How loperamide works
Loperamide acts on the so-called opioid receptors in the intestine, which are docking sites for certain hormones (endorphins) that slow down intestinal transit.
The dampened movements of the colon result in increased absorption of water from the digestive pulp, thickening it – stopping diarrhea.
Many other opioids, such as fentanyl, as well as opiates such as morphine, which are used as powerful painkillers, also cause a slowing of intestinal transit as a side effect.
Loperamide can also potentially act as an opioid in the central nervous system, producing analgesic and soporific effects. However, these effects do not occur in patients with a healthy blood-brain barrier, since loperamide that has penetrated is immediately transported out again via certain transport proteins.
Absorption, degradation and excretion
After ingestion, the active ingredient loperamide mainly binds directly to the intestinal wall. Portions absorbed into the blood are rapidly broken down by the liver, so that less than one percent of the ingested amount of active ingredient reaches the large bloodstream.
About eleven hours after ingestion, half of the active ingredient is excreted in the stool. The breakdown products that accumulate in the liver also leave the body in the stool.
When is loperamide used?
Loperamide is used for the symptomatic treatment of acute diarrhea in adolescents twelve years of age and older and adults when no causative therapy is available.
Special low-dose preparations are available for the treatment of children from the age of two.
A treatment duration of more than two days requires medical supervision.
How loperamide is used
At the beginning of treatment, adults take four milligrams of loperamide (usually two tablets or capsules), and later two milligrams after each unformed stool.
The maximum daily dose of six tablets or capsules (12 milligrams) must not be exceeded in self-medication.
In adolescents from twelve to 18 years of age, one tablet or capsule is taken at the beginning, then another after each unformed stool as well. The maximum daily dose is four tablets or capsules (8 milligrams).
Loperamide should not be used for diarrhea that is accompanied by fever, blood, or pus in the stool. These symptoms indicate a bacterial cause, which may be worsened by administration of the diarrhea medicine.
Due to the loss of fluids and salts (electrolytes) in severe diarrhea, it may be useful to replace the lost substances to the body during and after the diarrhea with so-called oral rehydration solutions.
What are the side effects of loperamide?
One in ten to one hundred people treated experience side effects such as headache, dizziness, constipation, nausea, and flatulence.
Furthermore, one in one hundred to one thousand people treated experience side effects such as drowsiness, abdominal pain, dry mouth, vomiting, indigestion, and skin rashes.
What should be considered when taking loperamide?
Contraindications
Loperamide should not be taken by:
- conditions in which slowing of bowel movements should be avoided (e.g., ileus, megacolon)
- @ diarrhea associated with fever and/or bloody stools
- diarrhea that occurs during or after taking antibiotics
- bacterial intestinal inflammations
- acute episode of ulcerative colitis
- chronic diarrhea in self-medication
Interactions
In addition, substances that block the corresponding transport protein at the blood-brain barrier can lead to increased loperamide concentrations in the central nervous system.
These drugs include, for example, quinidine (antiarrhythmic agent), ritonavir (HIV drug), itraconazole, ketoconazole (antifungal agent), gemfibrozil (blood lipid-lowering agent), and verapamil (cardiac drug).
Age restrictions
Loperamide may be used in low-dose dosage forms in children two years of age and older, and in capsule or tablet form in children twelve years of age and older. The drug is contraindicated in children under two years of age.
In patients with liver disease, loperamide may be taken only after medical clarification, since the breakdown of the active substance by the liver may be delayed.
Pregnancy and lactation
Only rarely is drug treatment indicated for diarrhea. If this is the case during pregnancy, loperamide is the drug of choice. If dietary measures are not sufficient, loperamide may also be used during breastfeeding.
If you are pregnant or breastfeeding, it is always advisable to seek medical clarification of the diarrhea.
How to obtain medication with loperamide
Preparations containing loperamide are available in small packs of up to twelve tablets or capsules containing two milligrams of active ingredient without a prescription in Germany, Austria and Switzerland, as this is the maximum dose for two days.
These packs are often printed with the name suffix “acute” to make it clear that they are intended for self-therapy of acute diarrhea.
If you still suffer from diarrhea after this, be sure to consult a doctor.
How long has loperamide been known?
Loperamide was discovered by scientists in Belgium in 1969. The publication of the new active ingredient in 1972 was followed by its market launch one year later. In the meantime, there are many generic drugs with the active ingredient loperamide.