A pharmacist counts pills in a pharmacy. File image: Reuters

Aspen Pharmacare is the best performing stock among Johannesburg's blue chip companies in the last six months, rising over 36 percent to 120.40 rand.

The southern hemisphere's biggest generic drugs maker that is 19 percent owned by Britain's GlaxoSmithKline has been driving earnings growth through acquisitions, rather than organically, according to Nino Frodema, a fund manager at Momentum Asset Management.

“Growing your earnings in this fashion does inevitably, increase the company's risk profile and it raises the question, just how sustainable their earnings growth profile is going forward?,” Frodema said in an emailed response to questions.

The Durban-based pharmacare acquired GlaxoSmithKline's over-the-counter products for $263 million last month and has reached a deal with the minority shareholders of its east Africa-focused unit, Shelys, to buy their 40 percent holding for $24 million.

Aspen also purchased the generics business of Australia's Sigma Pharmaceuticals for $879 million in 2010.

Share prices of smaller rivals Cipla Medpro and Adcock Ingram have grown 12.6 and 6.5 percent respectively.

Aspen's shares are down 0.4 percent in Thursday's trade, compared with 0.2 percent rise by the Top-40 index. - Reuters