What is a drug patent cliff?

The point at which a brand drug loses patent or regulatory protection and generic competitors can enter, typically causing a steep fall in the brand’s revenue. The size of the cliff depends on the spending behind the drug, not on the expiry date itself.

How is loss-of-exclusivity exposure measured here?

By joining FDA Orange Book patent and exclusivity expiries to CMS Medicare Part D gross spending, so drugs are ranked by the dollars at stake rather than by how soon a date falls.

Does an expiry in the window mean the drug goes generic then?

No, and this is the common misreading. The ranking uses each drug’s earliest listed protection. Most large brands carry later patents that continue to block entry for years. The dataset includes a column showing whether every protection lapses within the window.

Are biologics included?

No. This uses the FDA Orange Book, which covers small-molecule drugs. Biologics are listed in the Purple Book and are outside the dataset.

Drug Patent Cliff Tracker: Loss of Exclusivity by Part D Spend

Which drug patent and exclusivity expiries actually matter — ranked by the Medicare Part D spending behind them, not by date.

$213.1bn of Medicare Part D spending sits on drugs whose listed protection lapses in the next 24 months

Apixaban alone accounts for 15.1% of it — $32.2bn, with its earliest listed date 2027-05-21.

The top five carry 45.7% of the total. This is exposure, not forecast savings.

Of the 25 drugs ranked, 2 already have a marketed generic and 19 do not. For 4 we could not establish either way.

$135.1bn of this spending is on drugs with no marketed generic today. $4.5bn is on drugs where competition has already arrived — the listed date is not the start of competition for those. A further $17.6bn sits on drugs whose market status we could not establish; it is counted in neither figure above, and is a gap in our data rather than a finding about those drugs.

Ranked by Part D spending (2024, gross of rebates)

#	Drug	Part D spending	Earliest listed date	Generic today?	Applications
1	Apixaban ELIQUIS, ELIQUIS SPRINKLE	$32.2bn	2027-05-21	Approved, not marketed	4 approved
2	Semaglutide OZEMPIC, RYBELSUS	$24.2bn	2027-02-27	Brand only	0 approved
3	Empagliflozin JARDIANCE	$18.5bn	2026-12-20	Brand only	0 approved
4	Tirzepatide Mounjaro, ZEPBOUND	$12.3bn	2026-11-08	Brand only	0 approved
5	Lenalidomide Revlimid	$10.1bn	2027-04-27	Approved, marketing unknown	110 approved
6	Enzalutamide Xtandi	$5.8bn	2026-11-17	Brand only	0 approved
7	Sitagliptin JANUVIA, ZITUVIO	$4.9bn	2026-11-24	Approved, not marketed	9 approved
8	Tafamidis Vyndamax	$4.7bn	2026-12-19	Brand only	0 approved
9	Ibrutinib Imbruvica	$3.5bn	2027-06-28	Brand only	0 approved
10	Ruxolitinib JAKAFI, OPZELURA	$3.4bn	2026-11-24	Brand only	0 approved
11	Palbociclib Ibrance	$3.3bn	2027-09-05	Brand only	0 approved
12	Pomalidomide Pomalyst	$3.3bn	2027-05-14	Approved, marketing unknown	20 approved
13	Linaclotide Linzess	$3.1bn	2027-02-28	Brand only	0 approved
14	Valbenazine INGREZZA, INGREZZA Sprinkle	$3.0bn	2027-11-08	Approved, not marketed	2 approved
15	Zanubrutinib BRUKINSA	$2.9bn	2026-11-14	Brand only	0 approved
16	Acalabrutinib CALQUENCE	$2.9bn	2026-11-21	Brand only	0 approved
17	Osimertinib TAGRISSO	$2.7bn	2027-02-16	Brand only	0 approved
18	Cyclosporine CEQUA, Gengraf	$2.5bn	2027-11-03	Generic already marketed	28 approved
19	Upadacitinib Rinvoq	$2.4bn	2027-04-26	Brand only	0 approved
20	Apalutamide ERLEADA	$2.3bn	2027-03-27	Approved, marketing unknown	1 approved
21	Tiotropium Spiriva	$2.0bn	2027-04-10	Generic already marketed	1 approved
22	Darolutamide NUBEQA	$1.9bn	2028-06-03	Brand only	0 approved
23	Macitentan OPSUMIT	$1.9bn	2026-12-03	Approved, marketing unknown	5 approved
24	Rifaximin XIFAXAN	$1.8bn	2027-09-02	Brand only	0 approved
25	Apremilast Otezla	$1.7bn	2027-01-19	Approved, not marketed	15 approved

Showing the top 25 of 440 drugs with a listed event in this window.

How to read this

This total is the Medicare Part D gross spending associated with drugs that have AT LEAST ONE listed Orange Book protection event in the window. It is NOT the value of drugs "going generic". The ranking uses each drug’s EARLIEST listed protection, and most large brands carry later patents that continue to block generic entry for years afterwards — so a drug can appear here while remaining protected well beyond the window.
This is EXPOSURE, not forecast savings. It is the Medicare Part D spending recorded against drugs whose listed protection lapses in the window. Whether anything is actually saved depends on a generic launching, at what price, and how fast it takes share — none of which is in this data.
The spending figures are GROSS, before manufacturer rebates. CMS publishes Part D spending before rebates are applied, so the net cost to the programme is lower — materially lower on heavily-rebated brands — and these figures should not be read as net.
This ranks Orange Book drugs only: small molecules approved under an NDA or ANDA. Biologics are licensed under BLAs, appear in the FDA Purple Book, and are among the largest Part D line items. They are absent from this ranking, so it is not a complete picture of drug spending.
An expiry date is not a launch date, and a Paragraph IV settlement can let a generic arrive earlier than the date shown. Those agreements are private and are not in this data.
A drug that already has a marketed generic appears here too, because a listed protection is still lapsing — but its spending is already open to competition. The market-status column separates the two.
Spending is CMS Part D data for 2024. CMS publishes it annually in arrears, so it describes that year rather than today.

FDA Orange Book listings and CMS Medicare Part D Spending by Drug — informational, not legal, investment or medical advice, and not a forecast of generic entry or savings.

Data: FDA Orange Book patent/exclusivity listings and CMS Medicare Part D Spending by Drug — Orange Book snapshot ingested 2026-09-13 · CMS Part D spending for 2024 · source

Machine access — this tool is available as structured data for AI assistants and agents:
GET https://rxfinder.ai/tools/loe-exposure/data.json?window=…&limit=…