Eagan-based Prime Therapeutics has formed a strategic alliance with drugstore giant Walgreens that would combine the companies’ specialty and mail-order pharmacy businesses.

In addition, health plan subscribers with pharmacy benefits managed by Prime Therapeutics would have preferred access to Walgreens pharmacies as part of the agreement announced Monday.

Financial terms were not disclosed, but Prime officials believe it could spur growth that pushes the firm beyond its position as the country’s fourth-largest pharmaceutical benefits manager (PBM).

Prime Therapeutics is owned by 14 Blue Cross and Blue Shield insurance companies, so the agreement with Walgreens brings together two of the country’s strongest brands in health care, said Jim DuCharme, the chief executive of Prime Therapeutics, in an interview.

“Nobody in the industry has integrated and connected the health plan — the Blue plan — with the retail pharmacy network, with the PBM, for unification of data, technology and overall drug cost reduction,” DuCharme said. “So, that’s probably the most unique feature of this strategic alliance.”

Health insurers hire PBMs to manage the pharmacy benefit portion of health plans. That means everything from negotiating prices with drug companies to structuring formularies that stipulate patient co-payments for different medications.

PBMs assemble a network of retail pharmacies where health plan subscribers can get their prescriptions at the lowest cost. The companies also directly fill prescriptions for patients through mail-order pharmacies as well as specialty pharmacies focused on high-cost and complex medications.