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#pharmacology #selectivity #specificity #su803
Selectivity depicts a molecule with greater affinity for one receptor
(or
any process for that matter) over another. The key is that implicit
in this
definition (or rather characterization), is that the selectivity can be
"overcome" by overloading the system, and the "other" receptor
experiences
binding and/or activation.

Specificity takes selectivity one step further, where no increase in the
ligand or molecule of interest can activate the other receptor(s).
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PharmPK Discussion List Archive - PK2008445.html - 2008
ed,Bioanalytical Division,Bangalore,Email: vijay_b.aaa.aurigene.com Back to the Top On 9 Dec 2008 at 13:00:25, "Shawn Spencer" (shawn.spencer.aaa.famu.edu) sent the message The following message was posted to: PharmPKSure Vijay,<span>Selectivity depicts a molecule with greater affinity for one receptor(orany process for that matter) over another. The key is that implicitin thisdefinition (or rather characterization), is that the selectivity can be"overcome" by overloading the system, and the "other" receptorexperiencesbinding and/or activation.Specificity takes selectivity one step further, where no increase in theligand or molecule of interest can activate the other receptor(s).Hope that helps.CheersSHAWN SPENCER, PhD.Assistant Professor of BiopharmaceuticsDyson Bldg., Rm 227College of Pharmacy and Pharmaceutical SciencesFlorida A&M UniversityTallahassee, F




#pharmacology #selectivity #specificity #su803
Here are my two cents:

The words selectivity, specificity, and sensitivity (derived from
Latin seligere, specificus, sensitivus), can be confusing terms as
they are often used synonymously in the medical literature. However,
they should not be used interchangeably as each represents a different
phenomenon:

The word selectivity describes a drug's ability to affect a particular
cell populationin preference to others. Selectivity is generally a
worthy property in a drug because a drug having high selectivity may
have a dramatic effect when there is a single agent that can be
targeted against the appropriate molecular-driver involved in the
pathogenesis of a disease. Selectivity is used to describe the
ability of a drug to affect a particular population, i.e., gene,
protein, signaling pathway, or cell, in preference to others. For
example a selective drug would have the ability to discriminate
between cell or receptor populations, and so affect only one cell
population, and thereby produce an event.

Specificity, a term most often confused with selectivity, is used to
describe the capacity of a drug to cause a particular action in a
population. For example, a drug of absolute specificity of action
might decrease or increase, a specific function of a given gene or
protein or cell type, but it must do either, not both.

Sensitivity is used to describe the capacity of a population, to
respond to a drug's ability, to stimulate that entity at a specified
dose. The smaller the dose required producing an effect, the more
sensitive is the responding system. (The word used to describe this
activity in the drug which is the cause of the population sensitivity,
is potency).
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PharmPK Discussion List Archive - PK2008445.html - 2008
e of Pharmacy and Pharmaceutical SciencesFlorida A&M UniversityTallahassee, FL 32307shawn.spencer.aaa.famu.edu Back to the Top On 9 Dec 2008 at 13:45:13, "Murad Melhem" (melhemmr.at.gmail.com) sent the message Hi Veeravalli,<span>Here are my two cents:The words selectivity, specificity, and sensitivity (derived fromLatin seligere, specificus, sensitivus), can be confusing terms asthey are often used synonymously in the medical literature. However,they should not be used interchangeably as each represents a differentphenomenon:The word selectivity describes a drug's ability to affect a particularcell populationin preference to others. Selectivity is generally aworthy property in a drug because a drug having high selectivity mayhave a dramatic effect when there is a single agent that can betargeted against the appropriate molecular-driver involved in thepathogenesis of a disease. Selectivity is used to describe theability of a drug to affect a particular population, i.e., gene,protein, signaling pathway, or cell, in preference to others. Forexample a selective drug would have the ability to discriminatebetween cell or receptor populations, and so affect only one cellpopulation, and thereby produce an event.Specificity, a term most often confused with selectivity, is used todescribe the capacity of a drug to cause a particular action in apopulation. For example, a drug of absolute specificity of actionmight decrease or increase, a specific function of a given gene orprotein or cell type, but it must do either, not both.Sensitivity is used to describe the capacity of a population, torespond to a drug's ability, to stimulate that entity at a specifieddose. The smaller the dose required producing an effect, the moresensitive is the responding system. (The word used to describe thisactivity in the drug which is the cause of the population sensitivity,is potency).I hope this helps.Murad Back to the Top On 9 Dec 2008 at 20:11:17, =?ISO-8859-1?Q?Andr=E9_Mateus?= (andrenmateus.-at-.gmail.com) sent the message The following message was posted to




