Basic Pharmacology Flashcards
(107 cards)
1
Q
Pharmacokinetics
A
How a drug is absorbed, distributed, metabolized, and excreted
2
Q
Pharmacodynamics
A
Mechanism of action of a drug
3
Q
Routes of Administration
A
Oral (PO)
4
Q
Enteral
A
Route of administration via GI tract Includes Oral (PO) and Rectal (PR) Safest and easiest route Least expensive Must pass through GI tract (w/stomach acid, enzymes) & enter portal circulation for 1st-pass metabolism (1st-pass effect)
5
Q
What is the safest, easiest, and least expensive route of administration for medication?
A
Enteral aka oral (PO)
6
Q
Hepatic Portal Vein
A
A short vein that transports blood containing the medications, etc. to the liver for 1st-pass metabolism, before it’s filtered back into the general circulation
7
Q
1st-pass metabolism
A
Absorbed in the GI tract, enters portal vein to liver, metabolized, then enters general circulation
8
Q
2nd-pass metabolism
A
Eventually sent back to liver by arterial circulation for more metabolism
9
Q
Generally speaking, how long does it take once you take a pill to get a peak plasma level so that it can get to the brain?
A
~ 60 minutes
10
Q
Parenteral
A
Route of administration avoiding the GI tract and hepatic 1st-pass metabolism
11
Q
How long before the drug is distributed throughout the system via inhalation?
A
8 seconds
12
Q
Smoking and inhalant drugs of abuse are very reinforcing partially due to _____?
A
The very fast effects on CNS (about 8 seconds)
13
Q
Transmucosal
A
Across mucous membranes directly
14
Q
What are some of the methods of transmucosal administration?
A
Buccal or sublabial (e.g. nicotine gum)
Sublingual (SL) [e .g. nitroglycerine, alprazolam (XANAX)]
Sprayed into nose or sniffed (e.g. drugs of abuse and nasal decongestants)
15
Q
What are the methods of injection administration?
A
Intravenous (IV) or Intra-atrial (IA)
Subcutaneous (SQ or SC)
Intramuscular
Epidural
16
Q
What is the rate of dispersion for IV injection?
A
Very fast, seconds, but not as fast as inhalation
17
Q
What is the rate of dispersion for subcutaneous injection?
A
Hours, days, months
18
Q
What is the rate of dispersion for intramuscular injection?
A
~ 15 minutes
19
Q
Depot form
A
Type of intramuscular injection, allows for slow, controlled release (e.g. Risperdal Consta, Haldol Decanoate)
20
Q
Epidural
A
Injection into area just outside dura mater (outer layer of the meninges that surround CNS)
Used for chronic pain and childbirth
21
Q
What are the types of parenteral administration?
A
Inhalation, injection, transmucosal, transdermal,
22
Q
Transdermal
A
Type of
23
Q
LADME
A
Liberation Absorption Distribution Metabolism Excretion
24
Q
Liberation
A
release of drug from its dosage form
25
Absorption
movement of drug from administration site into the blood
26
Distribution
Movement of drug from intra-vascular to extra-vascular space
27
Metabolism
transformation of drug into compounds that are easier to eliminate (e.g. liver wants to make compounds more water soluble so that they can be excreted in the urine)
28
Excretion
elimination of drug or metabolite via renal, biliary, or pulmonary processes
29
Why are some drugs enteric coated?
Decreases irritation to stomach lining
Delays absorption until the intestine for those drugs that are better absorbed in the intestine (which is more alkaline than the stomach)
Particularly useful for those drugs that are either poorly absorbed or destroyed in acidic environment)
30
What is the bottom line of liberation and absorption?
TAKE DRUGS AS INSTRUCTED
31
Why are some drugs instructed to take on empty stomach?
Many drugs are absorbed better in stomach than the intestine (and vice versa)
Reaches desired concentration levels faster when taken on an empty stomach
32
What are some technologies for controlling release and absorption?
```
Sustained-release
Sustained-action
Extended-release
Controlled-release
Time release technology
```
33
What is the point of developing these technologies for controlling release and absorption?
To spread out the action of the drug, decrease side effects, and in general, make drugs more convenient to take (especially in children and stimulants)
34
Cytochrome P450 (CYP)
System in the liver that is the main system of enzymes that inactivate drugs
35
What are the most important CYP enzymes?
1A2, 2C9/19, 2D6 (30%), 3A4 (55%)
36
Three different groups of metabolizers
Poor (PM)
Rapid or extensive (i.g. normal)
Ultra-rapid (URM)
37
Different ethnic/racial groups vary in certain these enzymes, leading to ___________
varying degrees of metabolism and effects
38
What are some considerations that you need to make with elderly population?
- Overall, may be twice as sensitive to drugs, so the dose needs to be halved, usually
- Polypharmacy is common, thereby leading to many drug-drug interactions
39
What are some changes that influence metabolism in the elderly?
- Decreased hepatic (liver) & renal (kidney) function
- May have less effective barriers to absorption (GI, blood-brain-barrier)
- May have increased body fat
- May have more sensitive receptors
- Hepatic changes (decreased CYP2C19, hepatic mass, and circulation)
40
What are some sex differences to consider with medication metabolism?
- Females may have more sensitive receptors
- Possible hormone interactions
- Combined with phamacokinetics factors (e.g. more body fat, lower body weight), females may be twice as sensitive as males (dose may need to be halved)
41
What are the factors involved in inter-individual variability?
- Genetics (PM vs RM vs URM)
- Age
- Sex
- Environmental factors
- Disease
42
Types of DDI's
Additive
Synergistic
Antagonistic
Pharmacokinetic
43
DDI
Drug-Drug Interaction
44
What is the most common type of DDI?
