Why might the launch price of a new drug be a poor indicator of future expenditure for a drug? Which are the factors that determine the future prices and market shares of a drug? Understanding the answers to these questions can be crucial when conducting cost-effectiveness analyses i.e. when studying if it is desirable to publicly fund reimburse a new drug. This paper models and studies the price of a new drug along its life-cycle, from launch to discontinuation, to understand how the price of the drug evolves and to help inform cost-effectiveness evaluations.