Methoxyflurane

Question 1

Presentation

Answer 1

3 mL glass bottle

Question 2

Pharmacology

Answer 2

Inhalational analgesic agent at low concentrations

Question 3

Metabolism

Answer 3

Metabolised = mainly by the lungs
Metabolised = liver

Question 4

Indications

Answer 4

Pain relief

Question 5

Contras

Answer 5

Pre-existing renal disease/impairment
Concurrent use of tetracycline antibiotics
Exceeding total dose of 6 mL in 24 hrs
Personal or family history of malignant hyperthermia
Muscular dystrophy

Question 6

Precautions

Answer 6

Penthrox inhaler must be hand-held by the pt so that if unconsciousness occurs it will fall from pt’s face. Occasionally paramedic will need to assist but do so cautiously and continuously assess level of consciousness

Pre-eclampsia
Concurrent use with Oxytocin may cause hypotension

Question 7

Route of administration

Answer 7

Self-administration using penthrox inhaler

Question 8

Side effects

Answer 8

Drowsiness
Decrease in BP and bradycardia (rare)
Exceeding max dose of 6 mL in 24 hrs may lead to renal toxicity

Question 9

Special notes

Answer 9

Initial priming dose is 3 mL and provides approx 25 mins of analgesia.

Analgesia commences after 8-10 breaths and last for approx 3-5 mins once discontinued.

Do not administer in confined spaces.

Malignant hyperthermia is a rare condition that can be induced by volatile anaesthetics. Ask about personal or family history of reactions to inhaled anaesthetics.

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

Question 10

Pain relief guideline - Adult/Paediatric

Answer 10

Indicated for Moderate procedural pain or unable to administer Fentanyl IN

3 mL inhaled
Repeat 3 mL if required (max 6 mL)

Consider Paracetamol in combination with opioids