US pharmacy giant Walgreens has reported a 6.8 per cent sales fall for June compared with the same month last year, two weeks after it announced its partnership with Alliance Boots.

The pharmacy chain said June sales totalled £3.62 billon (US$5.63bn), down from £3.88bn (US$6.04bn) in June 2011, with "calendar day shifts" and the introduction of more generic drugs into the market having a significant impact.

The number of prescriptions filled at comparable Walgreens stores fell 11.9 per cent compared to June last year, when it still had a contract with the Express Scripts pharmacy network. The contract accounted for 12.6 per cent of prescriptions filled in June 2011.

"We realised this was a complex transaction and it would take time for investors to fully realise the vision we have in mind" Walgreens spokesperson

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Walgreens said a lower incidence of flu had hit its figures this year, as well as a shift in calendar days in June – this year the month had included one additional Friday and Saturday and one fewer Wednesday and Thursday. The US company said the introduction of more generic drugs into the market over the past year had also affected sales. Across the business, total pharmacy sales fell 10.7 per cent since last year. But Walgreens noted that, while customer traffic in comparable stores had dropped 2.3 per cent, shopping basket size rose 1.3 per cent.

Following its announcement of a £4.27bn merger with Alliance Boots on June 19, Walgreens shares took a downturn. But the company told C+D last month: "We realised this was a complex transaction and it would take time for investors to fully realise the vision we have in mind."

And last month Walgreens was optimistic about the company's future growth too. "Working together, Walgreens and Alliance Boots will have access to new customers, markets and lines of business across the US, Europe and key emerging markets, all of which will drive potential for diversification and growth," it said. "Our combined strength gives us the breadth, resources and expertise to create an unmatched global platform now and well into the future."