How Drug and Device Patents Get Extra Time Under Section 156

When a drug company invents a new compound, it can file a patent application fairly early in the development process. But the drug can't be sold until the FDA approves it, and that approval process typically takes years. By the time the drug reaches the market, a significant portion of the 20-year patent term may already have elapsed.

Section 156 of Title 35 was created to address this. It allows certain patents to be extended to compensate for time lost to FDA regulatory review.

What Section 156 actually does

It adds up to 5 years to the end of an eligible patent's term. The extension is calculated based on half the time spent in clinical trials plus the full time spent in the FDA approval review, minus certain offsets.

The total extended patent term, including the extension, cannot exceed 14 years from the date of FDA approval. So if approval happens late in the patent's life, the effective extension is limited even if the regulatory delay was long.

What patents are eligible

The extension is available for patents that claim:

• A human drug, antibiotic, or biological product (covered by an FDA NDA or BLA)
• A new animal drug
• A food or color additive
• A medical device requiring a premarket approval application (PMA)
• A veterinary biological product

Importantly, only one patent per product can receive a Section 156 extension. If the drug is covered by multiple patents, the patent owner must choose which one to extend.

The patent must be in effect when the extension is applied for, and it must claim either the approved product or a method of using or manufacturing that product.

How to apply

The patent owner must file an application with the USPTO within 60 days of the FDA approval. That deadline is strict. Missing it forfeits the right to the extension.

The USPTO and FDA work together to verify eligibility and calculate the extension period. The FDA certifies the regulatory review period, and the USPTO issues a certificate of extension.

Where to find PTE information

The FDA's Orange Book (for drugs covered by NDAs) and the Purple Book (for biologics) list patents associated with approved products. These databases show whether a patent has received a PTE and the extension's expiration date.

For medical devices, the FDA device approval database includes similar information.

The USPTO also maintains a searchable database of patent term extensions. Patent Center includes PTE information in the bibliographic data section for patents that have received extensions.

PTE vs. PTA: different rules, different calculations

Patent term adjustment (PTA) compensates for USPTO prosecution delays. PTE compensates for FDA regulatory delays. They apply different statutory frameworks and have different caps.

A patent can potentially qualify for both, but there are limits on stacking them. The interaction between PTA and PTE can be complex, particularly for pharmaceutical patents with long prosecution histories and significant FDA review periods.

Why this matters for generic drugs

PTE is a central factor in pharmaceutical patent strategy. It affects when generic manufacturers can enter the market. An extension of even 2-3 years on a blockbuster drug's patent can be worth billions of dollars to the originator company.

When analysts track pharmaceutical patent cliffs, they're looking not just at base 20-year terms but at which patents have been extended, by how much, and which extensions are expiring in upcoming years.

The Patent Sunset calculator includes PTE data in its calculations for pharmaceutical patents, reflecting the actual extended expiration date rather than the base 20-year term.