How to administer metronidazole (Gastrostomy Tube (GT)) via a G-tube (Gastrostomy Tube)?

Administration of Metronidazole via Gastrostomy Tube (G-tube)

Metronidazole can be safely administered through a gastrostomy tube by following a standardized protocol that includes proper tube flushing before and after administration, using appropriate syringes, and ensuring medication is given individually to avoid drug interactions.

Preparation and Administration Procedure

General Principles

• Use appropriate ancillaries including syringes with connectors of a recognized standard (ISO 80369-3/"ENFit") to avoid misconnection errors 1
• Administer drugs individually through the enteral feeding tube, never mixing medications prior to administration due to risk of drug-drug interactions 1
• Flush the tube before, between, and after each drug administration using 30 mL of water to prevent tube occlusion 1

Specific Steps for Metronidazole Administration

1. Verify tube placement before administering any medication 1
2. Pause enteral nutrition if continuous feeding is in progress
3. Flush the G-tube with 30 mL of water 1
4. Prepare the metronidazole:
   • For tablets: Crush thoroughly and mix with 15-30 mL of water
   • For liquid formulation: Use directly without further preparation 2
5. Administer the medication using an appropriate ENFit syringe 1
6. Flush the tube again with 30 mL of water after administration 1
7. Resume enteral nutrition if applicable, waiting at least 30 minutes if there are known drug-nutrient interactions 1

Important Considerations

Dosing Considerations

• Standard metronidazole dosing for C. difficile infection is 500 mg orally three times daily for 10 days when vancomycin or fidaxomicin are not available 1
• For fulminant C. difficile infection with ileus, intravenous metronidazole (500 mg every 8 hours) should be administered together with oral or rectal vancomycin 1

Medication Formulation

• Liquid formulations are generally preferred for G-tube administration to minimize the risk of tube occlusion 1
• If using tablets, ensure they are thoroughly crushed and dissolved to prevent tube blockage 1
• Metronidazole is available in various formulations including tablets and suspension (250 mg/5 mL) that can be used for G-tube administration 2

Potential Pitfalls and How to Avoid Them

• Tube occlusion: Always flush with at least 30 mL of water before and after medication administration 1
• Drug-nutrient interactions: Some medications may bind to enteral formula components, potentially reducing efficacy. Consider administering metronidazole at least 1 hour before or 2 hours after enteral feeding if interaction is suspected 1
• Inaccurate dosing: When using low-dose ENFit tip syringes, take measures to ensure correct drug dosing and avoid shaking the syringe to remove drug moat 1
• Cross-contamination: Never mix different medications prior to administration through the G-tube 1

Site of Drug Delivery Considerations

• The site of the enteral tube tip affects drug delivery and efficacy. G-tube delivers medication to the stomach, which is appropriate for metronidazole administration 1
• For patients with swallowing disorders or at risk of regurgitation, G-tube administration is safer than administration via upper gastrointestinal tract 1

By following these guidelines, metronidazole can be effectively and safely administered through a gastrostomy tube while minimizing complications such as tube occlusion and ensuring proper medication delivery.