M.Pharm or Med Chem after B.Pharm?
M.Pharm could be the natural choice after B.Pharm if you are intending for further studies in general pharma and research.
Med Chem is more niche and it is focussed on clinical trials, and hence your job search will thus be narrowed down to units that do clinical trials.
May be you could take up Med Chem for your higher research studies (Ph.D) if you later feel that your interest still lie in that area and you want to pursue it more.
Scope wise M.Pharm has wider scope currently compared to Med Chem as far as jobs are concerned after post graduation, while Med Chem will also give you a more focussed career in clinical trials units.
So, think over and make your choice wisely weighing pros and cons of each.