Naupastad 10 Drug Interactions

The main metabolic pathway of domperidone is through CYP3A4. In vitro data suggest that the concomitant use of drugs that significantly inhibit this enzyme may result in increased plasma levels of domperidone.
Increased risk of occurrence of QT-interval prolongation, due to pharmacodynamic and/or pharmacokinetic interactions.
Concomitant use of the following substances is contraindicated: QTc prolonging medicinal products: anti-arrhythmics class IA (e.g., disopyramide, hydroquinidine, quinidine); anti-arrhythmics class III (e.g., amiodarone, dofetilide, dronedarone, ibutilide, sotalol); certain anti-psychotics (e.g., haloperidol, pimozide, sertindole); certain anti-depressants (e.g., citalopram, escitalopram); certain antibiotics (e.g., erythromycin, levofloxacin, moxifloxacin, spiramycin); certain antifungal agents (e.g., pentamidine); certain antimalarial agents (in particular halofantrine, lumefantrine); certain gastro-intestinal medicines (e.g., cisapride, dolasetron, prucalopride); certain antihistaminics (e.g., mequitazine, mizolastine); certain medicines used in cancer (e.g., toremifene, vandetanib, vincamine); certain other medicines (e.g., bepridil, diphemanil, methadone); apomorphine, unless the benefit of the co-administration outweighs the risks, and only if the recommended precautions for co-administration are strictly fulfilled. Refer to the apomorphine package insert.
Potent CYP3A4 inhibitors (regardless of their QT prolonging effects), i.e.: protease inhibitors; systemic azole antifungals; some macrolides (erythromycin, clarithromycin, telithromycin).
Concomitant use of the following substances is not recommended: Moderate CYP3A4 inhibitors i.e. diltiazem, verapamil and some macrolides.
Concomitant use of the following substances requires caution in use: Caution with bradycardia and hypokalaemia-inducing drugs, as well as with the following macrolides involved in QT-interval prolongation: azithromycin and roxithromycin (clarithromycin is contra-indicated as it is a potent CYP3A4 inhibitor).
The previous list of substances is representative and not exhaustive.
Separate in vivo pharmacokinetic/pharmacodynamic interaction studies with oral ketoconazole or oral erythromycin in healthy subjects confirmed a marked inhibition of domperidone's CYP3A4 mediated first pass metabolism by these drugs.
With the combination of oral domperidone 10 mg four times daily and ketoconazole 200 mg twice daily, a mean QTc prolongation of 9.8 msec was seen over the observation period, with changes at individual time points ranging from 1.2 to 17.5 msec. With the combination of domperidone 10 mg four times daily and oral erythromycin 500 mg three times daily, mean QTc over the observation period was prolonged by 9.9 msec, with changes at individual time points ranging from 1.6 to 14.3 msec. Both the Cmax and AUC of domperidone at steady state were increased approximately three-fold in each of these interaction studies. In these studies domperidone monotherapy at 10 mg given orally four times daily resulted in increases in mean QTc of 1.6 msec (ketoconazole study) and 2.5 msec (erythromycin study), while ketoconazole monotherapy (200 mg twice daily) led to increases in QTc of 3.8 and 4.9 msec, respectively, over the observation period.