Pharmacology definition

Pharmacology (Greek: Pharmacon—drug; logos—knowledge) is the science of drugs, defined as the study of the interactions of exogenously administered chemical molecules with living systems, or any single chemical substance that can produce a biological response. These interactions are typically caused by the substance binding to regulatory molecules and activating or inhibiting normal body processes. These substances may be chemicals that are administered to achieve a beneficial therapeutic effect on a process within the patient or to have a toxic effect on regulatory processes in parasites that infect the patient. As a result, pharmacology is also defined as the study of all aspects of drug knowledge, but especially those that are relevant to effective and safe use for medicinal purposes.

Such intentional therapeutic applications may be regarded as the proper role of medical pharmacology, which is defined as the science of pharmacology concerned with the use of chemicals in the prevention, diagnosis, and treatment of disease, particularly in humans.

The history of pharmacology

Many plant and animal materials were undoubtedly recognized to be beneficial or toxic to prehistoric people. Most drugs were crude natural products with unknown compositions and limited efficacy for thousands of years. Only the overt effects of these substances on the body were known with some precision, but how they were produced was unknown. Early written records list a variety of remedies, including a few that are still considered useful drugs today. Most, on the other hand, were worthless or even harmful.

Rudolf Buchheim established the first institute of pharmacology in Germany in 1847, ushering in pharmacology as an experimental science. Oswald Schmiedeberg, known as the "Father of Pharmacology," and his many disciples, including (J Langley, T Frazer, P Ehrlich, AJ Clark, and JJ Abel) proposed some of the fundamental concepts in pharmacology in the late nineteenth century. Since then, drugs have been purified and chemically characterized, and a wide range of new highly potent and selective drugs have been developed. Many drugs' mechanisms of action, including molecular targets, have been identified. This has been made possible by the rapid growth of pharmacology, which serves as the foundation for rational therapeutics.

Important concepts

Pharmacodynamics and pharmacokinetics are the two main branches of pharmacology:

Pharmacodynamics (Greek: dynamic—power)

It is the effect of the drug on the body. This includes the physiological and biochemical effects of drugs, as well as their mechanisms of action at the organ system, subcellular, and macromolecular levels.

Pharmacokinetics (Greek: Kinesis—movement)

It is the body's response to the drug. This refers to the movement and alteration of the drug by the body, which includes absorption, distribution, binding/localization/storage, bio-transformation, and excretion of the drug.

Drug (French: Drogue—a dry herb)

Any substance or product that is used or is intended to be used to modify or investigate physiological systems or pathological states for the benefit of the recipient is referred to as a drug. It is the single active chemical entity in a medicine that is used for disease diagnosis, prevention, treatment, or cure.

The term "drugs" can also refer to addictive/abused/illicit substances. This restricted and derogatory sense usage, on the other hand, is an unfortunate degradation of a time-honored term.

Other important aspects of pharmacology include:

Pharmacotherapeutics

It is the use of pharmacological knowledge in conjunction with the disease, knowledge to prevent, mitigate, or cure disease. Pharmacotherapeutics includes the selection of the most appropriate drug, dosage, and duration of treatment while taking into account the specific characteristics of a patient.

Clinical pharmacology

It is the scientific investigation of drugs (both old and new) in humans. It includes pharmacodynamic and pharmacokinetic research in healthy volunteers and patients; drug efficacy and safety evaluations, as well as comparative trials with other forms of treatment; and monitoring of drug use patterns, adverse effects, and so on.

Clinical pharmacology's goal is to generate data for optimal drug use and the practice of "evidence-based medicine."

Chemotherapy

It is the treatment of systemic infection or malignancy with drugs that have selective toxicity for the infecting organism, or malignant cell while having no/minimal effects on host cells.

Toxicology

It is the study of the poisonous effect of drugs and other chemicals (household, an environmental pollutant, industrial, agricultural, and homicidal) with an emphasis on detection, prevention, and treatment of poisonings. It also includes the study of drug side effects, because the same substance can be either a drug or a poison depending on the dose.

Pharmacy

It is the art and science of compounding and dispensing drugs, as well as preparing appropriate dosage forms for drug administration to humans or animals. It involves gathering, identifying, purifying, isolating, synthesis, standardization, and quality control of medicinal substances. Pharmaceutics refers to the large-scale production of drugs. It is, first and foremost, a technological science.

