A coroner has found a man died after being prescribed five times the recommended maximum amount of a drug by a West Australian doctor.
Coroner Barry King investigated the death of 65-year-old Daniel Lahengking who died in 2009.
His findings were released on Friday.
Mr Lahengking and his wife, both from Indonesia, were visiting their daughter's family in WA in April 2009.
He visited Dr Dian Harun on April 17 because of pain in his joints.
He had run out of his arthritis medication that he usually bought from a local market in Indonesia and the joints in his hands and feet had became stiff and sore.
The doctor diagnosed him as suffering from rheumatoid arthritis and then prescribed the medication methotrexate at what Coroner King described as "an incorrectly high dosage".
She prescribed him methotrexate at 5mg a day for five days to be followed by 10mg daily for seven days.
According to information submitted at the inquest, for the treatment of rheumatoid arthritis, methotrexate is usually prescribed initially at a dosage of about 7.5mg per week with increases to a maximum of 20mg per week.
During the inquest it was found that the pharmacist who was asked to fill the prescription, Alison McPherson, "noted that the dosage was incorrect but dispensed the methotrexate after informing Mr Graham about the usual dosage".
Mr Lahengking took the methotrexate at the prescribed high dosage and suffered stomach pain, vomiting and excessive urination.
He returned to Dr Harun who diagnosed him with a urinary tract infection and over the next four days his symptoms persisted and he began to experience diarrhoea and mouth ulcers.
Mr Lahengking was admitted into Esperance Hospital on April 26 where he was treated by Dr Donald Howarth for methotrexate poisoning and septicaemia and then transferred to Royal Perth Hospital.
Following his initial admission into RPH, Mr Lahengking appeared to overcome the symptoms caused directly by the methotrexate overdose, but he developed other on-going conditions including tuberculosis, gastrointestinal bleeding and sepsis, which the Coroner found in the context of other medical conditions led to his death on August 15 2009.
According to Coroner King's findings, "the quality of medical care provided initially to the deceased was well below the standard reasonably expected in Australia".
"The cause of the failure was an inexplicably incompetent error by a suitably qualified general practitioner, which error had been identified but not effectively corrected by an apparently competent pharmacist for reasons that cannot now be ascertained.
"There is no doubt that the deceased was let down by the health care he received in Western Australia.
"It is a terrible irony that the deceased had come to Australia from a much less affluent society where he received apparently informal but effective treatment for a painful, but not life-threatening, condition.
"He was convinced to place his trust in modern western medical treatment, and the provision of that treatment not only failed him, it probably precipitated his death."
The cause of death was found to be organ failure.
Coroner King returned an open finding and has referred the matter to the Australian Health Practitioner Regulatory Agency.
