{"id":39907,"date":"2026-10-15T11:12:00","date_gmt":"2026-10-15T15:12:00","guid":{"rendered":"https:\/\/www.drugpatentwatch.com\/blog\/?p=39907"},"modified":"2026-10-14T22:40:31","modified_gmt":"2026-10-15T02:40:31","slug":"patent-expiration-is-a-trigger-what-you-really-need-is-the-opportunity-behind-it","status":"publish","type":"post","link":"https:\/\/www.drugpatentwatch.com\/blog\/patent-expiration-is-a-trigger-what-you-really-need-is-the-opportunity-behind-it\/","title":{"rendered":"Patent Expiration Is a Trigger. What You Really Need Is the Opportunity Behind It."},"content":{"rendered":"\n
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Merck says U.S. Patent No. 7,326,708 covers the sitagliptin salt in Januvia and expires on November 24, 2026 [1]. Settlements let generic companies enter in May 2026 [1]. Sandoz launched generic sitagliptin on May 26, 2026 [2]. That is 182 days before the patent expires. (This count is my calculation.)<\/p>\n\n\n\n

The patent date did not decide the launch date. A settlement did. The same pattern appears in Entresto, Eliquis, Revlimid and Humira. This article compares the dates, calculates the gaps, and shows how to turn a loss-of-exclusivity date into a revenue estimate.<\/p>\n\n\n\n

Data in this article is current to October 14, 2026. Documented facts carry a citation. Calculations and frameworks are labeled as analysis.<\/p>\n\n\n\n

The Short Answer: Patent Expiration Date vs. Generic Entry Opportunity<\/strong><\/h2>\n\n\n\n

What is the difference between patent expiration and generic entry?<\/strong><\/h3>\n\n\n\n

A patent expiration date is the day a legal right ends. A generic entry date is the day a generic product is first sold. The two dates can differ by years. FDA says patents “can be issued or expire at any time regardless of the drug’s approval status” [3]. FDA also says: “Periods of exclusivity and patent terms may or may not run concurrently” [3].<\/p>\n\n\n\n

What is a generic entry opportunity?<\/strong><\/h3>\n\n\n\n

A generic entry opportunity is the revenue a named company can earn from a drug after every legal, regulatory and supply barrier to that company has ended. It has four parts: the market size, the price after entry, the number of competitors, and the date the company can ship. A patent date gives you none of these four numbers.<\/p>\n\n\n\n

This definition is a working definition for this article. It is not an FDA term.<\/p>\n\n\n\n

What the Data Shows: Eight Findings on Expiry, Entry and Erosion<\/strong><\/h2>\n\n\n\n

Finding 1: Generic Januvia entered 182 days before its key patent expired<\/strong><\/h3>\n\n\n\n

Merck lists the sitagliptin salt patent (U.S. 7,326,708) as expiring on November 24, 2026, with pediatric exclusivity to May 24, 2027 [1]. Sandoz launched on May 26, 2026 [2]. Entry came 182 days before the patent expiry and 363 days before the end of pediatric exclusivity (analysis).<\/p>\n\n\n\n

The Janumet gap is larger. Merck lists the co-formulation patent (U.S. 8,414,921) as expiring on January 21, 2029, with pediatric exclusivity to July 21, 2029 [1]. Generic Janumet launched in May 2026 [2]. That is 971 days before the patent date (analysis).<\/p>\n\n\n\n

Finding 2: FDA approved the first generic Entresto 363 days before it launched<\/strong><\/h3>\n\n\n\n

FDA approved MSN’s generic sacubitril\/valsartan on July 24, 2024 [4]. Novadoz, which sells MSN’s product, launched it on July 22, 2025 [5]. The gap is 363 days (analysis). Approval did not equal launch.<\/p>\n\n\n\n

Finding 3: Eliquis has three different entry dates in three public sources<\/strong><\/h3>\n\n\n\n

Pfizer said in 2021 that generic apixaban could not launch before April 1, 2028, subject to appeals and challenges [6]. One commercial tracker lists the composition patent as expiring in November 2026 [7]. The same tracker lists a formulation patent to February 2031 and estimates a generic entry date of August 24, 2031 [7]. The spread from the first date to the last is about 57 months (analysis).<\/p>\n\n\n\n

Finding 4: U.S. Humira biosimilar entry came 1,568 days after European entry<\/strong><\/h3>\n\n\n\n

Amgen’s 2017 settlement with AbbVie set launch dates for its adalimumab biosimilar Amjevita of October 16, 2018 in Europe and January 31, 2023 in the United States [8]. Amgen launched in the United States on January 31, 2023 [9]. The gap between the two dates is 1,568 days, or 4.3 years (analysis).<\/p>\n\n\n\n

Finding 5: The median generic price falls from 69.6% of the brand price to 5.9% as entrants go from one to seven<\/strong><\/h3>\n\n\n\n

