Flashcards in Pharmacokinetics Deck (56)
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1
name the two general types of transport
-transcellular transport
-intercellular transport
2
name ways of transversing a cell membrane
-diffusion
-filtration
-facilitated diffusion
-active transport
-pinocytosis
3
whats the most common and important mode of transversing biological mambranes
diffusion
4
in which direction does diffusion go
down the cc gradient
5
what significantly influences diffusion
-lipid-water partition of drug
-thiccness of the cell membrane
6
how does the pk value influence drug transport
-different pk values will diffuse differently
7
the cc gradient affects the rate of filtration t/f
t
8
does facilitated diffusion requ. E ?
no
9
is facilitated diffusion saturable
yes
10
describe active transport
-requ. energy
-against cc gradient
-occurs only in one direction
-is saturable
11
describe the phases of absorption
1 - administration
2 -has to be taken up into bloodstream
3 - uptake into target organ
12
what could reduce compound absorption
- poor solubility
-chemical instability in stomach
-ianbility to penetrate int. wall
13
define bioavailability
the fraction of drug that reaches the bloodstream unaltered
-measrement of the extent of a therapeutically active drug that reaches systemic circulation and is available @ site of action
14
define absolute bioavailability
availability of active drug in circulation after non -IV admin.
15
what is the absolute bioavailability of drug admin. IV
1
16
name factors influencing bioav. (7)
-absorption rate
-degradation or metabolism of drug prior to hepatic absorption
-first pass effect
-food taken with p.o. admin
-other drugs
-intest. mot.
-liver state
17
is distribution reversible
yes
18
what does distribution depnd on
-permeability between tissues
-blood flow and perfusion rate
-ability of drug to bind to plasma proteins and tissues
19
rank the flow of the organs liver, bone, fat, skin, muscle, kidney, brain
brain, liver, kidney>muscle, skin> fat, bone
20
factors affecting drug distr.
-dose
-admin.
-membrane permeabilty
-blood perfusion
-lipid solubility
-ph-pka
-plasma protein binding
-intracellular binding
21
how do drugs travel in plasma
free or bound to plasma proteins
22
the drug plasma protein binding is always at least 10%
f
23
name the main points of plasma protein binding
-generally reversible
-only the free drugs diffuse through capillary walls
-extensive binding may prolong duration of action
-some plasma proteins bind many different drugs some just one
-changes in PPB can lead to change in drug effect
24
what is the volume of distr.
VD= volume of total body fluid in which the drug appears to be distributing
25
how would you calculate the vd
amount of drug administered/initial plasma cc
26
for the majority of the drugs the vd is an accurate representation of their actual distribution t/f
f
27
the lower the VD of a drug the more it spreads through the body t/f
f
28
What does a low VD indicate in regards to PPB
extensive plasma protein binding
29
A very high VD may indicate extensive tissue binding t/F
t
30
