Biogen Idec has posted first-quarter results which reveal a 41% leap in profits, while revenues rose 10% thanks to continued strong growth for its multiple sclerosis blockbusters Avonex and Tysabri.

Net income came in at $426.7 million, while revenues reached $1.42 billion, driven by Avonex (interferon beta-1a), which rose 7.1% to just over $746 million. Tysabri (natalizumab), to which Biogen has bought all the rights from partner Elan Corp, contributed $312.2 million, up 9%.

The rheumatoid arthritis and cancer drug Rituxan (rituximab), partnered with Roche, brought in $265 million, down 7%, while Fampyra, a prolonged-release tablet formulation of fampridine to improve walking in adults with MS licensed from Acorda Therapeutics, climbed 54% to $23.2 million. Sales of the psoriasis treatment Fumaderm (fumaric acid) climbed 8% to $14.3 million.

However most interest at the moment is on Tecfidera (dimethyl fumarate), Biogen's MS pill which was approved by the US Food and Drug Administration in March. The company is not giving any specifics about the drug's initial days on the market but says it is encouraged by the early signs of physician and patient interest.

Analysts believe Tecfidera will be a blockbuster and may have safety and efficacy advantages over MS tablets already on the market, namely Novartis' Gilenya (fingolimod) and Sanofi's Aubagio (teriflunomide). Michael Yee at RBC Capital Markets said Biogen has "the most comprehensive MS armamentarium with Avonex, Tysabri, and Tecfidera, with potential for sustained double-digit EPS growth for the next five-plus years".

Biogen chief executive George Scangos said "2013 is off to an exciting start", with the launch of Tecfidera in the USA, acquisition of full rights to Tysabri and a positive Phase III trial for Plegridy (peginterferon beta-1a) in the treatment of relapsing-remitting MS. He added that "we also are preparing for the potential launches in 2014 of our long-lasting clotting factor therapies for haemophilia, rFVIIIFc and rFIXFc,” claiming that "these therapies have the potential to transform the standard of care".