Psychiatrycommon
A 19-year-old man is brought to the emergency department by friends two hours after a party. He is frightened, is convinced the other guests were laughing at him, and says the last ten minutes have felt like an hour. He has eaten a whole packet of biscuits since arriving. Pulse is 116/minute, blood pressure 126/78 mmHg, temperature 36.8°C. His pupils are 4 mm and reactive, and the whites of his eyes are red. Speech is clear, gait is steady, and he is fully oriented. Which one of the following substances best explains his presentation?