Quaalude

[Sarah]

A pill/capsule that is a CNS Depressant (Central Nervous System) with similar properities to barbiturates, and similar addictive and withdrawal properities. It was quickly pulled from the markets in the USA as a result of wide-spread abuse, although it did enjoy a number of years as a near top-selling sedative/hypnotic before being made Schedule I and thus banned in the USA. Worldwide it is a Schedule II controlled substance under international law and thus available by prescription in most nations...
Quaalude is a brand-name for methaqualone (C16 H14 N2 O)... In other words, Methaqualone is a downer, a depressant, similar to barbiturates in most every way, although probably more addictive.

[Britney]

panty droppers

[Rihanna]

Slang for a type of methamphetamine called methaqualone. Functions as a sedative-hypnotic. Developed in the 60s by the same company that makes Maalox ( hence the double as ).
Word History: Maalox got its name for the ma in magnesium, the al in aluminum, and the ox from hydroxides. Quaalude borrowed the aa idea and the rest of the word perhaps derives from quiet interlude to describe the sedation effect.