Linking To And Excerpting From CoreIM's "Constipation Medications: 5 Pearls Segment"

Today, I review, link to, and excerpt from CoreIM‘s Constipation Medications: 5 Pearls Segment.

All that follows is from the above resource.

Constipation Medications: 5 Pearls Segment

Posted: April 30, 2025
By: Dr. Kalaila Pais, Dr. Allen Lee, Taylor Thompson, PharmD, Jack Sibilia, RN and Dr. Shreya P. Trivedi
Graphic: Dr. Jesse Powell
Audio: Dr. Shreya P. Trivedi
Peer Review: Dr. Adam Strauss, Dr. Brian Persaud

Podcast: Play in new window | Download

Time Stamps CME-MOC Show Notes Transcript References

Time Stamps

02:26 Pearl 1: High-Yield Reversible Causes of Constipation

09:03 Pearl 2: Deep Dive into Fiber, Hydration and Bulk-Forming Laxatives

15:06 Pearl 3: Osmotic and Stimulant Laxatives

25:39 Pearl 4: Suppositories and Enemas

34:05 Pearl 5: Opioid Induced Constipation

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Show Notes

Pearl 1: High-Yield Reversible Causes and Complications of Constipation

There are two types of constipation:

Primary constipation/Chronic idiopathic constipation: diagnosed using the Rome IV criteria

Patients must have two or more of the following for the last 3 months with symptom onset at least 6 months prior to diagnosis:

Straining during more than ¼ (25%) of defecations

Lumpy or hard stools more than ¼ (25%) of defecations

Sensation of incomplete evacuation more than ¼ (25%) of defecations

Sensation of anorectal obstruction/blockage more than ¼ (25%) of defecations

Manual maneuvers to facilitate more than ¼ (25%) of defecations (e.g., digital evacuation, support of the pelvic floor)

Fewer than three SBM per week

Loose stools are rarely present without the use of laxatives

Insufficient criteria for irritable bowel syndrome*

*Irritable Bowel Syndrome from StatPearls. Last Update: March 14, 2025.

Secondary constipation: which can be remembered using the mnemonic LMNOP

Lifestyle:

Patients who are bedbound or immobile, those with eating disorders and those with low fiber and water intake [dehydration] are at a higher risk of constipation

Metabolic:

Hypercalcemia, hypokalemia, hypomagnesemia and hypothyroidism can contribute to constipation

Neurologic:

Ensure that patients with neurologic dysfunction (e.g. spinal cord defects, history of CVA, dementia, Parkinson disease, multiple sclerosis) have aggressive bowel regimens on admission

Obstructive:

Consider structural causes of constipation including anal or intestinal strictures and obstructive tumors

Pharmacologic

Prescribed medications which are common offenders are antipsychotics, anticholinergics, narcotics, calcium channel blockers, tricyclic antidepressants

Over-the-counter medications including iron supplements, aluminum containing drugs, calcium supplements, antacids and antihistamines

Pearl 2: Deep Dive into Fiber, Hydration and Bulk-Forming Laxatives

Fruits vs Psyllium

Dried plums or prunes have been shown to be more effective for reducing constipation that psyllium

Kiwi may slightly increase stool frequency compared to psyllium

Fiber Supplementation (Psyllium, methylcellulose)

Mode of action: increases stool weight which can reduce transit time, increase water collection and bacterial mass from fermentation

Although there is evidence showing that soluble fibers (E.g. psyllium, inulin, oatmeal) improve constipation, the evidence for insoluble fiber (E.g. wheat bran) is inconsistent.

Psyllium should be taken at least 2 hours before or after other medications (e.g. levothyroxine, calcium supplements, zinc supplements) as it can reduce their absorption

Hydration

There is no benefit of increased hydration in patients who are adequately hydrated

Pearl 3: Osmotic and Stimulant Laxatives

Osmotic laxatives

Mode of action: draws fluid into the lumen of the bowels through osmosis

Time of onset:

Lactulose: 24-48 hours

Magnesium citrate: 0.5-6 hours

Magnesium oxide: 3-6 hours

Polyethylene glycol: up to 72 hours

Side effects and considerations

Magnesium supplements can be used in patients with renal impairment, but keep an eye on the magnesium level.

Lactulose can cause more bloating and cramping

Stimulant laxatives:

Mode of action: direct stimulation of colonic neurons

Time of onset: up to 6-12 hours and used as a rescue laxative

Side effects and considerations

There is no good evidence of their efficacy after more than four weeks

Studies have shown that stimulant laxatives do NOT damage the enteric nervous system

Tolerance to stimulant laxatives is uncommon.

Pearl 4: Suppositories and Enemas

Suppository vs enema

A suppository is a small solid capsule and an enema is a liquid medication

Types of enemas

Osmotic enemas: sodium phosphate enema, glycerine enema, lactulose enema

Lubricating enemas: mineral oil enema

Hypotonic enemas: tap water enema, soap sud enema

Considerations

Sodium phosphate enemas can cause electrolyte abnormalities, especially in elderly patients and those with renal dysfunction

Mineral oil enemas require patient retention

Discuss what is most comfortable for the patient

Discuss timing and preparation with your nursing colleagues

Pearl 5: Opioid Induced Constipation

Mode of action of opioids: act on the mu opioid receptors which cause inhibition of GI motility and water secretion and absorption in the GI tract resulting in constipation.

Transdermal formulations of opioids are shown to have less incidences of opioids induced constipation in comparison to oral

Peripherally acting mu opioid receptor antagonists (PAMORAs)

Mode of action: blocks the actions of opioids in the gut but do not affect pain control

It is recommended to stop treatment with other maintenance laxatives prior to starting PAMORAs

Side effects: abdominal pain, diarrhea, nausea