As lawful euthanasia inches closer to reality, there's been uncertainty about exactly what lethal concoction could be used by terminally-ill patients.

That is because drugs used elsewhere in the world, including pentobarbital (better known as Nembutal) and another barbiturate sedative known as secobarbital, are banned for human use in Australia.

Fairfax Media can reveal that instead of requiring these drugs to be legalised, it is likely compounding pharmacists in Victoria will create euthanasia powders with a mixture of substances already approved by the Therapeutic Goods Administration.

The legal drugs involved in these concoctions could include the painkiller morphine, anxiety drug diazepam (valium) and prescription medications often used to treat heart conditions and epilepsy.

The mixture would usually be in the form of the powder rather than a pill, and those allowed access to it would be required to store the lethal dose in a locked box, probably at their home.

People might mix the lethal power with a liquid, such as orange juice, in order to consume it, and take a premedication to prevent them from vomiting.

Former Australian Medical Association president and neurosurgeon Brian Owler, who chaired the ministerial advisory panel on assisted dying, said some people might require an injection, if physically unable to self-administer or digest the medication.

"There is obviously provision for other types of medication to be used in medical practitioner administration, if a person is physically unable," Professor Owler said.

Professor Owler said there had already been preliminary discussions with a number of pharmacists.