If Don Flounders waits for the asbestos-related mesothelioma that is ravaging his lungs to kill him, it will be a slow, painful death.
But one day -- maybe just weeks away and at the moment of his choosing -- the 78-year-old plans to drink a bitter mixture of alcohol and pentobarbital, a barbiturate that is used to euthanize pets.
Flounders told ABCNews.com that he flew halfway around the world from his native Australia to obtain the illegal drug in Mexico, which, like Switzerland, is fast becoming one of the recommended destinations for so-called death tourists.
The lethal drug, once widely available in the U.S. as a sleep aid and now used primarily in veterinary medicine, was an ingredient in the fatal cocktails that killed Marilyn Monroe and Judy Garland in the 1960s.
Since 2001, the pro-euthanasia group Exit International has helped nearly 300 people -- mostly Australians, New Zealanders and a handful of Americans -- to find what is being called "death in a bottle" in pet pharmacies in Mexico.
Commonly known as Nembutal, this concentrated drug will put Flounders to sleep quickly and quietly, by taking his breath away.
"I had no trouble whatsoever purchasing the poison," said Flounders from his home near Melbourne. "It will be completely painless. Of the various means, this is the easiest and most reliable. It's a way of achieving a peaceful death."
He will take the Nembutal with a glassful of his "favorite tipple" -- gin. "You swig it down and I'll just close my eyes," he told ABCNews.com. "It's that rapid."
Exit International's Web site says the best places to obtain pentobarbital are "20-odd [United States-Mexico] border crossings, from Tijuana in California through to Matamoros on the Gulf of Mexico."
The group provides information packets for these death tourists, with colorful photos of the packaging to help identify the drug among all the animal products for sale in these over-the-counter veterinary stores.
"There aren't that many drugs that a doctor can give you for a reliable, peaceful death," said Exit's founder and director Philip Nitschke.
"It's always drunk quickly," he told ABCNews.com. "I've never seen anyone finish their whiskey or French champagne."
Nitschke co-authored "The Peaceful Pill Handbook," the Australian version of the 1991 American Hemlock Society guide, "Final Exit," which lays out precisely how to end your life. The book is banned in Australia, where assisted suicide is now illegal.
"People know we are sympathetic," Nitschke told ABCNews.com. "We are drowning in patients coming along who are in dreadful trouble and say, 'Help us die.'"
Flounders learned about Nembutal from Exit International. He and his wife, Iris, had become members a decade before he was diagnosed with terminal cancer.
For 16 years, Flounders worked as an executive for Shell Oil in Melbourne, but he has since learned he had been working in a building contaminated with blue asbestos -- "the worst kind," he said.
Since then, his condition has worsened. Just this week, the couple was waiting for an ambulance to take him to the hospital for new tests because of excruciating back pain. Iris, who is 85, bought her own supply of Nembutal in Mexico and says she, too, might take her life at the same time. Iris says she does not have a terminal illness.
The couple have been married for 57 years and have two grown children who have been supportive of their decision.