Strong sales growth for arthritis drug Enbrel and pneumococcal vaccine Prevnar has helped US drugmaker post a 10% increase in revenues to $5.22 billion in the fourth quarter of 2006, although earnings fell short of analysts' expectations.

Net income was $855.4 million (+16.9%), or $0.63 per share, well down on consensus estimates of $0.71, which was put down to stock option expenses and higher-than-expected general and R&D costs. Wyeth also took a net charge of $63.8 million to cover “productivity initiatives.”

Back to the drugs and Enbrel (etanercept) climbed 40% to $416 million outside North America, where Wyeth has exclusive marketing rights, while Prevnar turnover was up 25% to $501.7%. Also contributing to the good performance was Wyeth's top-selling product, the antidepressant Effexor (venlafaxine), which rose 11% to $936.1 million in the quarter despite an increasingly competitive environment in the USA where generics abound.

Sales of the gastrointestinal drug Protonix (pantoprazole) were flat at $419.6 million, while Wyeth’s Zosyn (piperacillin/tazobactam) antibiotic climbed 21% to $249 million. The hormone replacement therapy range Premarin (conjugated oestrogens), which includes the controversial Prempro (conjugated estrogens/medroxyprogesterone acetate) brought in $262 million (+20%).

Chief executive Robert Essner was pleased with Wyeth’s showing in 2006 and noted that it achieved “a billion or multi-billion dollar status in annual sales in six product franchises.” He added that “with six regulatory filings involving four new pharmaceutical products completed during the year, combined with continued investments in R&D, Wyeth is positioned for strong growth in 2007 and beyond.”

Much is resting on Effexor follow-up Pristiq (desvenlafaxine), though last week the US Food and Drug Administration only issued an approvable letter for the drug, telling Wyeth it needs to sort out quality control at one of its manufacturing plants if it is to get the go-ahead to market its latest antidepressant.

Analysts were reasonably impressed with the figures and Bank of America issued a research note saying that “given its limited patent expirations and significant near-term pipeline opportunities,” Wyeth is attractively valued.