Quaalude was the strange trade name for a strangely named synthetic drug, methaqualone. It was first developed in India in 1951 first used in Germany and Japan, and called Mandrax in Britain. It was just one of many strange drugs with strange names developed by the pharmaceutical industry for strange reasons that ultimately proved to be too dangerous - even for conventional medicine.
Yet this never dissuades the drug industry from selling dangerous drugs to treat some illness or disease, for as long as possible, before it is eventually banned. They are quite willing to flirt with dangerous drugs for the sake of profit. And this drug became very popular - which means, for the pharmaceutical industry, it was very profitable.
It was prescribed by doctors in vast amounts to treat insomnia and anxiety during the 1960's, 1970's and 1980's, and it soon became very popular, and very easy to obtain. In the USA the drug became 'affectionately' known as "disco biscuits". They were one of the most frequently prescribed sedative in the USA, and elsewhere in the world - part of the sedative boom. It was the time that Librium and Valium were considered to be "wonder drugs".
However, the popularity of Quaaludes was not due to the drugs ability to treat insomnia and anxiety. It became a much sought-after recreational drug, providing users with a quickly obtained, long lasting, and powerful "high".
So like so many other pharmaceutical inventions it proved to be highly dangerous, killing many people, in overdose, and especially when mixed with alcohol, as it frequently was.
Even when not mixed with alcohol, or taken in overdose, the drug caused serious side effects/adverse reactions, including dizziness, nausea, vomiting, diarrhoea, abdominal cramps, fatigue, itching, rashes, sweating, dry mouth, tingling sensation in arms and legs, seizures, reduced heart rate, reduced breathing, erectile dysfunction, mental confusion, loss of muscle control, restlessness, irritability, nausea, vomiting, weakness, headache, insomnia, tremors, and more.
The pharmaceutical industry can cope with this kind of harm. They are well practised in the art of denial. But eventually, by the mid-1980's, the drug was prohibited because it was causing harm outside the conventional medical sphere, so its manufacture and distribution were made illegal.