Unscrupulous drug dealers are cutting heroin for sale on Kent's streets with an opiate 10,000 times more potent than morphine, an inquest heard.

Evidence of the use of the drug – a tranquilliser for large animals such as elephants – emerged at the hearing into the death of a 22-year-old man on a Canterbury housing estate.

Frank Brown was found collapsed at the foot of a block of flats off Sturry Road on April 30 and did not survive attempts to resuscitate him.

An inquest at Canterbury yesterday heard that toxicology tests detected the presence of the opiate carfentanil.

Coroner James Dillon said: “Drug dealers are beginning to cut this into their heroin. It’s more addictive than heroin and it’s cheaper.

“Carfentanil is an extremely potent chemical; it is 10,000 times more potent than morphine and is used on large animals like elephants. The dealers are creating a more dangerous product which people are going to come back for more often.

“Frank Brown may not have not known that Carfentanil was contained in the heroin he had bought.”

The inquest was told that on April 30 Mr Brown, who had worked as a landscape gardener before falling into a cycle of drug and alcohol abuse, had met up with fellow heroin user Carl Edwards.

They had gone together to buy drugs from a dealer who agreed to meet them close to the Canterbury City Council offices in Military Road.

Det Sgt Brian Doughty, who investigated Mr Brown’s death, told the hearing: “On the day in question, Carl Edwards had met Frank Brown in public toilets in Canterbury and both had decided that they needed to score. They bought five bags of dark heroin near the council offices and administered their own drugs."

"The dealers are creating a more dangerous product which people are going to come back for more often" - Coroner James Dillon

Both men fell asleep next to the block in Honeywood Close off Sturry Road. A couple coming out of the flats discovered the pair and, while Mr Edwards was alert and talking, Mr Brown remained on the ground.

The couple rang 999 and each performed CPR on Mr Brown.

Det Sgt Doughty added: “He was unresponsive. CPR was unsuccessful. There were no suspicious circumstances. Frank had died of a drugs overdose.”

Mr Brown was a father of two children by separate women but did not have contact with either child, the hearing was told. As a younger man he had become an apprentice landscape gardener but struggled with his mental health and drug and alcohol use.

He had been brought up by his grandmother, Dorothy, in Thanet. His mother died from a heroin overdose when he and his twin brother were just two.

The clinical cause of death for Mr Brown was given as cardiac respiratory failure following carfentanil overdose.

Mr Dillon said there was no evidence that Mr Brown had intended to end his own life. He recorded a conclusion that his death was drug-related.