Swiss firm Actelion has agreed to acquire CoTherix of the USA in a deal valuing the latter company at around $420 million.

The deal shores up Actelion’s position in the market for drugs to treat pulmonary arterial hypertension, a growing market in which Actelion has a strong position with its Tracleer (bosentan) product.

CoTherix has sold Ventavis (iloprost) Inhalation Solution, the only approved inhaled therapy for the treatment of PAH in the USA, since March 2005, and said recently it expects sales of the product to top $100 million next year. Sales in the first nine months of 2006 were a little under $50 million.

Tracleer sales were 652 million Swiss francs ($525m) in the first none months of the year, although analysts believe the product could come under pressure as competition in the sector builds. This will come from Pfizer’s already-marketed Revatio (ambrisentan), Myogen’s ambrisentan (due for approval in the USA later this year) and Encysive’s Thelin (sitaxsentan sodium), which was recently launched in the UK, its first EU market, but is delayed in the USA.

Actelion said it had already explored the use of Tracleer in combination with Ventavis in clinical trials.

Jean-Paul Clozel, the company’s chief executive officer, said: "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.”

The takeover, which has been endorsed by CoTherix' board, is still subject to regulatory approvals and expected to close in the first quarter of next year.

Shares in Actelion were up around 2% in mind-morning trading today, at 206 francs.