Who is the Primary Customer

In understanding the opportunity for success of the USA sales strategy by Polynovo I am keen to get your views regarding who you consider as the 'primary' customer? It is interesting that Pharma giant Merck's most important customer are not the patients who use its drugs or the physicians who prescribe them. Merck, instead has chosen research scientists in labs and universities around the world as its primary customer. The business is even configured like a research university. I know that if you do not identify your primary customer, management can sidestep difficult choices that might turn out badly. So getting back to PolyNovo in the USA, is the primary customer the patient, the physician, the hospital purchasing manager, the government ? How do you focus a sales team of three to get the best bang for buck?
Has PolyNovo clearly defined this?