Classification of Drugs Based on Therapeutic Action Chemical Structure and Mechanism of Action
A drug is any chemical substance that brings about changes in the functioning of living organisms. Pharmacology is the science that studies and deals with drugs in medicines and their mechanism of action, physical and chemical properties, metabolism toxicity and therapeutics. Principles of drug action and different types of drugs are used in the treatment and prevention of diseases in human beings
A branch of medicine and pharmaceutical sciences concerned with drugs or the aftereffect of medicine, where a drug may be defined as any artificial, natural, or endogenous molecule which exerts a physiological or biochemical effect on the cell, tissue, or organ of the body. To be more specific we can say that it is the study of the interactions that occur between a living organism and chemicals that affect biochemical processes. Substances possessing medicinal properties are considered pharmaceuticals.
Types of Pharmacology
Pharmacology has the following Branches:
1. Pharmacokinetics: It describes what our body does to a drug, referring to the movement of the drug in our body, through the body and out of the body. This process usually occurs in 4 phases in pharmacokinetics.
Absorption
Distribution
Metabolism
Excretion
Sometimes known by the acronym 'ADME'.
2. Pharmacodynamics: It is just the opposite of what pharmacokinetics is, it describes what a drug does to our body or how our body responds to the drug.
The study of the physiological, molecular and biochemical effects of drugs on the human body involves the study of post-receptor effects, chemical interactions and receptor bindings. Together pharmacokinetics and pharmacodynamics build a dose-response relationship.
Types of Drugs and Their Uses
Medicinal drugs are chemical drugs divided into different groups or classes based on their uses, chemical structure or mode of action. These classification systems are sometimes confusing as one drug type may be included in more than one class.
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Antimicrobial Drugs: Drugs are used for the prevention or treatment of diseases caused by microbes like bacteria, fungi, protozoa, viruses or helminths. They contain chemical substances which kill or reduce the metabolic products produced by the microorganisms. Antibiotics come under the category of antimicrobial drugs. Example- penicillin.
Immunosuppressants: Immunosuppressants are a group of medicines used to block the immune response and are generally administered to patients who have undergone organ transplantation or are suffering from an autoimmune disease. Some of the common immunosuppressants are drugs that contain polyclonal antibodies, monoclonal antibodies, glucocorticoids, etc.
Drugs that Affect Blood: There are drugs that have to activate or inhibit enzymes that are involved in the regulation of blood clotting within the blood vessels. These drugs are administered in conditions like atherosclerosis or any kind of blockage in arteries occurring in the blood flow. There are various drugs like anticoagulants, antiplatelet drugs and fibrinolytic drugs which are involved in controlling the coagulation process.
Cardiovascular Drugs: These affect the functioning of the heart and blood vessels. They are administered for cardiovascular diseases like hypertension, and atherosclerosis. These drugs also affect the functioning of the heart muscles, frequency and regularity of heartbeat, etc.
Endocrine Drugs: Drugs that are used to treat endocrine abnormalities. Their functioning includes changes in the regulation of the hormonal axis, effects on hormonal transport, as well as similar changes to counter-regulatory hormone systems. Endocrine drugs are used for the treatment of thyroid, Addison disease, etc.
Reproductive Drugs: These affect the functioning of our reproductive system. These drugs are used for treating reproductive diseases.
Central nervous system drugs: These affect the functioning of the central nervous system. These drugs are administered in order to produce changes in behaviour, a physical sensation or mental state. Local anaesthetics, on the other hand, induce a loss of sensation in just one area of the body by blocking conduction in nerves at and near the injection site.
Digestive System Drugs: These groups of drugs act on the digestive system by affecting the actions of the involuntary muscle (motility) and thus altering movement or also by altering the secretion of digestive juices or gastric emptying. Examples of major groups of digestive drugs include antidiarrheal drugs, laxatives, antiemetics, emetics, proton pump inhibitors, and antacids.
Dermatologic Drugs: Topical application of drugs provides a direct, localized effect on a specific area of the skin. When these drugs are applied to the skin, they may be dissolved in a variety of formulations, ranging from simple solutions to greasy ointments. These medications can relieve itching, exert a constricting or astringent action on the pores, or dissolve or remove the epidermal layers. The skin can be affected by other means like photosensitizing drugs, and pigmenting agents (psoralens).
