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Kinetics > 1 - Absorption > Flashcards

1 - Absorption Flashcards

1
Q

What is biopharmaceutics?

A

Relationship btwn physical and chemical properties of a drug in a dosage form and the pharmacologic response after administration

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2
Q

What is biopharmaceutics dependent on?

A
  • Chemical nature (ex: salt, ester)
  • Physical state (ex: liquid, solid, particle)
  • Type of dosage form (ex: tablet, injectable, inhalation)
  • Presence/absence of excipients
  • Pharmaceutical process (ex: type of granulation, tablet press, friability)
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3
Q

What is friability?

A

Ability to withstand degradation

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4
Q

What is pharmacokinetics?

A
  • Study and characterization of time course of drug absorption, distribution, metabolism, excretion, and release
  • The relationship of these processes to the intensity and time course of the therapeutic and adverse effects of drugs
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5
Q

What is bioavailability?

A

Rate and extent to which a drug is absorbed from a drug product into the body or to the site of action

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6
Q

What is pharmacodynamics?

A

The relationship between drug concentration at the site of action and pharmacologic response

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7
Q

What are some factors that affect absorption?

A
  • Transport processes
  • pH
  • Lipophilicity
  • Particle size
  • First-pass effect
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8
Q

What happens if a drug is protein bound?

A

Pharmacologically inactive

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9
Q

____ is the largest route of excretion

A

Renal clearance

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10
Q

____ MW drugs cannot be given orally because _____

A
  • High

- Have immediate availability in the body, so increased risk of adverse effects

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11
Q

Which dosage form is the safest to give and why?

A

Transdermal because it can be easily removed

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12
Q

Which route of administration is used for emergencies?

A

Intravenous

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13
Q

What are disadvantages to intravenous drugs?

A
  • Increased risk of adverse effects
  • Must inject solutions slowly
  • Not suitable for oily solutions or poorly soluble substances
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14
Q

Which route of administration is suitable for some poorly soluble suspensions?

A

Subcutaneous

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15
Q

Which route of administration is suitable for instillation of slow release implants?

A

Subcutaneous

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16
Q

What are disadvantages to subcutaneous drugs?

A
  • Not suitable for large volumes

- Possible pain or necrosis from irritating substances

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17
Q

What is the absorption pattern for subcutaneous drugs?

A
  • Prompt from aqueous solutions

- Slow and sustained from repository preparations

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18
Q

What is the absorption for intramuscular drugs?

A
  • Prompt from aqueous solutions

- Slow and sustained from repository preparations

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19
Q

Which type of intramuscular drugs are suitable for self-administration?

A

Repository preparations b/c slow and sustained release

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20
Q

What are disadvantages to oral drugs?

A
  • Requires px compliance

- Bioavailability potentially erratic and incomplete

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21
Q

What is plotted on a log dose effect curve and what is the shape of the data?

A
  • % max response vs % effective dose

- Shape is sigmoidal

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22
Q

How do hydrophilic drugs cross the lipid bilayer?

A
  • Channels (limit MW)

- Transport proteins (*main way drugs cross)

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23
Q

What is the problem w/ lipophilic drugs and the lipid bilayer? How is this overcome?

A
  • Lipophilic drugs can easily cross the lipid bilayer, but don’t want to cross into blood
  • Drug binds to albumin b/c drug has higher affinity for albumin than bilayer
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24
Q

How is the affinity of drugs for albumin increased?

A

Albumin proteins bump up against the lipid bilayer which increases the affinity

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25
Q

How is a drug transferred from albumin to a transporter?

A
  • Drug can jump in the free form or as a protein-bound drug
  • Ionic interaction b/c albumin and transport protein, so if charges line up correctly, binding site of albumin changes, causing affinity for drug to albumin to decrease a lot, making affinity for transport protein greater than for albumin
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26
Q

Where does a transport protein take a drug?

A

Into tissue

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27
Q

Which process/compound is responsible for side effects of drugs and why?

A

Transporters because they are present in tissues where you don’t want the drug to go

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28
Q

Which compounds are not able to cross to the absorption site? How is this overcome?

A
  • Ionized compounds

- Require a transport protein to cross

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29
Q

How do sublingual preparations avoid first pass metabolism?

A

Enter coronary arteries first

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30
Q

Where do disintegration and dissolution occur?

A

In the stomach where pH is low

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31
Q

For liquids, capsules, and tablets, which has the slowest and which has the fastest disintegration?

A

Slowest = liquid > capsule (no disintegration) > tablet (2x disintegration)

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32
Q

How do drugs cross intestinal microvilli?

A

Diffusion b/c no forces to pull the drug

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33
Q

Which formulation can bypass first pass metabolism and how?

A
  • Rectal suppositories

- Vessels supplying the rectum go into IVC and then into vasculature

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34
Q

A drug must be ______ before it can be absorbed

A

In solution

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35
Q

What is the pH of the stomach?

A

1-3

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36
Q

What is the pH of the duodenum?

