Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Normal Animal > Pharmacokinetics: Routes, Formulation, and Absorption > Flashcards

Pharmacokinetics: Routes, Formulation, and Absorption Flashcards

1
Q

Pharmacokinetics

A
  • what the body does to drug
  • absorption, distribution, metabolism, elimination (ADME)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what factors affect a drug’s ability to pass through membrane?

A
  • molecular weight
  • solubility
  • ionization status
  • concentration gradient
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

molecular weight physiochemical properties

A
  • smaller drugs cross membranes easier
    • 400-500 Da
    • range where most therapeutic drugs fall
  • exceptions
    • monoclonal antibodies
      • 20-50000 Da
    • drugs bound to protein
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

plasma protein binding

A
  • drug enters circulation and binds to protein
  • protein bound drugs remain in plasma until no longer protein bound
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

albumin plasma protein binding

A
  • albumin - weak acids, decreased with inflammation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

a1 acid glycoprotein plasma protein binding

A
  • a1 acid glycoprotein - weak bases, increased with inflammation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

solubility physicochemical properties

A
  • lipids vs. water
  • lipophilic drugs cross membranes easily and distribute widely
    • intracellular, abscesses, CNS, etc.
  • hydrophilic - confined to plasma and ECF
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

ionization physicochemical properties

A
  • unionized drugs distribute more widely and become more lipophilic
  • depends on pH and pka
    • “like unionized in like”
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

pka

A
  • pH at which 50% drug ionized and 50% is unionized
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

concentration gradient

A
  • higher concentration = more drugs for diffusion
    • can alter with dose and route
  • assume there is enough blood flow to area to deliver drug
    • affected by disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

passive diffusion

A
  • no external energy
  • equilibrium net transfer is zero
  • non selective
  • non saturable - first order (linear)
  • rate diffusion
    • proportional to (Ch-Cl)
    • concentration gradient
  • can pass through aqueous pores if water soluble, lipid soluble will go right through membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

carrier mediated transport

A
  • drugs lacking sufficient lipid solubility for passive
  • carrier may be specific for drug
  • competition for carrier
  • transport mechanism can be saturated
  • typically for drugs mimic endogenous substances (epi or norepi)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

carrier mediated facilitated diffusion

A
  • special transport proteins in membrane
  • goes with gradient
  • does not require energy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

active transport

A
  • carrier mediated
  • goes against gradient
  • requires energy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

clinical relevance of absoprtion

A
  • drug must be absorbed across membranes into systemic circulation in order to reach its site of action
  • routes play important role
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

how do you chose a route of administration?

A
  • formulation available of drug
  • therapeutic indiction (seizing cannot give oral drug)
  • pathophysiology of disease
  • target species
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what are the main routes of administration?

A
  • IV
  • IM
  • SQ
  • oral
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

intravenous

A
  • drug injected directly into bloodstream - skipping absorptive phase (100% absorption, cannot be more)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

advantages IV

A
  • highest concentrations
  • highest efficacy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

disadvantages IV

A
  • highest risk toxicity
  • technically most difficult
  • risk of intracarotid injection goes straight to brain causes seizure, coma, blindness, death
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

clinical relevance of IV injection

A

IV route preferred for ER for very sick animals whenever possible, ensures drug delivered

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

intramuscular injection

A
  • muscles highly vascular and absorption from IM route often high
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

advantages IM

A
  • easy to perform - large animal with large muscle masses (neonates and small animals do not)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

disadvantages IM

A
  • possibility of administering drug in a vessel
  • painful
  • drug may cause muscle necrosis, abscess, infection
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

clinical relevance IM

A
  • often 2nd choice for ER if cannot hit vein, take into account drug formulation
26
Q

subcutaneous injection

A
  • absorption moderate to high, more variable than IM
27
Q

advantages of SQ injection

A
  • easy to perform
  • less painful than IM
28
Q

disadvantages SQ

A
  • during dehydration and/or shock skin receives less blood flow
29
Q

clinical relevance of SQ

A
  • moderate to severe dehydration or shock can decrease absorption from SQ injection
30
Q

how are water soluble drugs given SQ absorbed

A
  • go from blob between cells (leave blob quickly bc lipophilic) absorbed faster
31
Q

how are lipid soluble SQ drugs absorbed

A
  • can go through cells
  • takes longer bc do not want to leave lipid blob quickly
    • more likely to form depot in IM/SQ space
    • does not mean less will be absorbed
32
Q

sustained release formulation

A
  • drug vehicle affects solubility and absorption
33
Q

fastest to slowest formulation absorption

A
  • slowest: solid dose form
  • oil based suspensions
  • oil based solutions
  • aqueous suspensions
  • fastest: aqueous solutions
34
Q

