Sorry you haven't had any replies. I'm not one, but I work with them sometimes. Many seem to be qualified (medical) doctors but I've known a few people from other scientific disciplines. They tend to be very bright, very literate and very numerate and have an enormous capacity for work. If that's you (they leave me on the floor!), I'd contact a few firms directly and ask about recruitment, or check websites. I don't know of courses; people I know have learnt on the job on a very steep learning curve! Good luck - it's a lovely sector: everyone I work with has a very good work ethic and is a delight to work with: positive, endlessly polite, team worker, etc.
I did contact a recruitment agency and they said that most people have a PhD but some manage to get in with a BSc/MSc and experience in healthcare/pharmaceuticals. I am not sure if it would be that bit too hard really. I am going to have a look at a few freelance vacancies and see what they are asking for.
I would think pharmaceutical knowledge is a big plus. If you work in the NHS (long may it reign), nothing else will be too hard. I got into it with dodgy degree qualifications because I lived close to my first client, and they thought I had potential to plug a few gaps as a freelancer. It grew and branched from there. I did have a lot of editorial experience, but ~no medical, and at times that is a sore trial but people put up with me because I spot things like missing headers and mislabelled footnotes! All the best.