What is the recommended dose and administration instructions for Golytely (polyethylene glycol) for bowel preparation?

Golytely Dosing and Administration for Bowel Preparation

Standard Dosing Regimen

For colonoscopy bowel preparation, Golytely (polyethylene glycol-electrolyte solution) is administered as 4 liters total, preferably using a split-dose regimen where 2 liters are consumed the evening before and 2 liters on the morning of the procedure. 1

Split-Dose Administration (Preferred Method)

The split-dose regimen is strongly recommended over day-prior or same-day dosing for morning colonoscopies because it produces superior bowel preparation quality. 1

Specific Timing Instructions:

• First dose: 2 liters consumed between 7 PM and 9 PM the evening before colonoscopy 1
• Second dose: 2 liters consumed between 7 AM and 9 AM on the day of colonoscopy 1
• Critical timing rule: Begin the second portion 4-6 hours before colonoscopy and complete at least 2 hours before procedure start 1

Why Timing Matters:

• Every additional hour between the last purgative dose and colonoscopy decreases the likelihood of adequate preparation by 10% 1
• The superiority of split-dosing progressively decreases after 4-5 hours and disappears after 5 hours from completion 1
• Finishing within 4 hours of colonoscopy produces significantly better preparation quality than finishing more than 4 hours before 1

Same-Day Dosing (Alternative for Afternoon Procedures)

For colonoscopies scheduled after 12 PM (afternoon procedures), same-day dosing of all 4 liters is an acceptable alternative with similar efficacy to split-dosing. 1

• Consume all 4 liters between 5 AM and 9 AM on the day of colonoscopy 1
• Same-day dosing provides better sleep quality but may cause more nausea 1

For Morning Procedures:

Same-day dosing for morning colonoscopies is less effective than split-dosing, though differences may not be clinically meaningful in all patients 1. Split-dosing remains preferred, with patients reporting greater willingness to repeat the regimen (88.5% vs 70.6%) 1.

Administration Instructions

Drinking Rate and Volume:

• Drink 1 liter every 30-45 minutes until effluent clears 1
• Total volume typically 4-5 liters, though some patients may require up to 8 liters for complete cleansing 1
• If unable to drink orally, administer via nasogastric tube 1

Adjunctive Medications:

• Metoclopramide 10 mg IV can be given 30 minutes before starting the preparation for prokinetic and antiemetic effects 1
• Repeat metoclopramide every 4-6 hours if nausea occurs 1

Dietary Modifications

Limit dietary modifications to the day before colonoscopy only for low-risk patients. 1

• Consume low-residue, low-fiber foods or full liquids for early and midday meals the day before 1
• This applies specifically to split-dose regimens in ambulatory patients at low risk for inadequate preparation 1

Volume Considerations

4-Liter vs 2-Liter Regimens:

While 2-liter regimens are suggested over 4-liter regimens for improved tolerability 1, the evidence shows:

• 4-liter PEG produces superior bowel cleansing compared to 2-liter PEG with adjuncts in standard-risk populations 2
• 4-liter preparations had significantly fewer failures (8/196) compared to 2-liter with senna (22/203, P=0.027) 2
• However, 2-liter regimens are better tolerated by patients 2

For low-risk patients only (no constipation, diabetes, advanced age, or prior inadequate preparation), 2-liter same-day dosing may be non-inferior 3. For all other patients, use the full 4-liter volume 2.

Special Populations and Safety

Contraindications for Golytely:

Golytely is preferred in patients at risk for electrolyte disturbances because it is iso-osmotic. 1

• Recommended for: Renal insufficiency, congestive heart failure, advanced liver disease 1
• Avoid hyperosmotic regimens (sodium phosphate) in patients at risk for volume overload or electrolyte disturbances 1

Monitoring Requirements:

• Patients with chronic kidney disease may require dialysis after purging 1
• Patients with severe congestive heart failure may require diuresis 1
• Complication rates remain low with PEG-based preparations 1

Patient Education and Navigation

Provide both verbal and written instructions for all components of bowel preparation. 1

• Consider telephonic or virtual navigation using automated electronic messaging to improve adequacy rates 1
• Document any adverse events to inform future preparation choices 4

Common Pitfalls to Avoid

• Do not use day-prior regimens for morning colonoscopies when split-dosing is feasible—this significantly reduces preparation quality 1
• Do not allow more than 5 hours between completion and colonoscopy—the benefit of split-dosing disappears after this interval 1
• Do not reduce volume to 2 liters in standard-risk or high-risk patients—this increases failure rates 2
• Do not assume all anesthesiologists accept 2-hour fasting after PEG—some prefer longer intervals despite ASA guidelines 1