intravascular

A
  • IV - directly inject into vein (or artery(
  • assume 100% absorption
35
Q

extravascular

A
  • every other route
  • assume less than 100% absorption
36
Q

enternal

A
  • administration via the GI tract
    • oral (per os; PO; by mouth)
    • per rectum, oral/buccal transmucosal
37
Q

parental

A
  • everything else
  • IV/IM/SC
38
Q

oral

A
  • absorption ranges from 0-100%
  • most variable
    • slowest
    • species differences
      • monogastrics vs ruminants
    • effects of feeding/diet
      • fat content
39
Q

clinical relevance of oral

A
  • oral is not preferred route for ER situations
40
Q

advantages oral

A
  • cheap
  • easy (in most animals)
41
Q

disadvantages oral

A
  • drug loss
    • administration
    • vomit/reflux
    • degradation by stomach acid
    • rumen/colon microbes
  • affect on GI flora
42
Q

reasons for poor oral bioavailability

A
  • drug not delivered from its formulation to absorption site in GIT
    • water soluble to go into solution
    • lipid soluble to be absorbed across GI membrane
  • formulations may have solubility enhancers - compounding
  • drug must go into solution before it can be absorbed, may be rate limiting step for lipid soluble drugs
  • drug decomposed in GIT - gastric acid or rumen microbes
  • drug complexed in GIT - chelate with cations
  • needs carrier mediated transport (too big, too water/lipid soluble, too ionized)
  • ion trapping
  • first pass metabolism
43
Q

ion trapping

A
  • stomach is highly acidic, weak acid is unionized in stomach and becomes trapped in gastric surface epithelial cells bc basic (problems with NSAIDs)
  • higher absorption of basic drugs in SI and higher surface area
44
Q

first pass metabolism

A
  • for some drugs large % of drug absorbed immediately metabolized in gut or liver prior to absorption into systemic circulation
45
Q

how to avoid first pass metabolism

A
  • alter route of administration
46
Q

oral transmucosal

A
  • aka buccal or sublingual
  • membranes are relatively permeable
  • rich blood flow
  • rapid uptake of drug into systemic circulation to avoid first pass metabolism
47
Q

other transmucosal routes

A
  • inhalation, nasal, ocular, vaginal, rectal
48
Q

advantages of per rectum

A
  • access (unconscious or vomiting patients)
  • taste (none)
  • can recover drugs before absorption is complete
49
Q

disadvantages of per rectum

A
  • limited surface area, lower fluid content, microbes (degrade drug)
  • too far cranial drains to portal vein through cranial rectal vein
  • drug may not stay where you put it
50
Q

transdermal

A
  • drug absorbed through skin into circulation
51
Q

transdermal vs. topical

A
  • topical stays on skin, transdermal goes into circulation not the same
52
Q

Cmax

A
  • maximum plasma concentration
  • units ug/mL (ng/mL)
  • typically highest for IV doising
  • typically lower for PO/IM/SC
53
Q

Tmax

A
  • time to maximum plasma concentration
  • units hr (min)
  • for IV dosing occurs within 2-3 minutes or less
  • highly variable for PO/IM/SC
54
Q

clinical relevance of Cmax and Tmax

A
  • Cmax determines the magnitude of effect and adverse effects
  • Tmax tells you when the effect/adverse effect will occur; used for drug monitoring
55
Q

area under curve

A
  • influenced by Cmax and Tmax
  • indicates how much drug is absorbed
56
Q

bioavailability (F%)

A
  • % of administered drug that appears in bloodstream after dosing
  • two types - absolute and relative
  • absolute compares EV drug to IV drug
57
Q

relative bioavailability (F%)

A
  • compares EV drug to EV drug
  • may be routes of administration
  • may be different formulation
58
Q

bioequivalence

A
  • two drugs have same effect
  • +/- 20%
59
Q

flip flop phenomenon

A
  • absorption phase is prolonged
  • sustained release or depot formulations
60
Q

clinical relevance of absorption

A
  • a drug needs to be absorbed to have an effect except topical
  • low bioavailability means no effect
  • high bioavailability still better most of the time
61
Q

gastrointestinal disease affect on absorption

A
  • enteral vs. parenteral
    • d+
    • proliferative diseases
    • v+/refluxing
  • oral admin is not best route for GI
62
Q

liver disease affect on absorption

A
  • can decrease first pass metabolism and therefore increase oral absorption of some drugs that normally undergo high first pass effects

Normal Animal (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions