In physiology Physiology is the science of the functioning of living systems. It is a subcategory of biology. In physiology, the scientific method is applied to determine how organisms, organ systems, organs, cells and biomolecules carry out the chemical or physical function that they have in a living system. The word physiology is from Greek φύσις, physis,, physiological tolerance or drug tolerance is commonly encountered in pharmacology Pharmacology is the study of drug action. More specifically, it is the study of the interactions that occur between a living organism and exogenous chemicals that alter normal biochemical function. If substances have medicinal properties, they are considered pharmaceuticals. The field encompasses drug composition and properties, interactions,, when a subject's reaction to a drug (such as an opiate In medicine, the term opiate describes any of the narcotic opioid alkaloids found as natural products in the opium poppy plant, as well as many semisynthetic chemical derivatives of such alkaloids painkiller, benzodiazepine A benzodiazepine is a psychoactive drug whose core chemical structure is the fusion of a benzene ring and a diazepine ring. The first benzodiazepine, chlordiazepoxide (Librium), was discovered accidentally by Leo Sternbach in 1955, and made available in 1960 by Hoffmann–La Roche, which has also marketed diazepam (Valium) since 1963 or other psychotropic drug) decreases[1] so that larger doses are required to achieve the same effect. Drug tolerance can involve both psychological drug tolerance Drug addiction is a pathological condition which arises due to frequent drug use. The disorder of addiction involves the progression of acute drug use to the development of drug-seeking behavior, the vulnerability to relapse, and the decreased, slowed ability to respond to naturally rewarding stimuli. The Diagnostic and Statistical Manual of and physiological In physiology, physiological tolerance or drug tolerance is commonly encountered in pharmacology, when a subject's reaction to a drug decreases so that larger doses are required to achieve the same effect. Drug tolerance can involve both psychological drug tolerance and physiological factors. Characteristics of drug tolerance: it is reversible, factors. Characteristics of drug tolerance: it is reversible, the rate depends on the particular drug, dosage and frequency of use, differential development occurs for different effects of the same drug. Physiological tolerance also occurs when an organism builds up a resistance to the effects of a substance after repeated exposure. This can occur with environmental substances, such as salt or pesticides.

Tachyphylaxis Tachyphylaxis is a medical term describing 'A rapid decrease in the response to a drug after repeated doses over a short period of time'. Increasing the dose of the drug will not increase the pharmacological response. Tachyphylaxis may develop with an initial dose. The cause of this phenomenon is depletion of the neurotransmitter that is involved is a medical term referring to the rapid decrease in response to a drug after repeated doses over a short period of time.

Mechanisms

There are two major mechanisms for tolerance:

See also

References

  1. ^ MeSH Medical Subject Headings is a comprehensive controlled vocabulary for the purpose of indexing journal articles and books in the life sciences; it can also serve as a thesaurus that facilitates searching. Created and updated by the United States National Library of Medicine (NLM), it is used by the MEDLINE/PubMed article database and by NLM's Drug+Tolerance
  2. ^ Klaassen, Curtis D. (2001-07-27). Casarett & Doull's Toxicology: The Basic Science of Poisons (6th ed.). McGraw-Hill Professional. pp. 17. ISBN The International Standard Book Number is a unique numeric commercial book identifier based upon the 9-digit Standard Book Numbering (SBN) code created by Gordon Foster, now Emeritus Professor of Statistics at Trinity College, Dublin, for the booksellers and stationers W.H. Smith and others in 1966 0071347216.
Medication A pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease > Pharmacology Pharmacology is the study of drug action. More specifically, it is the study of the interactions that occur between a living organism and exogenous chemicals that alter normal biochemical function. If substances have medicinal properties, they are considered pharmaceuticals. The field encompasses drug composition and properties, interactions,
Pharmacokinetics Pharmacokinetics, sometimes abbreviated as PK, is a branch of pharmacology dedicated to the determination of the fate of substances administered externally to a living organism. In practice, this discipline is applied mainly to drug substances, though in principle it concerns itself with all manner of compounds ingested or otherwise delivered

