I write about market entry, exit, and pricing, especially for biotechnology and pharmaceuticals. Regarding market entry, I am interested in how to encourage drug developers to enter therapeutic markets that would otherwise be neglected. I write about innovation incentives, including the priority review voucher. Regarding market exit, I write about drug and vaccine shortages. Early in my career, I was also interested in where businesses located. Finally, I am interested in drug pricing, including launch prices and patient prices (copayments).

Priority review vouchers

I was lead author of an article that became law. In 2006 we proposed a priority review voucher program to encourage innovation for neglected diseases(Ridley et al. 2006). We worked with members of the Senate for passage of the voucher law in 2007. The FDA has awarded more than 50 vouchers and vouchers sell for about $100 million each, so we created a multi-billion dollar market and encouraged new drugs that save lives. You can read more about the priority review voucher on Wikipedia or on my voucher page.


To encourage drug development for neglected diseases, government agencies can provide direct funding of clinical trials. However, some government agencies will free ride, diverting funds to other diseases and purposes. Another way to encourage drug development for neglected diseases is to offer transferable exclusivity vouchers.


In health care, shortages are surprisingly common. One cause of drug and vaccine shortages is low and inflexible prices. Manufacturers invest little in spare capacity if margins are thin. Rationing has been effective at mitigating the harm from a vaccine shortage, provided that some supply is available from a second manufacturer.


Government policy influences both drug launch prices and price changes.


When businesses cluster, they engage in more intense price competition. So why cluster? Followers cluster near leaders to i) free ride on the demand information of the market leader, ii) because they can differentiate their products and mitigate price competition, and iii) because zoning forces clustering.

For more information, see my Google Scholar page.