Amarin Reports Second Quarter 2016 Financial Results and Provides Update on Operations Second Quarter Net Product Revenue Up 85% vs. Prior Year Period Increasing Guidance on Full Year Net Product Revenue to $112-$125 Mil

Amarin Reports Second Quarter 2016 Financial Results and Provides Update on Operations

Second Quarter Net Product Revenue Up 85% vs. Prior Year Period

Increasing Guidance on Full Year Net Product Revenue to $112-$125 Million

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

BEDMINSTER, N.J., and DUBLIN, Ireland, August 4, 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 six months ended June 30, 2016, and provided an update on company operations.

Key Amarin achievements since March 31, 2016 include:

We continued to identify areas of expanded opportunity in our core commercial business and accelerated growth during the second

quarter, stated John F. Thero, president and chief executive officer. High-frequency calling on targeted physicians together with expanding managed care access and coverage have resulted in higher prescribing rates and overall improved

prescription growth. We look forward to continuing to expand market share based on our current indication and First Amendment promotional rights while preparing to potentially significantly expand the population of patients receiving Vascepa due to

high triglycerides after statin therapy assuming success of our ongoing cardiovascular outcomes study.

Increases in New and Recurring

Prescriptions Drive Steady Commercial Growth

During the second quarter, Amarin continued to see substantial prescription growth and steady

increases in prescription omega-3 and non-statin market share, particularly among detailed physicians. Increased switching of patients to Vascepa from earlier generation triglyceride lowering therapy (i.e., generic omega-3 ethyl ester mixtures and

fenofibrate products) is increasingly contributing to overall new prescription growth. Vascepa growth continues to be driven by focused message delivery, compelling supportive data and improved managed care coverage.

Normalized total Vascepa prescriptions, based on data from Symphony Health Solutions and IMS Health, totaled approximately 230,000 and 248,000, respectively,

for the three months ended June 30, 2016. These prescription levels represent growth of approximately 55% and 58%, respectively, from prior year levels, and approximately 14% and 16%, respectively, compared to Q1 2016. This increase in prescriptions

reflects the sales and marketing activities of both Amarin and our Vascepa co-promotion partner, Kowa Pharmaceuticals America, Inc.

Growth in both new and

recurring Vascepa prescriptions resulted in increased shipment volumes to wholesalers during the quarter. While prescription growth was the foundation for reported revenue growth in Q2 2016, the growth in revenue reported in Q2 2016 compared to Q2

2015 also included the effect of increased inventory levels at wholesalers and to a smaller extent higher net product pricing.

wholesalers tend to fluctuate based on seasonal factors, prescription trends and other factors. In Q1 2016, overall wholesaler inventory levels decreased from year-end 2015 calculated based on estimated days of Vascepa sales on hand. In

Q2 2016, the trend was reversed and overall wholesaler inventory levels increased. Consequently, we estimate that the net overall increase in wholesaler inventory levels contributed approximately $1.5 million to $1.8 million to net product

revenues for the six months ended June 30, 2016. During the same six-month period last year, we estimate that the impact of fluctuations in wholesaler inventory levels was more modest with lower net wholesaler inventory levels decreasing revenue by

less than $1.0 million.

On a quarterly basis, we estimate that the net overall increase in Q2 2016 wholesaler inventory levels from Q1 2016 added

approximately $2.9 million to $3.2 million to our reported revenues for the second quarter of 2016. The increase in inventory levels at wholesalers during Q2 2016 follows an estimated $1.2 million to $1.5 million decline in Q1 2016 revenues due

to reduced wholesaler inventory levels during the first three months of 2016. The foregoing estimates are based on inventory data provided to us by certain wholesalers and prescription data provided by Symphony Health Solutions and IMS Health.

Additional Endpoints and Second Interim Efficacy Analysis Strengthen REDUCE-IT Trial

The REDUCE-IT cardiovascular outcomes trial continues on schedule towards anticipated completion in 2017 and publication of results in 2018. The results of

this important trial, if successful, could lead to improved medical care for tens of millions of patients. As the trial progresses toward completion, Amarin has explored ways to mitigate regulatory risk, broaden the potential findings and accelerate

the availability of final data. To this end, the company recently amended the study protocol to add more pre-specified secondary and tertiary efficacy endpoints and a second protocol-specified interim efficacy analysis. The SPA amendment does not

change the primary endpoint or the overall size of the REDUCE-IT study, as confirmed with the FDA in the SPA agreement as amended. The SPA amendment does not change the company s prior guidance on timing.

In an effort to more broadly characterize the potential benefits of Vascepa, particularly among key patient subgroups, the study now includes more than 30

pre-specified secondary and tertiary endpoints designed to capture multiple potential drug effects in various subpopulations. The added endpoints could result in improved patient care for specific groups within the diverse population studied in

REDUCE-IT and are expected to support a variety of new publications furthering our goal to support informed medical decisions.

The first interim efficacy

and safety analysis by the independent data monitoring committee (DMC) at approximately 60% of targeted primary events is expected to occur in September or October 2016. 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 around mid-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 DMC s 60% and

80% interim analyses will each result in a recommendation to continue the REDUCE-IT study as planned.

Amarin will remain blinded to the interim and

ongoing results of the REDUCE-IT study as well as to any interim p-values and other statistical information until after the study is ready to be stopped, either at an interim analysis or at the final analysis.

