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Patent Expiration

The date when a drug's patent protection ends, allowing generic or biosimilar manufacturers to produce competing versions.

How It Works

U.S. utility patents run 20 years from the earliest non-provisional filing date under 35 U.S.C. 154, but effective market exclusivity for drugs is typically 8-15 years because patents are filed early in development, often before clinical trials begin. Patent Term Restoration under Hatch-Waxman (35 U.S.C. 156) can add up to 5 years to compensate for FDA review time, capped at 14 years of effective post-approval exclusivity. Drug makers layer patents strategically, so "patent expiration" rarely refers to a single date. Lipitor (atorvastatin) had its composition-of-matter patent expire November 2011 after a Ranbaxy Paragraph IV challenge and 180-day exclusivity; generic prices fell roughly 95% within 24 months, generating an estimated $30 billion in annual U.S. savings. Humira (adalimumab) had its composition patent expire December 2016, but AbbVie's patent thicket, reportedly 132 patents covering formulations, manufacturing, and methods of use, delayed U.S. biosimilar launch until January 2023, six years after European biosimilars entered. The Humira biosimilar wave (Amjevita, Cyltezo, Hyrimoz, Hadlima, Idacio, Yuflyma, Yusimry, Simlandi, and more by end of 2024) has achieved 15-30% list-price discounts against Humira's ~$6,600/month reference price, with net-price discounts often deeper through rebate arrangements. Revlimid (lenalidomide) had its composition patent expire in 2022 after a staggered settlement structure Celgene/BMS negotiated with nine generic manufacturers, creating a controlled launch with limited generic volume until March 2026 when unlimited generic entry begins.

Related Terms

  • Generic Drug, A medication that contains the same active ingredient, dosage, and form as a brand-name drug, approved after the original's patent expires, typically costing 80-95% less.
  • Patent Cliff, A sharp drop in a drug's revenue when its patent expires and generic competitors enter the market, often cutting prices by 80% or more.
  • Evergreening, Strategies drug manufacturers use to extend patent protection beyond the original expiration, including new formulations, delivery methods, or minor modifications.
  • Exclusivity Period, A period of market protection granted by the FDA (separate from patents) during which generic competitors cannot be approved, even if no patent exists.
  • Orange Book Listing, The FDA's publication of approved drug products with therapeutic equivalence ratings and associated patent and exclusivity information, used to determine generic substitution.

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About This Definition

This definition is part of the DrugPrice Drug Pricing Glossary, 49 terms explaining how prescription drug pricing works in the United States. All definitions are written in plain language for patients, caregivers, journalists, and healthcare professionals.

this entity is one of the U.S. Medicare prescription-drug pricing concepts that recurs across this site. The definition above is the technical answer; the paragraphs below add the practical context for how the concept connects to the CMS Medicare Part D Drug Spending data data behind every per-entity page on the site.

In the CMS Medicare Part D Drug Spending data data, this concept shapes one or more of the fields that drive the per-entity grades and rankings on this site. The methodology page describes which fields feed into which output; this glossary entry documents the underlying term.

Source: CMS Medicare Part D Spending, 2026.