As the fallout continues over revelations of a secret drug-testing regime in the AFL, Melbourne's Gawn said the deterrent for a first-strike positive test is diminishing.

"The deterrent is not there, or it's fading. There needs to be something bigger on the first strike," Gawn told Triple M radio on Thursday.

Under the AFL's drugs policy, a first strike results in a $5000 fine, counselling and target testing - but the player's club is not informed, other than the doctor.

AFL chief executive Andrew Dillon said on Wednesday the league was "unapologetic" about giving club doctors powers to withdraw players from games if they risked testing positive on match day.

AFL Players Association chief executive Paul Marsh insisted only an "incredibly small number" of players had been protected in such a way.

Marsh said speculation 100 players had been granted immunity by club doctors over drug test results is guesswork.

Only the AFL would know the true figure, he said.

"The commentary around this is that it's happening every week," Marsh told SEN Radio.

"I've been doing this job for nearly 10 years and there would be less than a handful of players that this has been an example for.

"(An) incredibly small number.

"Nowhere near the level as ... this story is suggesting."

Sport Integrity Australia is investigating the claims, raised under parliamentary privilege on Tuesday night by federal MP Andrew Wilkie.

Hawthorn coach Mitchell was surprised to learn of the practice and said coaches should be made aware of any positive test.

"The people that are in charge of your wellbeing and your welfare, they should know about your wellbeing and your welfare," Mitchell told reporters on Thursday.

"If you have the information that you think will help you make the best for them, that is really a big part of your job as a senior coach."

"We need to make the players the best they can be - not just as players, but as people. That's pretty important."

Adelaide coach Matthew Nicks stopped short of supporting Mitchell's sentiment.

"I understand where Sam's coming from when you're working with a player," Nicks said on Thursday.

"Not being an expert in that space, I don't actually know what's best for our players ... this is private medical information that we're talking about.

"You have to talk to our doctors about that and what's best ... and I think that's what the AFL has done."

Carlton coach Michael Voss said he was "disappointed" at the furore.

"We're all really surprised and somewhat disappointed with where it currently lies," Voss said.

Like Mitchell, Voss had never considered some players could have used the so-called medical model to fake an injury and avoid a potential match-day positive test.

And Fremantle coach Justin Longmuir concurred.

"There's never been a time that I've been suspicious," Longmuir said.

"The way the news has come out (it's) speaking about it happening at every club every second week, whereas I think we're talking about a small number of players."

Australian Associated Press