barbiturate

Hypnosedative drug, commonly known as a ‘sleeping pill’, consisting of any salt or ester of barbituric acid C₄H₄O₃N₂. It works by depressing brain activity. Most barbiturates, being highly addictive, are no longer prescribed and are listed as controlled substances.

Tolerance develops quickly in the user so that increasingly large doses are required to induce sleep. A barbiturate's action persists for hours or days, and can cause confused, aggressive behaviour or disorientation. Overdosing causes death by inhibiting the breathing centre in the brain. Short-acting barbiturates are used as anaesthetics to induce general anaesthesia; slow-acting ones may be prescribed for epilepsy.