Important classes of drugs

The chemical substances that change physical and physiological functions of the body are called drugs. For interconnection with such targets (macromolecules), drugs are made with low molecular mass i.e 150 micron to 500 micron. People take medicines to cure their disease by their doctor’s advice. 

When medicines are taken as per the doctor’s advice and in the prescribed quantity, they help cure diseases. But if they are taken beyond a limit, they can cause addiction, aggravate the condition or cause other complications, which might even prove to be fatal. Generally, “all medicines are drugs, but all drugs are not medicines”. By depending on actions, biological response, and their structure, drugs are divided into many classes. 

What are drugs? 

The chemical substances that can change physical and psychological function of the body are called drugs. When taken in prescribed quantities it can treat diseases and is called medicine, but when taken without prescription or in excess, it can be called drugs. Drugs can be classified into four classes depending on drug action, chemical structure, pharmacological effect and molecular targets. 

Classification of drugs 

The main four classes of drugs are: 

1. Pharmacological effect
2. Chemical structure
3. Drug action
4. Molecular target

Based on pharmacological effect

In this class action drugs are identified. For example: antacid used for bringing down stomach acidity, analgesic as pain killer, and to kill microorganisms antiseptic are used. This class is further classified into different types. 

Antacid: Antacid is used for relief in acidity. Generally, HCl is present in our stomach, which provides protection from antigen but sometimes, these acid levels are increased which results in health issues. Antacids are composed of aluminium and magnesium salt. Cimetidine and Ranitidine are examples of antacids.

Tranquilliser: Tranquilisers are mainly used for anxiety and stress. They are taken for a short duration because they are habit forming. Some common examples of tranquillisers are chlordiazepoxide, etizolam and equanil. 

Analgesics: Analgesics are commonly called painkillers. They provide relief in different kinds of pain. There are two kinds of analgesics used, one is non-narcotic analgesics and narcotics analgesics. Non-narcotic analgesics, like aspirin and paracetamol are non-addictive. Narcotic analgesics, such as Morphine ,Heroin and Codeine are addictive. 

Antihistamines: This class of drugs are used to treat allergic reactions. Brompheniramine and terfenadine are examples of antihistamines. 

Antimicrobials: As the name suggests, these are used to stop the growth of microorganisms such as bacteria, fungi and viruses.  Sulphapyridine ,Vancomycin , Ofloxacin and Chloramphenicol are examples of antimicrobials.

Antifertility drugs: These chemical substances subdue the hormonal effect that promotes pregnancy. And help in ovulation. They mainly act as conception. Synthetic progesterone derivative such as Norethindrone used as oral contraceptives.Novestrol (Ethynylestradiol) is also used as an antifertility drug.

Based on drug action

The way a drug works in a body called drug action. There are many drugs to treat a single disease, and all drugs have different actions. For example, hypertension can be treated by several drugs and different drugs have different actions. 

Based on chemical structure

Some drugs have similar drug action but different chemical structure. Drugs of similar chemical structure, like sulphonamides, have a similar impact on the body.Sulfonamide is an example of this categorization.

Based on molecular targets

Before attacking, the drug targets the macromolecules present inside the body. Target macromolecules are also called drug targets. Drugs with similar structure and similar mechanisms have the same target. Lipids, carbohydrates, protein and nucleic acid are the drug targets present inside the body. This categorization is most useful for chemists.

Uses of drugs

• When drugs can be taken according to prescription they provide many physical benefits. 
• Mental and physical disease can be treated.
• Drugs help maintain a healthy body.

Disadvantages of drugs

• Extended use can cause damage to the nervous system or various other parts of the body.
• Regular use may lead to drug addiction which can cause many diseases or even death.

Conclusion 

Chemical that affects our metabolism and provides treatment from ailments is called drug or medicine. Never take them in excess or without a doctor’s prescription as they are harmful. Medications mainly target proteins ,lipids carbohydrates etc.,(biological macromolecule known as target molecules. Medications interact with explicit targets which limits the side effects .It also confines drug’s action. Thus, drugs like antibiotics, tranquillisers, antiseptics, analgesics, antacids and disinfectants are utilised for specific purpose. Antifertility drugs are important to control increasing population.