Amarin Reports Third Quarter 2016 Financial Results and Provides Update on Operations Third Quarter Net Product Revenue Up 52% vs. Prior Year Period Maintaining Guidance on 2016 Net Product Revenue at $112-$125 Million;

Amarin Reports Third Quarter 2016 Financial Results

and Provides Update on Operations

Third Quarter Net Product Revenue Up 52% vs. Prior Year Period

Maintaining Guidance on 2016 Net Product Revenue at $112-$125 Million;

Anticipate Upper Half of Range

Management to Host Conference Call at 7:30 a.m. ET Today

BEDMINSTER, N.J., and DUBLIN, Ireland, November 3, 2016 Amarin Corporation plc (NASDAQ: AMRN), a biopharmaceutical company focused on the

commercialization and development of therapeutics to improve cardiovascular health, today announced financial results for the three and nine months ended September 30, 2016, and provided an update on company operations.

Key Amarin achievements since June 30, 2016 include:

Q3 2016 was another quarter of considerable progress for Amarin. Prescription growth for Vascepa was again greater than 50% compared to the

corresponding period of last year. REDUCE-IT continues to progress as expected and is now approximately one year from reaching the onset of 1,612 primary cardiovascular events which is the completion target for the study. We are pleased that

100,000 patients are currently using Vascepa each month to support their health, stated John F. Thero, president and chief executive officer. We are working to increase usage of

Vascepa based on the drug s already established positive efficacy, safety and tolerability profile while increasingly preparing for a market expanding opportunity for Vascepa upon achieving anticipated successful results in the REDUCE-IT

third quarter, Amarin continued to see substantial prescription growth and steady increases in prescription omega-3 and non-statin market share, particularly among detailed physicians. Vascepa growth continues to be driven by focused message

delivery, compelling supportive data and improved managed care coverage.

Amarin recorded net product revenue of $32.4 million and $21.3 million during

the three months ended September 30, 2016 and 2015, respectively, an increase of $11.1 million, or 52%. This increase in revenue was driven primarily by an increase in estimated normalized total Vascepa prescriptions. Based on data provided by

Symphony Health Solutions and IMS Health, estimated normalized Vascepa prescriptions totaled approximately 260,000 and 274,000, respectively, for the three months ended September 30, 2016. These prescription levels represent growth of approximately

54% and 56%, respectively, from prior year levels, and approximately 13% and 10%, respectively, compared to Q2 2016.

Inventory levels at wholesalers tend

to fluctuate based on seasonal factors, prescription trends and other factors. The level of inventories held by Amarin s distributors as of September 30, 2016 decreased as compared to inventories held at the beginning of the quarter calculated

based on estimated days of Vascepa sales on hand. Amarin estimates that product revenues during the quarter ended September 30, 2016 were negatively impacted by approximately $0.5 million to $0.8 million due to a net overall decrease in distributor

inventory levels during the quarter. The decrease in distributor inventory levels during the quarter ended September 30, 2016 follows an estimated $2.9 million to $3.2 million increase in the quarter ended June 30, 2016.

REDUCE-IT Trial Progressing on Schedule

REDUCE-IT cardiovascular outcomes trial continues to progress on schedule. Amarin expects the onset of the final primary cardiovascular event to occur in or about the fourth quarter of 2017 with the publication of results anticipated in 2018. The

8,175-patient outcomes study is evaluating whether treatment with Vascepa reduces cardiovascular events in patients who despite stabilized statin therapy have elevated triglyceride levels and other cardiovascular risk factors. The results of this

important trial, if successful, could lead to improved medical care for tens of millions of patients. The primary endpoint of this global, double-blind study is the time to the first occurrence of a composite of major adverse cardiovascular

events (MACE) and results will be compared between the Vascepa and placebo groups. The study is being conducted under a Special Protocol Assessment (SPA) agreement with the FDA.

The first interim efficacy and safety analysis by the DMC concluded in September 2016 after the occurrence of approximately 60% of targeted primary events. As

expected, the DMC recommended that

the trial continue as planned without modification. Preparations for the second planned interim efficacy analysis will be triggered by the onset of approximately 80% of the target aggregate

number of primary cardiovascular events in the study. Based on historical event rates, Amarin anticipates that the onset of approximately 80% of events will occur in the first half of 2017, with the second pre-specified interim efficacy and safety

analysis by the DMC expected in or about Q3 2017. As is typical of interim analyses, the statistical threshold for defining overwhelming efficacy on the primary endpoint that would call for stopping the study early in connection with such analysis

is considerably higher than the threshold for defining statistical significance after the expected completion of the study. Accordingly, Amarin continues to expect that the 80% interim analysis will result in a recommendation by the DMC to continue

the REDUCE-IT study as planned to completion of 100% planned events.

