"At the moment we've got a lot of very general talk, we talk about medical cannabis - actually there's no such thing. There's medical cannabis products.
"I think it would be very, very good to get some much more specific, scientific and clinical evidence about their efficacy before we can make decisions."
Pharmaceutical companies did not see New Zealand as a large enough market to conduct trials, Mr Dunne said.
The Government was looking at other possibilities but there was no "regulatory impediment".
Results from trials in Australia were at least two years away from being released - but New Zealand was "highly likely" to follow suit if medical marijuana products were approved, he said.
"We're looking quite closely at the prospect of trials in Australia, the United States...but the evidence at the moment from right around the world is that this process is occurring very, very slowly.
"That's the difficulty, we need people to come forward with products and there aren't actually that many products that have been proposed."
Medical cannabis lobby group United in Compassion chief executive Toni-Marie Matich told Q+A there was still stigma attached to medical cannabis products.
Her eldest daughter suffers from a progressive form of epilepsy and Ms Matich decided to use cannabis oil as a form of medication, resulting in a 50 per cent reduction in her seizures for almost two years.
But it was important to do research and get the products right, she said.
"What they're seeing is this global epidemic of medical cannabis...[but] it's not as broad as everyone thinks it is, therapeutically.
"We're in a unique position to take all of those negatives and positives and set our own platform and tone in New Zealand and have a global standard. And that's going to take time, it's not something we want to rush."
United in Compassion NZ will host a national symposium of international experts next year in Wellington.
