Methoxyflurane CPG

Question 1

Methoxyflurane - Presentation

Answer 1

3 mL glass bottle

Question 2

Methoxyflurane - Pharmacology

Answer 2

Inhalation analgesic agent at low concentrations

Question 3

Methoxyflurane - Metabolism

Answer 3

Excreted mainly by the lungs

By the liver

Question 4

Methoxyflurane - Primary emergency indications

Answer 4

1. Pain relief

Question 5

Methoxyflurane - Contraindications

Answer 5

1. Pre-existing renal disease / renal impairment
2. Concurrent use of tetracycline antibiotics
3. Exceeding total dose of 6 mL in 24hr period
4. Personal or family history of malignant hyperthermia
5. Muscular dystrophy

Question 6

Methoxyflurane - Precautions

Answer 6

1. The Penthrox inhaler must be hand-held by the Pt so that if unconsciousness occurs it will fall from the patient’s face. Occasionally the operator may need to assist but must continuously assess the level of consciousness
2. Pre-eclampsia
3. Concurrent use with oxytocin may cause hypotension

Question 7

Methoxyflurane - Route of administration

Answer 7

Self-administered under supervision using the hand held Penthrox inhaler

Question 8

Methoxyflurane - Side effects

Answer 8

Drowsiness

Decrease in blood pressure and bradycardia (rare)

Exceeding the maximum total dose of 6 mL in a 24hr period may lead to renal toxicity

Question 9

Methoxyflurane - Special notes

Answer 9

The maximum initial priming dose for Methoxyflurane is 3 mL. This will provide approximately 25 minutes of analgesia and may be followed by one further 3 mL dose once the initial dose is exhausted if required. Analgesia commences after 8 - 10 breaths and lasts approximately 3 - 5 minutes once discontinued.

Do not administer in a confined space. Ensure adequate ventilation in ambulance.

Malignant hyperthermia is a very rare condition that can be induced by volatile anaesthetics such as methoxyflurane. Ask Pt about any past history or family history of adverse reactions to inhaled anaesthetics.

In patients with muscular dystrophy, volatile agents may precipitate life-threatening rhabdomyolysis.