Shares of GW Pharmaceuticals (NASDAQ:GWPH) are down 9.4% at 5:56 p.m. EDT on Thursday after the drugmaker released second-quarter results that didn't live up to expectations.

On the surface, the sales jump for Epidiolex, which treats childhood epilepsy syndromes, looks great. Who's going to complain about a 72% year-over-year increase in sales to $117.7 million?

But a look at the previous quarter highlights how growth has ground to a halt -- for now at least. First-quarter sales of the marijuana-derived drug were $116.1 million, just slightly lower than the recently completed quarter.

The COVID-19 pandemic may have drawn some sales from the second quarter into the first quarter as people panicked about getting medication. Stocking after launches in Germany and the U.K. may have hurt the quarter-over-quarter comparison as well. But even factoring in those two issues, it's pretty clear sales growth has waned for now.

Doctor listening to a child's heart with a stethoscope.

Image source: Getty Images.

Looking forward, Europe and the rest of the world offer an opportunity for growth, considering that sales of Epidiolex (marketed as Epidyolex in Europe) outside the U.S. were just $6.6 million in the second quarter.

The Epidiolex franchise in the U.S. also has the opportunity to expand with the approval of the drug to treat tuberous sclerosis complex earlier this week. The expanded approval reduced the age range of patients approved to take the drug from two years of age or older down to one year of age or older. The additional year will help GW Pharmaceuticals pick up some additional patients who have Lennox-Gastaut syndrome or Dravet syndrome, which the drug was already approved to treat.

Looking a little further out, the biotech has a pipeline beyond Epidiolex, although it'll be a couple of years before those drugs start contributing to revenue growth.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.