ADME ADME is an acronym in pharmacokinetics and pharmacology for absorption, distribution, metabolism, and excretion, and describes the disposition of a pharmaceutical compound within an organism. The four criteria all influence the drug levels and kinetics of drug exposure to the tissues and hence influence the performance and pharmacological activity: Absorption In pharmacology , absorption is the movement of a drug into the bloodstream • Distribution Distribution in pharmacology is a branch of pharmacokinetics which describes the reversible transfer of drug from one location to another within the body • Metabolism Drug metabolism is the metabolism of drugs, their biochemical modification or degradation, usually through specialized enzymatic systems. This is a form of xenobiotic metabolism. Drug metabolism often converts lipophilic chemical compounds into more readily excreted polar products. Its rate is an important determinant of the duration and intensity • Excretion Excretion is the process of eliminating waste products of metabolism and other non-useful materials. It is an essential process in all forms of life. It contrasts secretion, where the substance may have specific tasks after leaving the cell (Clearance In medicine, the clearance is a measurement of the renal excretion ability. Although clearance may also involve other organs than the kidney, it is almost synonymous with renal clearance or renal plasma clearance. Each substance has a specific clearance that depends on its filtration characteristics. Clearance is a function of glomerular)

Loading dose In pharmacokinetics, a loading dose refers to an initial higher dose of a drug that may be given at the beginning of a course of treatment before dropping down to a lower maintenance dose • Volume of distribution The volume of distribution , also known as apparent volume of distribution, is a pharmacological term used to quantify the distribution of a medication between plasma and the rest of the body after oral or parenteral dosing. It is defined as the volume in which the amount of drug would need to be uniformly distributed to produce the observed blood (Initial The initial volume of distribution is a pharmacological term used to quantify the distribution of a drug throughout the body relatively soon after oral or intravenous dosing of a drug and prior to the drug reaching a steady state equilibrium. Following distribution of the drug, measurement of blood levels indicate the apparent volume of) • Rate of infusion In pharmacokinetics, the rate of infusion refers not just to the rate at which a drug is administered, but the desired rate at which a drug should be administered to achieve a steady state of a fixed dose which has been demonstrated to be therapeutically effective

Compartment In pharmacokinetics, a compartment is a defined volume of body fluids. It is distinguished from anatomic compartments, which are bounded by fasciae. It is used in multi-compartment models • Bioequivalence Bioequivalence is a term in pharmacokinetics used to assess the expected in vivo biological equivalence of two proprietary preparations of a drug. If two products are said to be bioequivalent it means that they would be expected to be, for all intents and purposes, the same • Bioavailability In pharmacology, bioavailability is used to describe the fraction of an administered dose of unchanged drug that reaches the systemic circulation, one of the principal pharmacokinetic properties of drugs. By definition, when a medication is administered intravenously, its bioavailability is 100%. However, when a medication is administered via

Onset of action Onset of action is the duration of time it takes for a drug's effects to come to prominence upon administration. With oral consumption, it typically ranges anywhere from 20 minutes to over an hour, depending on the drug in question. Other methods of ingestion such as smoking or injection can take as little as seconds to minutes to take effect • Biological half-life The biological half-life or elimination half life of a substance is the time it takes for a substance to lose half of its pharmacologic, physiologic, or radiologic activity, as per the MeSH definition. In a medical context, half-life may also describe the time it takes for the blood plasma concentration of a substance to halve ("plasma half- • Plasma protein binding A drug's efficiency may be affected by the degree to which it binds to the proteins within blood plasma. The less bound a drug is, the more efficiently it can traverse cell membranes or diffuse. Common blood proteins that drugs bind to are human serum albumin, lipoprotein, glycoprotein, α, β‚ and γ globulins

Phase 1 reaction Actions include oxidation, reduction, and hydrolysis • Phase 2 reaction Some phase 2 reactions include glucuronidation, sulfation, methylation, acetylation, Glutathione conjugation and amino acid conjugation

Therapeutic index The therapeutic index , is a comparison of the amount of a therapeutic agent that causes the therapeutic effect to the amount that causes death. Quantitatively, it is the ratio given by the lethal dose divided by the therapeutic dose. A therapeutic index is the lethal dose of a drug for 50% of the population (LD50) divided by the minimum effective (LD50 In toxicology, the median lethal dose, LD50 , LC50 (Lethal Concentration, 50%) or LCt50 (Lethal Concentration & Time) of a toxic substance or radiation is the dose required to kill half the members of a tested population. LD50 figures are frequently used as a general indicator of a substance's acute toxicity. The test was created by J.W/ED50 An effective dose in pharmacology is the amount of drug that produces a therapeutic response in 50% of the people taking it, sometimes also called ED-50. In radiation protection it is an estimate of the stochastic effect that a non-uniform radiation dose has on a human.It is measure of potency of the drug)
Pharmacodynamics Pharmacodynamics is the study of the physiological effects of drugs on the body or on microorganisms or parasites within or on the body and the mechanisms of drug action and the relationship between drug concentration and effect. One dominant example is drug-receptor interactions as modeled by