The nature of drugs

A drug, in the broadest sense, is any substance that, through its chemical actions, causes a change in biological function. Inorganic ions, nonpeptide organic molecules, small peptides and proteins, nucleic acids, lipids, and carbohydrates are examples of commonly used drugs. Some are naturally occurring in plants or animals, while others are partially or completely synthetic. Many natural drugs are alkaloids, which are molecules with a basic pH in a solution, usually due to amine groups in their structure. Many biologically significant endogenous molecules and exogenous drugs are optically active, which means they have one or more asymmetric centers and can exist as enantiomers. Enantiomers of optically active drugs typically differ in their affinity for biologic receptor sites, sometimes by more than 1000-fold. Furthermore, such enantiomers may be metabolized at different rates in the body, which could have serious clinical implications.

In most cases, the drug molecule acts as an agonist (activator) or antagonist (inhibitor) on a specific target molecule that regulates the biological system. A receptor is a name given to this target molecule. Chemical antagonists may interact directly with other drugs in a very small number of cases, whereas a few drugs (osmotic agents) interact almost exclusively with water molecules. Drugs can be chemicals that are synthesized in the body (e.g., hormones) or chemicals that are not synthesized in the body (i.e., xenobiotics).

Poisons are drugs that have almost entirely negative side effects. However, Paracelsus (1493–1541) famously stated that “the dose makes the poison,” implying that any substance can be harmful if consumed in the incorrect dosage. Toxins are poisons of biological origin, that is, poisons synthesized by plants or animals, as opposed to inorganic poisons such as lead and arsenic.

Drug-Drug interactions

As previously stated, the interactions between a drug and the body are conveniently classified into two classes. The actions of a drug on the body are referred to as pharmacodynamic processes, which include mechanisms of action as well as therapeutic and toxic effects. These properties determine the drug's classification, and they play a major role in determining whether that classification is an appropriate therapy for a specific symptom or disease. Pharmacokinetic processes refer to the actions of the body on the drug. Pharmacokinetic processes govern drug absorption, distribution, and elimination and are extremely important in the selection and administration of a specific drug for a specific patient, such as a patient with impaired renal function.

Drug nomenclature

A drug's name can be categorized into three types:

1. Chemical name: It chemically describes the substance, for example, 1-(Isopropylamino)-3-(1-naphthoxy) propane-2-ol for propranolol. This is inconvenient and unsuitable for prescribing. Before an approved name is coined, the manufacturer may assign a code name for convenience and simplicity.
2. Non-proprietary name: It is the name that has been approved by a competent scientific body or authority, such as the United States Adopted Name (USAN) council. Similarly, there is a drug's British Approved Name (BAN). An agreement to use the Recommended International Nonproprietary Name (rINN) in all WHO member countries keep the nonproprietary names of newer drugs uniform. The BAN for older drugs has also been modified to be more in line with rINN. Many older drugs, however, still have multiple non-proprietary names. The nonproprietary name may also be referred to as the (approved name) until the drug is included in a pharmacopeia. It becomes the official name after it appears in an official publication. In daily conversation, the term (generic name) is used instead of a nonproprietary name. This is etymologically incorrect: the term "generic" should refer to the compound's chemical or pharmacological group (or genus). This misunderstanding, however, is widely accepted and even used in official circles.
3. Proprietary (Brand) name: It is the name given to the product by the manufacturer(s), and it is his property or trademark. A single drug may have several proprietary names. Brand names are intended to be memorable, catchy, and often suggestive. In general, brand names differ from country to country, for example. Timolol maleate eye drops are marketed in the United States as TIMOPTIC, but in India as GLUCOMOL. In some countries, the same drug may be marketed under different brand names by the same manufacturer. Furthermore, combined formulations have multiple brand names. This is the source of much uncertainty in drug nomenclature.

Prescription and non-prescription drugs

According to drug regulations, the majority of drugs, including all antibiotics, must be sold at retail only with a prescription from a registered medical practitioner. These are referred to as (prescription drugs). Few drugs, however, such as simple analgesics (paracetamol aspirin), antacids, laxatives (senna, lactulose), vitamins, ferrous salts, and so on, are considered relatively safe and can be obtained without a prescription. These are 'non-prescription or [over-the-counter] (OTC) drugs that can be purchased even at grocery stores.