Horizon Pharma plc Increases Offer for Depomed, Inc. to $33.00 per Share

Price Increase Contingent on Engagement and Confirmatory Due Diligence

Horizon Pharma plc (NASDAQ: HZNP), a biopharmaceutical company focused on improving patients’ lives by identifying, developing, acquiring and commercializing differentiated and accessible medicines that address unmet medical needs, announced today that it has increased the value of its all-stock acquisition proposal to $33.00 per share from $29.25 per share, contingent on Depomed entering into good faith discussions regarding a transaction. The increased offer represents a 60 percent premium to the closing price of Depomed on July 6, 2015, the day prior to when Horizon’s initial proposal was made public.

“Based on discussions we’ve had with Depomed’s largest shareholders as well as our own shareholders, it is clear that they and the investment community strongly support a combination of our two businesses,” said Timothy P. Walbert, chairman, president and chief executive officer, Horizon Pharma plc. “We are resolute in our commitment to acquire Depomed and we call upon Depomed’s board of directors to listen to their shareholders, fulfill their fiduciary responsibilities and meet with us in order to promptly complete a negotiated transaction.”

The increased offer was communicated to the Depomed board of directors, Inc. today, July 21, 2015, the full text of which follows below:

July 21, 2015

Board of Directors Depomed, Inc. 7999 Gateway Blvd., Suite 300 Newark, CA 94560

Dear Madam and Sirs,

It has been almost two months since we formally communicated our proposal to acquire Depomed, Inc. (“Depomed”). We remain surprised and disappointed by your lack of willingness to engage in a constructive dialogue with the Horizon Pharma plc (“Horizon”) team regarding our offer.

We announced yesterday our estimated net sales for the second quarter of 2015 as well as new guidance with respect to estimated 2015 net sales and adjusted EBITDA. Horizon’s net sales for the second quarter of 2015 of $170 to $172 million represents an increase of greater than 50 percent versus the first quarter of 2015 and greater than 160 percent versus the second quarter of 2014. These results demonstrate the strength of our management team and the commercial model we have developed. We suggest our second quarter results and increased guidance should provide additional evidence of the value Horizon’s commercial and management teams would contribute to the future growth of Depomed’s medicines.

Since making our offer public on July 7, 2015, to acquire 100 percent of Depomed’s issued and outstanding shares of common stock for a price of $29.25 per share in Horizon ordinary shares, we have had the opportunity to discuss our proposal with both Depomed and Horizon shareholders. Based on our conversations with many of your shareholders, including some of your largest shareholders, we are confident they and the broader investment community believe a combination of our two companies represents clear and compelling strategic logic and would create significant immediate and long-term value for Depomed and Horizon shareholders.

As we have communicated to your advisors and you previously, Horizon remains committed to an acquisition of Depomed and we are prepared to consider all paths necessary to complete the transaction; however, our preferred path remains a friendly, negotiated transaction. To demonstrate our commitment to a friendly transaction, we verbally communicated to you an increase to our proposed price to acquire Depomed to $32.25 from $29.25 per share in Horizon ordinary shares. Despite this significant price increase, which we believed would act as a catalyst to facilitate engagement with Depomed, our revised proposal was summarily rejected. The continued lack of engagement with Horizon to negotiate a transaction as well as the governance measures you have put in place to disenfranchise your shareholders in an attempt to prevent or delay a transaction are inconsistent with how your investors have communicated they would like Depomed’s board and management to proceed.

In our effort to pursue a friendly, negotiated transaction, we are prepared to further increase our proposal price to $33.00 per share in Horizon ordinary shares, contingent on Depomed rapidly entering into good faith discussions regarding a transaction. Based on public information available to us, we believe $33.00 is a full and fair price for Depomed and represents an approximate 60 percent premium to the Depomed share price on the day prior to our original proposal being made public. We urge you to thoughtfully evaluate this revised proposal and engage with us to facilitate a transaction over the next several days. We and our advisors stand ready to immediately meet with your management team and board to negotiate a mutually acceptable agreement.

This letter does not create any binding obligation on the part of Horizon. No such obligation will exist until a mutually acceptable definitive agreement is executed.

Best regards,

Timothy P. Walbert Chairman, President and Chief Executive Officer