The classification of drugs and the reason for classification are as follows:
1. On the basis of pharmacological effect: This classification provides doctors the whole range of drugs available for the treatment of a particular type of problem Hence, such a classification is very useful to doctors.
2. On the basis of drug action: This classification is based on the action of a drug on a particular biochemical process Thus, this classification is important.
3. On the basis of chemical structure: This classification provides the range of drugs sharing common structural features and often having similar pharmacological activity.
4. On the basis of molecular targets: This classification provides medicinal chemists the drugs having the same mechanism of action on targets Hence, it is the most useful to medicinal chemists.