Emetrol (domperidone) is a dopamine antagonist with antiemetic properties. It has an antiemetic effect, calms hiccups and eliminates nausea in some cases. The action is due to blockade of central dopamine receptors. Due to this, inhibitory effect of dopamine on motor function of the gastrointestinal tract is eliminated and evacuatory and motility activity of the stomach is increased.
Emetrol is rapidly absorbed when taken orally on an empty stomach; maximum plasma concentration (Cmax) is reached after 60 minutes. The low bioavailability of oral domperidone (approximately 15%) is due to extensive first-pass metabolism in the intestinal wall and in 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. Decreased gastric acidity decreases the absorption of Domperidone. If the drug is taken orally after the meal, maximum absorption is slightly delayed and the area under the pharmacokinetic curve <> (AUC) is slightly increased.
Distribution. When administered orally, domperidone does not accumulate and does not induce its own metabolism; the maximum plasma level after 90 minutes (21 ng / ml) after two weeks of 30 mg per day was almost the same as after the first dose (18 ng / ml). Domperidone is 91-93% bound to plasma proteins. Distribution studies of domperidone conducted on animals using the preparation emetrol, labeled with 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.
Metabolism. Emetrol is rapidly and extensively metabolized in the liver by hydroxylation and N-dealkylation.
Excretion. Urinary and fecal excretion is 31% and 66% of the oral dose, respectively. Excretion of Emetrol in unchanged form is a small percentage (10% in the feces and approximately 1% in the urine). 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.
Emetrol (domperidone) is not recommended to use in case of motion sickness. The drug should be used with caution in elderly patients or patients with existing heart disease or with a history of heart disease. Cardiovascular effects. Emetrol has been associated with prolongation of the QT interval on ECG. During the post-marketing follow-up, very rare cases of QT prolongation and ventricular flutter-fibrillation were reported in patients taking domperidone. These reports included information about patients with other adverse risk factors, electrolyte disturbances and concomitant therapy that may be contributing factors. The QT interval prolongation observed in healthy volunteers when they used domperidone according to the recommended dosing regimen in the usual therapeutic doses (10 or 20 mg 4 times daily) was of no clinical significance. Concomitant use with apomorphine. Domperidone is contraindicated when used together with medicinal products that prolong the QT interval, including apomorphine, except in cases when the benefit of combined use exceeds the risks, and only in strict compliance with the recommended measures for combined use.