Additive
45
What is an example of synergistic effect?
Thyroid hormone + antidepressant
46
What can antagonistic drug effects lead to?
Decrease in therapeutic effect, as in taking a stimulant + depressant at the same time
47
Pharmacokinetic DDI
- One drug (or food) may alter absorption of another.
| - One drug may alter protein binding
48
When are additive drug effects considered good vs bad?
If the additive effect is therapeutic, it's good.
| If the additive effect is a side effect, it's bad.
49
A drug can _______ or _________ enzyme(s) that metabolizes itself or other drugs.
Inhibit, induce
50
Most important effects of inhibition or induction?
Those that involve CYP enzymes in the liver, the primary site of drug inactivation/metabolism
51
What is the result of inhibition?
increased plasma levels of substrate of a particular drug, which can lead to increased SE's or toxicity.
52
In terms of safety, which is the bigger problem? Inhibition or induction?
Inhibition
53
How quickly can DDI's occur?
almost immediately, within hours to days & can cause toxicity
54
Why do drugs inserts instruct you not to take the drug with grapefruit juice?
The oils in the grapefruit juice inhibit CYP3A4 in an irreversible fashion, causing increased plasma levels of 3A4-metabolized drugs (meaning the inhibition can last as long as 3 days)
- As many as 85 drugs can be affected from DDi's with grapefruit juice, including Abilify and Celexa
55
What is the bottom line for us as clinicians with regard to DDI's?
You must always instruct patient to ask doctor and pharmacist about potential drug-drug interactions for their medications, including food, OTC drugs, herbs, and supplements
56
Peak level
Drug concentration is at its highest
57
Trough level
Drug concentration is at its lowest
58
How do sustained release formulations affect peak and trough levels of drugs?
Decreases peaks and troughs, which typically translates into decreased side effects
59
First-order kinetics
Metabolism rate is a constant fraction of remaining drug.
60
Zero-order kinetics
An absolute amount is eliminated per hour (regardless of the concentration of the drug in blood)
61
What is an example of a zero-order kinetic substance?
Alcohol!
| Average = 10cc(ml) of 100% ETOH/hour (1 drink equivalent)
62
Steady State (SS)
plasma drug concentration does not change with repeated (or continuous) same dose administration
Drug in rate = drug out rate
63
Half Life (T1/2)
The time required for plasma concentration to decline by 50% of drug after one dose.
64
SS dosing is achieved with regular interval dosing after how many half lives?
6
65
How many half lives does it take for most of a substance to be eliminated?
6
66
What is the typical regimen of drug administration?
To take the drug at the end of each half life.
67
LD50
Lethal dose in 50% of animal test subjects
68
ED50
Dose that produces desired effect in 50%
69
Therapeutic index (TI)
Measure of relative safety
70
What is the formula for TI?
TI = LD50/ED50
71
Low TI
Less safe and possibly fatal with overdose
72
TD50
Toxic dose in 50% of human subjects
73
Formula for Safety Index
TD50/ED50
74
Therapeutic Window
Range between minimum effective concentrations for desired & adverse effects, the concentration level that is high enough to have a therapeutic effect and low enough to avoid adverse effects
75
Therapeutic Drug Monitoring (TDM)
Correlating plasma concentration with effects within a specific patient (e.g. blood draws to measure the levels of Lithium in bloodstream)
76
What is the point of TDM?
May help increase therapeutic effects or to avoid toxic side effects
77
Tolerance
Increased dose required for a response
78
Pharmacokinetic (metabolic) tolerance
More enzyme available to metabolize drug, resulting in increased dose required to maintain same level
79
Pharmacodynamic tolerance
Receptors decrease in number or sensitivity, resulting in increased dose required to maintain same response (down-regulation)
80
What are the two types of tolerance?
Pharmacokinetic (increased enzymes)
Pharmacodynamic (decreased receptors or sensitivity)
Behavioral
81
Physical dependence
Physical or psychological withdrawal symptoms occur when drug is discontinued
82
True or False: Physical dependence only occurs with tolerance, abuse, or substance dependence
FALSE; physical dependence can occur without tolerance, abuse ,or substance dependence
83
What is the general rule for discontinuing medication?
Never discontinue (D/C) a psychotropic abruptly but to titrate off slowly
84
q
every
85
qd
every day (should be written out)
86
qh
every hour
87
qhs
every night at bedtime
88
bid
twice a day
89
tid
three times a day
90
qid
four times a day
91
g or gm
gram
92
mg
milligram
93
µg, mcg
microgram
94
PO
by mouth
95
prn
as needed
96
Rx
prescription, technically means "take"
97
Stat, STAT
at once
98
i, ii, iii, iv, etc.
one, two, three, four, etc.
99
D/C
discontinue
100
w/
without
101
w/o
without
102
Direct Agonist
Activates receptor just as a natural NT does
103
Direct Antagonist
Blocks action of a natural NT by binding to the receptor, thereby preventing the natural NT from binding (but has NO EFFECT on the receptor)
104
Partial Agonist
exerts the same but weaker effect as a full agonist; but this is a complex mechanism that at times can result in a net agonist effect and at other times in a net antagonist effect in the same brain
105
Inverse agonist
exerts opposite effect as full agonist (causes the receptor to do the opposite thing as it would if the natural NT has bound to it)
106
Indirect agonist
Increases effectiveness of NT without binding to the receptor
107
Indirect antagonist
Decreases the effectiveness of NT without binding to the receptor
