A 65-year-old man is brought to the emergency department with new-onset confusion, suprapubic discomfort, and lack of urine output. His past medical history is significant for benign prostatic hyperplasia, hypertension, hyperlipidemia, and type 2 diabetes mellitus complicated by neuropathy. The patient also has a history of chronic insomnia and has been treated with several medications with little benefit. He does not know his current medications. On examination, the patient is afebrile, confused, and oriented only to self. Suprapubic fullness is present, but abdominal examination is otherwise unremarkable. A urinary catheter is placed and immediately drains 1000 mL of urine. Which of the following medications most likely has contributed to this patient's current condition?

Question

A 65-year-old man is brought to the emergency department with new-onset confusion, suprapubic discomfort, and lack of urine output.  His past medical history is significant for benign prostatic hyperplasia, hypertension, hyperlipidemia, and type 2 diabetes mellitus complicated by neuropathy.  The patient also has a history of chronic insomnia and has been treated with several medications with little benefit.  He does not know his current medications.  On examination, the patient is afebrile, confused, and oriented only to self.  Suprapubic fullness is present, but abdominal examination is otherwise unremarkable.  A urinary catheter is placed and immediately drains 1000 mL of urine.  Which of the following medications most likely has contributed to this patient's current condition?

Quizplus · Accepted Answer

11ec160b_3c5a_af99_9249_7bb858192750_MD0001_00 Tricyclic antidepressants (TCAs), such as amitriptyline, are occasionally used for insomnia or adjunctive pain management when other medications are not effective. However, TCAs have strong anticholinergic properties that can lead to significant adverse effects such as confusion, constipation, and acute urinary retention. Elderly patients are at increased risk for side effects due to comorbid conditions (eg, dementia, benign prostatic hyperplasia), decreased hepatic and renal clearance of medications, and a higher burden of concurrent medications that can interact with TCA's and contribute to adverse effects. As a result, TCAs are relatively contraindicated in elderly patients. (Choices B and F) Metformin can cause lactic acidosis, and atorvastatin can cause hepatitis and myositis. These drugs do not have significant anticholinergic side effects. (Choice C) Duloxetine is a dual serotonin and norepinephrine reuptake inhibitor used for the treatment of depression, anxiety, and a variety of chronic pain disorders. Duloxetine can cause confusion, but only rarely causes obstructive voiding symptoms. (Choices D and G) Finasteride and tamsulosin are used for treatment of benign prostatic hyperplasia and should not cause urinary obstruction or retention. (Choice E) Gabapentin is useful for painful diabetic neuropathy. It can cause sedation, confusion, and incoordination, but it does not have significant anticholinergic side effects. Educational objective: Tricyclic antidepressants have strong anticholinergic properties. Potential side effects include confusion, constipation, and urinary retention. These medications should be used with caution in elderly patients. __________ References: Effects of treatments for symptoms of painful diabetic neuropathy: systematic review. (http://www.ncbi.nlm.nih.gov/pubmed/17562735)

A 65-Year-Old Man Is Brought to the Emergency Department with New-Onset