My advice: put a lot of effort on presenting yourself as an expert in your field...I find this is a key in the healthcare/pharma market to make your "crowd" listen. Best way to do this is through content marketing tools (white papers, blog posts, social media activity - as others already suggested). Inspire them, offer information away for free that they can't get anywhere else, only from you. I wouldn't "write down" emails. No matter the audience, everybody looks at their emails...they just don't open those which are sales blasts or have irrelevant content.
And I agree, you need to meet them. I know that conferences can be expensive, but I find that it's still a great way to discuss with prospects and have a relaxed first discussion. I'd choose one event with the most relevant participant list and invest in a registration fee. I'd send out some personal emails to see if I can meet some interesting prospects there "to catch up".