Amarin will remain blinded to results of the REDUCE-IT study until after the study

is stopped and the database is locked at either the second interim analysis or at the final analysis.

Net product revenue for the three months ended September 30, 2016 and 2015 was $32.4 million and $21.3 million, respectively. Net product revenue for the

nine months ended September 30, 2016 and 2015 was $90.6 million and $54.6 million, respectively. These increases in net product revenue were primarily attributable to increases both in new and recurring prescriptions of Vascepa driven by

increased sales productivity.

In addition, Amarin recognized licensing revenue of $0.8 million and $0.5 million in the nine months ended September 30,

2016 and 2015, respectively, related to agreements for the commercialization of Vascepa outside the United States. Amarin s partners for China and for the Middle East and North Africa are working towards regulatory approval of Vascepa in their

respective territories.

Cost of goods sold for the three months ended September 30, 2016 and 2015 was $8.5 million and $7.5 million,

respectively. Cost of goods sold for the nine months ended September 30, 2016 and 2015 was $24.2 million and $19.5 million, respectively. Gross margin on product sales improved to 74% and 73% in the three and nine months ended September

30, 2016, respectively, as compared to 65% and 64% in the three and nine months ended September 30, 2015, respectively. The improvement in gross margin on product sales was primarily driven by lower active pharmaceutical ingredient cost.

Selling, general and administrative (SG&A) expenses in the nine months ended September 30, 2016 and 2015 were $80.1 million and $77.5 million,

respectively. The increase in SG&A expenses primarily reflects an increase in co-promotion fees payable to Kowa Pharmaceuticals America, Inc.

Research and development expenses in the nine months ended September 30, 2016 and 2015 were $39.8 million and $37.7 million, respectively. This increase in

expenses was primarily driven by quarterly variability in costs related to the REDUCE-IT study.

Under GAAP, Amarin reported a net loss applicable to

common shareholders of $15.8 million in the third quarter of 2016, or basic and diluted loss per share of $0.08. This net loss included $3.4 million in

non-cash stock-based compensation expense and a $3.6 million non-cash gain on the change in fair value of derivatives. Amarin reported a net loss applicable to common shareholders of $32.3

million in the third quarter of 2015, or basic and diluted loss per share of $0.18. This net loss included $3.9 million in non-cash stock-based compensation expense, a $0.2 million non-cash loss on the change in fair value of derivatives, and a

$1.6 million charge for a non-cash deemed dividend for accounting purposes.

Under GAAP, Amarin reported a net loss applicable to common shareholders of

$58.9 million in the nine months ended September 30, 2016, or basic and diluted loss per share of $0.31. This net loss included $10.4 million in non-cash stock-based compensation expense and an $8.2 million non-cash gain on the change in fair

value of derivatives. For the nine months ended September 30, 2015, Amarin reported a net loss applicable to common shareholders of $127.2 million, or basic and diluted loss per share of $0.71. This net loss included $10.2 million in

non-cash stock-based compensation expense, a $0.4 million non-cash loss on the change in fair value of derivatives, and $33.9 million in charges for non-cash deemed dividends for accounting purposes.

Excluding non-cash gains or losses for stock-based compensation, change in fair value of derivatives, and the non-cash deemed dividend, non-GAAP adjusted net

loss was $16.0 million for the third quarter of 2016, or non-GAAP adjusted basic and diluted loss per share of $0.08, compared to non-GAAP adjusted net loss of $26.5 million for the third quarter of 2015, or non-GAAP adjusted basic and diluted loss

Excluding non-cash gains or losses for stock-based compensation, warrant compensation, change in fair value of derivatives, and the

non-cash deemed dividends, non-GAAP adjusted net loss was $56.7 million for the nine months ended September 30, 2016, or non-GAAP adjusted basic and diluted loss per share of $0.29, compared to non-GAAP adjusted net loss of $82.8 million for the

nine months ended September 30, 2015, or non-GAAP adjusted basic and diluted loss per share of $0.46.

