Helen Henderson, 19, died after being taken to hospital from a party in Renfrew on Sunday night.
Police believe she may have taken the drug, which has the street name MCAT, along with the powerful painkiller ketamine.
As friends of the teenager paid tribute to her on social media yesterday, the two other party-goers, aged 24 and 31, remained in hospital. Two women, aged 18 and 19, have been released, police said. Officers are currently treating the 19-year-old’s death as “unexplained”, while a post-mortem examination is carried out.
However, the exact cause of death is unlikely to be established until the results of toxicology tests are known.
The victim, who was a keen Rangers fan, had been engaged to fiancé Cal Smith since 2011.
Her cousin Michelle, from Drumchapel, tweeted: “RIP to my cousin Helen. 19 years old is far to young to die #foreverinourhearts xx.”
Jade Rosie tweeted: “Not only my cousin – I’ve lost one of my best friends. I love you princess, always.”
Mephedrone, known variously as Meow Meow, Bubbles and MCAT, is derived from cathinone, a compound found in a plant called khat.
Previously one of a growing number of “legal highs”, it was made a class-B drug in 2010 after being linked to a number of deaths. The drug, which comes in capsules or as a white powder, can cause feelings of euphoria and increase alertness and talkativeness.
Police issued a warning over the drug earlier this week after the teenager’s death.
Detective Chief Inspector Arlene Smith said: “Given that other people have also fallen ill and are currently in hospital, Police Scotland has taken the decision to issue a warning.
“At this time, it may be that the drug involved is MCAT. However, witnesses believe that the woman may have also taken ketamine.”
Anyone who has taken the stimulant and is experiencing side-effects such as agitation, fever, tremors or confusion should visit their nearest accident and emergency.
Mephedrone was blamed for the death of 19-year-old Jordan Kiltie, from Ayr, who died in March 2010 after a night out.
And Greg Alexander, a 23-year-old from Selkirk, died a few hours after taking mephedrone in 2011.
However, a post-mortem examination failed to establish the cause of death, as the former soldier had various substances in his system as well as pre-existing health problems.
Earlier this year, police issued a warning over Ecstasy-like “Mortal Kombat” pills, after the death of a teenage girl.
Regane MacColl, 17, of Duntocher, near Clydebank, died on 1 February after falling ill at the Arches nightclub in Glasgow.