Methaqualone is a member of the class of quinazolines that is quinazolin-4-one substituted at positions 2 and 3 by methyl and o-tolyl groups respectively. A depressant that increases the activity of the GABA receptors in the brain and nervous system, it is used as a sedative and hypnotic medication. It became popular as a recreational drug and club drug in the late 1960s and 1970s. It has a role as a GABA agonist and a sedative.

Methaqualone is a DEA Schedule I controlled substance. Substances in the DEA Schedule I have no currently accepted medical use in the United States, a lack of accepted safety for use under medical supervision, and a high potential for abuse. It is a Depressants substance.

Methaqualone is a sedative-hypnotic drug that is similar in effect to barbiturates, a general central nervous system depressant. The sedative-hypnotic activity was first noted by Indian researchers in the 1950s and in 1962 methaqualone itself was patented in the US by Wallace and Tiernan. Its use peaked in the early 1970s as a hypnotic, sedative, and muscle relaxant commonly used for insomnia. It has also been used illegally as a recreational drug, commonly known as Quaaludes, Sopors, Ludes or Mandrax (particularly in the 1970s in North America) depending on the manufacturer. Since at least 2001, it has been widely used in South Africa, where it is commonly referred to as "smarties" or "geluk-tablette" (meaning happy tablets). Clandestinely produced methaqualone is still seized by government agencies and police forces around the world.