Long-term debt as of September 30, 2011 and December 31, 2010 is summarized in the following table:

As of September 30, 2011 senior convertible notes representing $205.0 million of principal debt are outstanding with a carrying value of $151.5 million.

On March 26, 2007, we issued $250.0 million of 2% senior convertible notes due March 2017 (senior convertible notes) in a public offering. Net proceeds from the issuance of the senior convertible notes were $241.8 million. The senior convertible notes are unsecured unsubordinated obligations and rank equally with any other unsecured and unsubordinated indebtedness. The senior convertible notes bear interest at a rate of 2% per annum, payable semi-annually in arrears on March 15 and September 15 of each year commencing on September 15, 2007.

The debt and equity components of our senior convertible debt securities are bifurcated and accounted for separately based on the value and related interest rate of a non-convertible debt security with the same terms. The fair value of a non-convertible debt instrument at the original issuance date was determined to be $148.1 million. The equity (conversion options) component of our convertible debt securities is included in Additional paid-in capital on our Condensed Consolidated Balance Sheets and, accordingly, the initial carrying value of the debt securities was reduced by $101.9 million. Our net income for financial reporting purposes is reduced by recognizing the accretion of the reduced carrying values of our convertible debt securities to their face amount of $250.0 million as additional non-cash interest expense. Accordingly, the senior convertible debt securities will recognize interest expense at effective rates of 8.0% as they are accreted to par value.

On March 24, 2009 we repurchased, in a privately negotiated transaction, $45.0 million in principal amount of our senior convertible notes due March 2017 for total consideration of approximately $21.2 million. The repurchase represented 18% of our then outstanding debt and was executed at a price equal to 47% of par value. Additionally, in negotiated transactions, we sold approximately 2.38 million call options for approximately $1.8 million and repurchased approximately 2.38 million warrants for approximately $1.5 million which terminated the call options and warrants that were previously entered into by us in March 2007. We recognized a $9.1 million gain in the first quarter of 2009 as a result of this debt extinguishment. For tax purposes, the gain qualifies for deferral until 2014 in accordance with the provisions of the American Recovery and Reinvestment Act.

As of September 30, 2011, we have accrued $0.2 million in interest payable to holders of the senior convertible notes. Debt issuance costs of $4.8 million have been capitalized and are being amortized over the term of the senior convertible notes, with the balance to be amortized as of September 30, 2011 being $2.1 million.

The senior convertible notes are convertible into shares of our common stock at an initial conversion price of $18.87 per share. The senior convertible notes may only be converted: (i) anytime after December 15, 2016; (ii) during the five business-day period after any five consecutive trading day period (the "measurement period") in which the price per note for each trading day of that measurement period was less than 98% of the product of the last reported sale price of our common stock and the conversion rate on each such day; (iii) during any calendar quarter (and only during such quarter) after the calendar quarter ending June 30, 2007, if the last reported sale price of our common stock for 20 or more trading days in a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter exceeds 130% of the applicable conversion price in effect on the last trading day of the immediately preceding calendar quarter; or (iv) upon the occurrence of specified corporate events. Upon conversion, holders of the senior convertible notes will receive shares of common stock, subject to ViroPharma's option to irrevocably elect to settle all future conversions in cash up to the principal amount of the senior convertible notes, and shares for any excess. We can irrevocably elect this option at any time on or prior to the 35th scheduled trading day prior to the maturity date of the senior convertible notes. The senior convertible notes may be required to be repaid on the occurrence of certain fundamental changes, as defined in the senior convertible notes. As of September 30, 2011, the fair value of the principal of the $205.0 million convertible senior notes outstanding was approximately $248.1 million, based on the level 2 valuation hierarchy of the fair value measurements standard.

Concurrent with the issuance of the senior convertible notes, we entered into privately-negotiated transactions, comprised of purchased call options and warrants sold, to reduce the potential dilution of our common stock upon conversion of the senior convertible notes. The transactions, taken together, have the effect of increasing the initial conversion price to $24.92 per share. The net cost of the transactions was $23.3 million.

The call options allow ViroPharma to receive up to approximately 13.25 million shares of its common stock at $18.87 per share from the call option holders, equal to the number of shares of common stock that ViroPharma would issue to the holders of the senior convertible notes upon conversion. These call options will terminate upon the earlier of the maturity dates of the related senior convertible notes or the first day all of the related senior convertible notes are no longer outstanding due to conversion or otherwise. Concurrently, we sold warrants to the warrant holders to receive shares of its common stock at an exercise price of $24.92 per share. These warrants expire ratably over a 60-day trading period beginning on June 13, 2017 and will be net-share settled.

