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Here is the summary of a paper describing a small scale study of the action of Loperamide and an interesting adjuvant for Lop, together with novel imaging techniques.

The full paper is available here :


[Note: quantification of gastric emptying times - of significance in Dumping Syndrome ]

Alimentary Pharmacology & Therapeutic

Volume 36, Issue 1

July 2012

Pages 64–73


The effects of loperamide, or loperamide plus simethicone, on the distribution of gut water as assessed by MRI in a mannitol model of secretory diarrhoea


E. Placidi,

L. Marciani,

C. L. Hoad,

A. Napolitano,

K. C. Garsed,

S. E. Pritchard,

E. F. Cox,

C. Costigan,

R. C. Spiller,

P. A. Gowland

First published: 14 May 2012Full publication history

DOI: 10.1111/j.1365-2036.2012.05127.xView/save citation

Cited by: 6 articlesRefresh citation countCiting literature

Funding Information

Correspondence to:

Prof. P. A. Gowland, Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham NG7 2UH, UK.

E-mail: penny.gowland@nottingham.ac.uk



Loperamide (LOP) is an anti-diarrhoeal agent which is thought to act largely by slowing transit with an uncertain effect on the fluid content of the small and large bowel in humans. Adding simethicone (SIM) to LOP improves its efficacy, but the mechanism of interaction is unclear. Novel MRI techniques to assess small bowel water content (SBWC) have shown that mannitol solutions markedly increase SBWC and can be used as a model of diarrhoea.


We aimed to use quantitative MRI techniques to compare the actions in the gut of LOP and LOP + SIM in a model of secretory diarrhoea using mannitol.


A total of 18 healthy volunteers ingested capsules containing placebo (PLA) or 12 mg LOP or 12 mg LOP + 125 mg SIM. After 100 min they were given a drink containing 5% mannitol in 350 mL of water. They underwent baseline fasting and postprandial serial MRI scans at 45 min intervals for 4.5 h after ingesting the drink. A range of MRI sequences was acquired to image the gut.


LOP and LOP + SIM significantly accelerated gastric emptying (P < 0.03) and reduced SBWC during the late phase (135–270 min after mannitol ingestion), P < 0.009, while delaying arrival of fluid in the ascending colon (AC). The relaxation time T2 of the contents of the AC was reduced by both drugs (P < 0.0001).


LOP and LOP + SIM accelerate gastric emptying, but reduce small bowel water content which may contribute to the delay in oral-caecal transit and overall anti-diarrhoeal effect.

1 Reply

Diarrhoea is something that has come up a number of times before. Sometimes it alternates with constipation, and may involve sudden loss of control, severe embarrassment in private or public, and a dispiriting amount of ruined underwear. It is a big issue.

You may know loperamide by the name Imodium. It is a standard answer to combatting diarrhoea.

Try lactose-free milk as an easy thing that will not do any harm to try, but for some, the results are remarkably good.

After trying the normal straightforward things, and if you have real problems, you might start asking whether you may have small intestine bacterial overgrowth (SIBO) which can be diagnosed at the hospital with a breath test. It is basically a problem with bacteria / bugs getting hold of your system that stomach acid would have sorted out, but this does not happen if you have no / less stomach to produce the acid, or if it has been switched off with omeprazole. You may need a specialist course of antibiotics from a good gastroenterologist to get things put right again.

Sometimes it is the result of chemotherapy / radiotherapy. It is one of the unspoken consequences of cancer treatment.