Pfizer has posted solid first-quarter financials but has warned that the near-term future looks a bit bleaker as generic competition takes its toil on the firm’s blockbuster antihypertensive Norvasc and the antidepressant Zoloft.

The company’s revenues were up 6.2% to $12.47 billion, and while net income was down 18% to $3.39 billion, or $0.48 per share, the decline was primarily due to restructuring and acquisition costs and the figures were ahead of analysts’ expectations.

Leading the revenue rise once again was the cholesterol-lowerer Lipitor (atorvastatin), sales of which climbed 8% to $3.36 billion, while Celebrex (celecoxib) for arthritis climbed 22% to $598 million. The erectile dysfunction drug Viagra (sildenafil) contributed $434 million (+11%), but the most pleasing performance came from Pfizer’s new epilepsy and neuropathic pain medication Lyrica (pregabalin), up 106% to $395 million.

As for its even newer products, Pfizer's novel pill for smoking cessation Champix/Chantix (varenicline) brought in $162 million, helped by an unbranded advertising campaign that is developing the market, while cancer drug Sutent (sunitinib) had sales of $102 million. Caduet, which combines Lipitor with Norvasc (amlodipine), leapt 89% to $146 million.

However it is the sales of Norvasc on its own, still Pfizer’s second bestseller, which is causing concern. They fell 10% to just under $1.1 billion, but the damage will be a lot more severe in the coming months as generic versions of the drug become more widely available. Copycat competition is already hurting Zoloft (sertraline) and sales crashed 81% to $779 million.

Exubera continues to disappoint

Pfizer has reduced its full-year revenue estimates by $1.2 billion to $47-$48 million to reflect the loss of patent exclusivity for Norvasc, which came six months earlier than expected, and has adjusted its earnings forecast to $2.08-$2.15 per share, down from $2.18-$2.25. Chief executive Jeffrey Kindler also noted that “the disappointing revenue performance” of Exubera (inhaled insulin) for diabetes is continuing and the firm will get more deeply involved in the more extensive market-development activities we now believe are necessary” to support the product, for which no quarterly sales figures were disclosed.

Mr Kindler also noted the firm’s concerns over a decision by a Canadian federal court in a case with Ranbaxy at the end of January which found Pfizer's atorvastatin patent to be invalid there and said that 2008 revenues could be significantly hurt if a final decision goes against the New York-based giant. US sales of Lipitor have experienced a modest decline as patients switch to cheaper generic forms of Merck & Co's rival product Zocor (simvastatin), but Pfizer is comfortable that it can regain its previous strength in the market.

FDA staff back HIV drug maraviroc ahead of review

Meantime, documents posted on the US Food and Drug Administration’s website, ahead of a review by the agency’s Antiviral Drugs Advisory Committee on April 24, say that Pfizer's Celsentri (maraviroc), the first in a new class of HIV/AIDS treatments called CCR5 antagonists, reduces viral levels in patients with the disease.

In the documents, FDA staff state that combined data from two trials involving treatment-experienced patients with CCR5-tropic HIV-1 showed that maraviroc plus optimised therapy was twice as likely to reduce viral loads to undetectable levels compared with optimised therapy alone. However, agency staff noted that while Celsentri did not appear to increase the risk of lymphoma or infections, it was associated with a possible "modest increase in liver-related side effects," so they have asked the panel to consider whether there is a need for special labelling or even additional clinical trials.