Branches of Pharmacology: Definition, Objective and All Branches Related to This Science

It is the science of drugs or medicines.

It is the study of chemical substances that interact with living beings through chemical processes, especially by binding to regulatory molecules, that is, receptors.

What is a drug?

The word drug comes from “Drogue,” which means a dry herb.

It can be defined as:

“Substance or material that is used or intended to be used to modify or explore physiological processes or disease states, for the recipient’s benefit.”

Purpose of pharmacology

The primary goal of the science of pharmacology is to determine and diagnose the following information for any drug that is pharmacologically and therapeutically active:

  • Dose.
  • Action mode.
  • Mechanism of action.
  • Pharmacological action.
  • Adverse effects.
  • Side effects.
  • Toxicidades.
  • Contraindications.
  • Drug interactions.
  • Drug-excipient incompatibilities.

Scope of pharmacology

The field spans several arenas throughout, such as the following:


  • Drug composition.
  • Synthesis and design of drugs.
  • Molecular and cellular mechanism.
  • Organ/system mechanism.
  • Signal transduction / cellular communication.
  • Interaction.
  • Toxicology.
  • Therapy.
  • Medical applications.
  • Preclinical/clinical studies.

Branches of pharmacology


Pharmacokinetics is derived from two words, Phar-macon, which means a drug, and kinetics, which means to set in motion.

It can be defined as:

“The branch of pharmacology that deals with the absorption, distribution, metabolism, and excretion of drugs and their relationship with the onset, duration, and intensity of the drug’s effect.”

What the body does to the drug is pharmacokinetics. For example, the absorption, distribution, metabolism, and excretion of paracetamol are included in the pharmacokinetics.


Pharmacodynamics is the branch of pharmacology that deals with the drug’s mechanism of action and the relationship between the concentration of the drug and its effect.

It studies drugs’ physical and chemical effects on the body, parasites, and microorganisms.

What the drug does to the body is Pharmacodynamics.

For example, adrenaline acts on adrenal receptors and stimulates the adenyl cyclase system producing effects such as cardiac stimulation, and hyperglycemia is studied in Pharmacodynamics.


The branch of pharmacology deals with the art and science of treating disease. It is the application of pharmacological information together with the knowledge of the condition to prevent and cure the disease.


Chemotherapy refers to treating diseases with chemicals that kill cells, especially those of microorganisms and neoplastic cells. It is classified into two divisions:

  1. Antibiotics: includes the choice of drugs that are more powerful against the body or less toxic. Examples include erythromycin given for gram-positive organisms and amino glycans for gram-negative organisms.
  2. Antineoplastics: Examples include: methotrexate, which is an anticancer drug. It inhibits dihydrofolate reductase and interferes with DNA synthesis and repair—Vinca alkaloids bind to microtubule tubulin and stop mitosis in metaphase.


Toxicology is the branch of pharmacology that includes studying the adverse effects of drugs on the body. It deals with the symptoms, mechanisms, treatment, and detection of poisonings caused by different chemical substances.

The main criterion is the dose. Essential drugs are high-dose poisons, and some toxins are low-dose essential drugs.

Clinical pharmacology

Clinical pharmacology is the scientific study of drugs in man. It includes pharmacokinetic and pharmacodynamic investigations in healthy or diseased individuals. It also compares placebos, medications on the market, and surveillance programs.

The main objectives are:

  • Maximize the effect of the drug.
  • Minimize adverse effects.
  • Promote prescription security.

The objectives include:

  • Generate optimal data for drug use.
  • Promote the use of evidence-based medicine.


Pharmacy is the branch of Pharmacology and is the art and science of composition through drug delivery, preparing the appropriate dosage form for administration to man and animals. The health profession combines health science with chemical science and effectively uses drugs.


Pharmacognosy is the identification of drugs simply by seeing or smelling them. It is a crude method that is no longer used.

It deals with medicines in raw or unprepared form and the study of the properties of drugs from natural sources or the identification of new drugs obtained from natural sources.


Pharmacoeconomics deals with the cost of drugs. In this discipline, the price of a drug is compared with another for the same use. Cheap pills are preferred.


The branch of pharmacology deals with genetic variations that cause differences in response to drugs between individuals or the population.

The example includes succinylcholine, a skeletal muscle relaxant used in general Anastasia. It is metabolized by pseudocholine esterase and has a short-lived action. The presence of the enzyme is determined by the gene, and the lack of it is inherited recessively. This can lead to respiratory paralysis, apnea, and death.


Pharmacogenomics is the broadest application of genomic technologies for new drug discovery and further characterization of older drugs.

Recombinant DNA technology involves the artificial joining of DNA from one species to another. E. coli is mainly used. In this way, we can obtain large amounts of the drug in purified form, which is less antigenic.

Examples include:

  • GH.
  • Interferon
  • Vaccines.


Pharmacoepidemiology deals with the effects of drugs on a large population. The results can be good or bad. It is done in three ways:

  1. Observational cohort studies.
  2. Case-control studies.
  3. Phase test.

Study Squad: Patients receiving medications are collected and followed to determine results. It is a prospective (prospective) investigation. However, it is time-consuming and lengthy.

Case-Control Studies: These are retrospective studies. They reverse the direction of scientific logic from looking forward to looking back.

Phase tests

These include different phases:

  • Human pharmacology (20 to 50 subjects), pharmacokinetics, and drug pharmacodynamics are observed.
  • Drugs are compared with placebos in therapeutic exploration (50 to 300 subjects).
  • Therapeutic confirmation (250 to 1000 subjects), safety, and efficacy of drugs are compared with drugs already present.
  • In therapeutic use (2,000 to 10,000 subjects), the opinion of the prescribing physicians is collected regarding dosage and efficacy. Surveillance programs are extended when conducted outside of hospitals.

Comparative pharmacology

This is the branch of pharmacology that deals with the comparison of a drug with another from the same or another group.


Dosage deals with drug dosing. The example includes acetaminophen administered three times a day as a 500 mg tablet.

Animal pharmacology

Animal pharmacology deals with the different properties of drugs in animals. A wide variety of animals are used, including rabbits, guinea pigs, etc.

The animals are administered drugs, and all parameters (their behavior, activities, vital signs, etc.) are recorded. Any changes are noted below. If it is helpful in animals, then the drug is tested in humans.