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Imodium is a medicine that is commonly used to treat diarrhea and is therefore also called an anti-motility medicine. The active ingredient of the medicine is Loperamide.

Mechanism of Action

Numerous opioid receptors are present in the muscular lining of the alimentary tract. Loperamide acts by binding with these receptors and thereby reducing the peristalsis, which is a wave-like motion generated in the gut in order to push the food forwards. When loperamide is taken, it reduces the speed at which food and water is pushed down the gut. This gives the intestine more time to absorb food and water into the body. As the water is reabsorbed, the consistency of the stools becomes firmer and the frequency of passing stools is reduced considerably.

Imodium (loperamide) is generally prescribed to treat :

  1. Acute diarrhea related to some gastrointestinal infection

  2. Chronic diarrhea associated with inflammatory bowel disease.

  3. In certain circumstances, Imodium is prescribed to reduce the amount of discharge flowing out of ileostomy openings.

For the treatment of acute diarrhea, Imodium is generally prescribed in the dose of 4 mg, followed by 2 mg after each loose stool. The daily dose should not be in excess of 16 mg. The initial dosage for chronic diarrhea is the same. The patient then takes a daily maintenance dose according to his requirement.

Loperamide is supposed to be a very safe drug. There are hardly any side effects, even when it is taken for a long duration, provided the patient does not exceed the daily recommended dosage. Some of the side effects associated with loperamide include:

  • Gastrointestinal effects: Some patients may complain of nausea, vomiting, pain in the abdomen and loss of appetite when on Imodium. These side effects are usually not due to the medicine. Rather, they can be attributed to the underlying gastrointestinal infection.

A few cases of toxic megacolon have been reported in patients taking loperamide in the long term, for ulcerative colitis or for pseudomembranous colitis caused by antibiotics.

Paralytic ileus with abdominal distention and appendicitis have been seen in patients on Imodium in rare cases.

Children are more likely to suffer from side effects as they show greater variability in response to Imodium. Dehydration may further increase the likelihood of side effects. Therefore, doctors recommend that loperamide should be stopped within 48 hours if the patient does not observe any improvement in his diarrhea. In case Imodium fails to act within 48 hours, efforts should be made to identify the underlying pathogen and specific antibiotics should be prescribed to get relief from diarrhea.

  • Effects on the nervous system: Some patients complain of drowsiness or dizziness after taking Imodium. Children are more susceptible to these side effects.

  • Addiction and dependence: There are no reported cases of addiction and dependence on Imodium, even when the medicine is taken for a long time in a dose prescribed by the physician. Laboratory monkeys have shown dependence on Imodium and severe withdrawal symptoms when they received more than 300 mg of medicine per day. This is much more than the maximum recommended dose of 16 mg per day in humans. Similarly, there is a documented case of a 26 year old male who had a history of drug and alcohol abuse. He is believed to have taken around 320 mg of Imodium daily and when the medicine was stopped, there were severe withdrawal symptoms.

  • Skin side effects: Certain patients taking Imodium complain of skin rashes or pruritus.

Thus we see that Imodium is a very safe drug which can be taken both to treat diarrhea in the short and long term without worrying much about the side effects.

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