Merck Slips Amid Warning About Zocor

One indicator of the significance in Vioxx's prescription decline will come Friday when Pfizer issues its second-quarter results and reveals information about Celebrex, a member of the same class of drugs as Vioxx.

Merck also reported that second-quarter sales for Zetia, a cholesterol drug developed in cooperation with Schering-Plough, advanced to $123 million, nearly triple the sales in the first quarter of 2003. Zetia became available in the U.S. in November. Still, Merck said its collaboration with Schering-Plough won't be profitable this year due to the costs of the product launch and joint venture spending with Schering-Plough.

Merck's core pharmaceutical business, excluding Medco, recorded an 8% gain in net income in the second quarter to $1.78 billion from $1.66 billion for the same period last year, and a 7% increase in revenue to $5.53 billion from $5.16 billion. On a standalone basis, Medco scratched out a 1% gain in net income to $105.2 million from $104.6 million. Revenue was virtually unchanged at $8.4 billion.

Merck's stock ended down $1.95, or 3.16%, at $59.82 on Monday, after falling as low as $59.28.