Matthew Perry used to go to Ozzy Osbourne's house for Alcoholics Anonymous (AA) meetings

In an extract from his book, Ozzy wrote of Matthew: "He used to come to our house for AA meetings, or so my wife tells me. The funniest, most talented bloke. And he was trying so hard."

The Paranoid rocker reflected on the sadness he felt upon hearing that Perry, who had played the role of Chandler Bing in the popular comedy, had passed away.

Ozzy wrote: "Then one day he listened to his addiction telling him it was OK to get loaded, and that was it - game over. I felt so sad when they said he'd been found in his hot tub, unresponsive, with ketamine in his system. He'd given everything to stay clean. But it wasn't enough."

The Prince of Darkness detailed how he thought about using a ketamine treatment similar to the one Matthew got hooked on in an attempt to combat his own addictions but the experience put him off from taking the drug completely.

Ozzy recalled: "They started me on this tiny dose. A microdose, they call it. But the second I felt it kick in - a very small but unmistakable altering of the mind - I was like, 'Oh, yeah, I could have some serious fun with this.'"

He added: "For the first time in years, I was able to be really honest with myself. When I walked out of that ketamine clinic, I told myself I'd never let addiction steal my spirit from me again."

Osbourne also reflected on how AA meetings were beneficial to him when he last "fell off the wagon" in 2012 as he attended 90 meetings in as many days in West Hollywood.

The heavy metal legend wrote: "It helped me, all that AA stuff. Got me started on the way back to being sober. If you're on your own, the voice in your head is so persuasive."