The drug which increase the activity of various subunit or parts of CNS (brain and spinal cord) are called CNS stimulant.

in CNS there are collection of cell which perform certain definite function are called as an center .e.g. respiratory center, vomiting center, heat regulating center, appetite controlling center.

Some type of drugs show mild CNS stimulant effect and produce toxic side effect in slight higher dose e.g. strychnine.

Other type of drug show mild CNS. stimulant effect as a side effect. e.g. Local Anesthetics (cocaine)

Sympathomimetics (dexamphetamine), Parasympatholytic (atropine)

CNS stimulant mainly used as an 1) Analeptics 2) Respiratory stimulant

They are also useful to increase mental alertness and produce wakefulness conditions.

To control appetite through CNS stimulant effect.

CNS stimulants Classification

CNS stimulants can be classified as

1)   Naturally occurring drugs

a)   Alkaloids :

i) Xanthine derivatives – Caffeine, Theophylline, Theobromin

ii) Other alkaloids –Strychnine, Lobeline

2) Synthetic drugs –Nikethamide, Picrotoxin

3) Miscellaneous drugs – Cocaine (local Anesthetics), Dexamphetamine (Sympathomimetics), Atropine (Anticholinergics)  

Analeptics are CNS stimulants which are used to reduce narcosis produced by CNS depression.

These drugs also act as respiratory stimulants and thus are used to counteract drugs –induced Respiratory Depression.


Structure of Caffeine:

Chemical name of Caffeine: 1, 3, 7 trimethyl Xanthine.

Physical properties of Caffeine:

It occurs as white crystalline powder or silky white crystals.

It is odorless.

It is bitter in taste.

When caffeine is recrystallised from water it contains one molecule of water of crystallization.

It is sparingly soluble in alcohol

Chemical properties of Caffeine:

When its solutions are treated with few drops of saturated tannic acid, solution a precipitate is produced which dissolves in excess of the reagent.

When few drops of iodine solution is added to its solution, a clear solution is obtained which on acidifying with dil.HCL give brown ppt.

Stability and storage of Caffeine:

It is decomposed by strong solution of caustic alkalies.

Its salts are decomposed by water. Hence it is stored in tightly closed containers.

Uses of Caffeine:

1. It is CNS stimulant and hence it is used

To produce state of wakefulness.

To enhance mental activity

To get relief from fatigue and mild depression.

To cause insomnia in moderate dose.

2. It has weak diuretic activity.

3. In combination with ergotamine, it is used to get relief from migraine.

4. It stimulate respiratory center.

Pharmaceutical formulation of Caffeine:

Aspirin and caffeine tablets.

Caffeine and sodium benzoate injection

Caffeine iodide elixir

Caffeine citrate tablets

Brand name of Caffeine:





Structure of Theophylline:

Chemical Name of Theophylline1,3-dimethylxanthine or 1,3-dimethyl-7H-purine-2,6-dione

Properties of Theophylline:

It is white crystalline powder.

It is odorless

It has bitter taste

It is slightly soluble in water but soluble in solution of alkali hydroxide

Chemical properties of Theophylline:

When Theophylline is treated with silver nitrate, it converted to silver Theophylline with the liberation of nitric acid.

Stability band storage of Theophylline:

Theophylline is stored in well closed containers.

Aminophylline absorb carbon dioxide with the liberation of Theophylline and affected by light.

Hence it is stored in well closed light resistant containers.

Uses of Theophylline:

1.       It is potent bronchodilator hence it is used

To control acute and chronic asthma

To treat chronic obstructive lung disease

To control acute Bronchospasm

2.       It has also diuretic action

3.       It has also stimulant action by cerebrum

4.       It is cued as respiratory stimulant in neonatal apnoea.

Pharmaceutical formulation of Theophylline:

Aminophylline injection

Aminophylline suppositories

Aminophylline tablets

Brand names of Theophylline:





Structure of Coramine:

Chemical names of Coramine: N, N diethyl, pyridine -3-carboxamide

Properties of Coramine:

It occurs as a colourless or slightly yellow oily liquid or crystalline mass.

It has faint aromatic odour

It has slightly bitter taste.

It cause burning sensation and leaves faint warm sensation on tongue

It is miscible in water, alcohol, and ether.

Chemical properties of Coramine:

When it is heated with sodium hydroxide solution, it decomposed to give diethyl amine

When it is heated strongly with sodium carbonate, it gives an odour of pyridine.

Stability and storage of Coramine:

It is affected by light and hence it is stored in tightly closed, light resistant containers.

Uses of Coramine:

It is used as an respiratory stimulant

It is weak analeptics and hence is used to overcome CNS depression, respiratory depression, and circulatory failure

Pharmaceutical formulation of Coramine:

Nikethamide injection

Brand name of Coramine:




Structure of Dexamphetamine:

Chemical names of Dexamphetamine: (2S)-1-Phenylpropan-2-amine

Properties of Dexamphetamine:

It is official as sulphate salt, which is white crystalline powder.

It is odourless and has saline and slightly bitter taste.

It is soluble in water.

It is dextrorotatory and is 3 to 4 times more potent than levo isomers.

Stability and Storage of Dexamphetamine:

It is affected by light and hence stored in well closed, light resistant containers

Uses of Dexamphetamine:

It is indirectly acting sympathomimetics with strong CNS stimulant action. it is used to treat


Attention deficit disorder in children

Exogenous obesity as it has anorexiant effect.

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