US drugmaker Forest Laboratories posted a 15% hike in first-quarter revenues to $816 million, helped by a pick-up in sales of flagship antidepressant Lexapro, although net income declined.

Net sales rose 12% to $759 million, with Lexapro (escitalopram oxalate) contributing $507 million, a 10% increase year-on-year. Net income, however, was down 7.4% at $200 million, although if a tax rebate received in the first quarter of 2005 was discounted, the result would have been a 15% increase.

Sales of Namenda (memantine), Forest’s N-methyl-D-aspartate (NMDA) receptor antagonist for the treatment of moderate and severe Alzheimer's disease, reached $151 million during the quarter, up 32%.

The increase in Lexapro sales is also a positive for Denmark’s H Lundbeck, which licenses the drug as well as Namenda to Forest. Shares in Lundbeck rose yesterday after Forest’s results statement was released

And Forest got more good news last week when a US court upheld its patent for the drug, extending out to 2012, which had been challenged by generic company Teva Pharmaceutical Industries.

Also included in net revenues was other income of $58 million, which included $42 million in contribution from Forest's Benicar (olmesartan medoxomil) co-promotion agreement, which rose 72%.

R&D spending increased 147% to $139 million. This figure included a license payment of $60 million to Spanish drugmaker Almirall for the US rights to LAS34273, a compound being investigated for the treatment of chronic obstructive pulmonary disease.

But shares in Forest slipped back after investors reacted to cautious statements, made in a webcast, that about the timings for approval and launch of two key pipeline products, the antibiotic faropenem and blood pressure drug nebivolol, partnered with Mylan Laboratories.

Faropenem is not due to reach the market until the middle of next year, said Forest, while nebivolol could also be approved around the same time, providing Forest can respond effectively to an ‘approvable’ letter sent by the US Food and Drug Administration to the company last year.