BBC recently compiled some nice, more dis-aggregated numbers on pharma marketing spend & profit margins using GlobalData. Numbers are for 2013 I believe. On first glance looks like the median ROI is similar to Forbes numbers that have been used to show high profitability earlier (e.g. by Prof Donald Light in this classic article)*.
BBC article: http://www.bbc.co.uk/news/business-28212223? [see table]
[This same data table shows that Marketing spend is greater than R&D spend for 9 of 10 top pharma companies.]
*The earlier Forbes numbers come from a slide compiled by Kaiser FF, but they no longer host the slide. Luckily it is still available as a cached version here.