Zoe Berry, who played one Test for the Black Ferns against England in 2012, and Glen Robertson, a former Junior World Championship winner and ex-member of the New Zealand sevens squad, were given four-year bans.
They are joined by two other club-level players in receiving suspensions, with Rhys Pedersen and Ben Qauqau-Dodds getting 21-month and two-year bans respectively.
Berry, Robertson and Pedersen were suspended for possessing and, in some cases, using or attempting to use the stimulant clenbuterol, while Qauqau-Dodds was charged with possession and use, or attempted use, of the anabolic steroid metandienone.
“What this investigation has revealed is that there is a lot of ignorance in our community game on the issue of performance-enhancing drugs,” New Zealand Rugby general manager Neil Sorensen said.
“What has happened to these four rugby players serves as a reminder that all athletes have to be very careful about what they put into their bodies.”