Hi,
It may result in harmful interactions. Based on the history, your sister has consumed high dose of Apo-Escitalopram along with another anti-depressant amitriptyline. Taking amitriptyline along Apo-Escitalopram can increase the risk of a  serious condition called the 
serotonin syndrome, the effects of which include confusion, hallucination, seizure, 
increased heart rate and blood pressure, fever, 
excessive sweating, or shaking, 
blurred vision, muscle spasm or stiffness, tremor, 
incoordination, stomach cramp, nausea, vomiting, and diarrhea. In its severe form coma and even death may also occur. She should be taken immediately to the ER of your near by hospital for urgent care.
Hope I have answered your query. Let me know if I can assist you further.
Regards,
Dr. Mohammed Taher Ali, General & Family Physician