[Discussion] can we stop arguing about 503B until somebody posts a number
Slightly embarrassed to be asking this, but: can we stop arguing about 503B until somebody posts a number.
Asked for potency testing on the finished preparation. They had it. I had assumed they would not.
On concentration, which is where I see people actually get hurt.
A compounded vial can be filled at a different concentration from the branded product you were previously using. If you carry over your old arithmetic — same number of units, different mg/mL — you draw a different amount and may not notice for weeks.
Read the label every time you switch. Redo the arithmetic on paper. Write the concentration on the vial. It is the same habit c/reconstitution keeps preaching and this is the case where it actually bites.
Why "compounded" is not "generic", written out because the confusion is constant.
A generic is an approved product demonstrated to be bioequivalent to a reference. A compounded preparation is made for a patient or, in the case of an outsourcing facility, under a different regulatory route entirely. It carries no equivalence claim and it is not required to demonstrate one.
That is not a quality judgement. Plenty of compounded preparations are made carefully in facilities with real testing programmes. It is a statement about what has and has not been established, and the difference matters when people assume the two are interchangeable.
Happy to answer the boring questions. Those are usually the ones worth asking.
best — the order this archive was captured in
The shortage list is the legal hinge: the permissions that allow certain compounding to happen at scale are tied to a drug’s shortage status, which changes.
Reminder that nothing here is medical advice and this board cannot tell you which arrangement to choose.
The five questions worth asking before you commit to any compounded arrangement.
Which facility, by name. Whether it is a 503A pharmacy or a 503B outsourcing facility. What concentration is on the label. What the beyond-use date is based on. Whether there is potency testing on the finished preparation rather than only on the starting material.
All five are answerable in one email and the pattern of what comes back is more informative than any of the individual answers. An organisation with a quality system finds these questions ordinary.
That figure is the starting material purity, not the finished preparation potency. Two different tests.
Concentration on the compounded vial was different from what I had been using and I nearly did the arithmetic on autopilot.
503A is patient-specific, 503B is outsourcing facility, they are not the same thing
503A or 503B — do you know which?
Yes — asking which facility, by name, is the single most useful question and most clinics will answer it.
if a clinic will not name the facility, that is your answer
That is not what patient-specific means. It refers to the prescription, not to a customisation of the formula.
Was there potency testing on the finished preparation, or only on the starting material?
Is the compound still on the shortage list where you are?
Correction: patient-specific refers to the prescription, not to a bespoke formulation. Common misreading and it changes the argument.
Correction: patient-specific refers to the prescription, not to a bespoke formulation.
Disagreeing with this bit: registration is not equivalence, and the two get run together constantly.
ask what the beyond-use date is based on
Paid noticeably more at one clinic than another for what turned out to be the same facility behind both.
Did they name the facility?
Disagree — a 503B being registered does not make its preparations equivalent to an approved product. Different regulatory category entirely.
Small fix — 503B facilities register with the regulator; 503A pharmacies are licensed by the state board. Different mechanisms.
ask which facility, then ask for their testing
Switched between two compounded preparations and the concentration on the label was different. Redid the arithmetic on paper before drawing anything.
Asked for the beyond-use date basis and got a real answer with a stability reference attached. Not universal, apparently.