Narcotics: Narcotics are compounds which possess general depressant action on the central nervous system. They can be classified into sedatives, hypnotics or tranquillizers and general anaesthetics:

(i) Sedatives: They cause a milder form of depression. The most widely used sedatives are the bromides and the bromo-compounds. KBr is the most commonly used bromide. Bromo valetone and velero bromine are used as sedatives.

(ii) Tranquilizers: These are the compounds that help in reducing anxiety by acting on nervous system. These induce sleep and can be habit forming. Examples are luminal, equanil, Seconal etc.

(iii) Anaesthetics: These are the compounds used to produce unconsciousness and muscular relaxation, sufficient to allow the performance of suigical operations. Examples are ethylene, Divinyl ether and cycloprone. Sometimes for small operations and tooth extracted the limited area is made senseless either by injecting or by local application of the drugs which are called local anaesthetics. Examples are cocaine, novocaine and xylocaine.