Constipation Medications For IBS-C
Many patients come to see me for constipation after visiting with a gastroenterologist . They have been told to take Miralax and increase fiber in their diet and even told to follow the low-fodmap diet.
For some this recommendation works, but for most it doesn't. An in-depth look at constipation is needed.
Including an investigation of causes related to constipation considering:
Diet, food intolerances, and nutrient deficiencies or excesses .
Drugs that are causing constipation.
Exercise and general activity.
Abdominal and pelvic floor adhesions.
Factors of motility such as thyroid disorders , gall bladder disorders, and hypochloridia.
Dysbiosis (yeast, parasitic, bacterial, viral) or bacterial overgrowth of the small intestine (methane dominant).
Anxiety, stress, or sleep disorders.
Rare causes of enteric nervous system constipation such as diabetes, lyme disease, and early parkinson's disease.
Genetic single nucleotide polymorphisms.
Recently some new recommendations by The American College of Gastroenterology came out for IBS-C meaning the Irritable Bowel Syndrome population with constipation as its predominant symptom (compared to diarrhea). First let's summarize the criteria needed for an IBS-C diagnosis.
After ruling out red-flag causes of constipation, an IBS-C diagnosis is made with the following criteria based on Rome 1V guidelines:
Recurrent abdominal pain, on average, at least 1 day/week in the last 3 months, associated with two or more of the following criteria:
Related to defecation
Associated with a change in frequency of stool
Associated with a change in form (appearance) of stool.
For the constipation subtype:
more than 25% of stools must be type 1 or 2 appearance (Bristol Stool Scale) and less than 25% must be type 6 or 7 stool appearance.
Criteria fulfilled for the last 3 months with symptom onset at least 6 months before diagnosis.
The drug category with the best evidence for constipation seems to be prosecretory agents. These agents work by creating a secretion in the lumen of the intestine of chloride , water, and bicarbonate via binding to guanylate cyclase-C receptors. It's actually mimicking what happens in infectious diarrhea to a mild degree.
The drugs that are available that were recommended with strong evidence are as follows:
1. Linaclotide (linzess) . The Number needed to treat (NNT) for improvements in constipation was 6 (NNT=6) and the NNT for improvements in abdominal pain was 8. Meaning 1 out of every 6 received some benefit. The main side effect was diarrhea.
2. Plecanatide (trulance): works like Linaclotide but is Ph dependent. The NNT for this drug is 10. 23.8% of people report side effects at the 3mg per day dose and 19.8% report side effects at the 6mg per day dose. Placebo in studies conducted head to head against Plecanatide reported 18.6% adverse side effects.
3. Lubiprostone (Amitiza): works a little different then above. Lubiprostone is a molecule that activates the intestinal chloride channel type 2 on the apical surface of small intestinal enterocytes. Activation leads to a chloride and water efflux into the luminal cavity, which results in accelerated GI transit. The NNT is about 12. It has additional side effects of Nausea along with diarrhea.
Of note secretory laxatives like Polyethylene Glycol (Mirax) continues to be generally thought of helping with improving spontaneous bowel movements but it doesn't help with other aspects of IBS-C such as pain. Also a new prokinetic medication Prucalopride (a 5HT-4 agonist) has now been approved in the United states.
As a Naturopathic Physician trained in a functional approach to health, I look upstream and downstream to figure out what's going on in the constipated patient. Brain/Mind related concerns are certainly a factor as well as microbiome imbalances. The biggest cause I see in my practice for constipation is overly restricted intake of carbohydrates. But this is such a fine balance because certain carbohydrates can make bloating and gas worse for some patients.
The use of medications might be helpful while figuring out the root cause but realize you might be training constipation for diarrhea. It's not uncommon that my constipation patient "begs" for diarrhea and my diarrheal patient begs for "constipation".
Regardless it takes a full on effort using an investigation of the root cause of the constipation and the employment of natural agents that are osmotic laxatives, stool softeners, and prokinetics to get things moving. Lifestyle and movement therapies such as daily walking, yoga poses, squatty potties, and biofeedback can certainly help. Of course fiber of all kinds (soluble, insoluble) is really important for healthy bowel movements but the addition of fiber may come with unwanted side effects (bloating , gas, cramping)
I have no problem prescribing the secretory agents if my patients want to try them but I just like them to know what they are getting into. But what I really invite my patient to is to engage in a project of investigating the root cause as we gain a process. Having a healthy daily bowel movement is something you take for granted unless you suddenly find it not happening anymore. Its a core process of detoxification and elimination in the body and needs to be taken seriously.