Identity should be confirmed by mass spectrometry or an equivalent orthogonal method — HPLC alone can miss substitutions.

Lyophilized products generally have a longer shelf life (often 12+ months). Pre-reconstituted solutions may expire in as little as 3 months, creating real inventory risk if demand is uneven.

Direct-to-patient shipping on a valid prescription is the standard workflow for compounded medications and is operationally simpler. Clinic-only shipping puts storage and inventory burden on your practice.

Benchmark the supplier's wholesale pricing against research-chemical retail prices (which many patients can find themselves). If the cost to you already exceeds typical retail, the unit economics will not work.

Search the FDA warning letter database, FDA Form 483 observations, state board disciplinary actions, and public news coverage. A history of recalls or enforcement action does not automatically disqualify a supplier, but it should change what you require of them going forward.