Aetna Inc. has hired another company to handle some pharmacy benefit management activities.

Aetna, Hartford (NYSE:AET), will be keeping its own pharmacy benefit manager (PBM) unit but getting some services from CVS Caremark, Woonsocket, R.I. (NYSE:CVS), the companies say.

Aetna will continue to manage clinical programs, protocols and PBM oversight.

CVS Caremark will administer Aetna’s retail pharmacy network and manage Aetna’s pharmacy customer operations and PBM member services operations.

CVS Caremark will also manage purchasing, inventory management and prescription fulfillment for Aetna’s mail-order and specialty pharmacy operations.

Although CVS Caremark will handle general PBM contracting, Aetna will handle rebate contracting and administration, sales and marketing activities, formulary design, integration of medical and pharmacy benefits, management of member appeals, and ownership and management of its mail-order and specialty pharmacies.

Aetna and CVS Caremark hope to put the agreement into effect Jan. 1, 2011.

CVS Caremark will be hiring about 800 Aetna PBM employees, and Aetna will be keep about 1,000 PBM employees, the companies say.