Keith Allen has defended a forthcoming Channel 4 programme in which he is seen under the influence of drugs.
The actor and father of singer Lily has been filmed after taking an ecstasy-like Class A drug to examine the effects.
He says it's "insane" to suggest it glamorises their use.
But one think-tank boss has criticised the show.
Julia Manning, chief executive of 2020 Health, said: "The first two words that come to mind are reckless and pointless.
"We are fully aware of the effects of class A drugs on the body."
Allen said the programme was designed as a "forensic analysis" of the effect of drugs.
He was among a number of participants who were monitored during the course of the trial, for which he took MDMA.
It is not the first time Allen has spoken of his drug use in interviews.
He has previously said he would be in favour of drugs being taxed, ensuring their use could be used to support public services.
Allen has also been speaking about his new single - a protest against the "corporatisation" of the London 2012 Olympics.
He said of the track, called The Official Fit Les Olympic Anthem: "I think that I'm giving voice to a lot of people in the country.
"A recent poll showed 56% of the people aren't satisfied with the way that it's been presented, the sponsors have got hold of these Games and kind of hijacked them and put us lot on the back burner.
"I think as a taxpayer I have got a right 'cos I helped to set up all this infrastructure for them to sell their stuff in, I have got a right to complain about it."