Outrozone (also referred to as Otrozone and Otrazone) was a chemical which could be used by Mechanoids as a narcotic. It came in the form of a pink liquid in plastic tube containers, that could be applied directly to the Mechanoid's stomach behind the chest monitor.
Usage and "zoneys"
Outrozone could instill feelings of relaxation, forgetfulness and temporary euphoria in a Mechanoid, which was very useful for a droid that had experienced trauma but was otherwise unable to delete such bad memories. Outrozone was highly addictive and habit forming, and Mechs hooked on it were derogatorily called "Zoneys".
One such "Zoney" was Able, the brother of Kryten, who was servant to a Simulant Trader aboard the SS Centauri. The Simulant Trader used the drug as a means to control Able. The drug had degraded Able's motherboard to the point where it would take him hours to pull up a piece of memory from his archives, and having a normal conversation was impossible with him.
When rescued, Able's drug-induced clumsiness nearly got the Boys from the Dwarf killed. However, Able achieved some redemption when he sacrificed his life to kill the Simulant and save the Dwarfers aboard Starbug. (RD: Beyond a Joke, Series VII)