Pharmacology: Definition, And Branches

Pharmacology is one of the most important subjects in the Pharmacy profession as well as in the medical field. Pharmacology is the cornerstone of the modern pharmacy.

What is Pharmacology?

The word pharmacology is derived from two Greek words, pharmacon meaning a “drug” and logos meaning “a reason”.

  • Pharmacology is the study of how medicinal substances interact with living systems.
  • Pharmacology is The study of drugs, their nature, their sources, and their properties, absorption, distribution, biotransformation, elimination, interactions, toxicology, and therapeutic applications.
  • Pharmacology is the study of the body’s reaction to drugs.
  • Pharmacology is the study of Pharmacokinetics and Pharmacodynamics of a drug.

In a broader sense, Pharmacology looks at how drugs work (a mechanism), their side effects and interaction with other drugs.

Pharmacology is at the center of biomedical science, combining chemistry, physiology, and pathology. Pharmacologists work closely with a number of other fields that make modern biomedical sciences, including neuro science, molecular and cellular biology, immunology, and cancer biology.

This subject explains what drugs are, what they do for physiological functions, and what the body does with them. Pharmacology also explains why a person may experience side effects when consuming drugs, and why there is such a broad view of the difference between drug actions among different people.

What is a Drug?

A drug is any chemical entity that causes a change in biological function in a living organism. some drugs are formed inside the body such as insulin and noradrenaline etc. Drugs that are introduced into the body from outside are called Xenobiotics.

How does it work?

Protein is present in many different forms in the body and has many different functions. Each protein has a specific function and is specific to the type of cell on which it functions. For example, there are certain types of proteins called receptors. Receptors embed in cell surfaces; there are different receptors for different types of cells. Liver cells have different receptors than heart cells. The receptor binds to other proteins and chemicals outside the cell, and this, in turn, changes how the cell functions.

Proteins also work on drug targets. In order for a drug to take effect, it must be protein-bound. It can be considered a lock and key system. Once the drug is attached to the receptor, it can have two important effects on the cell. It can produce a change in the response or it can stop a normal response from the cell.

If it produces a change in the response this will be called agonist and if it stops it will be known as antagonists.

Branches of Pharmacology

Following are the important branches of Pharmacology:

  • Pharmacodynamics
  • Pharmacokinetics
  • Chemotherapy
  • Therapeutics
  • Clinical Pharmacology
  • Pharmacogenetics
  • Pharmacognosy
  • Toxicology
  • Pharmacoepidemiology
  • Animal Pharmacology
  • Posology
  • Pharmacoeconomics
  • Comparative Pharmacology
  • Neuropharmacology
  • Psychopharmacology
  • Cardiovascular pharmacology
  • Pharmacovigilance

1. Pharmacokinetics

Pharmacokinetics refers to the movement of drugs inside, through and on the body. The nature of an individual’s response to a particular drug depends on the intrinsic pharmacological properties of the drug at its site of action. Pharmacokinetics investigates how the body absorbs, metabolizes and excretes drugs. A drug can be administered orally, parenterally (for example, by injection) or intravenously. The kidney is the main organ that filters drugs out of the body, but also the lungs and sweat glands play a minor role.

However, the rate of occurrence, intensity, and duration of the response generally depends on the following parameters:

  • The rate and extent of drug absorption.
  • The rate and extent of distribution of the drug in different tissues, including the site of action;
  • The rate of excretion of the drug from the body.

2. Pharmacodynamics

Pharmacodynamics is defined as the body’s response to the drug. It refers to the relationship between the concentration of the drug at the site of action and any resulting effect, namely the intensity and the time course of the effect and the side effects.

Pharmacodynamics is influenced by receptor binding and sensitivity, post-receptor effects and chemical interactions.

Pharmacodynamics and pharmacokinetics explain the effects of the drug, such as the relationship between dose and response. The pharmacological response depends on the binding of the drug to its target. The concentration of the drug at the receptor site influences its effect. The pharmacodynamics of a drug may be influenced by physiological changes due to diseases, genetic mutations, aging or other drugs. These changes are due to the ability of the disorders to modify receptor binding, to alter the number of binding proteins, or to decrease the sensitivity of the receptor.

3. Chemotherapy

Chemotherapy is the field of pharmacology that deals with the medicines used to treat cancer and malignancies with the help of cytotoxic and other drugs.

