Ann: Penthrox replaces Nitrous Oxide in New Zealand Ambulance, page-9

Yes in the prehospital environment.

Penthrox aka methoxyfluorane is an effective pain reliever however it is very toxic to the kidneys and scarce literature supporting its safety with repeated doses. The off gases produced can adversely effect the clinician administering it and hence due to the concerns most Unions are against it and there is a limit to the amount you can be exposed to in a day or week. The optional charcoal filter makes it a lot safer for bystanders at more cost obviously.

Definitely been around along time in Australia and just hasn't seemed to catch on to the rest of the world....yet.