A

5-7

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37
Q

What is the pH of the colon?

A

7-8

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38
Q

What dose absorption of a drug across the gut depend on?

A
  • pKa
  • Lipid solubility
  • pH of solution
  • Ionization (increased ionization decreases absorption)
  • Polarity
  • Lipophilicity
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39
Q

Does much absorption occur in the stomach?

A

No

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40
Q

Why are most drugs absorbed across the small intestine?

A
  • Large blood flow
  • Microvilli
  • Bile helps solubilize drugs
  • Presence of microflora (in some cases)
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41
Q

A drug w/ pKa = 3 is more soluble in ____ than _____

A

Duodenum than stomach

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42
Q

How many zones are in the liver and what are they separated based on?

A
  • 3 zones

- Separated based on size of liver cells

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43
Q

What is a simple unit of the liver composed of?

A

Hepatic portal vein and hepatic artery

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44
Q

What is the hepatic triad?

A

Hepatic artery, hepatic vein, and bile ductule

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45
Q

Where so the hepatic portal vein and hepatic artery feed into?

A

Sinusoids that dump into central vein, leading to IVC and the heart

46
Q

What happens when a person has nodules on their liver?

A

Nodules are fat deposits, so the fat puts pressure on structures like microsomes and nuclei, disrupting the internal infrastructure of the liver

47
Q

Can a cirrhotic liver be reversed?

A

No

48
Q

Can a fatty liver be reversed?

A

Yes, w/ diet and exercise

49
Q

How is the liver able to regenerate itself?

A
  • Cells closest to the central vein undergo apoptosis and slough off
  • New hepatocytes regenerate in zone 1 and push everything out (zone 1 becomes zone 2, 2 becomes 3)
  • Still hepatocytes but size, enzymes, and function will differ
50
Q

Can you transplant an adult liver into a child?

A

Yes, the liver will know the cavity is too small and will shrink to fit

51
Q

Endothelial cells in most organs are ______

A

Continuous (do not allow things to pass by conductive flow)

52
Q

What are fenestrations? Where are they found?

A
  • Small openings that allow plasma proteins through (not RBC’s)
  • Found in liver cells
53
Q

What happens once plasma proteins enter the fenestrations?

A

They must diffuse to enter hepatocytes

54
Q

Do hepatocytes have microvilli?

A

Yes

55
Q

Is the concentration on either side of hepatocytes and sinusoid the same?

A

Yes

56
Q

Blood supply from ___ and ____ mix before going down sinusoid into hepatic vein

A

Portal vein and hepatic artery

57
Q

Blood from portal vein and hepatic artery are rich in ____

A

Oxygen, nutrients, drugs, and toxins

58
Q

Which cells of the liver have the highest [ ] of metabolic enzymes and oxygen?

A

Zone 1 (closest to hepatic artery and portal vein)

59
Q

What happens to the cells as they get closet to central vein?

A

Drug [ ] (and [ ] of everything else) decreases

60
Q

What happens if a hepatocyte sense that there is nothing around it? Why do they do this?

A
  • Will travel to couple w/ another hepatocyte, then the couplet will migrate towards other hepatocytes to create a chain to form a sinusoid
  • Do this so that uptake proteins are everywhere else and export proteins are closer to the inside
61
Q

1 hepatocyte = ___ microns

A

15-20

62
Q

What is another name for a sinusoid?

A

Bile canaliculi

63
Q

Why is direct drug diffusion rare in the plasma membrane?

A

B/c surface of the cell has many components (proteins, glycolipids, oligosaccharides) and few areas of just lipid bilayer, so it is hard to find a direct lipophilic area for drug diffusion

64
Q

What do drug transporters control when they are in the membrane of cells?

A
  • Intracellular drug [ ]
  • Access to drug metabolizing enzymes
  • Systemic drug [ ], absorption, and excretion
  • Drug [ ] at site of action
65
Q

What travels through efflux transporters?

A

Drug and/or metabolite

66
Q

Do transporters only recognize one substrate?

A

No, can recognize many, sometimes from structurally unrelated classes

67
Q

What are the types of SLC transporters?

A
  • Organic anion transporters (OATs) and transport proteins (OATPs)
  • Organic cation transporters (OCTs)
  • Peptide transporters (PEPTs)
  • Multidrug and toxin extrusion protein (MATEs)
68
Q

What are the types of ABC transporters?

A
  • ABC = ATP binding cassette
  • P-glycoprotein (P-gp (ABDB1))
  • Breast cancer resistant protein (BCRP (ABCG2))
  • Multi-drug resistant proteins (MRPs)
  • Bile salt extrusion protein (BSEP)
69
Q

What is known when a drug is a substrate of a transporter?

A
  • Determinant of drug disposition (ADME)

- Prediction of potential drug-drug interactions (DDI)

70
Q

What is known when a drug is an inhibitor of a transporter?

A
  • Affects intracellular/systemic concentrations of affected drugs
  • DDI potential w/ other substrate drugs
71
Q

How do transporters cause DDIs?

