Mayne Pharma chief executive Scott Richards says US generic retail drug prices should stabilise after pressure from leading pharmacy chains to cut prices weighed heavily on the bottom line.

The impact of demands for more keen pricing from Wal-Mart Stores and Walgreens Boots Alliance steered Mayne to a full-year loss of $133.98 million, compared to a profit of $88.57 million a year earlier, with its bottom line marred by $184.4 million asset impairment flagged in the first half. The results also included stock adjustments, restructuring expenses and US tax items.