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PCEUT 510 > DDI-Gastrointestinal Absorption > Flashcards

DDI-Gastrointestinal Absorption Flashcards

1
Q

What are the Two general types of drug interaction mechanisms involving GI-absorption?

A
  1. INDIRECTLY

2. DIRECT

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2
Q

Indirectly

[Definition}

A

Occurs as a result of the action of the precipitating agent on gastrointestinal function = affects ABSORPTION of OBJECT drug

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3
Q

Direct

[Definition]

A

Occurs as a resulting action of one drug on another

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4
Q

What are the 4 indirect mechanisms affecting GI-absorption?

A
  1. Gastrointestinal motility
  2. Mucosal barrier function
  3. Gastric acid secretion
  4. Bile acid secretion
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5
Q 
Where is the major site of drug absorption? 
A. Small Intestine
B. Colon
C. Stomach
D. Kidney
A

A. is correct

Any changes to the small intestine can alter onset and rate of absorption of many drugs

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6
Q

Affecting this parameter of GI motility will alter onset and rate of drug absorption

A

Gastric emptying rate

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7
Q

Affecting this parameter will alter the residence time at the “absorption window”

A

Small intestine transit

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8
Q

[Increased/Decreased] motility [increase/decrease] residence time = INCREASES absorption/bioavailability

A

Decreased motility

increases residence time

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9
Q

[Increased/Decreased] motility [increase/decrease] residence time = DECREASES absorption/bioavailability

A

Increased motility

Decreases residence time

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10
Q

T/F

DDIs involving GI Motility are often formulation dependent

A

True

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11
Q

T/F

Interactions affecting GI motility are usually mild to modest in magnitude and not always clinically significant

A

True

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12
Q

Anti-diarrheal agents (Lomotil, Imodium) will [decrease/increase] motility?

A

Decrease

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13
Q

Opioid analgesics (hydrocodone, morphine) will [decrease/increase] motility?

A

Decrease

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14
Q

Anticholinergics will [decrease/increase] motility?

A

Decrease

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15
Q

Strong anticholinergics will [decrease/increase] motility?

A

Decrease

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16
Q

Older antiemetics (metoclopramide, domperidone) will [decrease/increase] motility?

A

Increase

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17
Q

Prokinetic agents will [decrease/increase] motility?

A

Increase

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18
Q

Cholinesterase inhibitors for Alzheimer’s will [decrease/increase] motility?

A

Increase

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19
Q

T/F

Diphenhydramine is a strong anticholinergic that will increase motility?

A

False
Strong anticholinergics will DECREASE motility
(other strong anticholinergics include TCAs like amitriptyline)

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20
Q

Donepezil, rivastigmine, galantamine are all examples of ___________ that [increase/decrease] motility?

A

Cholinesterase inhibitors for Alzheimer’s disease

INCREASE

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21
Q

5-HT4 agonist, guanylate cyclase-C agonist, and muscarinic agonist are all examples of_________ that [increase/decrease] motility?

A

Prokinetic agents

INCREASE

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22
Q

What class is linaclotide?

A

Guanylate cyclase-C agonist
Prokinetic agent
INCREASE motility

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23
Q

Cisapride, tegaserod are what class_______?

A

5-HT4 agonist
Prokinetic agent
INCREASE motility

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24
Q

Bethanechol is a _______ agonist that increases motility

A

Muscarinic agonist

prokinetic agent

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25
Q

T/F

Oxybutynin will SLOW GI motility

A

True

Oxybutynin is anticholinergic used for urinary incontinence

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26
Q

T/F

Benztropine, trihexyphenidyl will SLOW GI motility

A

True

These are anticholinergic drugs used in Parkinson’s disease

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27
Q

What is an agent that is used for motion sickness that will SLOW GI motility?

A

Scopolamine

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28
Q

This drug has an F~0.1%, poor mucosal permeability, absorption is limited by residence time in the small intestine

A

Desmopressin

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29
Q

Adding Loperamide to Desmopressin( poorly permeable drug) greatly [increases/decreases] the AUC of desmopressin?

A

INCREASES

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30
Q

Desmopressin + __________ greatly INCREASED its AUC/Concentration

A

Loperamide

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31
Q

Which is the OBJECT drug out of DDI of sotalol & cisapride?

