Table I.

Algorithm for price comparison by repurposing strategy type

Repurposing strategy	Price comparison	Rationale
Repositioning	Price per unit (e.g., mg): - Calculate price per unit (e.g., mg) for the source (‘P/unit A’) and repositioned product (‘P/unit B’) - Then, compare the calculated prices as follows:  • Price change=(‘P/unit B’ – ‘P/unit A’)/‘P/unit A’	The added value of a repositioned product lies in the different therapeutic use for the target product. In order to evaluate what exactly is the value attributed to the different therapeutic use of the target product, an assumption of price per mg allows one to offset variations for different doses used (i.e., pharmacodynamics variations).
Reformulations	Price per therapeutic dose (ideally maintenance dose): - For the source (A) and the reformulated product (B), define the therapeutic doses (D1 for A, D2 for B) - Calculate the prices per therapeutic dose (‘P/D1’ for A and ‘P/D2’ for B) - Then, compare the calculated prices as follows:  • Price change=(‘P/D2’ – ‘P/D1’)/‘P/D1’	The added value of a reformulation lies mainly is the difference in terms of ADME and/or convenience of administration. Because the therapeutic area for source and target products is the same, the comparison of equivalent therapeutic doses will provide the information regarding the added value considered for the reformulation.
Repositioning and reformulation	Price per equivalent unit dose: - Calculate price per unit (e.g., mg) for the source (‘P/unit A’) and target product (‘P/unit B’) - Define the therapeutic dose for each indication (D1 for A, D2 for B) - Then, calculate the unit price per therapeutic dose for each product (equivalent unit dose) (‘P/equivalent dose’=‘P/unit’ X D) - Finally, compare the calculated prices:  • ‘Price change’=(‘P/equivalent dose B’ – ‘P/equivalent dose A’)/‘P/equivalent dose A’	The evaluation of price per unit allows comparing beyond differences in therapeutic doses (i.e., adjusting for differences that may exist in terms of pharmacodynamics). After this, an adjustment is made to compare the price on the basis of the therapeutic doses in order to adjust for differences in ADME, if any.