"As the prices have increased, the demand has increased as well, which is exactly the opposite of what you'd expect to see given the laws of price and demand," said Josh Gray, vice president of research at Athenahealth.
"I really think this just reinforces the observation that the growth of EpiPens [prescriptions] has been seemingly imperious to their price increases," Gray said.
"This is not an area where parents want to cut corners for their kids, or adults for themselves," Gray said. "In this moment of decision, physicians are not going to be particularly price sensitive... they're going to keep their patients just as safe as they can."
"I can't see evidence that they're taking price into account, at least as it affects overall volume figures."
Mylan's EpiPen prescription volume may be being helped, at least somewhat, this year by the absence of a leading competing product, Sanofi's Auvi-Q, from the market.
Auvi-Q was subject to a mass recall last October after a series of suspected malfunctions in delivering the correct dosage of the drug epinephrine, which counters the effects of the potentially fatal allergic reaction anaphylaxis.
Sanofi said earlier this year it was dropping plans to re-enter the market.
However, Athenahealth's data shows that prescriptions for EpiPens in 2015 as of the third week of August — when Auvi-Q was still on the market — were 6 percent higher than the same period in 2014.
Public outrage over the cost of EpiPens exploded last month after consumers and elected officials highlighted the fact that the auto-injectors have increased in retail price more than 400 percent in recent years. Democratic presidential nominee Hillary Clinton called Mylan's actions "just the latest troubling example of a company taking advantage of its consumers," and said she was "calling on Mylan to immediately reduce the price of EpiPens."
On Wednesday, the Senate's Permanent Subcommittee on Investigations said it was opening a preliminary inquiry into Mylan's pricing and competition practices.
EpiPens were selling for $100 per two-pack back in 2008.
As the full retail price for the device rose to more than $600, Mylan CEO Heather Bresch's annual compensation has soared more than 700 percent, to $19 million. And Bresch, whose father is U.S. Sen. Joe Manchin, D.-W.Va., last year orchestrated a re-incorporation for Mylan in the Netherlands. That so-called inversion will net Mylan a nice break from U.S. taxes despite the fact that its main offices are in Pennsylvania.
A number of members of Congress have asked Bresch to explain EpiPen's price increases. Minnesota's attorney general is also investigating the product's price.
While some customers are paying the full price, there are coupons that can lower the cost to $300 for qualified customers. Others have much of the cost covered by their insurance plans.
But doctors routinely urge people with allergies and parents of kids with allergies to have multiple sets of EpiPens, for the home, school, car and workplace. That can increase out-of-pocket costs for customers.