If you take a big bet on an up-and-coming pharmaceutical maker and you turn out to be right, you should be able to reap some profit from your investment. That's what GlaxoSmithKline ($GSK) intends to do with a third of its stake in Aspen Pharmacare, a fast-growing South African drugmaker that has had a partnership with GSK since 2009.

GSK said it will sell up to 28.2 million shares of Aspen for R7.54 billion ($741 million). Aspen's stock, which is traded on the Johannesburg exchange, has skyrocketed nearly 67% in the last year, according to Bloomberg.

"GSK has a long and successful partnership with Aspen--and our investment in the company has grown in value significantly over time," GSK's head of strategy David Redfern said in a statement to Reuters. "Having assessed this investment we have now decided to realize some of this value without altering the basis of the partnership." After selling off this chunk of shares, GSK will maintain a 12% stake in Aspen and a seat on its board.

GSK first invested in Aspen as part of a strategy to grow its presence in emerging markets. GSK divested a manufacturing plant in Germany to Aspen, as well as several drugs, including cancer treatment Myleran (known as Busulfan in the U.S.) and antibiotic Septrin (Septra). GSK also transferred its marketing and distribution rights to all its products sold in South Africa, and the two agreed to collaborate on the commercialization of their product portfolios in the rest of sub-Saharan Africa.

Aspen, which also has an alliance with Merck ($MRK), has been charting impressive results of late. In September, it reported that its revenues jumped 27% to R19.3 billion ($1.9 billion) and its net income was up 25% to R3.52 billion ($354 million) in the year ending June 30. Aspen Group CEO Stephen Saad credited much of the company's global growth to its partnerships with GSK and Merck. In 2012, Aspen expanded its presence in Australia by paying GSK $268 million for the rights to 25 products it was no longer promoting there. Two years earlier, Aspen bought Australian generic-drug maker Sigma Pharmaceuticals for $880 million. Aspen plans to establish a presence in Russia and build on its operations in Latin America and Asia.

GSK isn't the only company angling for a position in South Africa's rapidly growing pharmaceutical industry. Chile's CFR Pharmaceuticals offered to pay R12.6 billion ($1.3 billion) in cash and stock for South Africa-based Adcock Ingram--a deal the two companies say they expect to consummate soon.