It caps a miserable start to 2025 for the 22-year-old, who is one of just four racers yet to have a scored a championship point this season.
An official statement from Doohan read: “I am very proud to have achieved my lifelong ambition to be a professional Formula One driver and I will forever be grateful to the team for helping me achieve this dream.
"Obviously, this latest chapter is a tough one for me to take because, as a professional driver, naturally I want to be racing.
"That said, I appreciate the team’s trust and commitment. We have long-term goals as a team to achieve and I will continue to give my maximum efforts in any way I can to help achieve those.
"For now, I will keep my head down, keep working hard, watch with interest the next five races and keep chasing my own personal goals.”
Colapinto gets chance to impress
Doohan crashed out on the opening lap at last weekend's Miami Grand Prix, perfectly summing up the way things have been going since stepping into Esteban Ocon's shoes.
He opted to take on the role of backup driver at Alpine during the off-season after missing out on a permanent spot on the grid, and now has the opportunity to prove he is deserving of the full-time seat alongside Pierre Gasly.
He won't have long to prepare for his Alpine debut, with the Emilia Romagna GP at Imola coming up next weekend.
And the pressure will be on to deliver some much-needed points for a team which currently sits ninth in the constructors' standings.