Emetrol (Domperidone) is a dopamine antagonist with antiemetic properties. Emetrol (Domperidone) slightly penetrates through the blood-brain barrier. Domperidone use is rarely accompanied by extrapyramidal side effects, especially in adults, but domperidone stimulates prolactin release from the pituitary gland. Its antiemetic effect is probably due to a combination of peripheral (gastrokinetic) action and antagonism to dopamine receptors in the chemoreceptor trigger zone, which is outside the blood-brain barrier in the posterior area (area postrema). Animal studies, as well as the low concentrations that have been determined in the brain, indicate a predominantly peripheral effect of domperidone on dopamine receptors.
Studies in humans have shown that when taken orally, emetrol increases pressure in the lower esophagus, improves antroduodenal motility, and accelerates gastric emptying. Domperidone has no effect on gastric secretion.
Emetrol (Domperidone) is rapidly absorbed when administered orally on an empty stomach, the maximum plasma concentration is reached after about 60 minutes. The low absolute bioavailability of oral domperidone (about 15%) is due to extensive first-pass metabolism in the intestinal wall and the liver. Although in healthy subjects the bioavailability of domperidone is increased when taken after meals, patients with gastrointestinal complaints should take domperidone 15-30 minutes before meals. Reduced gastric acidity decreases the absorption of domperidone. When the drug is taken orally after a meal, the maximum absorption is slightly slower and the area under the curve (AUC) is slightly increased. When oral administration domperidone does not accumulate and does not induce its own metabolism; maximum plasma level after 90 minutes (21 ng/ml) after two weeks of oral administration of 30 mg per day was almost the same as after the first dose (18 ng/ml). Emetrol (Domperidone) is 91-93% bound to plasma proteins. Distribution studies of domperidone conducted on animals using a preparation labeled with a radioactive isotope showed its significant distribution in tissues, but low concentration in the brain. In animals, small amounts of the drug penetrate through the placenta. Domperidone is rapidly and extensively metabolized in the liver by hydroxylation and N-dealkylation.
Urinary and fecal excretion is 31% and 66% of the oral dose, respectively. Excretion of the drug in unchanged form is a small percentage (10% in the feces and approximately 1% in the urine). The blood plasma elimination half-life after a single dose is 7-9 hours in healthy volunteers, but it is prolonged in patients with severe renal insufficiency.
It is mainly used to relieve symptoms of nausea and vomiting.
Emetrol can be combined with: neuroleptics, the effect of which it enhances; dopaminergic agonists (bromocriptine, L-dopa), undesirable peripheral effects of which, such as digestive disorders, nausea, vomiting, it suppresses without neutralizing the main properties. Since domperidone has a prokinetic effect on the stomach, theoretically it can affect the absorption of oral medications used as concomitant therapy, in particular the sustained release or enteric soluble dosage forms. However, in patients whose condition has already stabilized on the background of digoxin or paracetamol use, concomitant use of domperidone did not affect the blood levels of these drugs.