What constitutes a First in Class designation for new molecular entities? I've seen this term on FDA documents, as well as in databases (Chembl for example), but I was curious if there are any set criteria for First in Class drugs? The easy definition, in my mind, would be a drug that hits a novel target given its indication. However, if you look at antifungal drugs, you see that drugs with the same target for the same general indication (anti-fungal) treat completely different fungal infections because of their pharmacokinetics.

Are there discrete criteria for the FDA's first-in-class designation for New Molecular Entities?

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    $\begingroup$ This page on the FDA website gives a rather terse definition: "Drugs with a new and unique mechanism for treating a medical condition". I'm not sure how that's applied in practice, though. $\endgroup$
    – R.M.
    Jul 21, 2016 at 18:36
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    $\begingroup$ What is FDA? What is the biological problem regarding this molecule? $\endgroup$
    – David
    Dec 24, 2020 at 21:24
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    $\begingroup$ @David the FDA is the Food and Drug Administration in the US. Among other things, they are charged with regulating and approving pharmaceuticals. $\endgroup$
    – MattDMo
    Dec 25, 2020 at 17:30
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    $\begingroup$ @MattDMo — So the question is about public health policy in one particular country, and not about a problem in biology of the type defined in the Tour. $\endgroup$
    – David
    Dec 27, 2020 at 17:11

1 Answer 1


"First-in-class drugs are ones that use a new and unique mechanism of action for treating a medical condition. These products are often referred to as innovative and cited as offering new treatment options for patients."

Lanthier, M. et al. (2013) "An improved approach to measuring drug innovation finds steady rates of first-in-class pharmaceuticals, 1987-2011." J.Health Aff. (Millwood) 32:1433-9;

Pharmaceutical Research and Manufacturers of America. 2015b. Innovative Oncology Medicines Have Led to Impressive Gains in Patient Survivorship. Retrieved August 26, 2015. <www.phrma.org/innovative-oncology-medicines-have-led-to-impressive-gains-in-survivorship>."

From: Lexchin, J. (2016) "How Safe and Innovative Are First-in-Class Drugs Approved by Health Canada: A Cohort Study" Healthc. Policy 12:65-7.


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