Domperidone Product Information (Part 1)

Domperidone is a what we call a “Gastrointestinal Motility Modifier”.

Indications- What is domperidone used for?

Domperidone is indicated in the symptomatic management of upper gastrointestinal motility disorders associated with chronic and subacute gastritis and diabetic gastroparesis. It may also be used to prevent gastrointestinal symptoms associated with the use of dopamine agonist antiparkinsonian agents.

Unofficially or, “off-label”, it is also used to increase milk production in new moms (some women have a low milk supply). When used in this off-label manner, domperidone is considered a galactagogue. A galactagogue is a substance that promotes lactation in humans and other animals. It may be synthetic (domperidone), plant-derived, or endogenous.  To obtain a galactagogue effect, however, it must be used at higher doses, typically up to 8 tablets a day!

Pharmacology- How does it work as a drug?

Domperidone is what we call, pharmacologically,  a peripheral dopamine antagonist. It is structurally related to the butyrophenones with antiemetic (anti-nausea) and gastroprokinetic properties (increased stomach movement).

It increases gastric motility and peristalsis (contraction and relaxation of muscles), enhances gastroduodenal coordination and consequently facilitates gastric emptying and decreases small bowel transit time (the time it takes for food to travel from your mouth through your digestive tract to your anus is your bowel).

The way domperidone works is related to its peripheral dopamine receptor blocking properties. Emesis (vomiting) induced by apomorphine, Hydergine, morphine or levodopa through stimulation of the chemoreceptor trigger zone (situated outside the blood-brain barrier) can be blocked by domperidone. There is indirect evidence that emesis is also inhibited at the gastric level, since it also inhibits emesis induced by oral levodopa, and local gastric wall concentrations following oral domperidone are much greater than those of the plasma and other organs. It does not readily cross the blood-brain barrier and therefore is not expected to have central effects- unlike the popular drug called metoclopramide (Reglan®)

Domperidone elevates serum prolactin levels but has no effect on circulating aldosterone levels (See side effects for what this can cause).

Pharmacokinetics- What is the fate of the drug in your body?  Sciency Details…

In humans, peak plasma levels of the product occur within 30 minutes after oral (fasted -empty stomach) administration.  So ideally, you want to take the product 15-30 minutes before your meal.

Plasma concentrations 2 hours after oral administration are lower than following i.m. injection and this is likely the result of hepatic first-pass and gut wall metabolism. Peak plasma concentrations are 40 ng/mL following an i.m. injection of 10 mg, 20 ng/mL after a single 10 mg tablet, and 70 to 100 ng/mL after oral doses of 60 mg (tablets or oral drops). The half-life was calculated as approximately 7.0 hours in each case. The degree of human plasma protein binding was calculated from tritiated domperidone concentrations of 10 and 100 ng/mL as 91.7 and 93.0%, respectively.

The major metabolic pathways in humans are hydroxylation and oxidative N-dealkylation, the products of which are hydroxydomperidone and 2,3-dihydro-2-oxo-1-H-benzimidazol-1-propionic acid, respectively. In vitro metabolism experiments with diagnostic inhibitors revealed that CYP3A4 is a major form of cytochrome P450 involved in the N-dealkylation of domperidone, whereas CYP3A4, CYP1A2 and CYP2E1 are involved in domperidone aromatic hydroxylation. After oral administration of 40 mg domperidone to healthy volunteers, 31% of the radioactivity is excreted in the urine and 66% in the feces over a period of 4 days.

Domperidone (Motilium®) Side Effects

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