What are Quaaludes, what are the side effects of the drugs and was Richard Carpenter addicted to them?
Quaaludes, or Mandrax as the drug was called in the UK, was a powerful sedative and popular in the 1970s
QUAALUDE is the brand name for the sedative and hypnotic drug methaqualone and known as Mandrax in the UK.
The drug was first synthesised in India in 1951 by Indra Kishore Kacker and Syed Hussain Zaheer.
What are Quaaludes?
The drug was popular in the 1970s, especially in the US, and taken as a recreational drug.
It has been banned in the US for more than 30 years.
In Martin Scorsese's The Wolf of Wall Street film, Leonardo DiCaprio's character goes on a Quaalude binge, where he can barely speak and can't even walk.
The drug was called Mandrax (or known as "Mandies") in the UK and both here and the US it was used in the 1960s to treat insomnia and anxiety.
But the drug quickly became misused and was easily available in the US where it earned the nickname "Disco biscuits".
What are the side effects of the drugs?
David Herzberg, professor of history at the University at Buffalo, told the BBC: "It got the reputation of relaxing people so that they can have freer sex."
Justin Gass, author of the book Quaaludes (Drugs: The Straight Facts) now a professor of neurosciences at the Medical University of South Carolina, said the drug gave a "really powerful high" with the effects lasting up to six hours.
The drug was particularly dangerous when mixed with alcohol, leading users to fall asleep but never to wake up again.
According to Gass, Quaaludes have similar effects to the modern day Rohypnol, acting to erase memory and is a muscle relaxant.
Was Richard Carpenter addicted to them?
The drug was popular with musicians at the time.
David Bowie's song Time references "Quaaludes and red wine" while Frank Zappa speaks of "Quaalude moonlight".
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In the late 1970s Richard Carpenter, who had found fame singing with his sister Karen in The Carpenters, suffered from insomnia, panic attacks and depression and became addicted to Quaaludes.
In January 1979 semicomatose on Quaaludes, Richard fell down a flight of stairs backstage and finally confronted his addiction and booked into a six-week treatment programme in Kansas.
He described the first three weeks of the course as "hell on earth" but things started to get better after that and he took the rest of the year off to recover.