FDA analyzed products with first generic entry from January 2015 to December 2017. Using invoice prices, the median generic price was 69.6% of the brand price with one generic producer. It was 5.9% with seven [10]. The number of entrants decides the size of the prize.<\/p>\n\n\n\n

Finding 6: Revlimid generics had a 46-month ramp between first licensed entry and unlimited entry<\/strong><\/h3>\n\n\n\n

Celgene’s 2020 announcement says the earliest licensed generic entry continues to be March 2022. The same announcement lets Dr. Reddy’s sell unlimited quantities no earlier than January 31, 2026 [11]. The ramp between the two dates is about 46 months (analysis). A patent expiry date would not show this ramp.<\/p>\n\n\n\n

Finding 7: Generics fill 90 percent of U.S. prescriptions and take 12 percent of spending<\/strong><\/h3>\n\n\n\n

The Association for Accessible Medicines (AAM) reports these shares in its 2025 savings fact sheet [12].<\/p>\n\n\n\n

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“Generic share of total U.S. prescriptions filled: 90 percent.” “Generic share of total U.S. prescription drug spending: 12 percent.” (Association for Accessible Medicines, 2025 fact sheet) [12]<\/p>\n<\/blockquote>\n\n\n\n

AAM also reports $467 billion in generic and biosimilar savings for 2024 [12]. AAM is a trade group for generic and biosimilar makers. Read the numbers with that source in mind.<\/p>\n\n\n\n

Finding 8: Entry dates were public 3.7 to 5.4 years before the entry dates arrived<\/strong><\/h3>\n\n\n\n

Merck announced the May 2026 entry window for Januvia and Janumet on September 22, 2022 [1]. Sandoz launched on May 26, 2026 [2]. The notice period was 1,342 days, or 3.7 years (analysis).<\/p>\n\n\n\n

Amgen’s settlement with AbbVie was announced on September 28, 2017 and set a U.S. launch date of January 31, 2023 [8]. The notice period was 1,951 days, or 5.3 years (analysis).<\/p>\n\n\n\n

Celgene announced the Revlimid settlement on September 17, 2020, with an unlimited-entry floor of January 31, 2026 [11]. The notice period to that floor was 1,962 days, or 5.4 years (analysis). For Eliquis, Pfizer’s September 3, 2021 statement named April 1, 2028 as the earliest date [6]. That is 2,402 days, or 6.6 years, and the date has not yet arrived (analysis).<\/p>\n\n\n\n

The practical point is simple. Competitors could plan these entries years ahead. A team that waited for the patent expiry date to start planning started late.<\/p>\n\n\n\n

Reference table: dated cases in this article<\/strong><\/h3>\n\n\n\n
Product<\/th>Key patent or barrier<\/th>Date of barrier<\/th>Entry (permitted or actual)<\/th>Gap (analysis)<\/th>Source<\/th><\/tr><\/thead>
Januvia (sitagliptin)<\/td>US 7,326,708 salt patent<\/td>Nov 24, 2026 (pediatric to May 24, 2027)<\/td>Launch May 26, 2026<\/td>182 days before patent expiry<\/td>[1], [2]<\/td><\/tr>
Janumet (sitagliptin\/metformin)<\/td>US 8,414,921 co-formulation patent<\/td>Jan 21, 2029 (pediatric to Jul 21, 2029)<\/td>Launch May 2026<\/td>971 days before patent expiry<\/td>[1], [2]<\/td><\/tr>
Entresto (sacubitril\/valsartan)<\/td>US 8,101,659 with pediatric exclusivity<\/td>Jul 15, 2025<\/td>Launch Jul 22, 2025<\/td>7 days after the extended date<\/td>[13], [5]<\/td><\/tr>
Eliquis (apixaban)<\/td>US 6,967,208 and US 9,326,945<\/td>Nov 2026 and Feb 2031 (tracker listing)<\/td>Earliest permitted launch Apr 1, 2028<\/td>About 16 months after the 2026 date<\/td>[6], [7]<\/td><\/tr>
Revlimid (lenalidomide)<\/td>Settlement license terms<\/td>Mar 2022 (first licensed entry)<\/td>Unlimited entry no earlier than Jan 31, 2026<\/td>About 46 months of ramp<\/td>[11]<\/td><\/tr>
Humira (adalimumab)<\/td>Settlement and patent portfolio<\/td>Settlement-set Europe launch Oct 16, 2018<\/td>US launch Jan 31, 2023<\/td>1,568 days later than Europe<\/td>[8], [9]<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

The Seven Dates Between a Patent and a Launch<\/strong><\/h2>\n\n\n\n

Which dates matter when you plan for loss of exclusivity?<\/strong><\/h3>\n\n\n\n

Seven dates can apply to one drug. I use them as an original working taxonomy. They are not an industry standard.<\/p>\n\n\n\n