4.  Therapeutics

Therapy is the branch of pharmacology specialized in the treatment of diseases and in the art and science of healing. Therefore, in pharmacology, the treatments refer to the use of drugs and their method of administration in the treatment of diseases.

5. Clinical pharmacology

Clinical pharmacology promotes the rational use of drugs in humans by examining their corrective effects to increase the effect of the drug and reduce side effects.

This is the pharmacology with an added emphasis on the application of pharmacological principles and methods in the real world. This ranges from the discovery of new target molecules to the effects of drug use in the population.

6. Pharmacogenetics

Pharmacogenetic is the study of variability in drug response due to heredity. It is the study of the role of the genome in drug response. Pharmacogenomics analyzes how the genetic composition of an individual influences their response to medication.

7. Pharmacognosy

Pharmacognosy is the study of drugs derived from natural sources. This deals with the pharmacodynamics and the mechanisms by which substances, mainly from natural sources, directly or indirectly influence changes in living systems.

8. Toxicology

Toxicology is a branch of pharmacology devoted to the scientific study of the harmful effects of drugs on living organisms. This involves observing and reporting the symptoms, mechanisms, detection, and treatment of toxic substances, particularly in case of poisoning in humans.

Includes environmental agents and natural chemical compounds, as well as synthesized pharmaceutical compounds for medical use. These substances can have toxic effects on living organisms, including growth disorders, discomfort, illness, and death.

9. Pharmacoepidemiology

Pharmacoepidemiology is the branch of pharmacology that deals with the study of the use and effects of drugs in a large number of people. provides an estimate of the likelihood of a drug’s beneficial effects in a population and the likelihood of its adverse effects. This can be called a bridge science that encompasses both clinical pharmacology and epidemiology.

10. Animal Pharmacology

Animal pharmacology deals with the different properties of drugs in animals. A wide variety of animals are used, including rabbits, mice, guinea pigs, etc. The drugs are administered to the animals and all the parameters (behavior, activity, vital signs, etc.) are recorded. Each change is noted below. If it is useful in animals, the drug is tested in humans.

11. Posology

It is the branch of pharmacology and the therapies concern with determining the doses of the remedies; It is the science of dosage. For example, the usual dose of ibuprofen in adults and adolescents over 12 years is 200 mg to 400 mg three to four times a day.

12 Pharmacoeconomics

Pharmacoeconomics is the scientific discipline that concerns the cost and value of drugs, often with the aim of optimizing the allocation of health resources. For example, pharmacoeconomic studies can compare the costs of various drugs with results, such as the benefits for patients receiving drugs and the savings made by health systems through effective treatment or disease prevention.

13. Comparative pharmacology

It is a branch of pharmacology that compares one drug to another belonging to the same group or to the other.

14. Neuropharmacology

Neuropharmacology is a branch of neuroscience that studies the effects of drugs on the nervous system, including the brain, spinal cord, and nerves that carry information to and from different parts of the body. The goal of neuropharmacology, in general, is to understand the basic function of impulses and signals in the brain to determine the effects of drugs on the treatment of neurological disorders and dependence.

15. Psychopharmacology

Psychopharmacology is the scientific study of the effects of drugs on mood, sensation, reflection, and behavior. It is distinct from neuropsychopharmacology, which focuses on the correlation between changes in drug-induced nervous system function and changes in consciousness and behavior.

16. Cardiovascular pharmacology

Cardiovascular pharmacology is the study of the effects of drugs on the entire cardiovascular system. Cardiovascular Relative to the circulatory system, which includes the heart and blood vessels, transports nutrients and oxygen to body tissues and removes carbon dioxide and other wastes. Cardiovascular diseases are disorders of the heart and blood vessels and include arteriosclerosis, coronary artery disease, heart valve, arrhythmia, arrhythmia, heart failure, hypertension, orthostatic hypotension, shock, endocarditis, diseases of the aorta and its branches, disorders of the peripheral vascular system and congenital heart disease.

17. Pharmacovigilance

According to the World Health Organization,  “Science and activities related to the identification, evaluation, understanding, and prevention of adverse effects or any other possible problem related to drugs”

This Article is Written & Reviewed By A Registered Pharmacist: Manzoor Ahmad

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