داروشناسی مطالعهٔ تعامل بین موجودزنده و دارو یا موادشیمیایی دریافتشدهاست که بر عملکرد طبیعی یا غیرطبیعی بیوشیمیایی اثر میگذارد. دو حوزه اصلی فارماکولوژی، فارماکودینامیک و فارماکوکینتیک هستند. بهطور خلاصه فارماکودینامیک مطالعهٔ اثرات داروها بر بدن، و فارماکوکینتیک، اثر و رفتار بدن بر روی داروها است.
بعبارت دیگر فارماکودینامیک، مبحث فعلوانفعالات دارو در مواجهه با گیرندههای بیولوژیک، و فارماکوکینتیک بحث و تعریف در مورد جذب، توزیع، متابولیسم و دفع دارو در سیستمهای بیولوژیکی است. لازم به یادآوریاست که داروشناسی(Pharmacology) با داروسازی(Pharmacy) دو واژهٔ جدا از هم هستند که گاهی بهاشتباه بهجای هم بهکار میروند. فارماکولوژی چگونگی رفتار متقابل دارو و سیستمبیولوژیکی (بدن) است ولی داروسازی در رابطه با مواداولیه، آمادهسازی، توزیع، مقدار (دوز) در استفاده از داروهای بیخطر و مؤثر است.
Pharmacology is the branch of biology concerned with the study of drug or medication action, where a drug can be broadly defined as any man-made, natural, or endogenous (from within the body) molecule which exerts a biochemical or physiological effect on the cell, tissue, organ, or organism (sometimes the word pharmacon is used as a term to encompass these endogenous and exogenousbioactive species). 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. Pharmacodynamics studies the effects of a drug on biological systems, and Pharmacokinetics studies the effects of biological systems on a 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.
In the 17th century, the English Physician Nicholas Culpeper translated and used pharmacological texts. Culpepper detailed plants and the conditions they could treat. In the 18th century, much of clinical pharmacology was established by 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. Subsequently, the first pharmacology department in England was set up in 1905 at University College London.
Pharmacology developed in the 19th century as a biomedical science that applied the principles of scientific experimentation to therapeutic contexts. The advancement of research techniques propelled pharmacological research and understanding. The development of the organ bath preparation, where tissue samples are connected to recording devices, such as a myograph, and physiological responses are recorded after drug application, allowed analysis of drugs' effects on tissues. The development of the ligand binding assay in 1945 allowed quantification of the binding affinity of drugs at chemical targets. Modern pharmacologists use techniques from genetics, molecular biology, biochemistry, 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.
Study of pharmacology overlaps with biomedical sciences and study of the effects of drugs on living organisms. Pharmacological research can lead to new drug discoveries, and promote a better understanding of human physiology. Students of pharmacology must have detailed working knowledge of aspects in physiology, pathology and chemistry. Modern pharmacology is interdisciplinary and relates to biophysical and computational sciences, and analytical chemistry. Whereas a pharmacy student will eventually work in a pharmacy dispensing medications, a pharmacologist will typically work within a laboratory setting. Pharmacological research is important in academic research (medical and non-medical), private industrial positions, science writing, scientific patents and law, consultation, biotech and pharmaceutical employment, the alcohol industry, food industry, forensics/law enforcement, public health, and environmental/ecological sciences. Pharmacology is often taught to pharmacy and medicine students as part of a Medical School curriculum.
Psychopharmacology, also known as behavioral pharmacology, is the study of the effects of medication on the psyche (psychology), observing changed behaviors of the body and mind, and how molecular events are manifest in a measurable behavioral form. 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. Psychopharmacologists typically animal models to study psychotherapeutic drugs such as antipsychotics, antidepressants and anxiolytics, and drugs of abuse such as nicotine, cocaine and methamphetamine. The field of neuropsychopharmacology investigates drugs in the context of the overlap between the nervous system and the psyche.
Pharmacometabolomics, also known as pharmacometabonomics, is a field which stems from metabolomics, the quantification and analysis of metabolites produced by the body. It refers to the direct measurement of metabolites in an individual's bodily fluids, in order to predict or evaluate the metabolism of pharmaceutical compounds, and to better understand the pharmacokinetic profile of a drug. Alternatively, pharmacometabolomics can be applied to measure metabolite levels following the administration of a pharmaceutical compound, in order to monitor the effects of the compound on certain metabolic pathways(pharmacodynamics). This provides detailed mapping of drug effects on metabolism and the pathways that are implicated in mechanism of variation of response to treatment. In addition, the metabolic profile of an individual at baseline (metabotype) provides information about how individuals respond to treatment and highlights heterogeneity within a disease state. All three approaches require the quantification of metabolites found in bodily fluids and tissue, such as blood or urine, and can be used in the assessment of pharmaceutical treatment options for numerous disease states.
