Actress Sarah Jessica Parker said she is "disappointed, saddened and deeply concerned" after the price of the EpiPen soared hundreds of dollars.
The price of the product, which was less than $60 in 2007, rose to more than $600 recently. It is independently supplied by Mylan Pharmaceuticals.
"I do not condone this decision, and I have ended my relationship with Mylan as a direct result of it," Parker wrote on Instagram. "I hope (Mylan) will seriously reconsider the outpouring of voices of those millions of people who are dependent on the device, and take swift action to lower the cost to be more affordable for whom it is a life-saving necessity."
Parker, who was previously part of a campaign with Mylan, has a 13-year-old son, James, who has peanut allergies.
"The Epinephrine auto-injector is a vital part of our family's healthcare, as it is for the many who are at risk," Parker wrote.
The drugmaker responded to criticism Thursday by announcing it would offer discounts for the EpiPen, including coupons covering up to $300 "for patients in health plans who face higher out-of-pocket costs." Critics maintained that an unchanging list price would ultimately leave consumers bearing most of the costs.