By Brett Kelman and Rachana Pradhan for KFF Health News. Broadcast version by Danielle Smith for Tennessee News Service reporting for the KFF Health News-Public News Service Collaboration Four years ago, Tennessee became the first state to allow adults to buy the antiparasitic drug ivermectin from a pharmacy without first seeing a doctor. Pharmacies can use a pre-written, blanket prescription to sell to just about anyone who walks through their doors.