Penthrox® - "Green whistle"
- Methoxyflurane (C3H4Cl2F2O) is a volatile fluorinated hydrocarbon
- Colourless liquid analgesic with a fruity odour
- Highly lipophilic and rapidly absorbed via inhalation
- Potentiated through GABA receptors & two-pore K+ channels
- Metabolised in liver (CYP450 isozymes)
- Metabolites include: Fluoride, oxalic acid,di-fluoromethoxyacetic acid, di-chloroacetic acid
- 60% excreted in urine: fluorine, fluoride & oxalic acid
- Remainder is exhaled
- Metabolites can cause renal damage at high concentrations
- Emergency patient controlled analgesia for conscious adults with trauma associated moderate/severe pain.
- Max 2 x 3 mL doses in 24hrs and Max 15ml / week (potentially nephrotoxic).
- Single dose of Penthrox is 3 mLs (one bottle)
- Up to 1 hour of analgesia if used intermittently
- Max. dose not to exceed 6 mLs (2 bottles)
Contraindications - CHECK
C - Clinically significant cardiac or respiratory disease
H - Hypersensitivity to methoxyflurane (or any fluorinated anaesthetic)
E - Established or Hx malignant hypertherima
C- Consciousness altered
K - Kidney (eGFR < 45mL/min or on nephrotoxic antibiotics) or liver disease