"New Zealand rugby has a zero tolerance for the abuse of prescription medicines," NZRU GM of professional rugby Neil Sorensen said. "Their use is strictly controlled by team doctors.
"It is important to have good information, and to help us understand the issue better, we are surveying our extensive network of rugby and medical contacts to capture their experiences and knowledge of this type of abuse."
The issue was recently brought to light when it was found a handful of Kiwis players, reportedly including Sonny Bill Williams and Kieran Foran, mixed sleeping pills and energy drinks during last year's World Cup. The effect is said to be similar to some recreational drugs, but is not banned.
Former New Zealand under-20s rugby prop Tukiterangi Jahna Raimona also appeared in the Invercargill District Court recently when he admitted stealing a team doctor's pad and tried to obtain 160 prescription pills.
NZRL high performance manager Tony Iro said they will conduct their own testing for prescription drugs if they suspect a player has misused them and also expected Australian testers to take samples from the team around this year's Anzac test in Sydney on May 5. "If we suspect anything, we have the right to test when we want and for what we want."
"The use of those substances isn't conducive to what we consider peak performance and we would hand down appropriate penalties if any players tested positive.
"We saw the impact and effects of it [during the World Cup].
"The NRL have moved pretty quickly to have the testing introduced this season and I think it's a good move all round."
The NZRL has also amended its code of conduct, which must be signed by all players, and it received the support of the senior playing group.
Anecdotal evidence suggests the use of sleeping pills has been widespread in a number of sports for some time as players looked for a way to get around alcohol and drug policies.
It's not illegal and, previously, didn't contravene any anti-doping policies, but the NZRL held genuine concerns a player might not wake up after misusing sleeping pills.
The NRL will expand testing to include one for illicit drugs for two classes of prescription drugs - Benzodiazepines (which includes Valium, Serepax, Mogadon and Rohypnol) and Zolpidems (Stilnox, Zolsan and Stilnoct).