The duo last featured for the Reds during their defeat to Congolese side CARA Club in the CAF Confederation Cup last month.
"Saddick Adams will be out for 6 weeks. That's what the doctors are telling me and we hope he gets well soon," Fabin told Oyerepa FM in the aftermath of the game.
"Eric Donkor is also not well and is expected to return soon."
Kotoko defeated second-tier outfit New Edubiase United 2-0 in a pre-season friendly at the Baba Yara Sports Stadium on Sunday.
Strikers Federick Boateng and Obed Owusu found the back of the net to secure the win for the Porcupine Warriors.