Mobile App for medicine

I am looking to develop a comprehensive mobile app that can be used for both iOS and Android platforms. The main component of this app will be providing medical information, a conduit for communication, information retrieval and e-commerce. The app should feature functions that allow users to authenticate themselves, communicate (via text or phone call) and securely process payments. Additionally, the app must be able to collect data regarding medicine purchases, allowing users to easily look up pertinent information whenever needed.