A

If 2 drugs have the same carrier, the one w/ highest affinity will be taken up while the other will be eliminated

72
Q

What are SLC transporters generally responsible for?

A

Uptake of molecules into cells

73
Q

Where are most SLC transporters located?

A
  • Cell membrane

- Some located in mitochondria or other intracellular organelles

74
Q

How are SLC transporters named? Which family is an exception to this?

A
  • nXm
  • n = family number (1-52)
  • X = letter for subfamily
  • m = number representing individual family member
  • Exception = family 21 (OATPs)
75
Q

What happens if bile acids are not removed from a cell?

A

Will solubilize everything and cause apoptosis

76
Q

What are ABC transporters generally responsible for?

A

Efflux (removal) of molecules from cells

77
Q

Where are ABC transporters found? What do they use for energy?

A
  • Transmembrane

- Use ATP hydrolysis as an energy source to translocate substrates across membranes

78
Q

How are ABC transporters named?

A
  • xN
  • x = family (A-G)
  • N = number representing individual family member
79
Q

Are ABC transporters small or large?

A

Can be very large

80
Q

Do SLC and ABC transporters work together or against each other?

A

Together, in vectorial transport

81
Q

What are the main characteristics of active transport?

A
  • Can move substrate against [ ] gradient
  • Requires energy expenditure
  • At low [drug], rate is proportional to [drug]
  • At high [drug], carrier mechanism is saturated
  • Shows specificity in certain organs and certain transporters
  • Subject to competitive inhibition
  • Shows site specificity
  • Inhibited non-competitively by substances that interfere w/ respiration/energy production of cells
82
Q

What happens if the amino acids of an ABC transporter are changed?

A

There will be a dramatic change in the concentration-time curve (increased Cmax and greater AUC)

83
Q

How could you determine if a drug undergoes active transport or passive diffusion?

A

Active transport will diminish when temp. is decreased, but passive diffusion won’t b/c it is temp. dependent in Kelvin

84
Q

What influence does volume have on gastric emptying?

A
  • Larger starting volume = greater initial rate of emptying

- After initial period, rate slows

85
Q

What influence do fatty acids have on gastric emptying?

A

Reduce emptying, in proportion to chain length

86
Q

What influence do triglycerides have on gastric emptying?

A

Reduce rate of emptying, unsaturated more effective, linseed and olive oils most effective

87
Q

What influence do carbs have on gastric emptying?

A

Reduce

88
Q

What influence do amino acids have on gastric emptying?

A

Reduce, proportional to concentration

89
Q

What influence does osmotic pressure have on gastric emptying?

A
  • Increase at lower concentrations

- Decrease at higher

90
Q

What influence does the physical state of food have on gastric emptying?

A

Solutions or suspensions empty more rapidly than solids

91
Q

What influence do acids have on gastric emptying?

A

Reduce

92
Q

What influence do alkali chemicals have on gastric emptying?

A

Increase

93
Q

What influence do anticholinergics have on gastric emptying?

A

Decrease in emptying

94
Q

What influence do narcotic analgesics have on gastric emptying?

A

Decrease in emptying

95
Q

What influence does metoclopromide have on gastric emptying?

A

Increase in emptying

96
Q

What influence does ethanol have on gastric emptying?

A

Reduction

97
Q

What influence does body position have on gastric emptying?

A

Lying on left side reduces emptying

98
Q

What influence does viscosity have on gastric emptying?

A

Increase viscosity reduces emptying

99
Q

What influence does emotional state have on gastric emptying?

A
  • Aggressiveness increases contractions and emptying

- Depression reduces

100
Q

What influence do bile salts have on gastric emptying?

A

Reduces

101
Q

What influence do disease states have on gastric emptying?

A

Rate is reduced in some hypothyroidism, pyloric lesions

102
Q

What influence does exercise have on gastric emptying?

A

Vigorous exercise reduces

103
Q

What influence does gastric surgery have on gastric emptying?

A

Emptying difficulties can be a serious problem

104
Q

___ is a major factor in drug absorption in the gut

A

Food

105
Q

Should drugs be taken w/ water? Why?

A
  • Yes b/c helps disintegration and drug needs to be in solution to be absorbed
  • Don’t take w/ caffeinated drinks b/c can alter pH
  • Don’t take w/o water b/c can get stuck in esophagus and result in a delay of onset
106
Q

What are some factors that affect drug absorption?

A
  • Age (# of transporters)
  • Blood flow
  • pH
  • Food
  • Drugs
107
Q

What is intensity?

A
  • Distance btwn minimum effective concentration and Cmax

- May correlate w/ therapeutic window

108
Q

What is duration?

A

Time of onset to termination

109
Q

Can a drug have 2 Cmax values?

A

Yes, b/c food affects absorption

110
Q

What are some drug related factors that affect dissolution rate?

A
  • Solubility
  • Solvation
  • Crystalline
  • Particle size
  • Complexation

Kinetics (4 decks)

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