A heartbroken teenager has cried in court as she relived the moment she performed CPR on her friend who lay dying from a drug overdose following a marathon party.

Health care assistant Lauren Young sobbed as she told a court she tried to revive Helen Henderson.

Ms Henderson, 19, passed away after taking what’s believed to be a cocktail of mephedrone and ketamine during a party at her flat in Renfrew, near Glasgow.

Ms Young, also 19, said they had gone to watch Rangers Scottish Cup semi-final against Dundee United at Ibrox on April 12 2014.

Following the match, they went to a local pub and spent the rest of the day drinking and taking drugs.

Ms Henderson's fiance, Callum Smith, is on trial at Paisley Sheriff Court accused of supplying

Mr Smith, 25, denies supplying Helen and others with mephedrone, which is more commonly known as M-CAT or "meow meow."

Young said she had been drinking an orange flavour drink Mad Dog and had taken some M-CAT at the match.

Afterwards they and some friends had gone to the nearby The Angel Bar whee they took M-CATs.

Later in the evening the group headed back to the flat Ms Henderson shared with Mr Smith in Renfrew to continue their festivities.

The party continued into Sunday. An ambulance was called at around 10pm on Sunday night after Ms Henderson collapsed.

Ms Young told fiscal depute John Penman how she felt in the aftermath of her attempts to Ms Henderson.

She said: “I felt horrible, I was shaken.

“I’d just witnessed one of my best friends dying and I had to perform CPR on one of my best friends as well while she was dying. It was horrible."

When asked by Mr Penman if Mr Smith had sold her friend the drug, Ms Young replied: “That’s what she told me.”

Martin Shannon told the court he was left vomiting violently and his brother was left in a coma for eight weeks, after taking white powder they got from Mr Smith.

The trial before Sheriff James Spy continues.