Lopez was optioned to Triple-A Colorado Springs on Thursday.
The Brewers needed to clear a roster spot after recalling Orlando Arcia and plugging him into the lineup, and Lopez was the casualty in that case after a short cup of coffee with the big league club. Lopez tossed three scoreless and hitless innings in his one outing with the Brewers during his most recent callup. He figures to be on a short list of relievers to be recalled the next time the Brewers need a fresh arm.