The over-the-counter medicine business is proving to be a lucrative one. And it’s one that is doing well in the current environment of a gradually slowing economy. Some of the world’s largest pharmaceutical companies – faced with looming patent expirations on some of their best-selling prescription medicines – realized they needed to plow serious money into research and development. So, in some cases, there was a simple solution: divest the steady, consumer-facing business of selling over-the-counter drugs to fund drug development work. This is exactly what GSK PLC (GSK) did over two years ago…