Promethazine

Chemical

A phenothiazine dopamine antagonist anti-emetic

Use

  1. Nausea & vomiting
  2. Pruritus/allergies

Presentation

Tablets 10/25mg

Vial 25mg/mL

Route / Dose

(PO) 25mg TDS

(IV) 25 – 50mg BD

MoA

  • Competitive antagonist of H1 receptors
  • Nausea relief via anticholinergic actions @ CTZ

PD

CNS – sedation, anxiolysis, ↓motion sickness by suppressing vestibular end-organ receptors

GI – ↓LES tone

RESP – Bronchodilation, antitussive

PK

A

Well absorbed

D

93% PPB

V 2.5L/kg

M

Extensive 1st pass metabolism

E

2% unchanged in urine

Adverse Effects

Anticholinergic side effects

Extrapyramidal reactions

Jaundice

Photosensitivity

Excitatory phenomena

GI & Haemopoietic disturbances