Independent pharmacies' OTC sales could have slumped about 20 per cent in the past two years, a market research study has suggested.

The research, carried out by Zaicom Research Plus and based on the sales data of an independent group of 60 pharmacies, found OTC sales had fallen by a fifth since July 2010 in the group – dropping to a low of 1,300 non-prescription items per store in July this year.

The data was collected through the group's central buying and supply system, and Zaicom claimed it was a "good representative example of typical independent pharmacies".

"Patients have been shifting their buying patterns to the likes of supermarkets and Poundland" Fin McCaul, IPF

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But Numark marketing director Lynne Armstrong questioned whether the data was reflective of the entire independent sector. Although she said Numark's members had seen a decline in sales of some toiletries due to the multiples waging a "price war", she stressed that independents were holding their own in some categories. "The good news is that Numark members have got behind advice-driven sales on medicines," Ms Armstrong said. "P and GSL [medicines] are still performing well, with a significant increase of own-label lines."

The Independent Pharmacy Federation (IPF) highlighted that the research data was from a "small sample size", but said independents were facing a "difficult trading environment".

"The economy is in recession and patients have been shifting their buying patterns to the likes of supermarkets and Poundland," IPF chair Fin McCaul told C+D.

Avicenna CEO Salim Jetha agreed that competitive pricing at supermarkets was partly to blame, but said there were a number of factors that could be responsible for the decline in independents' OTC sales.

Mr Jetha cited the growth in online businesses and changes to market conditions as potential reasons, adding that regulatory pressures were forcing managers to spend time away from the front of the shop, where they could be driving sales.

Multiples appeared to enjoy more positive OTC sales this year, with Lloydspharmacy parent company Celesio reporting a boost in profits for the first quarter of 2012, driven by "good OTC business in the UK". And Boots reported little change to its OTC business in its 2011-12 results, as retail health sales showed a modest decline of 2.4 per cent compared to the year before.