case of diarrhea & mild cognitive impairment

Introduction

A 75 yo man comes to clinic with a chief complaint of non-bloody watery diarrhea that has continued for more than one week. He denies fever, nausea/vomiting, and significant abdominal pain other than some cramping associated with the diarrhea. He denies travel, sick contacts, risk factors for HIV1 or laxative abuse. He has not been recently prescribed antibiotics. Two weeks ago his neurologist increased his donepezil from 5 mg to 10 mg QHS.*

*He has been seeing a neurologist because of a concern for memory loss. He is still independent in his ADLs, both bADLs & iADLs. He continues to drive without accidents or citations and continues to manage his and his wife's finances.

History

• Past medical history:
  • chronic hypertension
  • osteoarthritis
  • glaucoma
  • mild cognitive impairment
• Social history:
  • married, 2 children
  • smoking 10 pack years, quit 35 years ago

Physical examination

• T = 37.0 C, heart rate = 51/min, respiratory rate = 18/min
• blood pressure = 122/62 mm Hg
• no murmurs, lungs clear, abdomen benign, no peripheral edema

Dosage

• lisinopril 10 mg QD
• HCTZ 12.5 mg QD
• simvastatin 20 mg QD
• aspirin 81 mg QD
• Timolol 0.5%, 1 drop OU QD
• tylenol 500-1000 mg TID prn for osteoarthritis
• donepezil 10 mg QHS

Laboratory

• none

Diagnostic procedures

• electrocardiogram: 1st degree AV block at 51/min
• MMSE: 28/30, 2 missed on recall

Management

• Stop donepezil. Contact neurologist.
  • Neurologist's office returns call
    • requests small bowel biopsy to rule out Whipple's disease prior to discontinuing donepezil
  • recommendation
    • deny neurologist's request. Risk/benefit unfavorable.
    • donepezil is not indicated for mild cognitive impairment
    • donepezil is most likely cause of diarrhea
    • it is more cost-effective to discontinue an unnecessary medication than it is to perform an invasive procedure (especially when it is likely you will have to discontinue the unnecessary medication in the end)
    • donepezil may be contributing to the patient's bradycardia
• follow-up
  • donepezil was discontinued and the diarrhea resolved.
  • the patient was grateful
  • repeat EKG after discontinuation of donepezil to assess heart rate & PR interval
    • Timolol although an ophthalmic agent does have systemic effects & as a beta-blocker AV block is potentially one of these
    • consider another glaucoma agent, latanoprost, dorzolamide ...
  • recheck the blood pressure, patient may be overmedicated
  • stop aspirin, no indication for primary prevention with aspirin
  • consider stopping simvastatin
    • the 2nd most common complaint of patients taking simvastatin (after myalgia) is memory loss
• Immunizations:
  • Herpes zoster vaccine
  • PCV13 & PPSV23
  • Tdap
  • influenza vaccine annually

More general terms

• case presentation