Last update and review: January 30, 2020.
A short summary.
Our comments and notes on causes of constipation, osmotic laxatives and prokinetics, safety of polyethylene glycol/macrogol (PEG).
“Constipation” by Nathan S. S. Atkinson for a 2019 nursing manual.
Nathan S. S. Atkinson wrote a chapter called “Constipation” for a 2019 book by Sturm A., White L. (eds) “Inflammatory Bowel Disease Nursing Manual”.
The chapter is well written overall. But there are several points that can be questioned. Below, we put our comment on a social network.
The New Neander’s Medical on January 30, 2021:
A book (the chapter written by Atkinson, 2019 (2)) claims high protein and low volume intakes are causes of constipation.
Analysis: The opposite is true. High protein effectively improve constipation. Low volume->better digestion in people with low stomach acid->less microbial activity and methane.
An informative figure with an abdominal X-ray of proximal constipation.
Osmotic laxatives and prokinetics.
Atkinson, 2019 (2):
Poorly absorbed but osmotically active agents draw water into the bowel lumen to soften stool. In years gone by magnesium salts, mineral oil and lactulose have been widely used. Lactulose particularly is associated with bloating and flatulence and so is poorly tolerated by many patients.
Polyethylene glycol (PEG or macrogol-3350(Movicol)).
Atkinson, 2019 (2):
In modern practice, polyethylene glycol (PEG or macrogol-3350) has become the osmotic laxative of choice. Low volume, safe and not fermentable, PEG produces a reliable catharsis for endoscopic procedures when balanced with isotonic electrolytes. Smaller doses are increasingly used in the management of constipation.
Macrogol (Laxido© or Movicol©) is licenced for 1–3 sachets/day for constipation and 8 sachets daily for 3 days for faecal impaction.
Movicol. Safety analysis.
The text below is adapted from another article on this website.
One of the therapeutic agents for constipation mentioned by Spiller, 2016 (1), is Movicol (polyethylene glycol (PEG or macrogol-3350)).
The patient leaflet Movicol does not mention any significant toxicity and sais Movicol can be taken during pregnancy. We need to dig into the “information for health professionals” to learn that, in animal trials, serious negative effects were observed:
reduction in fetal and placental weights, reduced fetal viability, increased limb and paw hyperflexion and abortions, were noted in the rabbit at a maternally toxic dose that was 3.3 x the maximum recommended dose in humans for treatment of chronic constipation and 1.3 x for faecal impaction. Rabbits are a sensitive animal test species to the effects of GI-acting substances and the studies were conducted under exaggerated conditions with high dose volumes administered, which are not clinically relevant.
The manufacturer of the drugs Movicol (polyethylene glycol (PEG or macrogol-3350)), Norgine Limited, and the UK medical bureaucrats who authorized the drug, wrote that the results in rabbits are not clinically relevant in humans. We think that ignoring the results on toxicity in animals is questionable. In general, it is recommended to explore natural ways to correct IBS-D (diarrhea) and IBS-C (constipation) before using drugs. If drugs are used, the available information on safety needs to be studied thoroughly.
Vitamin C (ascorbic acid) also acts as an osmotic laxative.
Atkinson, 2019 (2):
Vitamin C (ascorbic acid) also acts as an osmotic laxative when given in large doses; it is actively absorbed by two transporters that become saturated at 1–2 g per day. Doses of 6 g per day overwhelm the transporters and produce a well-tolerated osmotic laxative effect. Ascorbic acid therefore reduces the volume of bowel preparation to drink, generating the same quality cleansing but improving patient tolerability and adherence.
Working Group on IBS-D, IBS-C and “functional constipation”.
We invite medical practitioners and people interested in optimizing their health to join our Working Group on IBS-D, IBS-C and “functional constipation”.
Selected references.
1. Spiller R. Irritable bowel syndrome: new insights into symptom mechanisms and advances in treatment. F1000 Research 2016, 5(F1000 Faculty Rev):780.
2. Atkinson N.S.S. (2019) Constipation. In: Sturm A., White L. (eds) Inflammatory Bowel Disease Nursing Manual. Springer, Cham.