Pharmacology (from Greek φάρμακον, pharmakon, "poison" in classic Greek; "drug" in modern Greek; and -λογία, -logia "study of", "knowledge of") is the branch of medicine and biology concerned with the study of drug action, where a drug can be broadly defined as any
man-made, natural, or endogenous (within the body) molecule which exerts a biochemical and/or physiological effect on the cell, tissue, organ, or organism. More specifically, it is the study of the interactions that occur between a living organism and chemicals that affect normal
or abnormal biochemical function. If substances have medicinal properties, they are considered pharmaceuticals.
The field encompasses drug composition and properties, synthesis and drug design, molecular and cellular mechanisms, organ/systems mechanisms, signal transduction/cellular communication, molecular diagnostics, interactions, toxicology, chemical biology, therapy, and medical applications and antipathogenic capabilities. The two main areas of pharmacology are pharmacodynamics and pharmacokinetics. The former studies the effects of the drug on biological systems, and the latter the effects of biological systems on the drug. In broad terms,
pharmacodynamics discusses the chemicals with biological receptors, and pharmacokinetics discusses the absorption, distribution, metabolism, and excretion (ADME) of chemicals from the biological systems.
Pharmacology is not synonymous with pharmacy and the two terms are frequently confused. Pharmacology, a biomedical science, deals with the research, discovery, and characterization of chemicals which show biological effects and the elucidation of cellular and organismal function in relation to these chemicals. In contrast, pharmacy, a health services profession, is concerned with application of the principles learned from pharmacology in its clinical settings; whether it be in a dispensing or clinical care role. In either field, the primary contrast between the two are their distinctions between direct-patient care, for pharmacy practice, and the science-oriented research field, driven by pharmacology.
Dioscorides' De Materia Medica is often said to be the oldest and most valuable work in the history of pharmacology. The origins of clinical pharmacology date back to the Middle Ages in Avicenna's The Canon of Medicine, Peter of Spain's Commentary on Isaac, and John of St Amand's Commentary on the Antedotary of Nicholas. Clinical pharmacology owes much of its foundation to the work of William Withering.
Pharmacology as a scientific discipline did not further advance until the mid-19th century amid the great biomedical resurgence of that period. Before the second half of the nineteenth century, the remarkable potency and specificity of the actions of drugs such as morphine, quinine and digitalis were explained vaguely and with reference to extraordinary chemical
powers and affinities to certain organs or tissues. The first pharmacology department was set up by Rudolf Buchheim in 1847, in recognition of the need to understand how therapeutic drugs and poisons produced their effects.
Early pharmacologists focused on natural substances, mainly plant extracts. Pharmacology developed in the 19th century as a biomedical science that applied the principles of scientific experimentation to therapeutic contexts. Today Pharmacologists harness the power of genetics, molecular biology, chemistry, and other advanced tools to transform information about molecular mechanisms and targets into therapies directed against disease, defects or
pathogens, and create methods for preventative care, diagnostics, and ultimately personalized medicine.
Divisions
The study of chemicals requires intimate knowledge of the biological system affected. With the knowledge of cell biology and biochemistry increasing, the field of pharmacology has also changed substantially. It has become possible, through molecular analysis of receptors, to design chemicals that act on specific cellular signaling or metabolic pathways by affecting sites directly on cell-surface receptors (which modulate and mediate cellular signaling pathways controlling cellular function).
A chemical has, from the pharmacological point-of-view, various properties. Pharmacokinetics describes the effect of the body on the chemical (e.g. half-life and volume of distribution), and pharmacodynamics describes the chemical's effect on the body (desired or toxic). When describing the pharmacokinetic properties of a chemical, pharmacologists are often interested in L-ADME:
Medication is said to have a narrow or wide therapeutic index or therapeutic window. This describes the ratio of desired effect to toxic effect. A compound with a narrow therapeutic index (close to one) exerts its desired effect at a dose close to its toxic dose. A compound with a wide therapeutic index (greater than five) exerts its desired effect at a dose substantially below its toxic dose. Those with a narrow margin are more difficult to dose and administer, and
may require therapeutic drug monitoring (examples are warfarin, some antiepileptics, aminoglycoside antibiotics). Most anti-cancer drugs have a narrow therapeutic margin: toxic side-effects are almost always encountered at doses used to kill tumors.
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man-made, natural, or endogenous (within the body) molecule which exerts a biochemical and/or physiological effect on the cell, tissue, organ, or organism. More specifically, it is the study of the interactions that occur between a living organism and chemicals that affect normal
or abnormal biochemical function. If substances have medicinal properties, they are considered pharmaceuticals.
The field encompasses drug composition and properties, synthesis and drug design, molecular and cellular mechanisms, organ/systems mechanisms, signal transduction/cellular communication, molecular diagnostics, interactions, toxicology, chemical biology, therapy, and medical applications and antipathogenic capabilities. The two main areas of pharmacology are pharmacodynamics and pharmacokinetics. The former studies the effects of the drug on biological systems, and the latter the effects of biological systems on the drug. In broad terms,
pharmacodynamics discusses the chemicals with biological receptors, and pharmacokinetics discusses the absorption, distribution, metabolism, and excretion (ADME) of chemicals from the biological systems.
Pharmacology is not synonymous with pharmacy and the two terms are frequently confused. Pharmacology, a biomedical science, deals with the research, discovery, and characterization of chemicals which show biological effects and the elucidation of cellular and organismal function in relation to these chemicals. In contrast, pharmacy, a health services profession, is concerned with application of the principles learned from pharmacology in its clinical settings; whether it be in a dispensing or clinical care role. In either field, the primary contrast between the two are their distinctions between direct-patient care, for pharmacy practice, and the science-oriented research field, driven by pharmacology.
