Lecture 4 Part 1 Flashcards

1
Q

what is the goal of therapeutics

A

to achieve the desired beneficial effect with minimal adverse effects

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2
Q

as mentioned, the goal of therapeutics is to achieve the desired benefit with minimal adverse effects.

clinicians accomplish this by determining the proper dose of a drug.

HOW IS THE DOSE DETERMINED

A

determined by combining the principles of pharmacokinetics and pharmacodynamics

combining these principles helps to understand the dose-effect relationship

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3
Q

pharmacokinetics gives ___-___

pharmacodynamics gives ___-___

A

kinetics = dose-concentration

dynamics = concentration-effect

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4
Q

when the drug is absorbed, where does it go?

A

into systemic circulation

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5
Q

once a drug is absorbed into the systemic circulation, what are its potential fates?

A

-drug is eliminated (metabolized or excreted)

-drug is reversibly distributed into the tissues

-drug at the site of action

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6
Q

when a drug is at the site of action, what happens?

A

it produces its pharmacological effect (either a clinical response or toxicity or both)

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7
Q

true or false

the drug concentration at the site of action producing a pharmacological effect is related to pharmacodynamics

A

true

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8
Q

pharmacokinetics is involved with ADME.
what does ADME determine?

A

how rapidly and how long the drug will be at the target organ

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9
Q

pharmacodynamics involves what 2 properties?

A

the pharmacological effect and maximal efficacy

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10
Q

pharmacodynamics involves the pharmacological effect and the maximum efficacy.

this characterizes the relationship between….

A

the drug concentration and the effects it produces

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11
Q

true or false

a relationship does not exist between the beneficial or toxic effect of a drug and the concentration

A

false - a relationship does exist

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12
Q

the importance of pharmacokinetics and pharmacodynamics in patient care rests on the improvement in….

A

therapeutic benefit and REDUCTION in toxicity

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13
Q

pharmacokinetics is a _____ study and characterization of the time course of drug concentrations in the body

qualitative or quantitative?

A

quantitative

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14
Q

pharmacokinetics allows us to answer what 2 questions

A

when will the drug reach steady state levels

when will the drug be eliminated

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15
Q

what helps to establish dosage regiments that will result in improved drug utilization in patients?

A

pharmacokinetics

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16
Q

what physiological factors will modify pharmacokinetic properties of a patient?

A

sex
age
disease stage
genomics

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17
Q

what 2 disease states in particular will require dosage adjustment

A

heart failure and renal failure

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18
Q

the “standard” dose of a drug is obtained from what

A

studies on healthy volunteers with average ability to absorb distribute and eliminate the drug

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19
Q

pharmacokinetics is a discipline that uses mathematical formula to ____ the relationship between….

A

delineate the relationship between the dose of the drug administered and the final concentration of the drug at the site of action

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20
Q

define parenteral administration

A

administration by some route other than the GI tract

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21
Q

name the 3 major parenteral routes of administration

A

IV
SUBQ
IM

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22
Q

name 4 “other” parenteral routes of administration

A

epidural
inhalation
topical
intrathecal

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23
Q

define enteral administration

A

via the GI tract

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24
Q

name 3 major enteral routes of administration

A

oral
sublingual
rectal

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25
Q

true or false

the rectal route of administration could be considered parenteral or enteral

A

true

enemas are for local effect and don’t go through the GI but systemic suppositories do

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26
Q

which route of administration has the MOST RAPID onset?
what is the bioavailability?

A

IV
100% (by definition)

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27
Q

which route of administration has a bioavailability of 75 to less than or equal to 100%

A

IM and SC(SUBQ)

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28
Q

what is the most convenient route of administration? what is it’s bioavailability ?

A

oral
5 to less than 100%

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29
Q

which route of administration usually has very slow absorption and used for its lack of first pass effect? has a prolonged duration of action.

what is it’s bioavailability ?

A

transdermal patch
80- less than or equal to 100%

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30
Q

what is the bioavailability of inhalation? what is it’s onset?

A

5 - less than 100%
often very rapid onset

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31
Q

true or false

the rectal route of administration has less first pass effect than oral

also give the bioavailability of the rectal route of administration

A

true

30- less than 100%

32
Q

which has larger volume - IM or SC

A

IM has larger volumes
both may be painful

33
Q

true or false

first pass effect is not very important for oral drugs

A

false - may be important

34
Q

give the definition of bioavailability

A

the fraction of UNCHANGED DRUG that reaches systemic circulation following administration (by ANY route of administration)

35
Q

IV administration: bioavailability=___

other routes of administration=____

A

IV = 1

other routes = less than 1

36
Q

name the 2 major factors that reduce the bioavailability to less than 100%

A

incomplete absorption

first pass effect (liver metabolizes drug before it reaches systemic circulation)

37
Q

give the 3 steps of the drug absorption sequence.

bioavailability may be affected by which steps?

A
  1. across gut wall into portal circulation
  2. portal blood transports drug to liver
  3. drug may then reach systemic circulation

bioavailability may be affected by all 3 steps

38
Q

true or false

drug metabolism may occur:

-in the intestinal wall
-in the blood
-in the liver

A

true

39
Q

a basic drug will be better absorbed in the stomach or small intestine?

