Its pharmacy is based in Manchester, N.H., and its business operations are located in Somerville, Mass.
The value of the deal was not disclosed.
And Amazon CEO Jeff Bezos, the world's richest man, is creating a health care company along with JPMorgan Chase and Warren Buffett's Berkshire Hathaway.
Amazon, however, has threatened to cause the biggest disruption with stealthy moves to widen its product and distribution reach.
PillPack sells presorted packets of prescriptions drugs, delivering them to customers in their homes.
Contradictory reports from USA officials about trade policy have led the market to lurch between gains and losses, sometimes by the hour.
'Together with Amazon, we are eager to continue working with partners across the healthcare industry to help people throughout the U.S. who can benefit from a better pharmacy experience, ' Parker said in a statement.
That said, Pessina added, "We know that we have to change the level of our services to the customers, and we are working quite hard on that direction".
The PillPack deal is expected to close later this year.
The PillPack deal is already scaring investors in the top two drug store chains.
Its software platform, PharmacyOS, was built in-house and helps customers manage their pill intake with real-time notifications and an online dashboard.
PillPack has mail-order pharmacy licenses in all 50 states, which could allow Amazon to expand quickly. In January, Amazon, Berkshire Hathaway and JPMorgan Chase announced plans to create an independent company that's "free from profit-making incentive" and geared toward providing innovative healthcare solutions to their USA employees.
Amazon expects to complete the acquisition of PillPack sometime later this year.
The move (and that valuation hike) how signal how heated the e-health market is becoming, and also how Amazon views it as a key frontier in its bid to be the go-to place for anything a consumer might want or need.
TJ Parker, a second-generation pharmacist and the company's chief executive officer, and Elliot Cohen, a computer scientist and the chief technology officer, each own roughly 10 percent of the online prescription drug retailer, a person familiar with the matter said. In 2016, the pharmacy benefits company Express Scripts Holding Co. threatened to drop PillPack from its list of approved vendors because of its focus on delivery over storefront retail.