Diabetes Drugs: List Price Increases Were Not Always Reflected In Net Price; Impact Of Brand Competition Unclear.

List prices for brand-name drugs have risen steeply, often despite the introduction of competition from other brand-name drugs in the same therapeutic class. List prices, however, do not reflect any rebates that manufacturers provide payers. To understand how net prices (after rebates and other discounts) respond to competition, we compared changes in inflation-adjusted, revenue-weighted mean list and net prices of a one-month supply of three classes of diabetes drugs: glucagon-like peptide 1 (GLP1) agonists, dipeptidyl peptidase 4 (DPP4) inhibitors, and sodium glucose cotransporter 2 (SGLT2) inhibitors. These drug classes each had several brand-name products enter the market between 2005 and 2017. The annualized change in list price over this period was $75 (15 percent) for GLP1 agonists, $22 (8 percent) for DPP4 inhibitors, and $41 (11 percent) for SGLT2 inhibitors. In contrast, the annualized change in net price was $38 (10 percent) for GLP1 agonists, -$3 (-2 percent) for DPP4 inhibitors, and -$17 (-9 percent) for SGLT2 inhibitors, suggesting a variable impact of brand-name competition on net prices.