Amarin reported cash and cash equivalents of $117.6

million as of September 30, 2016. The cash balance includes an increase of $64.6 million in net proceeds from an equity financing completed in August. The primary purpose of that financing was to fund REDUCE-IT to completion. During the quarter

ended September 30, 2016, net cash used in operating activities, including REDUCE-IT costs, was $18.7 million, or approximately $2.7 million excluding REDUCE-IT costs, interest and royalties. As of September 30, 2016, the company had $17.5 million

in net accounts receivable ($22.5 million in gross accounts receivable before allowances and reserves) and $19.8 million in inventory.

30, 2016, Amarin had approximately 269.2 million American Depository Shares (ADSs) and ordinary shares outstanding, 32.8 million common share equivalents of Series A Convertible Preferred Shares outstanding and approximately 21.2 million equivalent

shares underlying stock options at a weighted-average exercise price of $3.36, as well as 10.3 million equivalent shares underlying restricted or deferred stock units.

Conference call and webcast information

Amarin will host a conference call at 7:30 a.m. ET today, November 3, 2016. The call will be webcast live with slides and accessible

through the investor relations section of the company s website at www.amarincorp.com, or via telephone by dialing 877-407-8033 within the United States or 201-689-8033 from outside the United States. A replay of the call will be made available

for a period of two weeks following the conference call. To hear a replay of the call, dial 877-660-6853 (inside the United States) or 201-612-7415 (outside the United States). A replay of the call will also be available through the company s

website shortly after the call. For both dial-in numbers please use conference ID 13649077.

Use of non-GAAP adjusted financial information

Included in this press release and the conference call referenced above are non-GAAP adjusted financial information as defined by U.S. Securities and Exchange

Commission Regulation G. The GAAP financial measure most directly comparable to each non-GAAP adjusted financial measure used or discussed, and a reconciliation of the differences between each non-GAAP adjusted financial measure and the

comparable GAAP financial measure, is included in this press release after the condensed consolidated financial statements.

Non-GAAP adjusted net loss was

derived by taking GAAP net loss and adjusting it for non-cash gains or losses for stock-based compensation, warrant compensation, change in fair value of derivatives, and non-cash deemed dividends. Management uses these non-GAAP adjusted

financial measures for internal reporting and forecasting purposes, when publicly providing its business outlook, to evaluate the company s performance and to evaluate and compensate the company s executives. The company has provided these

non-GAAP financial measures in addition to GAAP financial results because it believes that these non-GAAP adjusted financial measures provide investors with a better understanding of the company s historical results from its core business

While management believes that these non-GAAP adjusted financial measures provide useful supplemental information to investors regarding the

underlying performance of the company s business operations, investors are reminded to consider these non-GAAP measures in addition to, and not as a substitute for, financial performance measures prepared in accordance with GAAP. Non-GAAP

measures have limitations in that they do not reflect all of the amounts associated with the company s results of operations as determined in accordance with GAAP. In addition, it should be noted that these non-GAAP financial measures may

be different from non-GAAP measures used by other companies, and management may utilize other measures to illustrate performance in the future.

Amarin Corporation plc is a biopharmaceutical company focused on the commercialization and development of therapeutics to improve

cardiovascular health. Amarin s product development program leverages its extensive experience in lipid science and the potential therapeutic benefits of polyunsaturated fatty acids. Amarin s clinical program includes a

commitment to an ongoing outcomes study. Vascepa (icosapent ethyl), Amarin s first FDA approved product, is a highly-pure, omega-3 fatty acid product available by

prescription. For more information about Vascepa visit www.vascepa.com. For more information about Amarin visit www.amarincorp.com.

About VASCEPA (icosapent ethyl) capsules

VASCEPA (icosapent ethyl) capsules are a single-molecule prescription product

consisting of 1-gram or 0.5-gram of the omega-3 acid commonly known as EPA in ethyl-ester form. Vascepa is not fish oil, but is derived from fish through a stringent and complex FDA-regulated manufacturing process designed to effectively eliminate

impurities and isolate and protect the single molecule active ingredient. Vascepa is known in scientific literature as AMR101.

FDA-approved Indication

Important Safety Information for VASCEPA

FULL VASCEPA PRESCRIBING INFORMATION CAN BE FOUND AT WWW.VASCEPA.COM.

Vascepa has been approved for use by the United States Food and Drug Administration (FDA) as an adjunct to diet to reduce triglyceride levels in adult

patients with severe ( 500 mg/dL) hypertriglyceridemia. Vascepa is under various stages of development for potential use in other indications that have not been approved by the FDA. Nothing in this press