AMARIN OUTLINES NEW GO-TO-MARKET STRATEGY TO ACCELERATE VASCEPA (ICOSAPENT ETHYL) GROWTH IN U.S. Enables Amarin to Drive Additional Demand, Improve Patient Access & Education and Secure Proper Fulfillment and Reimburseme

GO-TO-MARKET STRATEGY TO ACCELERATE VASCEPA (ICOSAPENT ETHYL) GROWTH IN U.S.

Enables Amarin to Drive Additional Demand, Improve Patient Access & Education and Secure Proper Fulfillment and Reimbursement

DUBLIN, Ireland and BRIDGEWATER, N.J., Sep. 22, 2021 Amarin Corporation plc (NASDAQ: AMRN) today outlined its new Go-to-Market strategy to accelerate growth of VASCEPA (icosapent ethyl) in the United States, which focuses on

expanding healthcare professional engagement through a new omnichannel platform, enhancing managed care access and optimizing VASCEPA prescriptions for cardiovascular (CV) risk reduction.

Amarin is embarking on a transformation to a new, integrated

Go-to-Market approach in the U.S., furthering our mission of helping millions of untreated, at-risk patients gain access to

VASCEPA, said Karim Mikhail, Amarin s president and chief executive officer. We are seeing a dramatic shift in how physicians prefer to engage and are applying key learnings from our European launch initiatives as we work to

maximize our impact with both healthcare professionals and patients. We continue to believe that there is enormous opportunity for VASCEPA/VAZKEPA in the U.S. and throughout the rest of the world. With this new strategy, we are confident in our

ability to drive U.S. growth and realize the full potential of our first-of-its kind product as we continue to execute our global strategic plan to create value for all

Aaron Berg, Amarin s executive vice president and president, U.S., added, Our new Go-to-Market strategy is a more dynamic, nimble and efficient approach to educating healthcare professionals and patients about our product to reduce cardiovascular risk. We believe this strategy will allow

Amarin to accelerate VASCEPA prescription growth and drive an increasingly profitable U.S. franchise.

Key Strategic Priorities

Consistent with this model, Amarin will optimize its U.S. field force and focus on the most productive territories. This

will result in a reduction of Amarin s U.S. field force to approximately 300 sales representatives who will remain a critical part of the Company s commercial strategy going forward. Amarin will reinvest the realized net savings towards

its expanded educational and promotional efforts.

Mr. Berg concluded, Our people have always been and remain the foundation of our business. Decisions that impact people are never easy, and we are

making every effort to support those employees who are affected by our field force optimization.

Amarin is an innovative pharmaceutical company leading a new paradigm in cardiovascular disease management. From our scientific research foundation to our

focus on clinical trials, and now our commercial expansion, we are evolving and growing rapidly. Amarin has offices in Bridgewater, New Jersey in the United States, Dublin in Ireland, and Zug in Switzerland as well as commercial partners and

suppliers around the world. We are committed to rethinking cardiovascular risk through the advancement of scientific understanding of the impact on society of significant residual risk that exists beyond traditional therapies, such as statins for

cholesterol management.

About Cardiovascular Risk

Cardiovascular disease is the number one cause of death in the world. In the United States alone, cardiovascular disease results in 859,000 deaths per year.1 And the number of deaths in the United States attributed to cardiovascular disease continues to rise. In addition, in the United States there are 605,000 new and 200,000 recurrent heart attacks per

year (approximately 1 every 40 seconds). Stroke rates are 795,000 per year (approximately 1 every 40 seconds), accounting for 1 of every 19 U.S. deaths. In aggregate, in the United States alone, there are more than 2.4 million major adverse

cardiovascular events per year from cardiovascular disease or, on average, 1 every 13 seconds.

Controlling bad cholesterol, also known as LDL-C, is one way to

reduce a patient s risk for cardiovascular events, such as heart attack, stroke or death. However, even with the achievement of target LDL-C levels, millions of patients still have significant and

persistent risk of cardiovascular events, especially those patients with elevated triglycerides. Statin therapy has been shown to control LDL-C, thereby reducing the risk of cardiovascular events by 25-35%.2 Significant cardiovascular risk remains after statin therapy. People with elevated triglycerides have 35% more cardiovascular events compared to people

with normal (in range) triglycerides taking statins.3,4,5

About VASCEPA (icosapent ethyl) Capsules

VASCEPA (icosapent ethyl) capsules are the first-and-only prescription treatment approved by the U.S. Food and Drug Administration (FDA) comprised solely of the active ingredient, icosapent ethyl (IPE), a unique form

of eicosapentaenoic acid. VASCEPA was launched in the United States in January 2020 as the first and only drug approved by the U.S. FDA for treatment of the studied high-risk patients with persistent cardiovascular risk after statin therapy. VASCEPA

was initially launched in the United States in 2013 based on the drug s initial FDA approved indication for use as an adjunct therapy to diet to reduce triglyceride levels in adult patients with severe

( 500 mg/dL) hypertriglyceridemia. Since launch, VASCEPA has been prescribed over ten million times. VASCEPA is covered by most major medical insurance plans. In addition to the United States, VASCEPA is

approved and sold in Canada, Lebanon and the United Arab Emirates. In Europe, in March 2021 marketing authorization was granted to icosapent ethyl in the European Union for the reduction of risk of cardiovascular events in patients at high

cardiovascular risk, under the brand name VAZKEPA.