The chemical drugs list can be endless. There are numerous drugs for various diseases. These drugs are of vital importance to humankind. The knowledge of pharmacology and drugs is also indispensable to medical science. It helps create wonders in the human body and soothe numerous ailments.
Did You Know?
Drugs are often abused by people. Adolescence is a period when a lot of people indulge in drug abuse and dependency. This can be due to experimentation, curiosity or even depression. This can cause serious issues which lead to severe consequences and even death. Drugs abused are opioids, cannabinoids, coca alkaloids, etc. These when taken in overdose can cause life-threatening damages.
FAQs on Types of Drugs in Chemistry and Their Classification
1. What are drugs in chemistry?
A drug in chemistry is a chemical substance that alters the normal physiological function of the body when taken in small amounts. Drugs interact with specific biological targets such as receptors, enzymes, or ion channels to produce therapeutic or harmful effects. In medicinal chemistry, drugs are designed to:
- Prevent diseases (e.g., vaccines)
- Diagnose conditions (e.g., contrast agents)
- Treat illnesses (e.g., antibiotics, analgesics)
2. What are the main types of drugs in chemistry?
The main types of drugs in chemistry are classified based on their therapeutic effect or pharmacological action. Major categories include:
- Analgesics – relieve pain (e.g., aspirin, paracetamol)
- Antibiotics – kill or inhibit bacteria (e.g., penicillin)
- Antiseptics – prevent microbial growth on tissues
- Disinfectants – destroy microorganisms on surfaces
- Antacids – neutralize excess stomach acid
- Tranquilizers – reduce anxiety and induce calmness
3. What is the difference between antibiotics and antiseptics?
The main difference between antibiotics and antiseptics is that antibiotics act inside the body against bacteria, while antiseptics are applied externally to prevent infection.
- Antibiotics: Used internally; target specific bacteria; example – penicillin.
- Antiseptics: Applied to skin or wounds; prevent microbial growth; example – iodine solution.
4. What are analgesics and how do they work?
Analgesics are drugs that relieve pain without causing loss of consciousness. They work by blocking pain signals or reducing inflammation. Analgesics are classified into:
- Non-narcotic analgesics – e.g., aspirin, paracetamol; reduce pain and fever.
- Narcotic analgesics – e.g., morphine; act on the central nervous system for severe pain.
5. What are antacids and how do they neutralize stomach acid?
Antacids are basic substances that neutralize excess hydrochloric acid (HCl) in the stomach. They react with stomach acid to form salt and water. A common example reaction is:
Mg(OH)2(s) + 2HCl(aq) → MgCl2(aq) + 2H2O(l)
- Common antacids: magnesium hydroxide, aluminum hydroxide, sodium hydrogen carbonate
- Used to treat acidity, heartburn, and indigestion
6. What are tranquilizers in chemistry?
Tranquilizers are drugs that reduce anxiety, stress, and mental tension by acting on the central nervous system. They are commonly prescribed for mental disorders and insomnia. Examples include:
- Diazepam
- Alprazolam
7. What is the difference between disinfectants and antiseptics?
The key difference between disinfectants and antiseptics is that disinfectants are used on non-living surfaces, while antiseptics are safe for living tissues.
- Disinfectants: Used on floors, instruments, surfaces; example – 1% phenol solution.
- Antiseptics: Used on skin and wounds; example – dilute iodine solution.
8. What are broad-spectrum and narrow-spectrum antibiotics?
Broad-spectrum antibiotics act against a wide range of bacteria, while narrow-spectrum antibiotics target specific types of bacteria.
- Broad-spectrum: Effective against both Gram-positive and Gram-negative bacteria; example – tetracycline.
- Narrow-spectrum: Effective against specific bacteria; example – penicillin G.
9. How are drugs classified based on their source?
Drugs are classified based on their source into natural, semi-synthetic, and synthetic drugs.
- Natural drugs: Obtained from plants or animals (e.g., morphine from opium poppy).
- Semi-synthetic drugs: Chemically modified natural drugs (e.g., ampicillin).
- Synthetic drugs: Completely prepared in laboratories (e.g., paracetamol).
10. What is drug-target interaction in medicinal chemistry?
Drug-target interaction refers to the binding of a drug molecule to a specific biological target to produce a therapeutic effect. The target may be:
- Receptors
- Enzymes
- Ion channels
- Nucleic acids
