Shares in US drugmaker Eli Lilly fell more than 2% yesterday after the firm reported weaker-than-expected sales of some of its top products, and despite a 13% increase in net income.

First-quarter sales rose 6% to $3.72 billion, driven by Cymbalta (duloxetine) for depression and neuropathic pain, while net income came in at $835 million, said the firm. Analysts polled by Thomson First Call had expected sales of $3.8 billion.

At the heart of investor jitters seems to be a 3% decline in sales of Lilly’s flagship schizophrenia drug Zyprexa (olanzapine) to $1 billion, with a 5% decline in the USA despite price hikes.

Evista (raloxifene) for osteoporosis continued to suffer the effects of competition in the category, falling 3% to $242 million, although Lilly is hoping that new data in breast cancer prevention, due to be submitted to regulators later this year, can inject some new growth into the product.

But on the positive side, sales of Lilly's newer products grew 59% to $802 million and accounted for 22% of total sales, up from 14% of total sales a year ago.

Cymbalta was the firm’s strongest performer, up 118% to $233 million, although some analysts were disappointed that the sales were not even higher, and Lilly is hoping to add to sales momentum with a submission in generalised anxiety later this year. Meanwhile osteoporosis treatment Forteo (teriparatide) surged 90% to $127 million.

Other good performers were erectile dysfunction drug Cialis (tadalafil), sold by the Lilly ICOS joint venture, which saw turnover climb 48% to $223 million, lung cancer drug Alimta (pemetrexed) which rose 39% to $130 million and Gemzar (gemcitabine) for pancreatic cancer, up 11% to $339 million.

Strattera (atomoxetine) for attention deficit hyperactivity disorder (ADHD) climbed 27% to $152 million, although there was a decline in demand – brought about by a warning by the US Food and Drug Administration that it may be linked to liver damage – that was offset by higher prices.

Also hanging over Lilly is the ongoing threat of litigation surrounding Zyprexa, with lawsuits claiming that the drug has caused weight gain, diabetes and death. Last year, Lilly set aside $700 million to settle 8,000 lawsuits, but is facing a series of new claims that were filed before the March 1 deadline under US statute of limitations laws.