Exhibit 99.1

Reference is hereby made to the First Supplemental Indenture, dated as of March 26, 2007 (the “Indenture”), between ViroPharma Incorporated (the “Company”) and Wilmington Trust Company, as trustee (the “Trustee”), relating to the Company’s 2.00% Convertible Senior Notes due 2017 (CUSIP No. 928241AH1) (the “Notes”).  All capitalized terms used but not defined in this notice shall have the meanings ascribed to such terms in the Indenture.  A copy of the Indenture was included as an exhibit to the Company’s Current Report on Form 8-K, filed with the United States Securities and Exchange Commission (the “SEC”) on March 26, 2007, which is available on the SEC’s website at www.sec.gov.

On November 11, 2013, the Company entered into an Agreement and Plan of Merger (the “Merger Agreement”) by and among the Company,  Shire Pharmaceutical Holdings Ireland Limited, a company incorporated in Ireland (“Parent”), Venus Newco, Inc., a Delaware corporation and a wholly owned subsidiary of Parent (“Merger Sub”), and, solely for the purposes set forth in the Merger Agreement, Shire PLC, a company incorporated in Jersey, pursuant to which, among other things, Merger Sub will commence a cash tender offer (the “Offer”) for all of the outstanding shares of the Company’s common stock, par value $0.002 per share (the “Shares”), upon the terms and subject to the conditions of the Merger Agreement.

The Company’s board of directors has unanimously approved, and declared to be advisable, the Merger Agreement and the transactions contemplated therein, and intends to file a Solicitation/Recommendation Statement on Schedule 14D-9 with the SEC recommending that stockholders tender their Shares into the Offer.

Pursuant to the Merger Agreement, and upon the terms and subject to the conditions thereof, Parent has agreed to cause Merger Sub to commence a cash tender offer (as promptly as practicable, but in no event later than November 25, 2013) for all of the outstanding Shares at a purchase price of $50.00 per Share, net to the seller in cash, without interest and less any required withholding taxes (the “Offer Price”). As soon as practicable following the consummation of the Offer, and subject to the satisfaction or waiver of certain conditions set forth in the Merger Agreement, Merger Sub will merge with and into the Company (the “Merger”) pursuant to the provisions of Section 251(h) of the Delaware General Corporation Law (the “DGCL”) and the Company will survive as a wholly owned subsidiary of Parent.  At the effective time of the Merger, the Shares not purchased pursuant to the Offer (other than Shares

owned, directly or indirectly, by Parent or Merger Sub, the Company or any of its subsidiaries, and Shares owned by stockholders who have properly exercised any available rights of appraisal under Section 262 of the DGCL) will be automatically converted into the right to receive cash in an amount equal to the Offer Price.

If the Offer is consummated, it will constitute a Fundamental Change, and accordingly the Notes are convertible in connection with such Fundamental Change at the option of the holders pursuant to Section 12.01(e) of the Indenture at any time, after the Company gives this notice until the Fundamental Change Repurchase Date relating to such Fundamental Change, which will be no earlier than 20 calendar days after the consummation of the Offer.  If the Merger occurs, it will constitute an additional Fundamental Change under the Indenture, and accordingly the Notes are convertible at the option of the holders pursuant to Section 12.01(d) of the Indenture at any time, from the date hereof and until and including the date that is 30 Scheduled Trading Days after the effective date of the Merger.  In addition, in connection with the Merger, the Company’s common stock is expected to be delisted from the NASDAQ Global Select Market (the “Delisting”).  If the Delisting occurs, it will also constitute an additional Fundamental Change under the Indenture, and the Notes will be convertible in connection with such Fundamental Change at the option of the holders pursuant to Section 12.01(e) of the Indenture at any time, after the Company gives this notice until the Fundamental Change Repurchase Date relating to such Fundamental Change, which will be no earlier than 20 calendar days after the Delisting.  Pending anti-trust authority clearances, it is anticipated that the consummation of the Offer and the Merger will occur in the last quarter of 2013, the first quarter of 2014 or as soon as possible thereafter.  Solely for the purposes of this notice, pursuant to Sections 12.01(d) and 12.01(e) of the Indenture, the Company hereby notifies you that it currently anticipates that the Effective Date (as defined in the Indenture) of the Offer, the Merger and the Delisting will occur, on the 30th Scheduled Trading Day from the date of this notice.  The Company, however, is unable to give any assurances as to the actual date or dates such events will occur, if at all.

The Company issued a press release publicly announcing the execution of the Merger Agreement on November 11, 2013, and included a copy of the press release and the Merger Agreement as exhibits to the Company’s Current Report on Form 8-K, filed with the SEC on November 12, 2013.

IMPORTANT INFORMATION FOR INVESTORS AND STOCKHOLDERS

The Offer described in this document has not commenced.  This document does not constitute an offer to buy or a solicitation of an offer to sell any securities.  On the commencement date of the Offer, a tender offer statement on Schedule TO, including an offer to purchase, a letter of transmittal and related documents, will be filed with the SEC by Merger Sub and Parent, and a Solicitation/Recommendation Statement on Schedule 14D-9 will be filed with the SEC by the Company.  The Offer will only be made pursuant to the offer to purchase, the letter of transmittal and related documents filed as a part of the Schedule TO.  INVESTORS AND STOCKHOLDERS OF THE COMPANY ARE URGED TO READ BOTH THE TENDER OFFER STATEMENT AND THE SOLICITATION/RECOMMENDATION STATEMENT REGARDING THE OFFER, AND ANY AMENDMENTS OR SUPPLEMENTS THERETO, AND OTHER DOCUMENTS FILED WITH THE SEC WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION. Investors and stockholders may obtain a copy of these documents (when available) free of charge at the SEC’s website at www.sec.gov. The Company also will provide a copy of these materials without charge on its website at www.viropharma.com under the “Investors” section.

2