Prescription trends and costs associated with a new drug launch will pressure Bristol-Myers' ( BMY) gross margins, Prudential Securities said in a research note Monday. As a result, the brokerage lowered its estimate of the drug company's fourth quarter earnings to 26 cents a share from 31 cents and its 2003 estimate to $1.56 a share from $1.77. It left its investment rating at hold, saying uncertainty about the company's future earnings is priced in. The stock trades at $23.35. "With nearly all of its largest products either co-promoted in the U.S. or in-licensed at late stages of development, BMY's gross margin of 65.7% in 2003 is lower than most of its peers," Prudential wrote. "We see little going forward that substantially improves those margins."