I'd go through an inicial test phase using programmatic media buying to identify a few insights first. With that, I would probably target the most efficient channels and set up an inbound strategy to capture​ leads. I would also try Google AdWords, but I can see that being costly. Facebook interest targeting would be something to try, especially if there are user groups related to the specific medical conditions you need to target. To get to a more specific strategy or tactics, I would need to have more concrete information... Hope that helps!