GlaxoSmithKline has completed a previously-announced deal that increases its stake in Theravance, the firm's development partner for Relovair, the follow-up to respiratory blockbuster Advair.

Theravance's shareholders have approved the transaction, unveiled last month, at their annual general meeting which will see the UK drug major buy 10 million shares priced at $21.29 apiece. This means GSK now owns about 25.8 million shares, or 26.7% of Theravance's outstanding stock.

The companies have been partners for nearly ten years and have developed Relovair, which combines a once-daily inhaled corticosteroid (fluticasone) with a long-acting beta-agonist (vilanterol). Phase III development has been completed and GSK intends to submit regulatory applications for chronic obstructive pulmonary disease in the USA and Europe in mid-2012. A filing of the combo in Europe for asthma is scheduled around the same time.

Relovair has been dubbed 'Super Advair' as it is the follow-up product to GSK's biggest-selling drug Advair (salmeterol/fluticasone) but analysts have expressed concern about the strength of the data package that has been compiled. The two companies are also working on a bifunctional muscarinic antagonist-beta2 agonist for COPD which is in Phase II.

The deal comes a day after GSK agreed to acquire the shares it does not currently own in Anglo-German proteomics specialist Cellzome for £61 million.