Patients are being put at an increased risk of self-harm because of severe supply issues affecting two drugs used by thousands to treat depression, a psychiatrist has warned.

The anti-depressant Parnate, also known by its generic name tranylcypromine, has been listed as unavailable by the Therapeutic Goods Administration (TGA) since July, with the potential impact on patients noted as "critical".

The drug Nardil, which has the generic name phenelzine, is also unavailable and not expected to be back in supply until the end of March next year.

Queensland psychiatrist Howard Granger said Parnate and Nardil were two unique older-style medications that were often used when a patient had failed to respond to other anti-depressants.

"They are both quite powerful antidepressants which work by boosting the chemical dopamine in the body. They have been around a long time and they work quite uniquely, there is nothing really like them," Dr Granger said.

Dr Granger said the supply issues had been affecting a number of his patients.

"Just this morning, a lady came in who has been on (Parnate) and she was really anxious and bothered by the fact that it's been hard to get hold of.

"She is just about to run about and so that was obviously upsetting her a lot.

"It's an increasing problem that is hard to manage. You are put in a position of trying to find an alternative when most of the alternatives have been tried anyway and this is why they are on these medications in the first place."

Dr Granger said patients who had been taking the medication for depression were at risk of symptoms such as suicidal thoughts returning or being exacerbated if they were unable to take their usual medication.

"All of the usual bad stuff that can happen with depression, they are put at risk of that happening if you can't find something else that does a decent job," Dr Granger said.

According to figures supplied to nine.com.au by the Department of Health, more than 17,600 prescriptions were filled for Parnate in 2018-2019. During the same time frame 6500 scripts were filled for Nardil.

'I AM HAVING FULL-ON PANIC ATTACKS'

Janelle Macpherson, from Caboolture in south east Queensland, has been taking Parnate to treat her anxiety and depression, which came to a head after a bus accident left her with post traumatic stress disorder (PTSD).

Ms Macpherson said she first had trouble getting hold of her medication in September.

"I went down to my local chemist to put my prescription in and he said, 'we don't have any'," she said.

"I thought holy crap because you can't come off this medication abruptly. So my husband and I rang every chemist from Nambour to the Gold Coast.

"We finally found a chemist in Brisbane that had some and we drove the 100kms from Caboolture."

But the pharmacist could only give Ms Macpherson one packet, and by mid-October she was down to just three days' worth of medication, having been unable to find any other chemists with the drug in stock.

Ms Macpherson said she was forced to reduce her dose from two tablets to one a day in a bid to wean herself off the medication.

Parnate has been listed as unavailable from the TGA since July. (Supplied)

"I rang my psychiatrist and he said, 'all we can do for you, is you are going to have to go down to one dose a day, but I warn you you're going to have side effects'.

"I was thinking the side effects would be mild. Day two onto the one tablet I was having shakes, I couldn't stop crying. I stopped sleeping, I just couldn't sleep, then that was affecting the depression. It's been a rollercoaster," she said.

By the end of October, Ms Macpherson had run out of the drug completely, and said she began to have suicidal thoughts

"My life hasn't been the same since, I am having full on panic attacks at least three times per day and I am having suicidal thoughts as I don't know how much longer I can go on like this."

Ms Macpherson said she was frustrated because the advice given by the TGA on when Parnate would be back in supply kept on changing.

"At first it was September, and then the chemist told me it was mid-October and then finally November 27," she said.

Drug supplier Advanz Pharma, which is responsible for distributing the only version of the drug tranylcypromine currently listed on the pharmaceutical benefits scheme (PBS), said the medication was now expected to be back in supply by next week.

"There has been a manufacturing delay beyond our control. We can confirm that Parnate has been manufactured and we believe the medicine will be back in supply at pharmacies by next week," Advanz Pharma managing director David Frish said.

A TGA spokesperson said the department had approved the importation of other versions of tranylcypromine to help boost supply to patients dependent on the drug.

"Parnate is the only brand of tranylcypromine supplied in Australia. Given its use by people whose depression has not responded to other antidepressants and the potential impact of a change in treatment for people stabilised on Parnate, the TGA authorised the supply of overseas registered products under Section 19A of the Therapeutic Goods Act 1989 ," the spokesperson said.

However, the imported versions of the drug are not listed on the PBS.

Mr Frish said Advanz Pharma was one of the companies who had been authorised to supply an imported version of the medication.

Over the past few months, the company had been able to bring in limited amounts of tranylcypromine sourced from USA, Ireland and UK, he said.

"We have tried to provide access to as many patients as possible as the supply has been limited," Mr Frish said.

The company was voluntarily charging only the same price as the medication was listed for on the PBS, he said.

However, Ms Macpherson said she had been unable to find any imported versions of her medication at the PBS price.

Ms Macpherson said her local chemist eventually managed to find an imported version from another company which he ordered in – but she ended up paying $360 for 100 tablets.

Under the PBS, the same number of tablets normally cost $40, however Ms Macpherson is on a partial disability pension and said she usually paid just $5.

Ms Macpherson said she was only taking one tablet a day instead of two in a bid to make the medicine last longer.

"There is no way I can afford another $360 and there is no way I can trust that Parnate will be back on the shelves next week, because from my experience, (the dates) are like a dangling carrot, they keep getting pushed out all the time."

Ms Macpherson said the government needed to do more to ensure the drug was available at an affordable price for people like herself who desperately needed it.

"The government is playing with people's mental health and their lives - it's wrong," she said.

"I know how this is affecting me and I would hate anyone else to be going through what I'm going through."

However, the TGA said its hands were tied because it was up to the drug companies to apply to have their imported medications listed on the PBS.

"Where the TGA has authorised supply of an alternative product under Section 19A, the Government works with the sponsor of that product to expedite subsidisation of that brand through the PBS," a spokesperson said.

"Pharmaceutical companies, however, are private entities that make their own decisions regarding their products, and cannot be compelled by the Government to list a product on the PBS."

* Readers seeking support and information about suicide prevention can contact Lifeline on 13 11 14 or Beyond Blue on 1300 224 636.