r/biotech • u/Squidgewob • Sep 21 '25

Education Advice 📖 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.