Dioscorides' De Materia Medica is often said to be the oldest and most valuable work in the history of pharmacology. The origins of clinical pharmacology date back to the Middle Ages in Avicenna's The Canon of Medicine, Peter of Spain's Commentary on Isaac, and John of St Amand's Commentary on the Antedotary of Nicholas. Clinical pharmacology owes much of its foundation to the work of William Withering.
Pharmacology as a scientific discipline did not further advance until the mid-19th century amid the great biomedical resurgence of that period. Before the second half of the nineteenth century, the remarkable potency and specificity of the actions of drugs such as morphine, quinine and digitalis were explained vaguely and with reference to extraordinary chemical
powers and affinities to certain organs or tissues. The first pharmacology department was set up by Rudolf Buchheim in 1847, in recognition of the need to understand how therapeutic drugs and poisons produced their effects.
Early pharmacologists focused on natural substances, mainly plant extracts. Pharmacology developed in the 19th century as a biomedical science that applied the principles of scientific experimentation to therapeutic contexts. Today Pharmacologists harness the power of genetics, molecular biology, chemistry, and other advanced tools to transform information about molecular mechanisms and targets into therapies directed against disease, defects or
pathogens, and create methods for preventative care, diagnostics, and ultimately personalized medicine.
Divisions
- Clinical pharmacology: The basic science of pharmacology, with added focus on the application of pharmacological principles and methods in the medical clinic and towards patient care and outcomes.
- Neuropharmacology: Effects of medication on central and peripheral nervous system functioning.
- Psychopharmacology: Effects of medication on the psyche; observing changed behaviors of the body and mind, and how molecular events are manifest in a measurable behavioral form.
- Pharmacogenetics: Clinical testing of genetic variation that gives rise to differing response to drugs.
- Pharmacogenomics: Application of genomic technologies to new drug discovery and further characterization of older drugs.
- Pharmacoepidemiology: Study of effects of drugs in large numbers of people.
- Toxicology: Study of the adverse effects, molecular targets, and characterization of drugs or any chemical substance in excess (including those beneficial in lower doses).
- Theoretical pharmacology: Study of metrics in pharmacology.
- Posology: How medicines are dosed. It also depends upon various factors like age, climate, weight, sex, and so on.
- Pharmacognosy: A branch of pharmacology dealing especially with the composition, use, and development of medicinal substances of biological origin and especially medicinal substances obtained from plants. crude drugs obtained from natural source dried and then simply used
- Behavioral pharmacology: Behavioral pharmacology, also referred to as psychopharmacology, is an interdisciplinary field which studies behavioral effects of psychoactive drugs. It incorporates approaches and techniques from neuropharmacology, animal behavior and behavioral neuroscience, and is interested in the behavioral and neurobiological mechanisms of action of psychoactive drugs. Another goal of behavioral pharmacology is to develop animal behavioral models to screen chemical compounds with therapeutic potentials. People in this field (called behavioral pharmacologists) typically use small animals (e.g. rodents) to study psychotherapeutic drugs such as antipsychotics, antidepressants and anxiolytics, and drugs of abuse such as nicotine, cocaine, methamphetamine, etc.
- Environmental pharmacology: Environmental pharmacology is a new discipline. Focus is being given to understand gene–environment interaction, drug-environment interaction and toxin-environment interaction. There is a close collaboration between environmental science and medicine in addressing these issues, as healthcare itself can be a cause of environmental damage or remediation. Human health and ecology is intimately related. Demand for more pharmaceutical products may place the public at risk through the destruction of species. The entry of chemicals and drugs into the aquatic ecosystem is a more serious concern today. In addition, the production of some illegal drugs pollutes drinking water supply by releasing carcinogens. More and more biodegradability of drugs are needed. This field is intimately linked with Public Health fields.
The study of chemicals requires intimate knowledge of the biological system affected. With the knowledge of cell biology and biochemistry increasing, the field of pharmacology has also changed substantially. It has become possible, through molecular analysis of receptors, to design chemicals that act on specific cellular signaling or metabolic pathways by affecting sites directly on cell-surface receptors (which modulate and mediate cellular signaling pathways controlling cellular function).
A chemical has, from the pharmacological point-of-view, various properties. Pharmacokinetics describes the effect of the body on the chemical (e.g. half-life and volume of distribution), and pharmacodynamics describes the chemical's effect on the body (desired or toxic). When describing the pharmacokinetic properties of a chemical, pharmacologists are often interested in L-ADME:
- Liberation - disintegration (for solid oral forms (breaking down into smaller particles)), dispersal and dissolution
- Absorption - How is the medication absorbed (through the skin, the intestine, the oral mucosa)?
- Distribution - How does it spread through the organism?
- Metabolism - Is the medication converted chemically inside the body, and into which substances. Are these active? Could they be toxic?
- Excretion - How is the medication eliminated (through the bile, urine, breath, skin)?
Medication is said to have a narrow or wide therapeutic index or therapeutic window. This describes the ratio of desired effect to toxic effect. A compound with a narrow therapeutic index (close to one) exerts its desired effect at a dose close to its toxic dose. A compound with a wide therapeutic index (greater than five) exerts its desired effect at a dose substantially below its toxic dose. Those with a narrow margin are more difficult to dose and administer, and
may require therapeutic drug monitoring (examples are warfarin, some antiepileptics, aminoglycoside antibiotics). Most anti-cancer drugs have a narrow therapeutic margin: toxic side-effects are almost always encountered at doses used to kill tumors.
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