A 17-year-old female arrives at the emergency department via ambulance. On exam, she is agitated and confused. Her blood pressure is 160/110 mmHg, her heart rate is 140 beats/min, and her temperature is 39 C. She is diaphoretic, tremulous, and hyper-reflexive, but otherwise has a non-focal neurological exam. She is unable to give a detailed history. She has with her a bottle of phenelzine. Her friends report that she "wanted to celebrate her eighteenth birthday" with "something new." What other drug may she have taken to cause this presentation?