6. NovoLog

Novolog Pen
NovoLog turned in $1.64 billion in U.S. sales for Novo Nordisk in 2016.

Company: Novo Nordisk
2016 U.S. sales: $1.64 billion
Drug class: Fast-acting insulin

Fast-acting mealtime insulin NovoLog, also sold around the world as NovoRapid, did well last year for maker Novo Nordisk in the U.S. The product raked in 56% of its $2.96 billion in global 2016 sales in the States. But the company had been hoping it would have an even quicker version approved before the year closed.

That fast-acting formula, already marketed as Fiasp in the U.K., Germany, and Canada, accelerates NovoLog’s onset of action, and it has potential for dosing both before and after meals.

The FDA, though, had different ideas. In October, it handed the Danish drugmaker a complete response letter, requesting more immunogenicity and clinical pharmacology data before it wrapped its review.

But the company is hoping the regulatory hurdle won’t set it back too far, especially as it struggles, along with its fellow diabetes drugmakers, under increased U.S. payer pressure. It’s already resubmitted the med in the U.S., and none too soon: Novo Nordisk’s formulation patent on NovoLog is set to expire this month.

6. NovoLog