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ONE COMPARTMENT OPEN MODEL
TNTRAvENOUS BOLUS ADMI NIS TRATION.
" when a drug that distibues raptdly nthe body
ts qiven n the qonm o7 a raptd mtraeno us hection
(i-e v bolus or slug), ?t takes about one to three
mfhutes tor complete Crulation and theekore te the
The Model can be deprcted as fllows
Drug
Ka Input body tissues (Absovption)
to the body s dz dt
Bood othut
.The Generad Kapresson tor Rot o7 drug presentation
equation
dt
be
output
(eltrrtnation).
Snce, RaBe in oY absorption o absent, the
be comnes;
- Rate^ (tn)-^ Rate^ (out)^ )
-Rate ot
Metabolism Ecreton
-(2)
Tate of absor pion is negdeckd &n caleulations.
Sinst-orden
whene,
1
d
Ahe boduy.
climfnalion follo us hinefis, then i
Finst oydn^ elinfnaion^ rote^ Constont
X =^ Amount^ ob^ druq^ tn^ body^ at^ any^ time^ t
umaning to^ be^ eltminated.
've' Sian ndicas^ tha^ the^ dYug^ é^ befng^ Aost^ trom
ESTIMAT 1ON OF PHARMPCOKINErLC PARAMETER
Elontn ation^ Rate^ Conatunt^ (KE^ )
2 Elenfnaton^ Half^ 137e^ (ty).
3 Appar^ ent^ rolure^ o^ distrtbution^
(va)
4t clearane (ci).
1. Elfninate^ Rate^ Constant^ (Ke)
Inteqrotion o Equation (3)yield. , H).
whne Co (^) plasma (^) drug (^) cone (^) fromediately affer
I.V ?nieion
. Equaton(e) is that astathtShaight tne and
Gndtcates the Semi-loq dot ot loq C versus t will bt lineaY witth
. The eliifnaion Rate (onstant ds dintcdly obtahed
1Om he^ slope^ of^ the^ g^ line
LoqConcertrotion-s
d
" 14 hus units o min
Log 1
y- (^) întercept log (^) Co
Slope
Time
2.303 (ty-t)
EL?nfnation Halk Lefe (ty)
Also (aled os Biologit al Haly Lite
s the time taken oT the amOunt
oh druq in the body cs well as plasma Con entaian
to decdine by one - Half or 50% itt fnitia value
Halt,,l?e & aelated to eleination rate let Constont by tol louoing equalion;
ty, :^ 0.693.^ (9)
Seconday aromoter daperdert prfrnang poromakrs clearonce (cu) and aparent volume ok distrbution (vA)) O,693 Va (^) (to)
- (^) Appayent (^) volume of (^) Distribuon (va).
VA is (^) the (^) measure o (^) the (^) extnt ok (^) distibution ok drug and us enpressed fn I?tres.
on
Anount o drug n body
plagma dry concentecton
X C.
b} Hepatie^ cleavan^ ce^ i
X (^) : Vd
Rate oh^ elinsnotion^ by^ 1fver (oncentation
kmX
ct Orqan cleaYance
C
Rate o elinnation by orqan =
Clerqan
whne
Rate o pesertation to orqan
Rate o^ elininatio^ n^ Cn^ Cout
Rat h exit
trom the oggan.
ER = (Ctn - Cautcn
-(a4)
Eivsion of above equaton by concentraton of
drug that entess the orqan o elfnnation (c tn) yields an exorss ion for Cearane of drug by
Extacien Rato.
-(15)
& called as
orqan unds^ considaion.^ Thus,
Based on^ ER (^) values, (^) drugdrug
dru qs^ wi^ th^ Low
Can be (^) classtfied tnto (^3) qro (^) upsi
drens with^ ntermed+ate^ ER^ (betwten^ o,4^ -^ 0.3)
ER (below a3)
an todx
(above .4)
an fndux^ of^ houw^ Hienty^ the^ elminaing tt o drg
ER.
orqan clea1s the bloocd fluingyouwing tthroughit
