Unpacking the Definition: What is a first in class drug FDA?

October 15, 2025 •

3 min read

According to the Food and Drug Administration (FDA) Center for Drug Evaluation and Research, a first-in-class drug is a novel medication that employs a unique mechanism of action to treat a medical condition. This status is often a marker of significant innovation in the pharmaceutical industry and can offer a new therapeutic approach for patients.

Quick Summary

A first-in-class drug is a medication with a new and unique mechanism of action. This status indicates pharmaceutical innovation but is not a formal regulatory category by the FDA, though it is closely monitored.

Key Points

Novel Mechanism: A first-in-class drug is defined by its new and unique mechanism of action, addressing a medical condition in a way no previous drug has.
Informal Designation: The FDA tracks first-in-class drugs as a marker of innovation but does not consider it a formal regulatory category.
Potential for High Reward: These drugs can offer significant clinical gains and target unmet medical needs, representing a major leap forward in treatment.
Inherent Risks: Due to their novelty, first-in-class drugs carry greater uncertainty regarding long-term safety and efficacy compared to later entrants in a class.
Not a Guarantee for Success: Not all first-in-class drugs become blockbuster sellers, and many don't result in substantial added clinical benefit over time.
Expedited Review Often Included: Many first-in-class drugs may receive expedited regulatory review, such as Breakthrough Therapy Designation, due to their innovative potential.

What Defines a First-in-Class Drug?

A first-in-class (FIC) drug is a pioneering medication distinguished by its "new and unique mechanism of action" to address a specific medical condition. This means it targets a biological pathway, molecule, or process in a way that no other previously approved drug has. This novelty sets it apart from next-in-class drugs, which may offer incremental improvements but follow a similar pharmacological approach. The discovery often stems from deep scientific research.

Key characteristics of a first-in-class drug include novelty, innovation, potential impact on unmet medical needs, and inherent uncertainty regarding its safety profile compared to later-generation drugs.

The FDA's Role and Perspective

The FDA awards the "first-in-class" designation as a way to track and highlight innovation, but it is not a formal regulatory approval pathway. Many FIC drugs may qualify for expedited FDA programs like Breakthrough Therapy Designation if they demonstrate substantial improvement over existing therapies. The FDA's review considers the novelty of the mechanism, clinical evidence of safety and effectiveness, the potential to address unmet needs, and the overall risk-benefit profile.

Advantages and Risks of First-in-Class Drugs

First-in-class drugs offer significant advantages but also carry risks due to their novelty.

Advantages

Potential for Larger Health Gains: FIC drugs are often associated with larger incremental health gains compared to the standard of care at the time of approval.
Addresses Unmet Needs: They provide new treatment options for diseases with limited or no existing therapies.
Market Leadership and Innovation: FIC drugs can lead to market advantages and stimulate further research.

Risks and Challenges

Unpredictable Side Effects: The new mechanism of action can lead to unforeseen long-term side effects.
Clinical Trial Complexity: Designing and conducting clinical trials can be challenging due to the lack of established comparisons.
High Price Tag: Development costs often result in high pricing, raising concerns about access.
Sustained Efficacy: Initial benefits may not be sustained long-term.

First-in-Class vs. Breakthrough Therapy Designation

While related, FIC and Breakthrough Therapy Designation are distinct:


Feature	First-in-Class (FIC) Drug	Breakthrough Therapy Designation
Basis for Designation	Unique, novel mechanism of action.	Clinical evidence showing a substantial improvement over existing therapies for a serious condition.
Regulatory Status	An informal designation tracked by the FDA, not a formal regulatory pathway.	A formal regulatory program with defined incentives for expedited development and review.
Required Evidence	Relies on the scientific evidence of a new mechanism.	Requires preliminary clinical evidence demonstrating substantial improvement.
Benefit	Represents scientific innovation and potentially a new treatment paradigm.	Offers more intensive FDA guidance and an accelerated review.

Case Study: Tirzepatide (Mounjaro)

Tirzepatide (Mounjaro), approved for type 2 diabetes in 2022, is a first-in-class drug as a dual GIP and GLP-1 receptor agonist. Its novel dual mechanism distinguished it from existing GLP-1 agonists, leading to significant clinical outcomes and its FIC designation. This case highlights how a unique mechanism can result in a powerful new therapeutic option.

Conclusion

The designation of what is a first in class drug FDA signifies a crucial step in pharmaceutical innovation. These drugs, with their new mechanisms, offer new possibilities for patients, particularly those with unmet medical needs. While there are challenges and risks, the FDA's tracking of these drugs underscores their importance to public health. The development of first-in-class drugs drives the industry toward more effective and targeted treatments. For more detailed information on FDA drug approvals, you can visit the official FDA website.

Frequently Asked Questions

A first-in-class drug has a novel mechanism of action, meaning it is the first to use a specific approach. A next-in-class drug is a later-approved medication that uses a similar mechanism of action to an existing drug.

No, 'first-in-class' is not a formal regulatory status or approval pathway. The FDA tracks and reports on these drugs as a measure of innovation, but the designation itself carries no regulatory weight.

Benefits can include addressing unmet medical needs, providing greater incremental health gains compared to previous therapies, and offering market leadership for the developing company.

Risks include potential unforeseen safety issues due to the new mechanism, challenges in clinical trials, high pricing, and the possibility that the novel mechanism does not translate into substantial long-term clinical benefit.

Yes. A drug can be both first-in-class and receive Breakthrough Therapy Designation if it shows preliminary clinical evidence of substantial improvement over existing therapies for a serious condition.

The FDA evaluates all drugs based on their safety and efficacy through rigorous clinical trials. For a first-in-class drug, the review focuses heavily on the scientific evidence supporting the new mechanism and its overall risk-benefit profile.

An example is Tirzepatide (Mounjaro), a dual GIP and GLP-1 receptor agonist approved for type 2 diabetes, which offered a novel mechanism of action for this condition.