AdvancePCS

Aetna US Healthcare

Amerigroup

Anthem

Blue Cross/Blue Shield Federal

Index of State Blue Cross/Blue Shield Sites

Caremark:
primary formulary
preferred formulary

Chandler Group/Ameriscript

Cigna

Coventry Healthcare
includes:
Carelink
Coventry of the Carolinas
Coventry of Delaware
Coventry of Georgia
Coventry of Kansas
Coventry of Louisiana
Coventry of Nebraska
Group Health Plan, Inc.
Health America Pennsylvania
Health Care USA
Southern Health Services
Wellpath Community Health Plans

Health Net

Humana

Kaiser Colorado Springs

Merck Medco
(must register and check meds individually)

Mid Atlantic Medical Services (MAMSI)

Partners National Health Plans

Preferred Health Systems

United Healthcare

Trinity Health/Care Choices