21.   Pharmacy benefit managers like Medco play a critical role in determining which drugs consumers take for different ailments by offering financial incentives for people to select certain medicines.

22.   Pharmacy benefits managers, who serve as middlemen between drug companies and health plans, say the wrangling is worth it.

23.   Pharmacy benefit managers like PCS negotiate low prices from drug companies, then sell the drugs in bulk to health-insurance plans.

24.   Pharmacy benefits managers act as middlemen, buying drugs in huge amounts on behalf of large employers and unions.

25.   PCS Health Systems of Scottsdale, Ariz., another benefit manager, has been owned since January by Rite Aid, the drugstore chain.

26.   PCS is the largest of the prescription drug benefit managers, which employers and insurers hire to make price-cutting deals with drug manufacturers.

27.   Pharmacy benefit managers and HMOs typically establish lists of preferred drugs, known as formularies, and recommend low-cost generic versions of brand-name drugs.

28.   Pending lawsuits contend that some pharmacy benefit managers have violated their duty to act in the best interest of patients.

29.   Pharmaceutical benefit managers like PCS can demand deep discounts from drug manufacturers in return for a high volume of purchases.

30.   Pharmacists, meanwhile, are lobbying in several states for laws that would regulate pharmacy benefit managers more tightly.