L2: pharmacokinetics Flashcards
(97 cards)
1
Q
pharmacokinetics
A
how drug moves through body
2
Q
routes of administration
A
enteral and parenteral
3
Q
enteral
A
via alimentary canal
4
Q
types of enteral administration
A
oral, sublingual/buccal, rectal
5
Q
oral administration
A
by mouth
6
Q
first-pass effect
A
drug is absorbed from small intestine, transported to liver and metabolized before entering systemic circulation
7
Q
sublingual administration
A
placed under tongue
8
Q
buccal administration
A
between cheek and gums
9
Q
sublingual and buccal administration characteristics
A
- absorbed through oral mucosa into venous system
- no first-pass effect
- fast
- easier than oral or rectal
- limited amounts can be absorbed this way
10
Q
oral admin characteristics
A
- safe, easy
- drugs can be difficult to absorb
- some drugs can be broken down too quickly
- subject to first-pass effect
- less predictable rate of absorption
- extended release formula
11
Q
rectal administration
A
rectum
12
Q
rectal admin characteristics
A
- some drugs are not absorbed well through rectum
- rectal mucosa can be irritated
- useful if patient is unconscious or has profuse vomiting
- useful for local conditions
13
Q
parenteral administration
A
alternative routes
14
Q
inhalation administration
A
airways
15
Q
inhalation admin characteristics
A
- useful for drugs that are gases or in aerosol form
- pulmonary administration
- may be for systemic or local use
- large surface area for absorption
- fast entry into bloodstream
- some drugs can irritate the respiratory tract
- difficult to predict how much drug will reach the target tissue
- can be difficult to self-administer for some patients
- some drugs are trapped in respiratory tract
16
Q
injection administration
A
- may be for systemic or local use
- sterility is so important
17
Q
types of injection administration
A
intravenous, intra-arterial, subcutaneous, intramuscular
18
Q
intravenous (injection) characteristics
A
- directly to peripheral vein
- Bolus: accurate quantity of drug, delivered in a short time
- reaches target site quickly
- can result in more adverse rxns
- Drip: prolonged, steady infusion via IV cannula
- maintains specific level without fluctuations
19
Q
intra-arterial (injection) characteristics
A
- directly into arterial bloodstream
- difficult and dangerous because artery could be damaged
20
Q
subcutaneous (injection) characteristics
A
- injection of medication directly beneath the skin
- used for: local response and slow systemic release
- Pros: self-admin
- Cons: amnt of drug is low
21
Q
intramuscular (injection) characteristics
A
- injection into skeletal mm.
- useful for: local tx and prolonged release
- Cons: can cause pain + mm. soreness
22
Q
intrathecal administration
A
delivery of meds. within a sheath
23
Q
intrathecal admin characteristics
A
- allows for local delivery to spinal cord
- allows bypass of blood-brain barrier to treat central nervous system»_space; allows ability to treat CNS
- ex. subarachnoid or epidural space
24
Q
topical administration
A
skin surface
25
topical admin characteristics
- local conditions on skin
- poorly absorbed through skin
- mucous membrane topical use - either for local or systemic conditions
- well-absorbed
- can cause adverse effects if - large amount of drug is absorbed
26
transdermal administration
via skin without degrading the dermis
27
transdermal admin characteristics
- applying drugs directly to the surface of the skin with the intent of absorption through dermal layers and into subcutaneous tissue or peripheral circulation
- slow, controlled release
- methods: patch, iontophoresis (via electrical current), phonophoresis (via ultrasound)
28
absorption
entry of drug into body
29
bioavailability
extent to which the drug reaches the systemic circulation (percent of administered drug that reaches the bloodstream)
30
bioavailability and absorption depends on
route of administration and drug's membrane permeability
31
distribution
movement of drug to target site
32
factors affecting distribution
membrane/tissue permeability, blood flow, binding to plasma proteins, binding to sub-cellular compartments
33
membrane/tissue permeability
how easy it is for drug to get in
34
blood flow
how much of that drug gets to target tissue is dependent on the quality of blood flow to that tissue
35
volume of distribution
amount of drug administered / concentration of drug in plasma
36
if Vd = body fluid volume
uniform distribution
37
if Vd < body fluid volume
retained in plasma
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Vd > body fluid volume
sequestered in tissues
39
drug storage in non-target sites
adipose, bone, muscle, organs
40
what non-target sites are implicated in physical therapy
adipose, bone, muscle
41
possible adverse consequences of storage
toxicity (leads to local damage) and reservoir effects
42
reservoir effect
drug may not reach target so possible drug redistribution much later than intended
43
biotransformation
chemical changes that take place in the drug AFTER administration
44
where does biotransformation typically occur
