D2 Receptor Antagonists

Counselling:Oral solution and suspensions need to be shaken before use.

Monitoring:A baseline ECG is recommended before intramuscular dosing. During therapy, the need for ECG monitoring for QTc interval prolongation and for ventricular arrhythmias must be assessed in all patients, but continuous ECG monitoring is recommended for repeated intramuscular doses. ECG monitoring is recommended up to 6 hours after administration of haloperidol solution for injection to patients for prophylaxis or treatment of postoperative nausea and vomiting. Whilst on therapy, it is recommended to reduce the dose if QTc is prolonged, but haloperidol must be discontinued if the QTc exceeds 500 ms.

Greater risk of QT prolongation with use of IM depot injectable dosage forms of haloperidol.

Monitoring:Electrolyte disturbances such as hypokalaemia and hypomagnesaemia increase the risk for ventricular arrhythmias and must be corrected before treatment with haloperidol is started. Therefore, baseline and periodic electrolyte monitoring is recommendedCounselling:Avoid in pregnancy unless the benefit outweighs the risk Avoid breastfeeding unless the benefit outweighs riskC/I in patients < 18 years Risk of developing neuromalignant syndrome

Switch from mania to depression: There is a risk in the treatment of manic episodes of bipolar disorder for patients to switch from mania to depression. Monitoring of patients for the switch to a depressive episode with the accompanying risks such as suicidal behaviour is important in order to intervene when such switches occur.

The influence of renal impairment on the pharmacokinetics of haloperidol has not been evaluated. No dose adjustment is recommended, but caution is advised when treating patients with renal impairment. However, patients with severe renal impairment may require a lower initial dose, with further doses administered and adjusted according to the patient’s responseThe influence of hepatic impairment on the pharmacokinetics of haloperidol has not been evaluated. Since haloperidol is extensively metabolised in the liver, it is recommended to halve the initial dose.The recommended initial haloperidol dose in elderly patients is half the lowest adult dose. Further doses may be administered and adjusted according to the patient’s response. Careful and gradual dose uptitration in elderly patients is recommended.

Drowsiness – Take before bed, do not drive or operate machinery, be aware when drinking alcohol.

Counselling:Oral solution and suspensions need to be shaken before use.

CounsellingAvoid in pregnancy unless the benefit outweighs the risk Avoid breastfeeding unless the benefit outweighs risk Avoid direct sunlight- causes photosensitivity at high doses C/I in patients < 18 years Risk of developing neuromalignant syndrome

Switch from mania to depression: There is a risk in the treatment of manic episodes of bipolar disorder for patients to switch from mania to depression. Monitoring of patients for the switch to a depressive episode with the accompanying risks such as suicidal behaviour is important in order to intervene when such switches occur.

Counselling Reduced doses required for renal/ hepatic impairmentSmoking induces metabolism- alter dose accordingly

Metoclopramide Counselling: May cause drowsiness or dizziness - do not operate heavy machinery - do not operate heavy machinery If the patient has had Parkinson's or a history of seizures - increased risk of seizuresAvoid Alcohol Pregnancy and Breastfeeding - Use if Benefit > RiskSide effects: EPSEs, Seizures at high doses, Drowsiness, Diarrhea, Fatigue, Hyperprolactinemia

Side effect: Diarrhea

Metoclopramide works as a Muscarinic Acetyl Choline Receptor Agonist which is capable of causing a number of side effects; Increased salivationNausea and vomitingDiarrheaAbdominal crampsBlurred visionBradycardia Hypotension These side effects are usually well tolerated because this agonism is a minor part of the overall pharmacology.

Counselling pointsSigns and symptoms of cardiac arrhythmia such as dizziness, heart palpitations and fainting common side effects such as dry mouthuncommon side effects headache, diarrhoea, rash, pruritusHyperprolactinaemia is a side effect Domperidone can be exploited for this side effect and has an unlicensed as a galatagoguePF2014 breast feeding highlighted this useIt can be used in mothers with pre-term babies and insufficient milk supply

Pharmacist only consultation Data from 2014-2016 highlighted that Domperidone was inappropriately supplied to patients

Domperidone is associated with QT interval prolongation There is a greater risk in adults > 60 years of age Risk is also associated with patients taking other QT-interval prolonging drugs such as Olanzapine, fluoroquinolones, Amiodarone. Electrolyte imbalances such as hypomagnesemia and hypokalaemia can predispose patients to QT interval prolongation

This black triangle is a visual prompt for healthcare professionals. It is to highlight that this medicine is associated with additional monitoring to allow continued risk vs benefit analysis. Any healthcare professional is to report any suspect adverse drug reaction. Any reporting can be made through the HPRA using the reporting system. Due to the safety concerns, the pharmacist must be directly involved in the decision to supply the medicine to a patient.

Dual mechanism of action Domperidone acts as an antagonist at the dopamine D2 receptors in the CTZ. By inhibiting agonist activity in the CTZ it will not VC.