Pharmacogenomics is the application of genomic technologies to drug discovery and further characterization of older drugs. It investigates drugs in the context of all of an organism's genes. Similarly, pharmacogenetics is clinical testing of genetic variation that gives rise to differing response to drugs. It investigates drugs in the context of particular genes. Pharmacoepigenetics is an emerging field that studies the underlying epigenetic marking patterns that lead to variation in an individual's response to medical treatment.
Pharmacomicrobiomics, first used in 2010, is defined as the effect of microbiome variations on drug disposition, action, and toxicity. Pharmacomicrobiomics is concerned with the interaction between xenobiotics, or foreign compounds, and the gut microbiome. It is estimated that over 100 trillion prokaryotes representing more than 1000 species reside in the gut. Within the gut, microbes help modulate developmental, immunological and nutrition host functions. The aggregate genome of microbes extends the metabolic capabilities of humans, allowing them to capture nutrients from diverse sources. Namely, through the secretion of enzymes that assist in the metabolism of chemicals foreign to the body, modification of liver and intestinal enzymes, and modulation of the expression of human metabolic genes, microbes can significantly impact the ingestion of xenobiotics.
Clinical divisions and drug development
A toxicologist working in a lab
Clinical pharmacology is the basic science of pharmacology with an added focus on the application of pharmacological principles and methods in the medical clinic and towards patient care and outcomes.
Toxicology is the study of the adverse effects, molecular targets, and characterization of drugs or any chemical substance in excess (including those beneficial in lower doses). Toxicology may be regarded as a separate field to pharmacology. Similarly, pharmacotoxicology and neurotoxicology investigate the toxicity of substances from pharmacological and neurological perspectives.
Pharmacoeconomics refers to the scientific discipline that compares the value of one pharmaceutical drug or drug therapy to another. It is a sub-discipline of health economics. A pharmacoeconomic study evaluates the cost (expressed in monetary terms) and effects (expressed in terms of monetary value, efficacy or enhanced quality of life) of a pharmaceutical product. Pharmacoeconomic studies serve to guide optimal healthcare resource allocation, in a standardized and scientifically grounded manner.
Safety pharmacology specialises in detecting and investigating potential undesirable pharmacodynamic effects of new chemical entities (NCEs) on physiological functions in relation to exposure in the therapeutic range and above.
Posology is the study of how medicines are dosed. This depends upon various factors including age, climate, weight, sex, elimination rate of drug, genetic polymorphism and time of administration. It is derived from the Greek words πόσος posos meaning "how much?" and -λογία -logia "study of".
Pharmacocybernetics (also known as pharma-cybernetics, cybernetic pharmacy and cyberpharmacy) is an upcoming field that describes the science of supporting drugs and medications use through the application and evaluation of informatics and internet technologies, so as to improve the pharmaceutical care of patients. It is an interdisciplinary field that integrates the domains of medicine and pharmacy, computer sciences (informatics, cybernetics, interactive digital media, human-computer-environment interactions) and psychological sciences to design, develop, apply and evaluate technological innovations which improve drugs and medications management, as well as prevent or solve drug-related problems.
Photopharmacology is an emerging approach in medicine in which drugs are activated and deactivated with light. The energy of light is used to change for shape and chemical properties of the drug, resulting in different biological activity. This is done to ultimately achieve control when and where drugs are active in a reversible manner, to prevent side effects and exposure to the environment of antibiotics. Switching drugs 'on' and 'off' is achieved by introducing photoswitches such as azobenzene, spiropyran or diarylethene into the drug. By introducing the photoswitch, the drug has two different states between which can be switched with light. Since both states have a different structure, the activity of the drug is different hence the 'on' and 'off' state of the drug
Newspaper headlines from around the world about polio vaccine tests (13 April 1955)
Pharmacology can be studied in relation to wider contexts.
