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ESTRING

NDA

ESTRADIOL | N020472 | PFIZER INC

1 strength0 unique patents0 unique exclusivities

PTAB Proceedings

No IPR/PGR/CBM challenges found at the Patent Trial and Appeal Board

Patent Reexaminations

No ex parte or inter partes reexamination proceedings found at USPTO

Hatch-Waxman Litigation

No ANDA patent litigation cases (NOS 835) matched from PACER

Citizen Petitions

1 petition from Regulations.gov

Petition	Type	Filed	Status	Petitioner
Citizen Petition from Pfizer, Inc. FDA-2017-P-5081 · 5 docket documents Pfizer Inc. filed this citizen petition on August 17, 2017, requesting that the FDA issue a product-specific bioequivalence guidance document for generic versions of Estring (estradiol vaginal ring) under the ANDA pathway. Pfizer requests the guidance establish requirements for demonstration of comp	505(q)	2017-08-21	Partially Denied	Pfizer, Inc.

Source: Regulations.gov. FDA citizen petitions matched by application number.

Clinical Trials

385 trials from ClinicalTrials.gov — 2 recruiting, 4 active, 285 completed

Trial	Phase	Status	Sponsor	Enrollment	Dates
The Role of Estrogen in the Neurobiology of Eating Disorders NCT03740204	Phase 2	Active	Massachusetts General Hospital	120	2019-06-13 → 2026-12-31
Deslorelin Combined With Low-Dose Add-Back Estradiol and Testosterone in Preventing Breast Cancer in Premenopausal Women Who Are at High Risk for This Disease NCT00080756	Phase 2	Active	City of Hope Medical Center	11	2004-03-11 → 2024-10-15
Estradiol in Treating Patients With ER Beta Positive, Triple Negative Locally Advanced or Metastatic Breast Cancer NCT03941730	Phase 2	Active	Mayo Clinic	8	2019-08-28 → 2026-12-31
A Study to See Whether Estrogen Can Slow the Growth of Some ER Positive Breast Cancers NCT02238808	Phase 2	Active	AHS Cancer Control Alberta	19	2015-08 → 2028-06
Study to Assess Potential Impairments in Estradiol Augmentation of Gonadotropin Secretion in Polycystic Ovary Syndrome NCT03401047	Early Phase 1	Recruiting	University of Virginia	37	2017-11-30 → 2025-12-01
A Study to Assess the Effect of Venetoclax on Ethinyl Estradiol and Levonorgestrel in Female Participants With Different Hematological Malignancies NCT03557619	Phase 1	Recruiting	AbbVie	12	2019-07-30 → 2026-03-21
Norethindrone/Ethinyl Estradiol 0.4 mg/35 Mcg Chewable Tablets Under Fasting Conditions NCT01340625	Phase 1	Completed	Teva Pharmaceuticals USA	36	2006-12 → 2007-01
Nanoparticulate Versus Micronized Steroids Delivery for Transdermal Hormone Replacement Therapy NCT02467673	Phase 2	Completed	University Potiguar	185	2012-01 → 2012-07
A STUDY TO ESTIMATE THE EFFECT OF PF-06651600 ON THE PHARMACOKINETICS (PK) OF ORAL CONTRACEPTIVE (OC)NCT03608241	Phase 1	Completed	Pfizer	12	2018-09-21 → 2018-11-23
Study of Physiological and High Dose Estradiol in the Treatment of Hormone Receptor Positive Metastatic Breast Cancer NCT00324259	Phase 2	Completed	Washington University School of Medicine	66	2004-08 → 2014-08

Source: ClinicalTrials.gov. Trials matched by ingredient name.

Drug Pricing (NADAC)

National Average Drug Acquisition Cost — Week of 2026-07-15 | 1 NDC

Highest NADAC/Unit

$551.29

per ea

Lowest NADAC/Unit

$551.29

per ea

Brand NDCs

Generic NDCs

NDC Description	NADAC/Unit	Unit	Type	Generic NADAC	Effective
00013104201ESTRING 7.5 MCG/DAY (2 MG) RING	$551.29	EA	Brand	—	2026-06-17

Source: NADAC (data.medicaid.gov). Prices reflect national average acquisition costs for retail community pharmacies.

VA Federal Supply Schedule

Government-negotiated contract prices | 2 NDCs (1 FSS, 1 Big4)

Lowest Price

$414.67

Highest Price

$574.03

FSS NDCs

Big4 NDCs

Description	Price	Type	Vendor	Contract End
00013-1042-01ESTRING 2MG VAGINAL RING	$574.03	FSS	Pfizer Inc.	06/30/2029
00013-1042-01ESTRING 2MG VAGINAL RING	$414.67	Big4	Pfizer Inc.	06/30/2029

Source: VA Federal Supply Schedule (va.gov). Prices are government-negotiated contract prices.

