The spike followed several events.
First, Mylan introduced a generic version of EpiPen in December. That product — identical to its brand-name sibling — sells for around $300, or half of the list price of brand-name EpiPens.
Second, on Jan. 11, Cigna announced that it would no longer cover the brand-name EpiPen, but instead would cover the cheaper generic version from Mylan.
A day later, pharmacy giant CVS Health said it would sell a two-pack of generic Adrenaclick auto-injectors for just $109.99, almost half of what it had sold those EpiPen competitors for previously.
And then, in mid-February, drugmaker Kaleo reintroduced Auvi-Q to the U.S. market. Kaleo, which is privately held, had previously sold Auvi-Q in partnership with Sanofi.
Auvi-Q has a byzantine pricing structure. People who pay cash at the pharmacy counter have to pay around $360 for a two-pack. Families with annual incomes of less than $100,000 will get the package for free. But health insurers are being charged $4,500 for the devices, with insured customers paying $0 out of pocket.
All four of those developments could be having an impact on Mylan's revenue for EpiPen, even accounting for the fact that its own generic version is probably contributing to the rise in prescriptions for alternative products.
"The generic's [EpiPen] cheaper than the brand name," noted Anna Zink, senior data engineer, athenaResearch, an Athenahealth division.
Zink told CNBC that the data collected by Athenainsight from prescribing doctors did not indicate what percentage of alternative prescriptions to EpiPen came from Mylan's generic product.