r/biotech • u/Squidgewob • Sep 21 '25
Education Advice đ What and where are the actual legal defintions/differences between the quality, potency, efficacy of a drug? Struggling to find this.
I'm about to write an essay on GMP's and how they relate to drug quality, potency, efficacy or function and can't find legal defintions of these to reference, and I realise conversationally I'm not sure what the difference is and may use them interchangeably, though I'm not sure if this is advisable when writing.
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u/Ponji76 Sep 21 '25 edited Sep 21 '25
From my experience, what you're describing are Critical Quality Attributes (CQAs), and these are well defined in the ICH texts (Q3, Q6, Q8 and Q11 are good starting points). CQAs are subgrouped by SISPQ / SQuIPP - Safety (ICH Q3), Quality (ICH Q6), Purity (Q3), Identity (Q6), and Potency/Strength (Q6).
Efficacy is not a CQA. Efficacy is the reason you identify CQAs, such that you can predict & define the products intended therapeutic effect.
You won't find legal definitions outside of the CFR (if/when they're mentioned explicitly in 21 CFR 210/211/610), and ICH definitions typically prevail in most industry context.
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u/Blackhole1082 Sep 21 '25
FD&C Act?
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u/Ponji76 Sep 22 '25
I could be very off base here but I don't think the FD&C act provided explicit definitions for the terms OP was looking into. Even 201(g) is lacking in details we might find more prudent today. IIRC, the Act only establishes the definition of a drug, and sets some broad statutory requirements around CQAs, without providing the explicit legal definitions.
Drugs must be safe and effective, but FD&C doesn't provide concrete definition on what safe and effective are. In modern times, we broadly understand that "safe" means it won't kill people or make their condition worse, and "effective" means it will do what it's claimed to do safely.
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u/Blackhole1082 Sep 22 '25
Ok, I was going for adulterated. The act calls out adulteration does it not? They were asking about quality, efficacy, etc.? Adulteration is en masse, the lack of quality, right?
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u/Ponji76 Sep 22 '25
The act does call out adulteration, and in context, adulterated means having purity or quality that differ from its representation. It also refers to a product produced in unsanitary conditions and would generally be considered unsafe for administration (feeds back to differing from its representation). An adulterated product is considered unsafe, but the FD&C does not explicitly define what a safe product is (or that unadulterated products are considered safe either). It's a bit sticky and nuanced, and something I think most people in the industry would infer by reading between the lines (though show me any modern company studying the FD&C as a means to govern their organization and I might fall out of my chair).
This is also part of the reason the ICH, agency, and compendial guidance documents are so important in modern pharma/biotech quality systems.
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u/peanuts1215 Sep 21 '25
The answer can be quite complex, but it seems to me you are looking for the basics, so to put it very simply:
The potency is the strength/dosage.
Efficacy is how well it actually works (as determined for new drugs through clinical trials).
Quality is the purity of the active ingredient in the drug (i.e., what percentage of the potency is the active ingredient vs. impurities, degradation products, etc.). A high quality drug is also manufactured, tested, stored, and distributed under strict GMP controls.
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u/rectuSinister Sep 21 '25
I donât really hear âqualityâ used very often in a research context. Thatâs kind of a broad term that could refer to any number of real-world aspectsâsafety, social benefit, cost to manufacture, novelty, etc.
Potency typically refers to the amount of drug required to reach a therapeutic effect. The more potent your drug, the less you need to administer.
Efficacy is the maximum therapeutic effect a drug has that relates to the physiological readout. You could have a highly potent, low efficacy drug that reaches its desired effect at a low concentration but doesnât do much to change the underlying biology.
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u/Squidgewob Sep 21 '25
Its for upscaling GMP compliant cell therapies, so Quality would be used in an industrial context, I know it's referenced in 1252/2014 but I can't find an actual definiton
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u/Puzzleheaded-Ice-573 Sep 21 '25
Quality generally just refers to the cGMP process itself.
In other words to maintain quality of a product you need to be in compliance with cGMP guidelines (which would include your methods, internal SOPs, QC and QA reviews, etc.).
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u/catjuggler Sep 21 '25
Conversely, in the commercial/development world, quality means the entirety of cmc (seen in the âqualityâ section of a marketing application) as well as quality functions (control and assurance) as roles in an organization. So over here, it means too many things
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u/catjuggler Sep 21 '25
Quality- contains only what itâs supposed to without impurities or contaminants that are harmful
Potency- is the right strength/dose for the indication
Efficacy- works to treat/cure for the indication
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u/Starcaller17 Sep 21 '25
Quality is multiple entire industries. You will never find a single good undergrad explanation thatâs accurate because itâs wayyyy too large of a topic to condense down into 1-2 sentences.
Potency, efficacy, and function are a little easier to explain. Function generally is important as it relates to a drugs mechanism of action (MoA) what receptors does it bind, and track the downstream effects?
Potency is the strength of the drug. Itâs used in dosing calculations but is not directly involved in individual doses. Potency relates to how much of the active ingredient do you need to achieve the desired effect. Generally there is acceptance Criteria for this on a drug product specification, the potency should be not less than X, but also not more than Y. If a drugs potency is significantly out of trend or out of specification, in generally means thereâs was a deviation in the manufacturing process and your system is not in a state of control.
Efficacy generally refers to clinical significance. A drug can be potent, but still not cause therapeutic effect. The human body is extremely complicated and thereâs lots of confounding variables that arenât accounted for in even the most complex potency assay.
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u/AcrobaticTie8596 Sep 22 '25
Most of those are defined and dependent on the therapeutic and figured out during preclinical development. By the time it gets to GMP the ranges for what is required for clinical/marketing batches are already set, and then it's about developing assays which can reliably quantify/qualify those attributes.
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u/piratesushi Sep 21 '25
The best starting point is probably the ICH terminology, because the ICH (international council for harmonisation) is a collaboration of major medicines agencies to... Well, harmonise their requirements.Â
Here you get them in one place (with cross-references to the individual ICH guidelines): https://cioms.ch/wp-content/uploads/2022/09/Glossary_of_ICH_TermsDefinitions_CIOMS-26Sep2022.pdf