Swiss biotech Serono posted a 20% hike in third-quarter net profits this morning, something that will be pleasing for Merck KGaA, the German drugmaker in the process of acquiring the business.

The $171 million profit came in a little ahead of analysts’ expectations and on the back of a 9.5% increases in revenues to $699 million, once again driven by Serono’s multiple sclerosis drug Rebif (interferon beta-1a).

“We have delivered an excellent quarter with strong performance of our leading product, Rebif, and our company has again generated strong cash flow, said Serono’s chief executive officer Ernesto Bertarelli.

Worldwide sales of Rebif came in at $375 million, up 18% despite increasing competition in the market for MS drugs. Encouragingly Rebif sales rose by nearly a third in the USA, said Serono, and the company expects further upside from a new formulation of the drug that is currently under review in the USA and Europe.

This formulation offers improved tolerability and lower tendency to cause allergic reactions than the current version.

There was also positive news to report on Raptiva (efalizumab), Serono’s psoriasis drug that at one point was earmarked as a product that could reduce the company’s reliance on Rebif. Sales rose more than 80% to $18 million, though it is not growing as strongly as hoped, in part because of a warning added to its labelling last year warning of a risk of haemolytic anaemia with the drug. Serono has started a massive Phase IV evaluation to try to restore confidence in its safety.

Sales of growth hormone Saizen (somatropin) were slightly down at $50.5 million, although the Serostim formulation used to treat AIDS wasting grew 9.5% to $19.5 million.

Novantrone (mitoxantrone) sales in the third quarter fell 85% to $2.8 million, hit by the introduction of generics in the US in April.