Buy Methoxyflurane (Penthrox) Cas 76-38-0

Methoxyflurane, sold under the brand name Penthrox (the “green whistle”) among others, is an inhaled medication primarily used to reduce pain following an injury.^[9][10] It may also be used to reduce pain associated with minor medical procedures.^[11] Onset of pain relief is rapid and a standard dose typically lasts for up to 30 minutes.^[11] Use is only recommended with direct medical supervision.^[9]

Common side effects include anxiety, headache, sleepiness, cough, and nausea.^[9] Serious side effects may include kidney problems, liver problems, low blood pressure, and severe anaesthetic reactions such as malignant hyperthermia.^[9][11] It may be used during pregnancy or breastfeeding, however there may be additional harmful side effects.^[8][12] It is only recommended in those who have a normal level of consciousness and stable blood pressure and heart rate.^[11] It is classified as a volatile anaesthetic.^[11]

It was first made in 1948 by William T. Miller and came into medical use in the 1960s.^[13] It was used as a general anesthetic from its introduction in 1960 until the late 1970s.^[14] In 1999, the manufacturer discontinued methoxyflurane in the United States, and in 2005 the Food and Drug Administration withdrew it from the market, due to reports of nephrotoxicity and hepatotoxicity.^[14][15] As of April 2025, it is used in New Zealand, Australia, Ireland, and the United Kingdom for acute pain.^[9][16][17]

Methoxyflurane is used for relief of moderate or severe pain as a result of trauma.^[10][9] It may also be used for short episodes of pain as a result of procedures.^[11]

Each dose lasts approximately 30 minutes.^[18] Pain relief begins after 6–8 breaths and continues for several minutes after stopping inhalation.^[19] The maximum recommended dose is 6 milliliters per day or 15 milliliters per week because of the risk of kidney problems, and it is not recommended to be used on consecutive days.^[11] Despite the potential for kidney problems when used at anesthetic doses, no significant adverse effects have been reported when it is used at the lower doses (up to 6 milliliters) used for pain relief.^[20][21][22] Due to the risk of kidney toxicity, methoxyflurane is contraindicated in people 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.^[21]

It is self-administered to children and adults using a hand-held inhaler device.^{[23][20][24][21]} A non-opioid alternative to morphine, it is also easier to use than nitrous oxide.^[11] A portable, disposable, single-use inhaler device, along with a single 3 milliliter brown glass vial of methoxyflurane allows people who are conscious and hemodynamically stable (including children over the age of 5 years) to self-administer the medication, under supervision.^[11]

In prehospital care Penthrox offers an alternative to Entonox, it being smaller, lighter and not contraindicated with chest injuries.^[25]