Metoclopramide

Chemical

A benzamide dopamine antagonist antiemetic & prokinetic

Use

  1. Nausea & vomiting
  2. Hiatus hernia, reflux, gastritis

Presentation

Tablets 10mg

Ampoule 10mg/mL

Dose

10mg TDS

Route

PO/IV/IM

MoA

GI effects: primarily by ↑CHOLINERGIC ACTIVITY

  1. Inhibits pre & post synaptic D2 receptor
  2. Stimulates 5HT4 receptor (releasing ACh from cholinergic neurons)
  3. Antagonises pre-synaptic inhibition of muscarinic receptors (sensitizing these receptors, resulting in direct sm m contraction)

↓

 

↑LES + gastric tone

↑gastric P

Acceleration of gastric emptying

 

Antiemetic effects:

  1. Central D2 blockade
  2. ↓sensitivity of visceral afferents supplying VC

PD

GI

  • ↑LES tone
  • ↑Gastric emptying

CNS

  • ↑threshold for vomiting
  • Neuroleptic effects 2° dopamine antagonism

CVS

  • ↓BP
  • Arrhythmias

Metabolic

  • Stimulates prolactin release
  • ↑aldosterone secretion

PK

A

OBA 30 – 97% PO

Wide availability 2° 1st pass conjugation

D

20% PPB

VD 2 – 3.5L/kg

M

Liver sulphation

E

80% PO dose excreted in 24hrs

20% unchanged

t1/2 2.6-5hrs

Not removed with dialysis

Adverse Effects

  • Extrapyramidal SE (crosses BBB) → akathisia, oculogyric crisis → in high dose
  • Drowsiness, fatigue
  • Bowel disturbances