A

Sotalol

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32
Q

Adding this prokinetic agent to sotalol lowered Sotalol’s F by 30% [from 1.00 to 0.70]

A

cisapride

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33
Q

This oral cytotoxic antibiotic was shown to affect digoxin and methotrexate absorption

A

Neomycin

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34
Q

What is the mechanism of oral cytotoxic antibiotics and antineoplastic agents that leads to drug malabsorption?

A

Damage the intestinal microvilli

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35
Q

What two agents are responsible for decreasing oral drug bioavailability due to suppression of gastric acid production?

A

H2-antagonists
PPI
elevate fasting gastric pH to >3

36
Q

Reduced acidity, caused by H2 antagonist/PPI use, will impede the dissolution of POORLY soluble [acidic/basic] drugs?

A

BASIC drugs

with pKa >3

37
Q

All of the following are basic drugs and will be affected by the use of H2-antogonist/PPI use EXCEPT?
A. Ketoconazole, itraconazole (antifungals)
B. Indinavir, atazanavir (protease inhibitors)
C. Majority of tyrosine kinase inhibitors
D. Phenytoin

A

D. is incorrect

Phenytoin is an example of an acidic drug

38
Q

[Ketoconazole/itraconazole/Fluconazole] will NOT have its absorption significantly affected by H2 antagonists/PPIs?

A

Fluconazole

39
Q

Sorafenib, axitinib & crizotinib are all ________ of tyrosine kinase inhibitors affected by reduced gastric acid production

A

Exceptions

40
Q

Use of this substance counteracted omeprazole’s effect on ketoconazole absorption

A

Coca-Cola

41
Q

Omeprazole has no affect on the absorption of this antifungal

A

Fluconazole

42
Q

What is the object drug out of ketoconazole and omeprazole in the presence of Coca-Cola?

A

Both would be considered the Object drug

43
Q

How are the Cmax and AUC of tyrosine kinase inhibitors affected by PPIs?

A

Decreased

44
Q

Drug induced choleresis by these two agents decrease the bile acid concentration in the intestinal fluid which DECREASES the dissolution and absorption of what type of drugs?

A

Phenobarbital & Valproic acid

Decrease dissolution & absorption of very lipid soluble drugs like Griseofulvin

45
Q

Direct Mechanisms Involve

A
  1. Physicochemical interactions between TWO drugs

2. Modulation of uptake and efflux transporter expression/activities at the intestinal mucosa

46
Q

Physicochemical type interactions are ________ and USUALLY can be_______ by timing of the administration of the interacting medication.

A

Agent-specific

avoided/minimized

47
Q

Direct Antacid-drug interactions include all of the following EXCEPT?
A. Chelation
B. Neutralization of gastric acid
C. Absorption
D. Accelerate/delay gastric emptying & intestinal transit time

A

B is incorrect
Neutralization of gastric acid is an INDIRECT mechanism

D is partially correct in that
Al3+ antacids = Constipation
Mg2+ antacids = diarrhea

48
Q

T/F

Antacids are not the same with respect to POTENTIAL and MAGNITUDE of interactions

A 
True 
Because of differing:  
1. Acid neutralizing capacity 
2. Stability of the metal chelate
3. Effects of metals on gut motility 
4. Absorptive capacity
49
Q

Which transporter at the intestinal mucosa will affect absorption?

A

Pg-P

50
Q

Which antacid cation SLOWS gut motility?

[Al3+, Mg2+]

A

Al3+

Constipation

51
Q

Which antacid cation ACCELERATES gut motility?

[Al3+, Mg2+]

A

Mg2+

Diarrhea

52
Q

What is the effect on gut motility when you add Al3+ and Mg2+ together?

