NEW YORK (AP) _ Merck's second-quarter earnings rose 12 percent, driven mostly by strong U.S. sales of its cholesterol-lowering pill Zocor and its pharmacy benefit management business.

Merck made a $1.48 billion profit in the second quarter, or 61 cents per share, compared to $1.32 billion or 54 cents per share in the same period a year ago. Results matched Wall Street's expectations.

Sales in the quarter rose 24 percent to $8.02 billion from $6.47 billion.

Zocor, Merck's top-selling drug, posted a 12 percent increase in sales to $1.09 billion in the second quarter, including a 20 percent jump in the United States. Part of the reason for higher sales is that U.S. doctors are increasingly prescribing higher doses of Zocor.

Despite the increase in U.S. sales, Zocor has steadily lost market share to Warner-Lambert and Pfizer's Lipitor, which is marketed as a more potent cholesterol drug. Zocor still has bigger worldwide sales largely because Lipitor has yet to enter the Japanese market.

Other drugs that helped Merck's earnings were the blood pressure medication Cozaar/Hyzaar, up 37 percent to $335 million, another blood pressure pill Prinivil, up 26 percent to $215 million and osteoporosis pill Fosamax, up 48 percent to $245 million.

Merck-Medco, which manages pharmacy benefits for large employers and health insurers, had $3.76 billion in revenues in the quarter, up 33 percent from a year ago.

Merck's total sales received a boost because of an accounting change in how the company records revenues from a joint marketing program with the former drug manufacturer Astra.

Vioxx, Merck's new arthritis and pain drug which was launched in the United States in May, had $97 million in sales.

One continuing disappointment for Merck is its baldness drug Propecia, what had flat sales of $45 million in the quarter.

For the first six months, Merck made $2.78 billion profit, or $1.15 per share, compared to $2.48 billion or $1.01 per share.

Sales in the first six months rose 24 percent to $15.55 billion from $12.53 billion.

Shares of Merck fell 56 3/4 cents to $68.81 1/4 in trading on the New York Stock Exchange.