Methoxyflurane - Medical Use

Medical Use

Methoxyflurane has been extensively used since the 1970s in Australia as an emergency analgesic for short-term use, mostly by the Australian and New Zealand Defence Forces, and the Australian ambulance services. The drug is currently only available from one manufacturer (Medical Developments International, Melbourne, Victoria, Australia). It is self-administered to children and adults using the Penthrox inhaler, a hand-held inhaler device. A non-opioid alternative to morphine, it is also easier to use than nitrous oxide. As of 2010, methoxyflurane was listed under the Pharmaceutical Benefits Scheme for the initial management of pain due to acute trauma, as well as for brief painful procedures such as changing of wound dressings or for patient transport. A portable, disposable, single-use inhaler device (the Penthrox inhaler), along with a single 3 milliliter brown glass vial of methoxyflurane is provided in doctor's kits that allows conscious hemodynamically stable patients (including children over the age of 5 years) to self-administer the drug, under supervision. The device is often referred to as the "green whistle", due to its appearance.

Each 3 milliliter dose lasts approximately 30 minutes. Pain relief begins after 6–8 breaths and continues for several minutes after stopping inhalation. The maximum recommended dose is 6 milliliters per day or 15 milliliters per week because of the risk of cumulative dose-related nephrotoxicity, and it should not be used on consecutive days. Despite the potential for renal impairment when used at anesthetic doses, no significant adverse effects have been reported in the literature when it is used at the lower doses (up to 6 milliliters) used for producing analgesia and sedation. Due to the risk of organ (especially renal) toxicity, methoxyflurane is contraindicated in patients with pre-existing kidney disease or diabetes mellitus, and is not recommended to be administered in conjunction with tetracyclines or other potentially nephrotoxic or enzyme-inducing drugs.