21.   Pharmacy benefit managers often receive payments or rebates from drug makers to include their drugs on lists of preferred medicines.

22.   Pharmacy benefit managers organize the market for prescription drugs, securing deep discounts from drug manufacturers and retail pharmacies for large employers or health plans.

23.   Pharmacy benefits managers administer pharmaceutical benefits for health plans, HMOs and employers.

24.   Rep. Ron Wyden, D-Ore., who requested the GAO report, said the pharmacy benefit managers should be a defense against high drug prices for consumers.

25.   RxHub, another project that hopes to link doctors and pharmacies, is sponsored by pharmacy benefit managers, including Merck-Medco, Express Scripts and AdvancePCS.

26.   Restrepo said that pharmacy benefit managers have been reluctant to work with the online pharmacies, making it virtually impossible for them to get customers.

27.   Some critics have raised questions about how much pharmacy benefit managers really save employer health plans.

28.   Stuart L. Bascomb, executive vice president of Express Scripts, said some drugs would not be affordable for many people without the discounts obtained by pharmacy benefit managers.

29.   Such companies, known as pharmacy benefit managers, see the Medicare population as an attractive market.

30.   Still, because the pharmacy benefit managers and the drug makers can keep their price decisions well out of public view, questions continue to arise.