Mr McClay said that previously there had been an estimated 20-30 stores selling psychoactive substances in Rotorua with as many as 300 different products available.
Following legislation last year that was reduced to four Rotorua shops and 36 products.
Mr McClay said he expected their temporary retail licences to be cancelled.
He said an amendment to the act meant that any future product could not be tested upon animals to prove low risk of harm.
"This too is a good result for our community. As minister responsible I put in place a complete restriction on animal testing until an expert committee of scientists and representatives of the animal welfare community had fully considered the issue.
"Scientists have said that some level of animal testing would be required to prove these drugs are safe, however parliament decided that while this was acceptable for medicines that could save lives, to test recreational drugs on animals was a step too far. I happily cast my vote against animal testing.
"This is an issue that I have consulted widely on in my electorate over the last 12 months and I am grateful to all those who made their views known to me. The removal of these drugs and banning of animal testing is an excellent result."
"A month ago I joined with Rotorua people to committed to ridding our community of this poisonous muck. Last night Parliament made good on this promise."
The Government has warned of heavy penalties for selling, making or possessing synthetic drugs after the deadline of midnight tonight, when all remaining products will be stripped from shelves.
Parliament yesterday began debating an emergency law change under urgency, which will ban all remaining party pills and synthetic cannabis until a rigorous testing regime is in place.
It will come into effect tomorrow at 12.01am.
Health Minister Tony Ryall said that at this point, all interim approvals for psychoactive drugs would be revoked, remaining products would be recalled and retail licences would be cancelled.
"It will also become illegal to possess these products, so anyone thinking of stocking up ... should bear that in mind."
The penalty for possessing a small amount of a psychoactive substance is a $500 fine.
Possessing a large amount with intention to supply is punishable by up to two years' jail or a fine of $500,000.
Retailers and manufacturers will not be compensated for their losses.
Officials estimate that the industry was making about $140 million a year.
The Ministry of Health warned that between 150 and 200 people had developed dependence on legal highs and would require withdrawal management.
Mr Ryall clarified that the psychoactives testing regime would accept overseas animal drug trials which proved that a product was unsafe.
Mr Ryall said the 41 products which had temporary waivers were not linked to adverse reactions when they were approved last year.
But since the bill passed in August, health authorities had reported an increase in serious reactions including vomiting, seizures and psychotic episodes.
