As a few people have pointed out now, the insurance companies would be the customer. If your software allows patents with disease X to recover 5% faster and they spend a billion on disease X claims each year your software instantly has 50m value to them. You should be able to find a bunch of examples of how much Americans spend on different medications a year, extrapolate the differences in recovery rates from correct and incorrect prescriptions to that value.
Additionally, I'm sure they audit Dr prescriptions, if you get the insurance companies to use your service in the audits the hospitals will also purchase it to pre-audit themselves. Perhaps the drug companies can mandate its use. If you can't get a business to want your product, make them need it :)