What is the comparison between magnesium citrate and Polyethylene Glycol (PEG) 3350 plus electrolytes (PegLyte), a brand name for a bowel prep solution containing polyethylene glycol 3350?

From the Guidelines

For bowel preparation before colonoscopy, magnesium citrate is preferred over PegLyte 4L due to its superior tolerability and lower volume, although PegLyte 4L may be considered for patients with electrolyte concerns or kidney issues 1. When considering bowel preparation options, it's essential to weigh the efficacy, safety, and tolerability of each regimen. Magnesium citrate and PegLyte 4L are both effective, but they have different characteristics that may make one more suitable than the other depending on individual circumstances.

• Magnesium citrate is a lower-volume alternative that works as an osmotic laxative, drawing water into the intestines and stimulating bowel movements.
• It's typically easier to consume (usually 300-360 mL) and has a more palatable taste for many patients.
• However, magnesium citrate should be avoided in patients with kidney disease as it can cause magnesium toxicity.
• It may also cause more significant electrolyte disturbances and dehydration compared to PegLyte 4L. On the other hand, PegLyte 4L is generally considered the gold standard for bowel preparation due to its high efficacy and safety profile.
• It works by drawing water into the bowel to flush out contents without significant fluid or electrolyte shifts.
• However, the main drawback is the large volume (4 liters) that must be consumed, which many patients find difficult to tolerate. According to a recent study published in Gastroenterology 1, sodium picosulfate plus magnesium citrate was associated with a higher rate of adequate bowel preparation quality compared to PEG-based regimens, particularly for volumes less than 4L.
• Additionally, the study found that sodium picosulfate plus magnesium citrate was tolerated better than PEG-ELS, with a higher proportion of patients completing the regimen and willing to repeat it.
• However, when restricting the comparison to 4L PEG-based regimens, sodium picosulfate plus magnesium citrate was no longer associated with superior bowel preparation quality. In terms of patient adherence and willingness to repeat the preparation, magnesium citrate-based regimens tend to have higher rates compared to PegLyte 4L 1.
• The study found that patient adherence to the regimen was higher for low-volume preparations, such as magnesium citrate, compared to high-volume preparations like PegLyte 4L.
• Similarly, patient willingness to repeat the preparation was higher for low-volume preparations. Overall, while both magnesium citrate and PegLyte 4L are effective options for bowel preparation, magnesium citrate may be preferred due to its superior tolerability and lower volume, although PegLyte 4L may be considered for patients with specific concerns or conditions 1.

From the FDA Drug Label

Active Ingredient Magnesium citrate 1.745g per fl oz ACTIVE INGREDIENT (IN EACH DOSE) (Bottle Only) Polyethylene Glycol 3350,17 g (cap filled to line) (Packet Only) Polyethylene Glycol 3350,17 g The FDA drug label does not answer the question.

From the Research

Bowel Preparation Comparison

• Mg citrate and PegLyte 4L are two different bowel preparation methods used for colonoscopy.
• A study published in 2020 2 compared the efficacy and patient tolerability of sodium picosulfate magnesium citrate (SP-MC) solution with polyethylene glycol (PEG) solutions, and found that the SP-MC plus bisacodyl group had better patient tolerability and satisfaction compared to the PEG groups.
• Another study published in 2019 3 compared the bowel cleansing efficacy, safety, and patient tolerability of same-day and split-dose bowel preparation using 4L of polyethylene glycol, and found that the same-day dosing with 4L of polyethylene glycol was a feasible bowel preparation method.
• A meta-analysis published in 2012 4 found that 4-L split-dose PEG is better than other bowel preparation methods for colonoscopy, with a pooled odds ratio for excellent or good bowel preparation quality of 3.46.
• A prospective audit published in 2012 5 compared the efficacy, safety, and acceptability of low-volume polyethylene glycol (2L) versus standard volume polyethylene glycol (4L) versus magnesium citrate plus stimulant laxative as bowel preparation for colonoscopy, and found that the magnesium citrate plus stimulant laxative group had superior mucosal cleansing.
• A review published in 2016 6 discussed the importance of optimal bowel preparation for colonoscopy and the potential benefits of combination bowel preparation methods, including the use of magnesium citrate.

Key Findings

• Mg citrate may be better tolerated by patients compared to PegLyte 4L 2, 5.
• PegLyte 4L is a commonly used bowel preparation method, but may have poorer palatability and higher incidence of adverse events compared to other methods 3, 4.
• Combination bowel preparation methods, including the use of magnesium citrate, may be effective and well-tolerated alternatives to traditional methods 6.