What are the differences between ColonLYTELY (polyethylene glycol‑based bowel preparation) and PicoPrep/GlycoPrep (sodium picosulfate‑magnesium citrate bowel preparation)?

Differences Between ColonLYTELY and PicoPrep/GlycoPrep

For ambulatory patients at low risk for inadequate bowel preparation, low-volume preparations like PicoPrep/GlycoPrep (sodium picosulfate-magnesium citrate) offer similar bowel cleansing efficacy to ColonLYTELY (4L PEG) with significantly superior patient tolerability and willingness to repeat the preparation. 1

Key Compositional Differences

ColonLYTELY (High-Volume PEG-ELS)

• Volume: 4 liters of polyethylene glycol-electrolyte lavage solution 1
• Mechanism: Iso-osmotic, isotonic agent that works through osmotic lavage without significant fluid or electrolyte shifts 1
• FDA-approved formulation among several 4L PEG-ELS products including Golytely, Colyte, Gavilyte, and Nulytely 1

PicoPrep/GlycoPrep (Sodium Picosulfate-Magnesium Citrate)

• Volume: Ultra-low volume preparation (typically 2-3 sachets dissolved in small amounts of water, plus additional clear fluids) 1
• Mechanism: Stimulant laxative (sodium picosulfate) combined with osmotic agent (magnesium citrate) 1
• Requires consumption of additional clear fluids to achieve adequate hydration 1

Efficacy Comparison

Bowel Cleansing Quality

• No significant difference in overall adequacy: Meta-analysis of 11 trials (3,097 patients) showed sodium picosulfate did not significantly differ from PEG-ELS in bowel cleanliness (OR 0.92; 95% CI 0.63-1.36) 1
• 4L PEG slightly superior in direct comparison: Adequate preparation rates were 90% with 4L versus 89% with 2L preparations (P=0.02), though this difference disappeared after adjusting for variables including colonoscopy timing 1
• Ultra-low volume sodium picosulfate (<1L) has unacceptably low adequacy: Only 75% adequacy rate across 19 trials (n=10,287), making it unsuitable for general use 1
• Split-dosing dramatically improves sodium picosulfate efficacy: Split-dose regimen showed significantly higher bowel cleanliness (OR 3.54; 95% CI 1.95-6.45) compared to day-before dosing 1

Proximal Colon Cleansing

• 2L PEG with ascorbate provides superior proximal colon cleansing compared to sodium picosulfate-magnesium citrate, with significantly better cleansing in the ascending colon (p=0.024) and cecum (p=0.003) 2

Tolerability and Patient Experience

Patient Satisfaction

• Sodium picosulfate-magnesium citrate has markedly superior tolerability: Patient willingness to repeat was 91.9% versus 66.9% with 4L PEG (P<0.01) 1
• Lower rates of nausea and pain with low-volume preparations compared to high-volume PEG 1
• Better palatability and satisfaction with sodium picosulfate-magnesium citrate, though compliance may be slightly lower 3
• Significantly fewer side effects: Nausea and vomiting were more common with PEG-EL (38% vs 13%; p<0.05) 4

Completion Rates

• Higher non-completion rates with 4L PEG: Up to 14% of patients failed to complete PEG-EL preparation due to side effects 4

Safety Considerations

Electrolyte Disturbances

• Sodium picosulfate-magnesium citrate causes transient electrolyte shifts: Higher rates of hypokalemia (7.3% vs 4.1%), hyponatremia (3.7% vs 1.0%), hypochloremia (3.7% vs 0.3%), and hypermagnesemia (11.6% vs 0%) on day of colonoscopy, though these normalize by Day 30 5
• 4L PEG-ELS is safer in volume-sensitive patients: Because it is iso-osmotic and isotonic, it is preferred for patients with renal insufficiency, congestive heart failure, and advanced liver disease 1, 6

Contraindications for Sodium Picosulfate-Magnesium Citrate

• Avoid in chronic kidney disease: Magnesium-based preparations should be avoided in patients with CKD due to risk of magnesium toxicity 1, 6
• Contraindicated in severe renal impairment, CHF, and conditions with fluid/electrolyte sensitivity 6, 5
• Risk of acute phosphate nephropathy and volume overload with hyperosmotic preparations 6

Clinical Decision Algorithm

Choose 4L PEG (ColonLYTELY) When:

• Patient has chronic kidney disease, congestive heart failure, or advanced liver disease requiring iso-osmotic preparation 1, 6
• Patient has history of inadequate bowel preparation or is at high risk for poor prep 1
• Creatinine clearance <30 mL/min 6
• Patient requires maximum proximal colon cleansing quality 2

Choose Sodium Picosulfate-Magnesium Citrate (PicoPrep/GlycoPrep) When:

• Patient is ambulatory and at low risk for inadequate preparation 1
• Patient tolerability and compliance are primary concerns 1
• Patient has normal renal function (no CKD) 1
• Patient has no volume-sensitive comorbidities 6
• Always use split-dose regimen to optimize efficacy 1

Common Pitfalls to Avoid

• Do not assume low-volume automatically means less fluid consumption: Sodium picosulfate requires large quantities of additional clear fluids beyond the preparation volume 1
• Never use sodium picosulfate-magnesium citrate in CKD patients: Risk of magnesium accumulation and toxicity 1, 6
• Avoid day-before dosing with sodium picosulfate: Split-dosing is essential for adequate efficacy 1
• Do not use ultra-low volume (<1L) sodium picosulfate preparations: Inadequate cleansing rates make them unsuitable for general use 1
• Monitor electrolytes in at-risk patients using sodium picosulfate: Transient shifts occur more frequently than with PEG 5
• Ensure proper dissolution of sodium picosulfate powder: Direct ingestion of undissolved powder increases risk of nausea, vomiting, and electrolyte disturbances 5