Pharmacoenvironmentology or 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 are 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. This field is intimately linked with Public Health fields. Environmental pharmacology studies the environmental effect of pharmaceuticals and personal care products (PPCPs) is currently being widely investigated. PPCPs include substances used by individuals for personal health or cosmetic reasons and the products used by agribusiness to boost growth or health of livestock. More than twenty million tons of PPCPs are produced every year. PPCPs have been detected in water bodies throughout the world. The effects of these chemicals on humans and the environment are not yet known, but to date there is no scientific evidence that they affect human health. This relates to the broader fields of ecology and public health.Environmental pharmacology considers the effect of pharmaceuticals and personal care products in the environment.
Interactions between proteins are frequently visualized and analyzed using networks. This network is made up of protein–protein interactions from Treponema pallidum, the causative agent of syphilis and other diseases.
Theoretical pharmacology is a relatively new and rapidly expanding field of research activity in which many of the techniques of computational chemistry, in particular computational quantum chemistry and the method of molecular mechanics, are proving to be of great value. Theoretical pharmacologists aim at rationalizing the relation between the activity of a particular drug, as observed experimentally, and its structural features as derived from computer experiments. They aim to find structure—activity relations. Furthermore, on the basis of the structure of a given organic molecule, the theoretical pharmacologist aims at predicting the biological activity of new drugs that are of the same general type as existing drugs. More ambitiously, it aims to predict entirely new classes of drugs, tailor-made for specific purposes. Similarly, pharmacometrics are mathematical models of biology, pharmacology, disease, and physiology used to describe and quantify interactions between xenobiotics and patients (human and non-human), including beneficial effects and adverse effects. It is normally applied to quantify drug, disease and trial information to aid efficient drug development, regulatory decisions and rational drug treatment in patients.
Experimental pharmacology involves the study of pharmacology through bioassay, to test the efficacy and potency of a drug.
Ethopharmacology (not to be confused with ethnopharmacology) is a term which has been in use since the 1960s and derives from the Greek word ἦθος ethos meaning character and "pharmacology" the study of drug actions and mechanism.[clarification needed] Ethopharmacology relates to ethology and studies drugs in the context of animal behaviours.
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).
Medication is said to have a narrow or wide therapeutic index,certain safety factor 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, aminoglycosideantibiotics). Most anti-cancer drugs have a narrow therapeutic margin: toxic side-effects are almost always encountered at doses used to kill tumors.
The metabolic stability and the reactivity of a library of candidate drug compounds have to be assessed for drug metabolism and toxicological studies. Many methods have been proposed for quantitative predictions in drug metabolism; one example of a recent computational method is SPORCalc.[dead link] If the chemical structure of a medicinal compound is altered slightly, this could slightly or dramatically alter the medicinal properties of the compound depending on the level of alteration as it relates to the structural composition of the substrate or receptor site on which it exerts its medicinal effect, a concept referred to as the structural activity relationship (SAR). This means that when a useful activity has been identified, chemists will make many similar compounds called analogues, in an attempt to maximize the desired medicinal effect(s) of the compound. This development phase can take anywhere from a few years to a decade or more and is very expensive.
These new analogues need to be developed. It needs to be determined how safe the medicine is for human consumption, its stability in the human body and the best form for delivery to the desired organ system, like tablet or aerosol. After extensive testing, which can take up to 6 years, the new medicine is ready for marketing and selling.
As a result of the long time required to develop analogues and test a new medicine and the fact that of every 5000 potential new medicines typically only one will ever reach the open market, this is an expensive way of doing things, often costing over 1 billion dollars. To recoup this outlay pharmaceutical companies may do a number of things:
Carefully research the demand for their potential new product before spending an outlay of company funds.
Obtain a patent on the new medicine preventing other companies from producing that medicine for a certain allocation of time.
The inverse benefit law describes the relationship between a drugs therapeutic benefits and its marketing.
When designing drugs, the placebo effect must be considered to assess the drug's true therapeutic value.
Drug development uses techniques from medicinal chemistry to chemically design drugs. This overlaps with the biological approach of finding targets and physiological effects.
The drug must be found to be effective against the disease for which it is seeking approval (where 'effective' means only that the drug performed better than placebo or competitors in at least two trials).
The drug must meet safety criteria by being subject to animal and controlled human testing.
Gaining FDA approval usually takes several years. Testing done on animals must be extensive and must include several species to help in the evaluation of both the effectiveness and toxicity of the drug. The dosage of any drug approved for use is intended to fall within a range in which the drug produces a therapeutic effect or desired outcome.
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