A

small intestine because it will be unionized

40
Q

the liver may excrete the drug ___

A

in the bike

41
Q

true or false

the oral route is most preferred and most common

A

true

42
Q

name 3 reasons why oral bioavailability may be reduced

A

-the drug may not be soluble enough in aqueous environment (no dissolution= no absorption)

-the absorption may be incomplete due to biological barriers OR drug metabolism in the gut (drug may be inactivated in the gut)

-1st pass effect

43
Q

true or false

a drug cannot be inactivated in the gut

A

false - it can

due to biological barriers or drug metabolism in the gut

44
Q

how can absorption vary in different areas of the gut?

A

due to:

-pH
-food present in the gut
-gastric emptying
-IN GENERAL, drugs tend to be more readily absorbed from the small intestine than stomach due to large surface area and villi

45
Q

explain the surface area of the small intestine

A

with no villi would be 3300 cm squared

it has microvilli so it’s 2,000,000cm squared

ALLOWS FOR BETTER ABSORPTION THAN THE STOMACH

46
Q

true or false

drugs tend to be more readily absorbed in the stomach than the small intestine

A

false - more readily absorbed in small intestine due to large surface area

47
Q

true or false

the intravenous route of administration is when the drug is introduced directly into the bloodstream

A

true

48
Q

give the advantages of IV route of administration

A

-most rapid onset
-bioavailability is 100%
-safe for narrow therapeutic index drug bc a control injection can be made slowly and stopped quickly
-good for a highly metabolized drug bc 1st pass is bypassed

49
Q

give disadvantages of the IV route

A

-drug can’t be recalled once injected-

-embolism risk

-catastrophic effects may happen

-if excessive fluid is injected will lead to congestive heart failure

50
Q

how does absorption occur in the IM and SC routes of administration?

A

by simple diffusion

from the extra cellular site of injection into the circulation

51
Q

in IM and SC, what is the rate of absorption limited by

A

the area of absorption

the solubility of the drug in the interstitial fluid (no dissolution=no absorption)

52
Q

where is the drug injected in IM

A

into skeletal muscle

53
Q

where is the drug injected in subcutaneous

A

under the skin

54
Q

what are the advantages of IM

A

absorbed rapidly
large amounts are often feasible

55
Q

what are the disadvantages of IM

A

inconvenient most of the time
not good for those with poor circulation

painful

56
Q

name advantages of SUBQ

A

good for small amount of drug and long term drugs

57
Q

name disadvantages of subq

A

absorbed slowly
not good for those with poor circulation
may be painful
necrosis

58
Q

explain the intra-arterial route of administration

A

occasionally a drug is injected into an artery to localize its effect in a particular tissue or organ (TREATMENT OF LIVER TUMORS/head/neck cancers)

diagnostic agents sometimes administered intra arterial (technetium-labeled serum albumin)

59
Q

explain the intrathecal route of administration

A

local and rapid effects on the meneinges or cerebrospinal axis(spinal anesthesia, treatment of acute CNS infections and brain tumors)

sometimes injected directly into subarachnoid spaces

60
Q

give 2 advantages of oral route

A

easy to administer
economic (cheap)

61
Q

give disadvantages of oral

A

many factors affect its absorption
stomach situation (pH, presence or absence of food)
first pass effects
emesis (vomit) may occur

62
Q

is sublingual enteral or parental

A

can be considered both? does bypass hepatic metabolism but on slides says enteral

63
Q

explain how the sublingual route of administration works

A

direct absorption into systemic circulation.
bypasses hepatic portal and first pass
prevents the destruction of the drug by intestinal enzymes or low pH

64
Q

what is the environment like in the sublingual route of administration? is this an advantage?

A

slightly acidic with a high water composition - advantage

65
Q

state advantages of the sublingual route of administration

A

-bypasses the liver

-a drug that is absorbed from the oral cavity gains access to the systemic circulation

-slightly acidic environment with high water composition

-thin and highly vascularized epithelium

-drugs are kept in this kind of environment when placed under the tongue

66
Q

true or false

sublingual drugs must be kept under the tongue until they are dissolved

A

true

67
Q

what may be limiting in the sublingual route of administration

A

relatively large doses

68
Q

name advantages of rectal route

A

-partly avoids first pass (drugs absorbed from lower part of the rectum bypass liver – ~50%)

-drug cannot be destroyed by intestinal enzymes or low stomach pH

-patients who are unconscious or vomiting

-drugs with bad taste or odor

69
Q

name some disadvantages of rectal route

A

absorption can be irregular, incomplete, and may irritate the mucosal membrane

70
Q

what is the most rapid absorption route

A

inhalation

inhaled as a gas and enters circulation through diffusion across the alveolar

71
Q

name advantage and disadvantage of inhalation

A

advantage - fast access to circulation dc of large surface area and AVOIDS FIRST PASS

-disadvantage: only a few drugs can be used by inhalation

72
Q

name 2 drugs that are available via intranasal

A

salmon calcitonin - peptide hormone used to treat osteoporosis - nasal spray

cocaine is sniffed

73
Q

topical drugs are used when what kind of effects are desired? give an example

A

local effects

atropine is instilled directly into the eye to dilate the pupil

74
Q

explain the transdermal route

A

achieves systemic effects

-drug applied to skin

-used for SUSTAINED delivery - such as nitroglycerin - an antianginal

75
Q

true or false

transdermal route of administration is for local effects

A

false - systemci

76
Q
A