Indications and Limitation of Use (in the United States)

VASCEPA is indicated:

The effect of VASCEPA on the risk for

pancreatitis in patients with severe hypertriglyceridemia has not been determined.

Important Safety Information

FULL U.S. FDA-APPROVED VASCEPA PRESCRIBING INFORMATION CAN BE FOUND

Forward-Looking Statements

This press release contains forward-looking statements which are made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of

1995 and other securities laws. Any statements contained herein which do not describe historical facts, including, among others, statements regarding beliefs about Amarin s

go-to-market strategy and its ability to accelerate growth of VASCEPA in the United States, including through enhanced managed care access, prescription optimization and

capitalizing on existing revenue growth opportunities; beliefs about physician engagement; expectations regarding Amarin s ability to drive U.S. growth, create shareholder value and drive an increasingly profitable franchise; plans regarding

Amarin s key strategic priorities, including to expand healthcare provider engagement, enhance managed care access and optimize prescriptions for cardiovascular risk reduction; plans to reduce the Amarin field force and support impacted

employees; beliefs that there will be enormous worldwide opportunity for VASCEPA and expectations regarding the full potential of VASCEPA as a first-of-its kind

product. These forward-looking statements are not promises or guarantees and involve substantial risks and uncertainties, which could cause actual results to differ materially from those described or projected herein, including (among others):

Amarin may be unsuccessful in implementing its go-to-market strategy or, even if successful, may not achieve the expected results of such efforts; the risk that Amarin

has overestimated the market potential for VASCEPA in the United States, Europe and other geographies; the possibility that VASCEPA may not receive regulatory approval in the

China region or other geographies on the expected timelines or at all; the risk that additional generic versions of VASCEPA will enter the market and that generic versions of VASCEPA will achieve

greater market share and more commercial supply than anticipated, particularly in light of the recent and disappointing outcome of Amarin s litigation against two generic drug companies and subsequent requests for appeal; the risk that the

scope and duration of the COVID-19 pandemic will continue to impact access to and sales of VASCEPA; risks associated with Amarin s evolving enterprise; uncertainties associated generally with research and

development, clinical trials and related regulatory approvals; the risk that sales may not meet expectations and related cost may increase beyond expectations; the risk that patents may be determined to not be infringed or not be valid in patent

litigation and applications may not result in issued patents sufficient to protect the VASCEPA franchise. Further, Amarin s ability to effectively commercialize VASCEPA and maintain or grow market share will depend in part on Amarin s

ability to continue to effectively finance its business, VASCEPA approval in geographies outside the U.S., efforts of third parties, Amarin s ability to create and increase market demand for VASCEPA through education, marketing and sales

activities, to achieve broad market acceptance of VASCEPA, to receive adequate levels of reimbursement from third-party payers, to develop and maintain a consistent source of commercial supply at a competitive price, to comply with legal and

regulatory requirements in connection with the sale and promotion of VASCEPA and to secure, maintain and defend its patent protection for VASCEPA. A list of additional risks and uncertainties, and further description of the foregoing risks and

uncertainties, associated with an investment in Amarin can be found in Amarin s filings with the U.S. Securities and Exchange Commission, including Amarin s quarterly report on Form 10-Q for the

quarter ended June 30, 2021 and subsequent filings with the Commission. Existing and prospective investors are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date they are made. Amarin

undertakes no obligation to update or revise the information contained in its forward looking statements, whether as a result of new information, future events or circumstances or otherwise. Amarin s forward-looking statements do not reflect

the potential impact of significant transactions the company may enter into, such as mergers, acquisitions, dispositions, joint ventures or any material agreements that Amarin may enter into, amend or terminate.

Availability of Other Information About Amarin

and others should note that Amarin communicates with its investors and the public using the company website (www.amarincorp.com), the investor relations website (investor.amarincorp.com), including but not limited to investor

presentations and investor FAQs, Securities and Exchange Commission filings, press releases, public conference calls and webcasts. The information that Amarin posts on these channels and websites could be deemed to be material information. As a

result, Amarin encourages investors, the media, and others interested in Amarin to review the

information that is posted on these channels, including the investor relations website, on a regular basis. This list of channels may be updated from time to time on Amarin s investor

relations website and may include social media channels. The contents of Amarin s website or these channels, or any other website that may be accessed from its website or these channels, shall not be deemed incorporated by reference in any

filing under the Securities Act of 1933.

Amarin Contact Information

Amarin Corporation plc

In U.S.: +1 (908) 719-1315

IR@amarincorp.com (investor inquiries)

Amarin Corporation plc

In U.S.: +1 (908) 892-2028

PR@amarincorp.com (media inquiries)