The 29-year-old former rugby league player, pictured left, has won 23 caps since making his Scotland debut just over three years ago and he scored his eighth Test try in his last appearance, against England last year. But injury has seen him fall behind Graeme Morrison and Scott Barrow in the Glasgow midfield pecking order.
"I need games; it's as simple as that," he said. "Playing for Scotland was a fantastic experience and I am very proud of my 23 caps, but when I know I'm still capable of playing at a high level I don't want to give up on it.
"I haven't been getting the chance as much as I'd like and at my age I don't think I can sit around on the bench or out of the match squad hoping next year or the year after will change."
Hugh Campbell, Glasgow's head coach, said: "Andy's contract was due to finish at the end of this season and he requested an early release, so it's by mutual agreement that he's leaving."