What are the guidelines for medication management and bowel prep in patients undergoing colonoscopy?

Medication Management During Colonoscopy Preparation

For patients undergoing colonoscopy, proper medication management during bowel preparation is critical, with specific medications requiring temporary discontinuation while others should be continued to minimize risks of complications. 1

General Medication Management Principles

• Most routine medications can be taken with small sips of water up to 2 hours before the procedure 2
• Clear fluids are allowed up to 2 hours before the procedure, making traditional overnight fasting from midnight unnecessary 2

Specific Medication Categories

Anticoagulants and Antiplatelets

• Anticoagulant and antiplatelet management requires careful consideration of bleeding vs. thrombotic risks:

1. Aspirin and NSAIDs:

   • Can be continued even for procedures involving polypectomy 3
   • No significant increase in post-polypectomy bleeding compared to patients not taking these medications 3

2. Thienopyridines (e.g., Clopidogrel/Plavix):

   • Should be discontinued 7 days before colonoscopy with planned polypectomy 4
   • Continuing clopidogrel increases risk of delayed post-polypectomy bleeding (RR 3.10) 5
   • Can be restarted immediately post-procedure if no complications 4

3. Warfarin:

   • Should be discontinued 5-7 days before colonoscopy with potential polypectomy 4
   • Target INR ≤1.5 for safe procedure 4, 6
   • Can typically be restarted 1 day post-procedure if no complications 4

4. Direct Oral Anticoagulants (DOACs):

   • Have rapid onset/offset of action
   • Periprocedural bridging generally not necessary 3
   • Management should be based on bleeding risk of procedure and patient's thrombotic risk

Diabetes Medications

• Metformin:

  • Should be reviewed and potentially adjusted in patients with borderline GFR (category G3b) 2
  • Consider temporary discontinuation during bowel prep to prevent dehydration-related complications

• GLP-1 receptor agonists:

  • May delay gastric emptying and affect bowel preparation 1
  • Should be stopped 1-7 days before procedure (depending on specific agent) 1
  • Decision to continue or withhold should be made case-by-case 1

Antihypertensives

• ACE inhibitors/ARBs:

  • Should be held on the day of preparation and procedure to minimize risk of worsening renal function 2
  • Can increase risk of dehydration-related complications during bowel prep

• Other antihypertensives:

  • Management should be individualized with assistance of prescribing clinician 1
  • Morning doses on procedure day may be taken with small sips of water

Special Considerations

Patients with Renal Impairment

• For patients with impaired renal function (GFR <60 ml/min/1.73m²):
  • Avoid sodium phosphate preparations due to risk of acute kidney injury 2
  • PEG is the only recommended bowel preparation 2
  • Monitor for signs of dehydration during preparation 2
  • Consider IV hydration with normal saline if necessary 2

High-Risk Patients

• For patients at high risk for inadequate preparation:
  • Consider additional bowel purgatives 1
  • Risk factors include: prior inadequate preparation, history of constipation, use of opioids or other constipating medications, prior colon resection, diabetes mellitus, or spinal cord injury 1

Common Pitfalls and How to Avoid Them

1. Medication discontinuation errors:

   • Inappropriate discontinuation of antiplatelet agents in low-risk procedures
   • Failure to discontinue high-risk medications before high-risk procedures
   • Solution: Follow procedure-specific guidelines for each medication class

2. Inadequate monitoring:

   • Failure to check INR before procedure in patients on warfarin
   • Solution: Verify INR is ≤1.5 before proceeding with colonoscopy 6

3. Dehydration and electrolyte disturbances:

   • Increased risk with certain medications (diuretics, ACE inhibitors)
   • Solution: Monitor for signs of dehydration, encourage additional clear fluid intake, consider baseline electrolyte testing 2

4. Inappropriate bridging therapy:

   • Unnecessary bridging increases bleeding risk
   • Failure to bridge high-risk patients increases thrombotic risk
   • Solution: Individualize bridging decisions based on patient's thrombotic risk profile

By following these evidence-based guidelines for medication management during colonoscopy preparation, clinicians can minimize risks while ensuring adequate bowel preparation for successful procedures.