The Reds optioned Maxwell to Triple-A Louisville on Monday.
Maxwell will cede his spot on the active roster and in the Cincinnati bullpen to right-hander Pierce Johnson (elbow), who was reinstated from the 15-day injured list in a corresponding move. During his latest stint in the majors, Maxwell made nine appearances and submitted a 7.00 ERA, 2.11 WHIP and 8:8 K:BB in nine innings while gathering one save and one hold.