The Reds designated Buchanan for assignment Sunday.
Buchanan's stay on the Reds' 40-man roster lasted just one day, as Cincinnati called him from Triple-A Louisville to serve as a bulk reliever in Saturday's 5-4 loss to the Brewers. After relievers Fernando Cruz and Buck Farmer covered the first three innings, Buchanan entered for the next 3.1 innings, giving up one earned run on two hits and two walks while striking out one. If Buchanan isn't claimed off waivers, he'll likely stick around in the Cincinnati organization and report back to Louisville.