Toxicity Toxicity is the degree to which a substance is able to damage an exposed organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ (organotoxicity), such as the liver (hepatotoxicity). By extension, the word may be (Neurotoxicology A neurotoxin is a toxin that acts specifically on nerve cells , usually by interacting with membrane proteins such as ion channels) • Dose-response relationship The dose-response relationship, or exposure-response relationship, describes the change in effect on an organism caused by differing levels of exposure to a stressor (usually a chemical) after a certain exposure time. This may apply to individuals (eg: a small amount has no observable effect, a large amount is fatal), or to populations (eg: how (Efficacy In a healthcare context, efficacy indicates the capacity for beneficial change of a given intervention (e.g. a medicine, medical device, surgical procedure, or a public health intervention), Potency In the field of pharmacology, potency is a measure of drug activity expressed in terms of the amount required to produce an effect of given intensity. A highly potent drug evokes a larger response at low concentrations, while a drug of lower potency (ibuprofen, acetylsalicylic acid) evokes a small response at low concentrations. It is proportional)

Antimicrobial pharmacodynamics Antimicrobial pharmacodynamics is a term used to describe the relationship between concentration of antibiotic and its ability to inhibit vital processes of endo- or ectoparasites and microbial organisms. This branch of pharmacodynamics relates concentration of an anti-infective agent to effect, but specifically to its antimicrobial effect: Minimum inhibitory concentration Minimum inhibitory concentration , in microbiology, is the lowest concentration of an antimicrobial that will inhibit the visible growth of a microorganism after overnight incubation. Minimum inhibitory concentrations are important in diagnostic laboratories to confirm resistance of microorganisms to an antimicrobial agent and also to monitor the/Bacteriostatic Bacteriostatic antibiotics limit the growth of bacteria by interfering with bacterial protein production, DNA replication, or other aspects of bacterial cellular metabolism • Minimum bactericidal concentration/Bactericide
Agonism and antagonism

Agonist: Inverse agonist • Irreversible agonist • Partial agonist • Superagonist • Physiological agonist

Antagonist: Competitive antagonist • Irreversible antagonist • Physiological antagonist

Other: Binding • Affinity • Binding selectivity • Functional selectivity
Other

Drug tolerance: Tachyphylaxis

Drug resistance: Antibiotic resistance • Multiple drug resistance
Related fields/subfields Pharmacogenetics • Pharmacogenomics • Neuropsychopharmacology (Neuropharmacology, Psychopharmacology)
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'Drug Tolerance' News
It's time to bury all those 'shovel-ready' words and phrases - Dubuque Telegraph Herald
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It's time to bury all those 'shovel-ready' words and phrases

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"Make no mistake" that while we're "moving forward" into 2010, we should have "zero tolerance " for school officials who expel little kids for bringing ...



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Most importantly, imitrex results in drug tolerance .
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Most importantly, imitrex results in drug tolerance .

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Because imitrex is addictive, you take the risk of becoming dependent on it if you don't take it under the supervision of your doctor. There is too much violence i...

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Does drug tolerance decrease over time?
Q. I've noticed how easy it is to become "habituated" to drugs, and to start tolerating them more and more. I'm not addicted in a physical sense, so that's not the issue. I've been on Ambien (zolpidem) since I was 18 - I'm 23 today. I started with 5mg, but have now been upped to 25mg a day, which is how high my doctor will go. Keep in mind that the normal dose for Ambien is 5-10mg a night. Even the 25mg is starting to work less efficiently for me, which is why I'll more than likely be switching to a different drug that doesn't work as well soon. (I've tried all hypnotics, benzos, barbiturates, and melatonin drug; Ambien is the only thing that really works well for me) I was wondering how long it takes your body to "reset" its tolerance… [cont.]
Asked by ShaunAverett - Thu Jul 10 03:08:53 2008 - - 1 Answers - 0 Comments

A. nah, a year seems fine...all drug tolerance goes down eventually, but it takes more time for some and quite a bit less for some...like caffine takes 8-10 weeks to get out of your system...check out the pharmacology of it...
Answered by The Knight in Shining Armour - Thu Jul 10 03:38:06 2008

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