Switzerland-based drugmaker Actelion has confirmed the initiation of preliminary discussions with US-based ZS Pharma over a potential transaction.

ZS Pharma has also confirmed participation in discussions with Actelion which may or may not lead to any transaction.

Bloomberg reported sources familiar with the matter as saying that Actelion made an offer last month to buy ZS Pharma in a deal worth $2.5bn.

"The acquisition will enable Actelion to expand its treatments for pulmonary arterial hypertension."

In a corporate statement, ZS Pharma said it will not ‘disclose any developments unless and until it otherwise deems further disclosure is appropriate or required’.

According to Actelion, the acquisition will enable the company to expand its treatments for pulmonary arterial hypertension, while maximising its market value.

Biopharmaceutical company ZS Pharma has offices in Redwood City, California and Coppell, Texas. Its lead therapeutic candidate ZS-9 (sodium zirconium cyclosilicate) is an investigational treatment for hyperkalemia.

Actelion focuses on the discovery, development and commercialisition of new drugs for diseases with significant unmet medical needs, such as pulmonary arterial hypertension.

Its portfolio of PAH treatments comprises the spectrum of disease, from WHO Functional Class (FC) II through to FC IV, with oral, inhaled and intravenous medications.

In June, reports emerged that Ireland’s Shire made an informal approach to Actelion for a £12.4bn takeover.