From the Guidelines
Domperidone's side effects are primarily related to its potential to cause cardiac issues, such as QT prolongation and ventricular tachycardia, as well as other less common side effects.
Common Side Effects
- Cardiac side effects, including QT prolongation and ventricular tachycardia, which can be severe and require drug cessation 1
- Other less common side effects, which have not been extensively studied in large RCTs ### Less Common Side Effects
- Extrapyramidal side effects are less common with domperidone compared to metoclopramide, due to its selective antagonism of peripheral D2 dopamine receptors 2
- Tachyphylaxis is not typically associated with domperidone, unlike erythromycin 3 ### Important Considerations
- The risk of QT prolongation and torsade de pointes with oral domperidone appears to be low, but caution is still advised, especially with intravenous bolus doses 4
- Patients should be monitored for cardiac side effects, particularly when using domperidone long-term 2
- The safety profile of domperidone is generally considered better than metoclopramide, which can cause somnolence, depression, hallucinations, and extrapyramidal symptoms 4
From the FDA Drug Label
The safety of EQUIDONE Gel has not been evaluated in breeding, pregnant and lactating mares other than in the last 45 days of pregnancy and the first 15 days of lactation Do not use in horses with suspected or confirmed gastrointestinal blockage, as domperidone is a prokinetic drug (it stimulates gut motility). Use of EQUIDONE Gel may cause a false positive on the milk calcium test used to predict foaling. Significant inhibition of domperidone metabolism may occur when co-administered with drugs such as erythromycin and ketoconazole. The side effects of Domperidone include:
- Gastrointestinal blockage (contraindication)
- False positive on the milk calcium test used to predict foaling
- Potential increased drug exposure when co-administered with certain drugs, such as erythromycin and ketoconazole, due to CYP3A4 inhibition 5
From the Research
Side Effects of Domperidone
The side effects of domperidone have been reported in several studies, including:
- Headache, tachycardia/palpitations, and diarrhea were the most common side effects reported by 44 patients in a study of 115 patients treated with domperidone for gastroparesis 6
- Genetic polymorphism in the KCNH2 gene was associated with effectiveness of domperidone, while polymorphism in the ABCB1 gene was associated with the efficacious dose 7
- Side effects were seldom reported with therapeutic doses of domperidone, and the drug did not aggravate extrapyramidal side effects of neuroleptic drugs 8
- Domperidone may cause QT prolongation and is associated with increased risk of ventricular tachyarrhythmia and sudden cardiac death, particularly when co-administered with QT-interacting medications 9, 10
- Other reported side effects of domperidone include nausea, vomiting, and stomach fullness, although these symptoms were also improved in many patients treated with the drug 6, 8
Factors Influencing Side Effects
Several factors may influence the occurrence of side effects with domperidone, including:
- Age: older patients may be more likely to experience benefits from domperidone, but may also be at increased risk of side effects 7
- Genetic polymorphisms: certain genetic variations may affect the response to domperidone and the risk of side effects 7
- Co-administration of other medications: QT-interacting medications may increase the risk of cardiac side effects with domperidone 9, 10
- Underlying medical conditions: patients with pre-existing cardiac disease may be at increased risk of side effects with domperidone 10