Methoxyflurane

Question 1

What is the presentation?

Answer 1

3mL ampoule for inhalation via Penthrox inhaler

Question 2

How does it work?

Answer 2

A halogenated ether that produces powerful modification of the awareness of pain with an associated light headed sensation.

Question 3

What is the onset and peak?

Answer 3

6-8 breaths/ 1-2 min onset with maximum level after 2-4 minutes.

Question 4

What are the indications?

Answer 4

Pain

Question 5

What are the contraindications?

Answer 5

Patients who are unable to understand or co-operate.
Patients with severe renal impairment.
Patients with head injury and altered consciousness that prevents co-operation with its use.
Hypersensitivity e.g. malignant hyperthermia

Question 6

What are the precautions?

Answer 6

Use PenthroxTM inhaler with charcoal filter attached

Where administration in transit is necessary, the rear extractor fan must be used and the rear facing seat should remain vacant

Instruct the patient to breathe in through their mouth and out through their mouth via the inhaler. For maximum effect cover the air dilutor hole.
Initial breath is strong and may cause the patient to cough, so advise to take gently

Watch for drowsiness

If oxygen is required deliver separately

Place in a sealed plastic bag when not in use

Question 7

What are the doses?

Answer 7

Initial dose: 1 x 3ml ampoule.
Subsequent dose: 1 x 3ml ampoule after 15 minutes if still in severe pain or pain returns, once only.
Maximum dose: 6ml/24 hrs or 15ml (5 doses) per week.

Question 8

What are the side effects?

Answer 8

Lightheaded
Dizziness
Drowsy
Nausea
Malignant hyperthermia