New Zealand's drug-buying agency is hoping to save a few dollars with the introduction of a new antidepressant.

PHARMAC is now funding the drug mirtazpine.

Medical director Peter Moodie says it is less expensive than venlafaxine, which is currently the only antidepressant specifically funded for treatment-resistant depression. He says the new drug is likely to produce savings compared to current antidepressant spending over the next five years.

Dr Moodie says there are some people who do not respond to the existing anti-depressants and to have one more is very useful. He says New Zealand spends about 20 million dollars a year on antidepressants.