Complex sentence: GSK's drugs and vaccines earned £21.3 billion in 2013; its top-selling products that year were Advair, Avodart, Flovent, Augmentin, Lovaza and Lamictal.
Split into simpler sentences: GSK's drugs and vaccines earned £21.3 billion in 2013. Its top-selling products that year were Advair, Avodart, Flovent, Augmentin, Lovaza and Lamictal.