Australians battling breast cancer, Parkinson's disease and psoriasis will save hundreds of dollars a year on medicine as a wave of 1400 drugs become eligible for extra subsidies under the pharmaceutical benefits scheme from Sunday.

But the biggest benefits are set to go to up to 285,000 Australians with schizophrenia who will get access to a drug that costs $1700 for $38.

From October 1, REXULTI, an antipsychotic tablet, will become one of only a handful of mental illness medications to be added to the scheme. The structure of the program means that for concession card holders it will only cost $6.30.

The drug works by rebalancing dopamine and serotonin to help clearer thinking, mood and behaviour.

Up to 50 percent of people with schizophrenia attempt suicide, according to Neuroscience Research Australia, while average life expectancy is reduced by up to 18 years.

The research institute puts the total cost to the economy at $2.6 billion per year in direct health costs and productivity.

University of Melbourne Professor Pat McGorry, the president of the Schizophrenia International Research Society, said schizophrenia typically appeared in early adulthood at a time when a person's whole life is before them.

"New, more effective, and safer treatments are a welcome addition to this challenging illness," he said.

Federal Health Minister Greg Hunt said four million Australians will have a mental health episode each year, affecting almost every family.

"This is the 12th new or amended listing on the scheme for patients with mental illness since the Coalition came into government," he said.

On Sunday, Mr Hunt will announce patients with high blood pressure and stomach acid will also see discounts, as will women on birth control and those getting treatment for endometriosis as part of $75 million in out-of-pocket savings for patients over the next four years.

Medicine to treat heart disease such as Statins have been discounted by 700 per cent since their patent expired four years ago and generics were shifted on to the scheme.

Consumers using Artovastatin, which used to cost up to $70, will now cost $10.30 for a packet of 30 tablets after the $7.15 pharmacy dispensing fee is added to the over-the counter cost as is the case with most medicines.

The Pharmacy Guild's Greg Turnbull said consumers may see some cheaper prices for their medication.

"Pensioners and concession cardholders who fill about 70 per cent of pharmaceutical benefits scripts, will not see a change because they pay no more than the $6.30 patient co-payment," he said.

Some general patient medications like antiviral treatment Zovirax, used to treat herpes and chickenpox, will have their retail price fall by a dollar, as will stomach acid tablets.

???But the biggest savings for taxpayers are set to be made on highly specialised and expensive drugs such as Imatnib, used in chemotherapy and worth almost $3000 for a packet of 30.

The government will pay multinational drug companies $562 less per packet for the 400 mg tablet from Sunday, while also saving $294 a packet on medication for patients battling leukemia and AIDS.

Mr Hunt said the reductions will deliver an estimated savings to taxpayers of $430 million over the next four years.

Those savings estimates have proved flexible in the past. The final budget outcome released on Tuesday showed the government spent $700 million more on the scheme than was budgeted in the past year alone.

Labor's health spokeswoman Catherine King said more affordable medicine for Australians was always welcome news but said the government had still only listed a fraction of the medicines that could be on the scheme.

With Adam Gartrell

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