Pharmac's chief executive Steffan Crausaz will step down to take up a new role in the private sector in the new year.
Crausaz headed up the government drug-buying agency for more than six years and worked at Pharmac for more than 14 years, leading the extension of its scope into hospital medicines, vaccines, and medical devices, Pharmac said.
"When Pharmac does its job well more patients are able to benefit from medicines and health services that otherwise would not be available to them. It has been a privilege to have been given the opportunity to contribute to this goal," he said.
Pharmac said information on his replacement will be provided separately.
The news comes as the Trade and Export Growth Minister David Parker said the revamped Comprehensive and Progressive Agreement for the Trans-Pacific Partnership includes greater protection for Pharmac.
"The Pharmac model continues to be protected. Further improvements now achieved include suspension of patent extensions which could have increased the cost of medicine to the government," Parker said in a statement.
One of Labour's campaign promises was to fund Pharmac to get New Zealanders "the latest medicines quicker," arguing that the state agency had been underfunded under the previous government.