Walgreen (WBA 3.01%) reported its fiscal Q1 2013 results today. According to an official statement from the company, net profit measured by GAAP standards dropped by over 25% year over year during the quarter to land at $413 million ($0.43 per share). Net sales totaled $17 billion, a fall of nearly 5% from Q1 2012.

The company intimated that the shortfall was due to several factors, including the continuing impact of customer loss resulting from a dispute with Express Scripts (ESRX)

Additionally, the company made a change in the way it accounted for its 45% stake in European pharmacy conglomerate Alliance Boots. The modification negatively affected results by $0.07 per share, instead of the previously expected accretion of $0.03.