>Can selling begin in a country once the reimbursement is negotiated?<
Selling can begin even before reimbursement is negotiated if someone wants to pay for the drug out of pocket. Since this is rarely done, however, the establishment of a reimbursement schedule in a given country is necessary for significant sales in that country.
Other than reimbursement, there is no impediment that I’m aware of.
“The efficient-market hypothesis may be
the foremost piece of B.S. ever promulgated
in any area of human knowledge!”