The sponsors of the new system, called RxHub, said their three companies managed drug plans with 125 million members who used about half of the 2.5 billion prescriptions filled last year.
As the country's third-largest pharmacy benefit manager, Express gets paid by corporate and government health plans to manage drug plans and to wrangle discounts out of drugmakers.
The business of managing drug plans has become increasingly controversial.
IMS and its competitors gather the data through contracts with retail pharmacy chains and companies that manage drug plans for insurers, then sell it to pharmaceutical companies.
Express Scripts, which manages drug plans, has a lab that studies how workers use (legal) drugs and how they might be nudged to take the right ones at the right time.
At Medco Health Solutions, which manages drug plans for 62 million people, the number of its client companies requiring employees to obtain approval in advance for some costly drugs rose 70percentto to 560, last year.
But the company, which manages drug plans and discount cards for more than 50 million people, will still promote certain drugs "on our own nickle," a company spokesman said.
The growth in spending on prescription drugs slowed in the first months of 2003, moderating a long climb, according to a customer survey released today by Express Scripts, a company that manages drug plans for 50 million people.
Raymond V. Gilmartin, Merck's chairman and chief executive, said that the company would spin off part of Merck-Medco, the unit that manages drug plans for employers, in an initial public offering as early as this summer, and sell the remainder of business over the following 12 months.
They bought many of those medications as members of managed care drug plans run by pharmacy benefit managers, companies that arrange discounts from retail drugstores and often operate mail-order pharmacies on behalf of employer health plans.
