Pharmacokinetics (Test 1) Flashcards
1
Q
process by which drug moves from site of administration, across cell membranes, and enters the blood
- how the drug get into the body
- from the time the drug gets into the body until it hits the blood vessel
A
absorption
2
Q
how soon effects of the drug begin
A
rate of absorption
3
Q
intensity of the effects of the drug
A
amount of absorption
4
Q
factors affecting drug absorption (5)
A
- rate of dissolution/solubility
- drug routes
- blood flow to tissues
- conditions of GI tract
- drug interactions
5
Q
factors affecting drug administration
A
compliance, medication errors, diff swallowing, wrong form
6
Q
3 ways drug move across cell membrane
A
- pass through channels or pores
- transport systems (active/passive)
- direct penetration
7
Q
explain lipid soluble drugs vs water soluble drugs in relation to the cell membrane
A
lipid soluble drugs cross cross cell membrane faster than water soluble drugs
8
Q
- use energy in the form of ATP
- cross from area of lower concentration to area of higher concentration
A
active transport
9
Q
area of high concentration to area of low concentration; requires no energy
A
passive transport
10
Q
drugs that use direct penetration
A
lipid soluble drugs and water soluble drugs
11
Q
drug routes (3)
A
- enteral
- parenteral
- topical/inhalants
12
Q
goes through the GI tract and undergoes 1st pass effect
A
enteral drug route
13
Q
outside the GI tract; most injections
A
parental drug route
14
Q
skin & mucus membranes
A
topical/inhalants
15
Q
meds by mouth (po)
A
enteral
16
Q
advantages of enteral medications
A
- easiest & cheapest
- self-administration
- safer than injections
17
Q
disadvantages of enteral medications
A
- less reliable due to 1st pass effect
- may be inactivated by gastric acids or enzymes
- may cause GI irritation
18
Q
speed of absorption (po meds) fastest to slowest
A
- liquids (elixirs, syrup)
- suspensions (MOM)
- powders (BC)
- capsules
- sustained release (SR)
- extended release (XL) - tablets
- enteric coated
19
Q
other enteral medications
A
rectal suppositories
gastric/NG tubes
20
Q
explain first pass effect
A
- medication is taken in through mouth or rectum
- it goes into the GI tract and is absorbed into portal vein
- it is then transported into the liver; enzymes break it down
- it is then transported into the blood and distribution begins
(all enteral medications must undergo 1st pass effect which means it has to go into the liver before undergoing systemic circulation)
21
Q
factors that decrease enzyme activity in the liver and effect 1st pass effect
A
- age: elderly and infants
- liver disease: cirrhosis
22
Q
parental route injections
A
IV, IM, SQ, or SC
23
Q
IV advantages
A
- preferred route in an emergency
- 100% absorption; greatest control
- can administer large volumes & irritant drugs
24
Q
IV disadvantages
A
- expensive, time-consuming, irreversible
- higher infection rates
- must read labels
25
IM/SQ factors
- affected by blood flow to tissue
- SQ has slower absorption rate (bc has less vessels)
- used for depot preps
- painful, may cause nerve damage or tissue injury
26
Topical med routes
SL (tongue), buccal (cheek), vaginal, rectal, ID (intradermal, inhalants
27
forms of inhalants
nebulizers, gases, sprays, powders
28
advantages of topical medications
deliver a constant amount of drug over long time
29
disadvantages of topical medications
- slow onset, except inhalants
| - absorption varies w/ form and area of application
30
local effects
affect one body system or a single organ
| ex. antacids, visine
31
systemic effects
affect multiple body systems or organs
| ex. antibiotics, antiinflammatories
32
describe blood flow to tissues
the greater the blood flow to an area the greater the rate of absorption
33
way to increase blood flow to tissues and speed of absorption; contrarily how to decrease blood flow to tissues and limit absorption
application of heat; application of cold
34
highly vascular areas vs low vascular areas
HVA absorb medications faster than LVA
35
examples of highly vascular areas
intestinal tract, lungs, and skeletal muscle
36
examples of. low vascular areas
adipose tissue, edematous tissue, bone
37
conditions of GI tract
- surface area
- GI motility
- pH partitioning
38
describe how surface area affects absorption
the larger the surface ares; the faster the rate of absorption
- Gastric by pass surgery
39
describe how GI motility affects absorption
the greater the contact time, the greater the rate of absorption
40
describe constipation related to absorption
more contact time of drug; so absorption should be greater
41
describe diarrhea or vomiting in relation to absorption
less contact time so absorption should be less
42
the amount of drug that is absorbed into the blood stream and available to exert a systemic effect
bioavailability
43
multiple drugs with identical active ingredients in the same dosage forms, with the same route of administrations, exerting the same effect (generic drugs vs brand drugs)
bioequivalent
44
movement of drug throughout body to gain access to target cell and allow drug to exit vascular system for elimination
- where drug goes to in the body
