CYP3A4 and heart disorder: Moreover, prolonged QT intervals have been described when domperidone was administered in patients with concurrent electrolytic disorders (e.g., hypokalemia, hypomagnesemia, hypocalcemia) and/or some risk factors (e.g., older age, female sex, sleep apnea, complete atrioventricular block, dilated cardiomyopathy, and bradycardia) [11], or in association with other drugs that directly increase the QT interval or, indirectly, compete with domperidone metabolism and elimination (cytochrome P450-3A4 inhibitors) [12,17,18,19].