Vraxoin

Vraxoin (also known as XYP or "vrax") was a dangerous, addictive drug. It was a grey, ash-like powder that also appeared as a sparkly gold powder (possibly the refined form) which could be taken orally. It was discovered on the Cygnus Rim around 1999; it was consumed by snorting the substance. (PROSE: Christmas on a Rational Planet) The drug caused a slightly drunken effect and apathy, then extreme anger during withdrawal. (TV: Nightmare of Eden) Vrax-users (also known as Vrax-Heads) were also known to become shaky and to lose strength and concentration after taking the drug. (PROSE: Mean Streets) The Fourth Doctor mentioned it had caused chaos on several planets. (TV: Nightmare of Eden)

Vraxoin was originally made from a type of fungus, but in order to finally solve the vraxoin problem, officials incinerated the entire planet on which the only known source existed. This eliminated vraxoin trade for some time, until a second source — the Mandrels — was located by a zoologist named Tryst on the planet Eden. (TV: Nightmare of Eden)