Medicare Part D Spending

CMS annual spending data for Estring (2024)

Total Spending

$49.2M

Total Claims

90,750

Beneficiaries

33,078

Avg Cost/Unit

$539.53

Spending Trend

$41.7M(2019)→$42.7M(2020)→$47.0M(2021)→$50.4M(2022)→$50.3M(2023)→$49.2M(2024)

YoY Change:-1.9%

5yr CAGR:+2.9%

Source: CMS Medicare Part D Spending by Drug (2024). Shows gross drug cost under Part D.

API Supply Chain12 active DMFs19 inactive

10 active API suppliers hold Drug Master Files for this ingredient.

ASPEN OSS BVESTRADIOL

DMF 38291980

GEDEON RICHTER PLCESTRADIOL USP

DMF 40661981

BAYER AGESTRADIOL

DMF 46841982

KINDEVA DRUG DELIVERY LPESTRADIOL TRANSDERMAL DRUG DELIVERY SYSTEM

DMF 98411992

VALDEPHARMESTRADIOL HEMIHYDRATE

DMF 229722009

VALDEPHARMESTRADIOL BENZOATE

DMF 238362010

ZHEJIANG XIANJU PHARMACEUTICAL CO LTDESTRADIOL HEMIHYDRATE USP, NON-STERILE, BULK DRUG SUBSTANCE

DMF 239422010

LUPIN LTDESTRADIOL HEMIHYDRATE USP

DMF 258162012

SYMBIOTEC PHARMALAB PRIVATE LTDESTRADIOL HEMIHYDRATE USP

DMF 341472019

ASPEN OSS BVESTRADIOL 3-ACETATE

DMF 347382020

HUBEI GEDIAN HUMANWELL PHARMACEUTICAL CO LTDESTRADIOL HEMIHYDRATE

DMF 435612026

YANGZHOU AURISCO PHARMACEUTICAL CO LTDESTRADIOL HEMIHYDRATE

DMF 439512026

SCHERING AGInactiveESTRADIOL ENANTHATE

DMF 10931967

ORTHO PHARMACEUTICAL CORPInactiveESTRADIOL 17-A-IN PROPYLENE GLYCOL : PARENTERAL

DMF 16551971

ROUSSEL CORPInactiveESTRADIOL BENZOATE

DMF 22911974

ORGANON INCInactiveESTRADIOL

DMF 26771976

MITSUBISHI CHEMICAL INDUSTRIES LTDInactiveESTRADIOL

DMF 31751978

DIOSYNTH BVInactiveESTRADIOL BENZOATE

DMF 35801979

MEDIMPEX NORTHAMERICA INCInactiveESTRADIOL DIPROPIONATE

DMF 40731981

DIOSYNTH BVInactiveESTRADIOL VALERATE MICRO

DMF 42671981

ROUSSELL UCLAFInactiveESTRADIOL USP

DMF 56861985

DR REDDYS LABORATORIES LTDInactiveESTRADIOL

DMF 69461987

ROUSSELL UCLAFInactiveESTRADIOL

DMF 88191990

PHARMACIA AND UPJOHN SUB PFIZER INCInactiveESTRADIOL

DMF 105361993

CYGNUS INCInactiveESTRADIOL TRANSDERMAL DELIVERY SYSTEM (E2 III TDS)

DMF 106511993

NV ORGANONInactiveESTRADIOL BENZOATE

DMF 150852000

DIOSYNTH BVInactiveESTRADIOL GLUCOSIDE

DMF 157592001

MILLICENT HOLDINGS LTDInactiveESTRADIOL 3 ACETATE

DMF 161202002

CATALENT PHARMA SOLUTIONS LLCInactiveESTRADIOL VAGINAL SOFT GELATIN CAPSULES

DMF 228432009

BEIJING KEYIFENG BIOTECH DEVELOPMENT CO LTDInactiveESTRADIOL USP, NON-STERILE, BULK DRUG

DMF 240852010

ZHEJIANG XIANJU JUNYE PHARMACEUTICAL CO LTDInactiveESTRADIOL

DMF 241922010

Source: FDA Drug Master Files (fda.gov). Type II API DMFs matched by ingredient.

Approval Letters

10 letters from Drugs@FDA

Date	Submission	Document
Feb 12, 2026	SUPPL -22	View Letter (PDF)
Feb 16, 2024	SUPPL -20	View Letter (PDF)
Feb 16, 2024	SUPPL -20	View Letter (PDF)
Apr 28, 2023	ORIG -1	View Letter (PDF)
Jul 28, 2022	SUPPL -19	View Letter (PDF)
Nov 6, 2017	SUPPL -16	View Letter (PDF)
Sep 30, 2015	SUPPL -13	View Letter (PDF)
Sep 30, 2015	SUPPL -12	View Letter (PDF)
Aug 14, 2014	SUPPL -11	View Letter (PDF)
Aug 27, 2008	SUPPL -7	View Letter (PDF)

Source: Drugs@FDA application documents.

Products (1)

#001 — 0.0075MG/24HR

RLD

0 patents0 exclusivities▴

INSERT, EXTENDED RELEASE;VAGINAL | Approved: Apr 26, 1996

No patent or exclusivity listings for this strength.