receptor workbook

8/8/2019 Receptor Workbook

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Pharma codyn am ics:

Mec ha nism s of ActionRecepto r inte ra ctionEnzym e inte ra ction

Nonspecific inte ra ctions


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Inst ructo rs ma y wish to inse rtEIC Imag e #2:

Drugs and Recepto rs

and possiblyEIC Imag e #7:

Drug-Recepto r Inte ra ctions: Definitions


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Receptor: Any cellul ar ma crom olecule t ha t a drug binds to initi a te its effects.

D rug: A chem ica l subst ance t ha t inte ra cts wit h a biolo gica l syste m to p roduce a physiolo giceffect


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All drugs ar e c hem ica ls but not a ll chem ica lsar e d rugs.ability to bind to a recepto r is m edi a ted by t hechem ica l st ructu re of t he d rug tha t a llows it tointe ra ct wit h com ple m ent ar y su rf aces on t herecepto r.

Drugs t ha t inte ra ct wit h recepto rs can beclassified as bein g eit he r a gonists or a nt a gonists


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A nt a gonists

hav e t he ability to bind to t he recepto r but donot initi a te a cha nge in cellul ar function.

Because t hey occupy t he recepto r, they c anprevent t he bindin g and t he action of ag onists. Hence t he te rm ant ag onist.Antag onists ar e a lso refe rr ed to as bl ockers.


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U n like competitive a nt a gonists, the bl ocking

a ctivity of irreversi bl e receptor a nt a gonistsca n not b e overcome b y incre a sing thea gonist concentr a tion


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F u ll a nd P a rti al A gonists

Fu ll A gonists : C om pounds t ha t ar e able toelicit a max ima l response followin g recepto r occup a tion and activa tion.Pa rti al A gonists : C om pounds t ha t can activa terecepto rs but ar e un able to elicit t he max ima lresponse of t he recepto r syste m .


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receptors


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Fa ctors Governing D rug A ction

A ffinity is a me a sure of the tightness th a t a drug b inds to the receptor.

Intrinsic a ctivity is a me a sure of the ab ility of a drug once b ound to the receptor togener a te a n effect a ctiv a ting stimu lus a ndproducing a ch a nge in ce ll u la r a ctivity.


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T he bindin g of a drug to a recepto r is

dete rm ined by t he followin g forces:Hydrogen bonds

Ionic bonds

Van de r Waa ls fo rces

C ova lent bonds


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D ose-Response Curves

D ose-response re la tionships a re a commonw a y to portr a y d a t a in b oth ba sic a nd c linic al science.For ex a mp le, a clinic al study m a y ex a mine

the effect of incre a sing a mounts of a na n al gesic on p a in thresho ld


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A plot of d rug concent ra tion ([D]) ve rsus effect (E/E max ) (or for tha t ma tte r DR/RT ) is a rect angular hype rbol a . Notice howthe d rug effect reaches a pla te au o r max im um . T h is is bec ause

the re ar e a finite nu m be r of recepto rs. Hence , the responsem ust e ventu a lly reach a max im um


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T he T her a peutic IndexT he t he ra peutic inde x is t he ra tio of t he ED50

of a drug to p roduce a to xic effect to t he ED50to p roduce a the ra peutic effect.


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D RU G AND SOLUT ION MEA SU REMEN TS

oz. OunceG, gm gramgr gra in

gtt d ropKg kilogramL lite r

m cg m icrogramm Eq m illiequi va lentmg m illigramm l m illiliterpt pintqt qu ar tT bs , T tablespoonTsp , t te aspoon


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D RU G D OSAGE FORMS

cap capsuleDS double st ren gthEC ente ric co a ted

Elix elixirLiq liquidSol solutionSupp supposito ry

Susp suspensionSyr syrupTab t ablet


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T IMES O F D RU G AD MIN IST RAT ION

ac befo re m ea lsad lib as desi redBid twice a dayT id t hr ee ti m es a dayQid fou r tim es a daypc afte r m ea ls

Prn as needed

Da ily Eve ry dayQ h (hr ) eve ry hou rQ2h (hr ) eve ry 2 hou rsQ3h (hr ) eve ry 3 hou rsSta t-imm edi a tely

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