Actelion Ltd has entered into a definitive agreement to acquire CoTherix, Inc., a biopharmaceutical company with its headquarters in Brisbane, California. CoTherix currently markets Ventavis (iloprost), the only approved inhaled therapy for the treatment of Pulmonary Arterial Hypertension in the United States.

The transaction has been approved unanimously by the boards of directors of both companies. Actelion will commence a cash tender offer of USD 13.50 per CoTherix Inc. share, for a total acquisition price of approximately USD 420 million (CHF 525 million). This represents an approximate premium of 72 per cent over the closing price 1 month prior, and a 21 percent premium over CoTherix's closing price of USD 11.20 on Friday, November 17, 2006. Subject to regulatory clearance and other customary closing conditions, the transaction is expected to conclude early in Q1 2007.

The directors and executive officers of CoTherix and additional stockholders, together owning approximately 32% of the outstanding shares, have agreed with Actelion to tender their shares pursuant to the offer, subject to customary terms and conditions, including termination rights.

Actelion has had a longstanding relationship with CoTherix, developed through a shared focus on Pulmonary Arterial Hypertension. This relationship was extended with CoTherix's clinical STEP trial investigating the combined use of Tracleer and Ventavis®. Based on that relationship, the two companies had previously commenced discussions regarding the strong strategic fit between the two businesses. Those discussions were placed on hold due to certain contractual obligations of CoTherix. Last Friday, after the close of the Swiss market and following the earlier than expected conclusion of these obligations CoTherix inquired of Actelion whether it wished to resume discussions. Following this, Actelion completed its due diligence and the companies finalized negotiations, resulting in the Boards of Directors of both companies approving the transaction and entering into the definitive agreement.

Jean-Paul Clozel, MD and chief executive officer, commented: "We expect that the transaction will generate immediate substantial value, adding top-line revenue and bottom-line cash earnings by leveraging our existing marketing and sales infrastructure in the United States and expanding the reach of Ventavis."

Jean-Paul Clozel continued: "CoTherix and its employees have done an outstanding job with Ventavis, a product commercially available in the US since March 2005. Through the acquisition of CoTherix, Actelion will further lead the drive towards improved PAH therapy, both today with the existing form of Ventavis and potentially tomorrow through improved delivery systems and dry-powder inhalation to further enhance convenience for patients."

Jean-Paul Clozel added: "By introducing our orally available dual endothelin receptor antagonist Tracleer (bosentan) in late 2001, Actelion has always led the drive for improved PAH therapy. By applying the proven abilities of our drug development team with those of CoTherix, we are committed to accelerating Ventavis' develop ment in order to support today's trend of combining agents from multiple drug classes to improve treatment outcomes for patients."

Donald J. Santel, chief executive officer of CoTherix, Inc, said: "Our vision for CoTherix has been to advance the therapeutic options for patients with cardiovascular disease. Through the efforts of our talented and dedicated employees, we've been successful in introducing Ventavis, the first non-invasive prostacyclin for PAH in the United States. The proposed combination with Actelion, a global leader in cardio-pulmonary medicine, will further accelerate this vision and provide additional benefit to the patient population we've been privileged to serve."

Jean-Paul Clozel concluded: "This acquisition will leave unchanged the Actelion culture with its desire to discover, develop and market new innovative medicines. Actelion has never been in a better position for substantial future growth from our rapidly expanding product pipeline, with possibly five different compounds in Phase III in 2007."

Pursuant to the Agreement and Plan of Merger between the parties, Actelion will commence a tender offer to purchase all the outstanding shares of CoTherix, Inc. for USD 13.50 per share on 8 December 2006. This offer is subject to cu stomary conditions, including the tender of at least a majority of the shares of CoTherix common stock outstanding and clearance under the United States Hart-Scott-Rodino Antitrust Improvements Act. Following the successful completion of the tender offer, a subsidiary of Actelion is expected to merge with CoTherix, resulting in CoTherix becoming a wholly-owned subsidiary of Actelion. Lehman Brothers is acting as an adviser to Actelion in relation to this transaction. CIBC World Markets Corp. is acting as financial advisor to CoTherix.

On 30 September 2006, Actelion has reported cash, cash equivalents and short-term deposits and marketable securities of CHF 636.3 million. The financing of the acquisition can therefore be made entirely from the existing cash balance. In addition, on 9 November 2006, the company priced a CHF 460 million zero-coupon, zero yield to maturity convertible bond with a settlement date of 22 November 2006. The transaction is not subject to a financing condition.