A Houston doctor is accused of poisoning her lover’s coffee with a chemical found in antifreeze, but claims she’s totally innocent.

Ana Maria Gonzalez-Angulo, an oncologist specializing in breast cancer, allegedly dosed Dr. George Blumenschein’s coffee with the chemical and told him the reason it tasted so sweet was because she’d put Splenda in it. He says she gave him a second cup, and within hours he was in the emergency room with slurred speech, loss of fine motor skills, central nervous system depression, cardiopulmonary complications and renal failure.

Rather than Splenda, it was ethylene glycol, which is also used for medical purposes and is reportedly found quite easily at the hospital the two worked at, University of Texas M.D. Anderson Cancer Center. But Gonzalez-Angulo maintains her innocence.

“She is a distinguished citizen and scientist, and these allegations are totally inconsistent with her personal and professional life,” attorney Derek Hollingsworth said in a statement.

Gonzalez-Angulo has been charged with aggravated assault, but it’s not clear just yet what her motive may have been. She’s free on $50,000 bail; Dr. Blumenschein, meanwhile, has had to undergo dialysis for kidney failure.