The purchased call options are expected to reduce the potential dilution upon conversion of the senior convertible notes in the event that the market value per share of ViroPharma common stock at the time of exercise is greater than $18.87, which corresponds to the initial conversion price of the senior convertible notes, but less than $24.92 (the warrant exercise price). The warrant exercise price is 75.0% higher than the price per share of $14.24 of our price on the pricing date. If the market price per share of ViroPharma common stock at the time of conversion of any senior convertible notes is above the strike price of the purchased call options ($18.87), the purchased call options will entitle us to receive from the counterparties in the aggregate the same number of shares of our common stock as we would be required to issue to the holder of the converted senior convertible notes. Additionally, if the market price of ViroPharma common stock at the time of exercise of the sold warrants exceeds the strike price of the sold warrants ($24.92), we will owe the counterparties an aggregate of approximately 13.25 million shares of ViroPharma common stock. If we have insufficient shares of common stock available for settlement of the warrants, we may issue shares of a newly created series of preferred stock in lieu of our obligation to deliver common stock. Any such preferred stock would be convertible into 10% more shares of our common stock than the amount of common stock we would otherwise have been obligated to deliver under the warrants. We are entitled to receive approximately 10.87 million shares of its common stock at $18.87 from the call option holders and if the market price of ViroPharma common stock at the time of exercise of the sold warrants exceeds the strike price of the sold warrants ($24.92), will owe the counterparties an aggregate of approximately 10.87 million shares of ViroPharma common stock.

The purchased call options and sold warrants are separate transactions entered into by us with the counterparties, are not part of the terms of the senior convertible notes, and will not affect the holders' rights under the senior convertible notes. Holders of the senior convertible notes will not have any rights with respect to the purchased call options or the sold warrants. The purchased call options and sold warrants meet the definition of derivatives. These instruments have been determined to be indexed to our own stock and have been recorded in stockholders' equity in our Condensed Consolidated Balance Sheets. As long as the instruments are classified in stockholders' equity they are not subject to the mark to market provisions.

On September 9, 2011, we entered into a $200 million, three-year senior secured revolving credit facility (the "Credit Facility"), the terms of which are set forth in a Credit Agreement dated as of September 9, 2011 (the "Credit Agreement") with JPMorgan Chase Bank, N.A., as administrative agent, BMO Harris Financing Inc., TD Bank, N.A. and Morgan Stanley Bank, NA as co-syndication agents and certain other lenders.

The Credit Facility is available for working capital and general corporate purposes, including acquisitions which comply with the terms of the Credit Agreement. The Credit Agreement provides separate sub-limits for letters of credit up to $20 million and swing line loans up to $10 million.

The Credit Agreement requires us to maintain (i) a maximum senior secured leverage ratio of less than 2.00 to 1.00, (ii) a maximum total leverage ratio of less than 3.50 to 1.00, (iii) a minimum interest coverage ratio of greater than 3.50 to 1.00 and (iv) minimum liquidity equal to or greater than the sum of $100,000,000 plus the aggregate amount of certain contingent consideration payments resulting from business acquisitions payable by us within a specified time period. The Credit Agreement also contains certain other usual and customary affirmative and negative covenants, including but not limited to, limitations on capital expenditures, asset sales, mergers and acquisitions, indebtedness, liens, dividends, investments and transactions with affiliates.

Our obligations under the Credit Facility are guaranteed by certain of our domestic subsidiaries (the "Subsidiary Guarantors") and are secured by substantially all of our assets and the assets of the Subsidiary Guarantors. Borrowings under the Credit Facility will bear interest at an amount equal to a rate calculated based on the type of borrowing and our senior secured leverage ratio (as defined in the Credit Agreement) from time to time. For loans (other than swing line loans), we may elect to pay interest based on adjusted LIBOR plus between 2.25% and 2.75% or an Alternate Base Rate (as defined in the Credit Agreement) plus between 1.25% and 1.75%. We will also pay a commitment fee of between 35 to 45 basis points, payable quarterly, on the average daily unused amount of the Credit Facility based on our senior secured leverage ratio from time to time.

As of the date of this filing, we have not drawn any amounts under the Credit Facility.

As of September 30, 2011, we have accrued $0.0 million in interest expense for the revolver. Financing costs of approximately $1.6 million incurred to establish the Credit Facility were deferred and are being amortized to interest expense over the life of the Credit Facility, with an unamortized balance of $1.6 million as of September 30, 2011.