Elan Corp has posted a loss for the third quarter, but sales of its multiple sclerosis blockbuster Tysabri continue to grow.

The Irish drugmaker’s net loss came in at $43.6 million, compared with a profit of $52.3 million a year ago, though the latter was boosted by a $107.7 million gain from the divestment of its Alzheimer's disease programme to Johnson & Johnson last year. Revenues for the quarter dipped 2% to $281.4 million.

Global turnover of Tysabri (natalizumab) climbed 9% to $307.2 million, while Elan’s share of sales from the drug, which is marketed with Biogen Idec, reached $215.9 million, up 19%. Sales of the antibiotic Azactam (aztreonam), which is off-patent and which Elan has ceased to market, fell to just $600,000 from $19.8 million a year earlier, though another antibiotic Maxipime (cefepime) brought in $2.5 million, up almost 39%. The severe pain treatment Prialt (ziconotide), which had sales in the like, year-earlier period of $4.7 million, has been divested to Azur Pharma and contributed nothing to the third-quarter figures.

As for the Elan Drug Technologies business, revenues were down 9% to $62.3 million, due to a collapse in manufacturing revenues and royalties from King Pharmaceuticals’ off-patent muscle relaxant Skelaxin (metaxalone). The latter was somewhat offset from cash coming in from Abbott Laboratories’ cholesterol drug TriCor (fenofibrate) and Acorda Therapeutics' new multiple sclerosis drug Ampyra (fampridine prolonged-release) tablets which contributed $14.1 million.

Ian Hunter, an analyst at Dublin stockbroker Goodbody, said the figures were "steady", but he described Tysabri's performance as "slightly disappointing". Elan and Biogen had noted that 75,500 patients have now been exposed to the product in a marketing setting, thus "implying that 27.8% of those who have been on the drug have quit".

Use of Tysabri has been linked to the risk of developing a rare but potentially fatal brain disease, progressive multifocal leukoencephalopathy.