GlaxoSmithKline has agreed to sell about a third of its stake in South Africa's Aspen Pharmacare, banking about £425 million in the process.

The UK drugs major said it had agreed to the sale of 28.2 million shares in Aspen for 7.06 billion rand. This will leave GSK with 56.5 million shares, representing a 12.4% stake in the Durban-headquartered company.

GSK said its "close relationship" with Aspen will not be affected by the transaction, as it will retain a seat on the latter's board and "intends to remain a significant shareholder". The company added that it has agreed not to dispose of any further shares in Aspen for six months following
completion and the proceeds will be used for general corporate purposes.

David Redfern, GSK chief strategy officer, said the firm has "a long and successful partnership with Aspen — and our investment in the company has grown in value significantly over time". He added that "we have now decided to realise some of this value without altering the basis of the partnership".

GSK acquired a stake in Aspen in 2009 when the firms entered into two collaborations in sub-Saharan Africa. Aspen has since acquired a number of over-the-counter and prescription brands from GSK, most recently the thrombosis drugs Arixtra (fondaparinux) and Fraxiparine (nadroparin), and the facility in France where the treatments are produced. That deal is expected to close before year-end and Aspen is paying £700 million in cash and £100 million for inventory.