NEW YORK (AP) — Drugstore operator Walgreen Co. said Thursday that its sales grew in October, but the results were weaker than expected and the company acknowledged a dispute with pharmacy benefits manager Express Scripts Inc. is hurting its results.

The company said sales at locations open at least a year increased 2.6 percent for the month. Sales at stores open at least one year is considered a key measurement of retailer health because it excludes results from stores that opened or closed over the last 12 months. Thomson Reuters says analysts were expecting those sales to rise 4.9 percent.

Walgreen said pharmacy revenue from stores open at least a year rose 3.1 percent and revenue from "front-end" sales of items like cosmetics increased 1.7 percent. Both fell short of analyst estimates. Prescriptions filled at those stores increased 2.5 percent. The company said it believes its impending split with Express Scripts reduced prescriptions by 0.6 percent.