From the Guidelines
Managing chronic constipation while on GLP-1 medications requires a multi-faceted approach, starting with dietary assessment and fiber supplementation, particularly with psyllium, as first-line therapy, as recommended by the American Gastroenterological Association-American College of Gastroenterology clinical practice guideline 1.
Key Recommendations
- Increase fluid intake to at least 2-3 liters daily and incorporate more fiber gradually, aiming for 25-30 grams per day through fruits, vegetables, and whole grains.
- For over-the-counter remedies, begin with osmotic laxatives like polyethylene glycol (Miralax) at 17g daily, which draws water into the bowel without causing dependence, as supported by a strong recommendation with moderate certainty of evidence 1.
- Stimulant laxatives like bisacodyl (5-10mg) or senna (8.6-17.2mg) can be used short-term, as recommended by the panel with strong recommendation and moderate certainty of evidence 1.
Implementation Considerations
- Dietary assessment is important to determine total fiber intake from diet and supplements, and fiber supplements can be used as first-line therapy for CIC, particularly for individuals with low dietary fiber intake 1.
- Among the evaluated fiber supplements, only psyllium appears to be effective, with very limited and uncertain data on bran and inulin 1.
- Adequate hydration should be encouraged with the use of fiber, and flatulence is a commonly observed side effect with the use of fiber 1.
Prescription Medications
- For persistent constipation, prescription medications such as linaclotide (145-290mcg daily), plecanatide (3mg daily), or lubiprostone (8-24mcg twice daily) may be necessary, as they work by increasing intestinal fluid secretion and motility.
- It's essential to maintain a consistent bowel routine and consider timing GLP-1 medication doses to minimize constipation effects, as constipation on GLP-1 agonists occurs because these medications slow gastric emptying and intestinal transit as part of their mechanism to reduce appetite and improve glycemic control.
From the Research
Treatment of Chronic Constipation while on GLP-1
- The treatment of chronic constipation in patients with diabetes, including those on GLP-1 receptor agonists, typically involves a step-wise approach 2
- Initial management includes dietary and lifestyle changes, such as increasing fiber intake and exercise 2
- If these changes are ineffective, laxatives may be prescribed, starting with bulking agents like psyllium, bran, or methylcellulose, followed by osmotic laxatives like lactulose, polyethylene glycol, or lactitol if necessary 2
- Stimulant laxatives like bisacodyl, sodium picosulphate, or senna may be used if osmotic laxatives are not effective 2
- Newer agents, such as chloride-channel activators and 5-HT4 agonists, may be considered for severe or resistant cases 2
Efficacy and Safety of OTC Therapies for Chronic Constipation
- A systematic review found good evidence to recommend polyethylene glycol or senna as first-line laxatives, and moderate evidence supporting fiber supplements, fruits, stimulant laxatives, and magnesium-based products 3
- Common adverse events associated with OTC laxatives include diarrhea, nausea, bloating, and abdominal pain, but no serious adverse events were reported 3
GLP-1 Receptor Agonists and Gastrointestinal Side Effects
- GLP-1 receptor agonists can cause gastrointestinal side effects like nausea and vomiting, which may be mitigated by conjugation with vitamin B12 or development of dual agonists with glucose-dependent insulinotropic polypeptide (GIP) 4
- The incidence and severity of nausea and emesis related to GLP-1 receptor agonists can be reduced with continued treatment and are less frequent with longer-acting formulations 5
Practical Considerations for Clinical Practice
- GLP-1 receptor agonists are a class of injectable glucose-lowering agents that lower A1C with added benefits of weight loss and improved cardiovascular risk markers 5
- Selection of the most appropriate GLP-1 receptor agonist for individual patients is important, considering factors like efficacy, safety, and potential gastrointestinal side effects 5