Brainscape's Knowledge GenomeTM

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


See full index

1. Pharmacology > Pharmacokinetics Absorption > Flashcards

Pharmacokinetics Absorption Flashcards

1
Q

Pharmacokinetics

A

Passage of drugs across the cell membrane
Drug movement in the body: Absorption, distribution, metabolism, and excretion (ADME)

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

Pharmacodynamics

A

What the drugs do to the body (therapeutic effects)

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

Absorption

A

Process where drugs enter the blood stream without being chemically altered
OR
Movement of a drug from its site of application into the blood

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

Increased drug concentration and drug action…

A

Increases absorption and distribution

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

Decreased drug concentration and drug action…

A

Decreases metabolism and excretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Factors that influence absorption rate

A
  1. Types of transport
  2. Routes of administration
  3. Physiochemical properties of the drug
  4. Concentration of the drug
  5. Protein binding
  6. Dosage forms
  7. Circulation at the site of absorption
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Passive diffusion

A

Continues till equilibrium is attained on either side of the membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is passive diffusion dependent on?

A

Concentration gradient
Drug molecular size
Lipophilic nature of the molecule
Temperature
Thickness of the membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Lipophilic gradient and passive diffusion

A

Higher the lipid solubility, higher the diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Temperature and passive diffusion

A

Lower the temperature, slower the diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Enteral administration

A

Through GI tract
Oral: min to hrs
Sublingual/ buccal: 3-5 minutes
Rectal: 5-30 min

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Parenteral administration

A

Through injection
IV: 100% F, 30-60 sec
IM: 10-20 min
SubQ: 15-30 minutes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Dermal administration

A

Epidermic, installation and irrgation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Inhalation administration

A

Vaporization, gas inhalation, nedbulization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Transdermal administration

A

Patch, microneedle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Major factors in small intestine diff species that effect absorption

A

pH
Epithelial surface
Surface area
Motility
Efflux proteins: P-glycoprotein (takes drug out of cell)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

_______ and _________ are rapidly and efficiently absorbed

A

Lipid soluble and Unionized drugs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Water parturition coefficient (PC)

A

High PC= more absorption
(higher lipid to water= more absorption)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What solution causes drugs to be absorbed rapidly?

A

Drugs in aqueous solutions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Rate of absorption

A

solutions –> emulsions –> suspensions –> capsules –> tablets –> sustained release products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What drugs cross the capillary membrane?

A

Drugs with molecular weight less than 50-600 Da

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What drugs enter the cell via aqueous filled channels?

A

Small, water-soluble molecules and ions below 50 Da

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

What happens when the ph and pKa are equal

A

50% of drug ionised and 50% unionised

23
Q

What happens when pH is one unit below the pKa?

A

Acid is 9% ionized and base is 91% ionized

24
Q

What happens when pH is 2 units below pKa?

A

Acid becomes 1% ionized and base becomes 99% ionized

25
Q

What is an exception to the pH and pKa rules?

A

Strong acids and strong bases remain ionized at all body pH
Weak acids and bases are unionized

26
Q

pH- partition hypothesis

A

Basic drugs in the blood (pH 7.4) readily enter into acidic tissues and fluids
Acidic in acidic medium: unionized

27
Q

Ion trapping

A

Ionized drug gets trapped on one side of a membrane that divides 2 compartments that contains fluids of different pH values

28
Q

When would ion trapping occur

A

When a drug found in low concentration in the blood (pH7.4) is found in a higher concentration in the urine (pH5)

29
Q

Why does ion trapping occur?

A

Because only unionized, hydrophobic, uncharged, lipid soluble drugs can pass through cell membranes

30
Q

Example of ion trapping

A

Weak organic base diffused passively from blood (pH- 7.4) to rumen fluid (pH5.5) –> once passing, base drugs in acids become ionized (broken down, bad) –> ion trapping because they cannot pass the membrane –> cycle of reabsorption and not being excreted –> overdose

31
Q

Where will acidic drugs be more absorbed?

A

Stomach because stomach is more acidic (like/like= unionized= more absorption)

32
Q

In the intestine (pH 7.8), which will be better absorbed, a weak acid or a weak base?

A

Weak base because base/base = unionized and better absorption

33
Q

If we alkalinize the urine of 7.8, will a lower or higher percentage of a weak acid be ionized, compared when the urine pH was 6.0?

A

Higher percentage because a weak acid is ionized in the basic solution

34
Q

Other factors influencing absorption

A
  1. Blood circulation at site (increase blood flow= increased absorption
  2. Absorption surface area
  3. GIT functional integrity
35
Q

GIT functional integrity

A

An increase in gastric emptying time, the drug absorption will be more
ex: diarrhea drug absorption is reduced due to increased peristaltic activity

36
Q

Bioavailability (F)

A

The % or fraction of administered drug by any route that reaches circulation in a chemically unchanged form

37
Q

Which route should have 100% bioavailability?

A

Intravenous route because it’s put directly into circulation

38
Q

Oral bioavailability

A

F=60%

39
Q

How is bioavailability described?

A
  1. Cmax (peak plasma concentration)
  2. Time to reach Cmax
  3. AUC
40
Q

Bioavailability equation

A

F= (AUC)oral / (AUC) iv

41
Q

Bioavailability equation with different doses

A

F= 100 ( ( AUC po x Div) / (AUC iv x Dpo) )

42
Q

What factors affect bioavailability?

A

First pass effect
Gastric emptying
Drug solubility/ dissolution (salt forms will increase dissolution)
Drug stability in GI fluids

43
Q

First-Pass metabolism

A

Increased FPM will decrease F
Absorbed drug moves via protal circulation to liver
High extracted drug may be removed with “first pass”
Should give these drugs via IV not orally

44
Q

Which drugs have extensive first pass effect?

A

Morphine
Propanolol
Buprenorphine
Diazepam
Midazolam
Pethidine

45
Q

Efflux proteins or transporters

A

Move drugs and other chemicals out of the cell
Normal protective mechanism
Important for drug resistance (brain)

46
Q

Distribution

A

Process where drug reversibly leave the blood stream and enter the extravascular fluid and tissue
Determines the transport of drugs to their site of action

47
Q

Highly perfused organs

A

Liver, kidney, GI tract, brain, lungs
Receive rapidly high levels of drug

48
Q

Less perfused organs

A

Muscle, bones, fat tissue

49
Q

Plasma-protein binding

A

Reduces efficiency of drug distribution
PP bound drugs non-diffusible

50
Q

Plasma protein bound drugs

A

Pharmacologically inactive and less efficacious and potent
Don’t undergo metabolism and excretion via glomerular (limits filtration)
Long plasma half-lives
Narrow therapeutic index and small volume of distribution

51
Q

What are acidic and basic drugs bound to?

A

Acidic: albumin
Basic: a1-acid glyco protein

52
Q

What does drug binding do?

A

Slows the rate where the drug reaches a concentration sufficient to produce a pharmacologic effect

53
Q

Blood brain barrier

A

Formed by endothelial cells
Doesn’t permit ionized and non-lipid soluble drugs
TJs!!!!

54
Q

Placenta

A

Highly ionized drugs and drugs with low lipid solubility excluded
Tetragenic drugs (causing birth defects) blocked

55
Q

Milk

A

Mammary gland- lipid barrier and many drugs readily diffuse from plasma into milk
Max residue levels in milk

56
Q

Volume of distribution (Vd)

A

Dose / plasma concentration
Decreased by plasma protein binding
Increased by tissue binding

1. Pharmacology (29 decks)

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