The struggle is REAL! MDs used to get paid by Pharma labs to get their attention (real life exemple: $30-80 just to fill a tiny online form). To my experience (consulting & entrepreneurship in healthcare/medtech), I would say that most MDs do not like emails, social media or cold calls. The best way to have their attention is to get recommandation from other professional... Maybe you should try to contact some specialized medical associations or communities (dedicated groups on LinkedIn, experts on Clarity / Quora, etc.) Hope that it helps!