Safe use of Penthrox inhaler

What cautions are needed when using methoxyflurane?

Methoxyflurane (Penthrox inhaler) is a self-administered inhaled analgesic for short-term use in acute trauma and during brief painful procedures such as wound dressing.1 It is mostly used by paramedics but is also PBS-listed for the doctor’s bag.2 

Exceeding the maximum dose of 6 mL per day or 15 mL per week, or administering methoxyflurane on consecutive days, could cause renal toxicity. It is contraindicated in people with renal impairment.

Do not give methoxyflurane to people with cardiovascular instability, respiratory depression, head injury or in an impaired conscious state.3 It may not be suitable for acute coronary syndrome pain or migraine and concomitant use with beta blockers may cause hypotension.

Avoid use in children under five years as they cannot self-monitor pain or self-administer the inhaler and may also be more prone to deep sedation.