Compounding pharmacies, compared.

A compounding pharmacy is not an FDA-approved drug manufacturer. It prepares medications under federal exemptions — and which exemption it operates under shapes everything about quality oversight and how you can buy from it.

503A pharmacies compound patient-specific prescriptions under state licensure; they're exempt from pre-market approval and federal CGMP. 503B outsourcing facilities register with the FDA, follow CGMP, accept inspection, and can compound in larger batches for office use without patient-specific prescriptions. The trade-off is oversight versus flexibility. For the full regulatory picture, see compounded vs branded peptides and how peptides are prescribed.

What this means when you're buying. If you need office stock ready before a specific patient walks in, that's 503B territory; if you're filling an individual prescription, that runs through 503A. Several larger operators hold both registrations (Empower and Belmar do), so the same company can serve either need — but only the 503B side carries the FDA CGMP-and-inspection paper trail.

Beyond the 503A/503B line, the quality signals worth checking are PCAB accreditation (voluntary, via ACHC), NABP standing, and — for anything sterile or injectable — adherence to USP <797> (sterile preparations) and <800> (hazardous drugs). Those, plus a facility's FDA inspection record, are what we weigh in each profile below.

One caveat up front: legal status here moves. After the 2025 shortage delistings of semaglutide and tirzepatide, bulk 503B compounding of those specific molecules lost its footing — what a given pharmacy may compound can change quarter to quarter, so every profile is dated. See our regulatory tracking for the timeline.