Anti-emetic

Dopamine Antagonist

Level 3

1. Prokinetic
2. Antiemetic
3. Migraine
4. Reflux oesophagitis

PO/IV

CVS: Hypotension after IV; Dysrhythmias and QTc

GIT
1. Selective stimulation of gastric muscarinic receptors
- Coordinated GIT contraction (accelerates gastric emptying)
- Increased amplitude and frequency of Longitudinal muscle contraction
- Lowers threshold for peristaltic reflex to occur
2. Direct action on smooth muscle to increase tone (including increased LOS)
3. Reduces intestinal muscle fatigue

CNS
- Neuroleptic effects
- Extrapyramidal effects
- Increase prolactin

GU- Increased uterine peristalsis

20% PB

Benzamide D2-R antagonist

1. Decreased sensitivity of visceral afferents to vomit center
2. Central D2 blockade increased threshold at CTZ
3. Selective GIT muscarinic effects leading to prokinesis
4. Other effects:
- Inhibition of 5-HT3
- Anti-H1 effects

1. EPS
2. Dizziness
3. NMS
4. QTc prolongation

Rapid oral absorption with variable BA (30-90%) due to first pass conjugation

Vd 2-3L/Kg

Hepatic metabolism to sulfate conjugate

80% renally excreted (20% of this is unchanged)

T1/2= 2.5-5 hours

Dopamine Antagonist

1. Antagonism of peripheral D2 receptors
2. Selective stimulation of gastric muscarinic receptors
- Coordinated GIT contraction
- Increased amplitude and frequency of Longitudinal muscle contraction
- Lowers threshold for peristaltic reflex to occur
3. Direct action on smooth muscle to increase tone (including increased LOS)
4. Reduces intestinal muscle fatigue
5. Decreased sensitivity of visceral afferents to vomit center
6. Central D2 blockade increased threshold at CTZ

1. Drowsiness, dizziness and fainting
2. EPS- including oculogyric crises
3. Neuroleptic malignant syndrome
4. QTc prolongation and conduction abnormalities
5. Abdominal cramping
6. Hyperprolactinaemia
7. Hypertension in phaeochromocytoma

Rapidly absorbed with variable F (30-100%) due to First pass metabolism

Vd 2-3.5L/kg

Hepatic sulfate conjugation
Excretion

80% renally excreted, 20% of this unchanged

T1/2= 2-5 hours