#pharmacology #selectivity #specificity #su803
A method is specific if it produces a response for only one single
analyte. Since it is almost impossible to develop a chromatographic
assay for a drug in a biological matrix that will respond to only the
compound of interest, the term selectivity is more appropriate.
Selectivity of a method is its ability to produce a response for the
target analyte which is distinguishable from all other responses (e.g.
endogenous compounds).
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PharmPK Discussion List Archive - PK2008445.html - 2008
NIPER,Sec-67, S.A.S. NagarMohali, Punjab-160062 Back to the Top On 11 Dec 2008 at 13:04:41, "Sivacharan Kollipara" (Sivacharan.Kollipara.-at-.ranbaxy.com) sent the message The following message was posted to: PharmPKDear Sachin,<span>A method is specific if it produces a response for only one singleanalyte. Since it is almost impossible to develop a chromatographicassay for a drug in a biological matrix that will respond to only thecompound of interest, the term selectivity is more appropriate.Selectivity of a method is its ability to produce a response for thetarget analyte which is distinguishable from all other responses (e.g.endogenous compounds).J. LIQ. CHROM. & REL TECHNOL., 23(3), 329-354 (2000).You can also find the cross references in the same article.Hope this helps.RegardsSivacharan KolliparaMetabolism & Pharmacoki




Specificity vs. Selectivity, and the Therapeutic Window
#pharmacology #selectivity #specificity #su803

If a drug has one effect, and only one effect on all biological systems it possesses the property of specificity. In experience, the vast majority of drugs are selective rather than specific. This is the case because most drugs will act on more than one receptor site once they reach an appropriately high concentration. Two examples include: a) verapamil, a blocker of L-type Ca channels, but which blocks Na channels at high concentrations; b) yohimbine a drug used therapeutically as an α2-adrenoceptor blocker but which also blocks 5-HT receptors, α1-adrenoceptors, Na channels, monoamine oxidase, and cholinesterase at higher concentrations. The concentration range over which a drug produces its therapeutic effect is known as its therapeutic window. An illustration of the therapeutic window for selective blockade of α2-adrenoceptors by yohimbine is shown in Figure 11.

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ses when stimulated. These receptor subtypes are not typically expressed in equal amounts in the same tissue (e.g. vascular smooth muscle contains more α receptors (α » β ), whereas bronchial tissue contains more β receptors (β » α). <span>Specificity vs. Selectivity, and the Therapeutic Window If a drug has one effect, and only one effect on all biological systems it possesses the property of specificity . In experience, the vast majority of drugs are selective rather than specific. This is the case because most drugs will act on more than one receptor site once they reach an appropriately high concentration. Two examples include: a) verapamil, a blocker of L-type Ca channels, but which blocks Na channels at high concentrations; b) yohimbine a drug used therapeutically as an α2-adrenoceptor blocker but which also blocks 5-HT receptors, α1-adrenoceptors, Na channels, monoamine oxidase, and cholinesterase at higher concentrations. The concentration range over which a drug produces its therapeutic effect is known as its therapeutic window . An illustration of the therapeutic window for selective blockade of α2-adrenoceptors by yohimbine is shown in Figure 11. Figure 11. The therapeutic window for selective blockade of α2 - adrenoceptors by yohimbine. Similar to most drugs, yohimbine lacks true specificity in its biological actions.