Net product revenue for the

three months ended June 30, 2016 and 2015 was $32.8 million and $17.7 million, respectively. Net product revenue for the six months ended June 30, 2016 and 2015 was $58.1 million and $33.3 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 and a significant increase in the level of inventories held by independent wholesalers, our customers,

as of June 30, 2016.

Based on year-to-date results and anticipated trends, Amarin is increasing its guidance estimate for total 2016 net product revenue

to $112 million to $125 million. Amarin expects continued total prescription (TRx) growth to drive increased full-year 2016 revenue despite the potential impact of periodic fluctuations in wholesaler inventory levels. Amarin continues to expect

that, based on its projected revenue growth, the company is positioned to enter 2017 cash flow positive from commercial operations, excluding REDUCE-IT and other R&D expenses not required to sustain current commercial operations.

In addition, Amarin recognized licensing revenue of $0.5 million in the six months ended June 30, 2016 related to

agreements for the commercialization of Vascepa outside the United States. Based upon current estimates, Amarin anticipates approximately $1.1 million in licensing revenue to be recognized in aggregate during 2016 from existing agreements, including

the $0.5 million recognized in the first six months of 2016.

Cost of goods sold for the three months ended June 30, 2016 and 2015 was $8.9 million and

$6.4 million, respectively. Cost of goods sold for the six months ended June 30, 2016 and 2015 was $15.8 million and $12.0 million, respectively. Gross margin on product sales improved to 73% in the three and six months ended June 30, 2016

as compared to 64% in the three and six months ended June 30, 2015. 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 six months ended June 30, 2016 and 2015 were $54.1 million and $50.8 million,

respectively. The increase in SG&A expenses primarily reflects a $4.9 million increase in co-promotion fees payable to Kowa Pharmaceuticals America, Inc., resulting from a year-over-year increase in gross margin on product sales in 2016

coupled with an increase from 15% to 19% of aggregate Vascepa gross margin earned by Kowa Pharmaceuticals America, Inc.; and an increase in non-cash stock-based compensation expense, partially offset by a decrease in legal fees. Focused on continued

increases in sales productivity, the company currently anticipates its SG&A costs in 2016 as a whole will be substantially consistent with that in 2015, with the exception of non-cash costs and anticipated increases in the co-promotion fees

earned by Kowa Pharmaceuticals America, Inc. associated with anticipated increases in net product revenues.

Research and development expenses in the six

months ended June 30, 2016 and 2015 were $26.3 million and $24.6 million, respectively. This increase in expense was primarily driven by the timing of REDUCE-IT expenses. Research and development costs in 2016, excluding non-cash costs, are

expected to be similar in aggregate to 2015, including annual REDUCE-IT costs of approximately $30 million to $40 million until study completion with quarterly variability due to the timing of study-related costs.

Under GAAP, Amarin reported a net loss applicable to common shareholders of $13.4 million in the second quarter of 2016, or basic and diluted loss per share

of $0.07. This net loss included $3.4 million in non-cash stock-based compensation expense and a $5.8 million non-cash gain on the change in fair value of derivatives. Amarin reported a net loss applicable to common shareholders of $62.9

million in the second quarter of 2015, or basic and diluted loss per share of $0.35. This net loss included $3.2 million in non-cash stock-based compensation expense, a $0.6 million non-cash loss on the change in fair value of derivatives, and

a $31.3 million charge for a non-cash deemed dividend for accounting purposes.

Under GAAP, Amarin reported a net loss applicable

to common shareholders of $43.1 million in the six months ended June 30, 2016, or basic and diluted loss per share of $0.23. This net loss included $7.0 million in non-cash stock-based compensation expense and a $4.6 million non-cash gain on

fair value of derivatives. For the six months ended June 30, 2015, Amarin reported a net loss applicable to common shareholders of $94.8 million, or basic and diluted loss per share of

$0.53. This net loss included $6.3 million in non-cash stock-based compensation expense, a $0.1 million non-cash loss on the change in fair value of derivatives, and $32.2 million in charges for non-cash deemed dividends for accounting

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 $15.8 million for the second quarter of 2016, or non-GAAP adjusted basic and diluted loss per share of $0.09, compared to non-GAAP adjusted net loss of $27.7 million for the second quarter of 2015, or non-GAAP adjusted basic

and diluted loss per share of $0.15.

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 $40.7 million for the six months ended June 30, 2016, or non-GAAP adjusted basic and diluted loss per share of $0.22, compared to non-GAAP adjusted net loss of $56.3

million for the six months ended June 30, 2015, or non-GAAP adjusted basic and diluted loss per share of $0.32.

Amarin reported cash and cash equivalents

of $72.5 million at June 30, 2016. Net cash used in operating activities in the quarter ended June 30, 2016 of $9.0 million decreased compared to $25.6 million in the corresponding quarter of 2015 as a result of increased collections due to higher

revenues, which resulted in decreased net loss. As of June 30, 2016, the company had $17.6 million in net accounts receivable ($21.5 million in gross accounts receivable before allowances and reserves) and $20.3 million in inventory.

As of June 30, 2016, Amarin had approximately 184.6 million American Depository Shares (ADSs) and ordinary shares outstanding, 32.8 million common share

equivalents of Series A Convertible Preferred Shares outstanding and approximately 20.6 million equivalent shares underlying stock options at a weighted-average exercise price of $3.42, as well as 10.4 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, August 4, 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 13641286.

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