NU Online News Service, Aug. 1, 12:53 p.m. – Merck Inc., Whitehorse Junction, N.J., has temporarily withdrawn plans for an initial public offering for its Medco Health Solutions Inc. subsidiary “due solely to market conditions,” the company said yesterday in a document filed with the U.S. Securities and Exchange Commission.

“Merck remains fully committed to the establishment of Medco Health as a separate, publicly traded company and intends to complete the separation within 12 months, subject to market conditions,” the company said.

Medco, based in Franklin Lakes, N.J., is a major pharmacy benefits manager and also the operator of a major mail-order pharmacy.

The SEC approved Merck’s IPO plans for Medco early in July, but Merck has been facing questions about whether the unit will be independent enough from Merck to do a good job of managing pharmacy benefits, and an article in the Wall Street Journal that criticized the approach the unit has used to calculate its revenue.

Despite the recent attacks, the unit’s finances are strong, and sales at its home-delivery and Internet-based prescription operations are up, Merck says.