Criminals are being hit in the pocket by investigators targeting cutting agents used to reap vast profits from small amounts of class A drugs.
Huge quantities of pharmaceutical drugs benzocaine and lidocaine are being used to bulk up cocaine.
Officers seized two tonnes of benzocaine in just one week after monitoring the underground trade for six months.
The drugs cost around £10 a kilo to buy but can be sold for up to £50,000 a kilo once mixed with often tiny amounts of cocaine.
Investigators swooped on 83 barrels of benzocaine after it was delivered to four customers at Felixstowe sea port and Stansted Airport.
The seizure was the equivalent of one fifth of Britain's annual legitimate use of the drug as a dental anaesthetic and ingredient in medical creams and sprays.
It is the cutting agent of choice for drug dealers because it has a numbing sensation when placed on the skin, like cocaine.
One Serious Organised Crime Agency (Soca) officer said: "These are targeted preventative measures to stop the criminal market.
"We expect this to seriously damage the criminal base and impact heavily on the market.
"It is keeping money out of the trade because they cannot maximise their profits, money that is often reinvested in criminal activity.
"Drug dealers are greedy people who want to make as much profit as possible, but people will be less inclined to buy drugs as the quality gets poorer and poorer."
The importation of benzocaine and lidocaine is not regulated, but supplying them to the underground drug trade is an offence.
The drugs are used in first aid ointments, throat sprays and sunburn remedies but there is no legitimate use of them in a white powder form.
One 25 kilo barrel of benzocaine costs about £300 from suppliers in China and India and can be sold on the black market for up to £1,800.
But the big profits are made by dealers who then use it to bulk up class A drugs, sometimes selling cocaine as little as 2% pure.
The chemicals have also been used to cut recently banned drugs such as Naphyrone and Mephedrone.
Officials at Soca began targeting cutting agents in a bid to disrupt the lucrative cocaine trade.
They spent months analysing the supply of cutting chemicals before swooping on the most prolific suspicious importers.
Businessmen behind the 83 barrels delivered to Felixstowe and Stansted could not explain their use and the drugs were incinerated.
Investigations continue into the networks behind the cutting agents and some individuals could face charges of conspiracy to supply class A drugs.
Soca has also taken down a series of websites used to sell the drugs on, redirecting users to another page warning they may be committing a crime.
Officers said no more benzocaine was imported in the five weeks after the seizures, forcing up prices and denting the profits of dealers.
The Soca officer said drug dealers use the cutting agents despite evidence they may be dangerous to users and in some cases "cocaine" is being sold that is 100% benzocaine.
He said: "It makes it easier to conceal the fact that drugs have been cut and so maximises the profit at all levels without losing customers. It is one of the reasons we routinely see drug seizures of only 5-10% purity.
"The chemical properties of these cutting agents have enabled traffickers to target younger people in the UK, from mid-teens to early twenties, with more 'affordable' cocaine that masks its lower purity."
The officer added drug dealers may be forced to smuggle the cutting agents into the country and poorer substitute chemicals, making them more vulnerable to detection and upsetting users.