in liver via first-pass effect (metabolite)
45
biotransformation reactions (phase 1)
oxidation, reduction, hydrolysis
46
oxidation
addition of oxygen or removal of hydrogen
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reduction
opposite of oxidation
48
hydrolysis
breakdown into separate parts
49
enzyme induction
prolonged drug use enables enzymes to more easily break down the drug
50
adverse result of enzyme induction
tolerance (dependence issue)
51
elimination
needed to terminate drug's effects and remove it from body
52
excretion
removal of drug from body
53
where does excretion occur
kidneys or lungs if drugs are inhaled
54
what helps excretion occur
biotransformation creates polar, water-soluble metabolite
55
elimination rates
clearance and half life
56
clearance
systemic or organ-specific ability to eliminate drug
57
systemic clearance (CLsystemic)
rate of drug elimination / concentration of drug in plasma
58
organ-specifc clearance (CLorgan)
Q x (Ci - Co)/Ci
59
elimination rates through half life
amount of time necessary for 50% of the drug remaining to be eliminated
60
what is half life dependent on
clearance and volume of distribution which can be affected by disease states
61
implications of using a loading dose
inc. in half life takes less amount of time to get to ideal drug concentration in plasma
62
factors effecting drug response and elimination
genetics, disease, drug interactions, age, diet, sex, environmental
63
pharmacodynamics
how a drug interacts with the body
64
receptor
component of a cell that interacts with a drug and initiates the chain of biochemical events leading to the drug's observed effects
65
how do most drugs exert their effects
via receptor
66
types of receptors
cell surface, intracellular
67
What type of receptor can be linked directly to ion channels?
ligand-gated channel
68
What effect does receptor activation have on membrane permeability?
It changes (increases or decreases) membrane permeability
69
What happens when a drug binds to a ligand-gated ion channel receptor?
The receptor activates and opens a pore, allowing ions to pass through
70
what are G-proteins
type of cell surface receptor that links to G-protein to activate which allows G-protein to alter activity of an intracellular effector
71
intracellular receptors
endrogenous hormone (made by body) or hormone-like drug binds to receptor in cytoplasm or nucleus
72
what ability do intracellular receptors have that cell surface receptors don't
the ability to cross the membrane
73
what do intracellular receptors do in the nucleus
affect gene expression
74
what characteristics determine the drug's ability to bind to a receptor
drug size and shape relative to the receptor's binding site
75
affinity
amount of attraction of the drug for the receptor
76
how is affinity determined
by the amount of drug needed to bind to unoccupied receptorsa
77
allosteric modulators
local regulators that can bind to receptor at a different site and change the affinity of a drug for the receptor
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why does affinity matter
it can cause side effects!!
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selective drug
affects only one type of cell or tissue and produces a specific type of physiological response
80
nonselective drug
affects multiple cell or tissue types and has beneficial effects and non-beneficial effects
81
what is the dose response curve
related to the number of receptors that are bound by the drug
82
what is proportional to the number of receptors that are occupied
drug response
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agonist
drug that binds receptor and causes a change in the cell's function
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full agonist
agonist that does causes max response (aka strong agonist)
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partial agonist
agonist that does not cause a max response
86
antagonist
drug that binds receptor but does not cause a functional response (blocker)
87
competitive antagonist
competes with agonist to occupy same receptor
88
noncompetitive antagonist
irreversible antagonist that forms strong bond to receptor
89
mixed agonist-antagonist
drug that acts as an agonist on some receptor subtypes and an antagonist on others
90
inverse agonist
drug that binds to the same receptor as agonist but has the opposite effect on cellular function
91
receptor regulation types
desensitization, super-sensitivity, down-regulation, up-regulation
92
desensitization
brief, transient, decrease in receptor responsiveness
93
super-sensitivity
increased response of a tissue or receptor system to a drug or endogenous substance
94
down-regulation
slower, more prolonged process that dec. number of available receptors
95
up-regulation
increases the number of available receptors
96
non-receptor drug mechanism characteristics
alter synthesis of cell components, direct chemical reactions, direct alteration of enzyme function, chelation of harmful agents
97
what is the non-receptor drug mechanism
some drugs do not exert effects by binding to a specific component
