Amitriptyline/administration & dosage; Amitriptyline/adverse effects; Pain, Postoperative/drug therapy; Pain, Postoperative/prevention & control; Preoperative Care/methods; Adult; Aged; Amitriptyline/blood; Analgesics, Non-Narcotic/administration & dosage; Analgesics, Non-Narcotic/adverse effects; Analgesics, Non-Narcotic/blood; Bradycardia/chemically induced; Cohort Studies; Dose-Response Relationship, Drug; Drug Administration Schedule; Female; Heart/drug effects; Heart/physiology; Humans; Injections, Intravenous/adverse effects; Injections, Intravenous/statistics & numerical data; Male; Middle Aged; Pain Measurement; Pain, Postoperative/physiopathology; Preoperative Care/statistics & numerical data; Sleep Stages/drug effects; Sodium Channel Blockers/administration & dosage; Sodium Channel Blockers/adverse effects; Sodium Channel Blockers/blood; Treatment Outcome; Xerostomia/chemically induced