- when drug hits the blood vessel
distribution
45
site of action where the drug response occurs (pharmacodynamics)
the target cell
46
factors affecting distribution
- blood flow
- plasma protein binding/affinity
- tissue trapping
- physiological barriers
47
describe blood flow or perfusion in relation to distribution
greater the perfusion the faster the distribution
48
high perfusion areas
brain, heart, major arteries, lungs, kidneys
49
poor perfusion states
shock, hypotension, peripheral vascular diseases, vasoconstrictor drugs, abscesses, and large neoplasms
50
2 forms that drugs circulating the blood exist in
1. free drugs/unbound drugs
| 2. protein bound drugs
51
free to circulate and bind to targets and produce a response (pharmacodynamics)
free drugs/unbound drugs
52
- physically attached to a binding site, on albumin molecule
| - inactive until released from the protein; do not produce a response
protein bound drugs
53
conditions that reduce albumin binding sites
- hypoalbuminemia
| - malnutrition
54
certain tissues can trap drugs preventing them from free distribution to the body
tissue trapping
| ex. lipid soluble drugs, tetracyclines, iodine containing drugs, B-vitamins & fat soluble vitamins
55
areas in the body which have anatomic configurations to prevent free drugs from entering
physiological barriers
56
ex of physiological barriers
- blood brain barrier
- placenta barrier
* * 1st trimester: majority of birth defects associated w/ drugs
* * 3rd trimester: placenta begins to wear down & allowing medications to cross (baby gets more effect of drug)
57
FDA pregnancy risk categories
only give A and B drugs to patient
58
- biological transformation of a drug into an inactive metabolite, a more soluble compound, or a more potent metabolite
- liver converts lipid soluble drug into water soluble compound to increase elimination
- how the body chemically modifies the drug
metabolism or biotransformation
59
factors affecting metabolism
- disease state (liver disease)
- enzyme activity
- age: elderly & infants
- food/drug interactions
60
a drug is metabolized by an enzyme which results in the increased activity of that enzyme. the multiple enzymes increase the speed of drug metabolism
enzyme induction
61
primary site of metabolism
liver (enzyme p-450)
62
removal of drugs from the body
excretion
63
primary site of excretion
kidney
64
factors affecting excretion (3)
1. blood circulation
2. pH of urine
3. age
65
normal waste products from metabolism of drugs in the body (excretion phase)
BUN lab
66
catobolism (body breaks down own cells)
- occurs in patients w/ renal failure
- growth spurt of child
(excretion phase)
creatinine lab
67
high BUN level; normal creatinine level
dehydration
68
low BUN level; normal creatinine level
overhydration
69
elevated BUN; elevated creatinine level
renal failure
70
additional routes of elimination
- lungs
- sweat gland
- mammary
- salivary
- bowel
71
drugs in the bile are secreted into the intestine, some is reabsorbed into the blood, the rest is secreted in the feces
enterohepatic recycling
72
plasma drug levels after a single dose of an oral medication
single dose time course
73
time interval bw administration of drug and the first sign of action
onset of action
74
the lowest plasma concentration that will produce a therapeutic effect
minimal effective concentration (MEC)
75
highest plasma concentration attained from a single dose
peak plasma effect
76
time interval bw onset of action and termination of action
duration of action
77
the range plasma concentration in which the drug effect is produced without producing toxicity
therapeutic range
78
plasma concentration of a drug that results in dangerous adverse effects
toxic level
79
period of time in which the drug effect is no longer seen
termination of effects
80
the time required for the amount of drug in the body to decrease by 50%; determines dosing intervals
drug half-life
81
drug levels with repeated doses
multiple dose time course
82
effects of multiple dose time course
- drug accumulation
- plateau/steady state: allows drug to accumulate in the blood until a state is achieved where the amount of drug eliminated equals the dose administered
- takes 4-5 half lives to reach a steady state
83
the concentration of a drug in the blood which correlates to the drug's response
plasma drug levels
84
importance of measuring plasma drug levels
allows us to adjust dosages and times of administration when the drug is not therapeutic or it becomes toxic
85
goal of peak and trough levels
to keep the peak level below the toxic concentration and the trough level above the MEC to maintain therapeutic levels
86
how to reduce fluctuations of multiple drug dosing
- give continuous infusions
| - reduce dosage size and interval
87
technique used when a drug has a long half-life (explain it)
loading doses vs maintenance drugs
- administer a large initial dose (loading dose) to increase blood plasma levels, then give smaller doses (maintenance dose) to maintain blood plasma levels
88
once the drug is discontinued, it will take 4-5 half lives to be eliminated from the body
decline from plateau