A

Nil effect

53
Q

Which antacid cation has the most acid neutralizing capacity?
[Ca2+, Na+, Mg2+, Al3+]

A

Ca2+

54
Q

For BASIC drugs; Increases in gastric pH potentially leads to [increased/decreased] ionization which [slows/promotes] dissolution & [reduces/accelerate]________

A 
Decreased ionization
Slows dissolution
Reduces
Bioavailability 
example:
Itraconazole-antacids
55
Q

For ACIDIC drugs: Increases in gastric pH potentially leads to [increased/decreased] ionization which [slows/promotes] dissolution & [reduces/accelerate]________

A 
Increased Ionization 
Promotes dissolution
Accelerates
Absorption 
example: 
Sulfonylurea antidiabetic drugs
56
Q

Increased dissolution of _______ coating in a raised gastric pH patient will lead to premature drug release in the stomach

A

Enteric
example:
enteric-coated aspirin

57
Q

Levothyroxine taken with Al3+ or Ca2+ containing antacids resulted in significant [increase/decrease] of bioavailability due to what two properties?

A

Decreased bioavailability
Due to:
1. absorption
2. elevation in gastric pH

58
Q

These classes of antibiotics will chelate to Al3+ and Mg 2+ antacids, causing major bioavailability problems.

A
  1. Tetracycline

2. Quinolones

59
Q

Which antacids show less/minimal problems when administered with quinolones?
[Al3+, Mg2+, Ca2+]

A

Ca2+

Separation of 2(before) or 4 (after) hours seems to help with all antacid associated issues

60
Q

Ciprofloxacin + CaCO3 antacid [decreases/increases] AUC?

A

Decreased AUC

61
Q

__ containing antacids can SLOW drug absorption and decrease efficacy if it depends on adequate peak concentration
[Mg2+, Al3+, Ca2+]

A

Al3+
examples:
isoniazid
fenamate NSAIDs

62
Q

Antacids with this cation can enhance absorption rate and bioavailability of sulfonylureas (glyburide) causing EXCESSIVE _________

A

Mg2+

Hypoglycemia

63
Q

Iron supplements can interfere with absorption of these antibiotics via chelation

A
  1. Tetracycline

2. quinolones

64
Q

What are 4 direct-acting precipitants that DECREASE bioavailability?

A
  1. Iron supplements
  2. Sucralfate
  3. Pepto-Bismol
  4. Orlistat
65
Q

This metal supplement will interfered with L-DOPA & Carbidopa bioavailability through what Two mechanisms?

A

Iron

  1. Chelation
  2. Fe-mediated redox-degradation
66
Q

Sucralfate is salt of sulfated sucrose based on this cation?
[Mg2+, Ca2+, Al3+]

A

Al3+

67
Q

Sucralfate [decreases/increases] bioavailability of quinolones

A

Deceases

68
Q

Pepto-Bismol will interfere with absorption of

[tetracycline, quinolones, both]

A

Tetracycline

69
Q

This OTC drug reduces absorption of fat-soluble drugs

A

Orlistat

example:
1. Cyclosporine
2. Lamotrigine
3. Amiodarone
4. Levothyroxine

70
Q

T/F

Antacid interactions are unavoidable if the patient is taking antacids throughout the day?

A

True

71
Q

Bile acid sequestrants are [cation/anion] exchange resins

A

anion

72
Q

What types of drugs are: Cholestyramine, colestipol and colesevelam?

A

Bile acid sequestrants

73
Q

Anion-exchange resins (bile acid resins) bind acidic drugs such as 1. ________, 2._________ and 3._________ as well as a few lipophilic basic drugs, such as diltiazem

A

Acid drugs

  1. Warfarin
  2. Thiazide diuretics
  3. Gemfibrozil
74
Q

Anion-exchange resins (bile acid resins) bind acidic drugs such as warfarin, thiazides and gemfibrozil as well as a few lipophilic basic drugs, such as _______

A

Lipophilic drug

1. Diltiazem

75
Q

Bile acid resins accelerate the clearance of drugs that undergo this maneuver

A

ENTERO-HEPATIC CIRCULATION

76
Q

Mycophenolic acid undergoes entero-hepatic circulation, when combined with cholestyramine its AUC [increases/decreases] due to increased clearance

A

AUC Decreases

77
Q

This phosphate binder interferes with the oral absorption of digoxin, enalapril, warfarin, iron, ciprofloxacin and quetiapine

A

Sevelamer

(newer agent sucroferric oxyhydroxide interacts with:

  1. Doxycycline
  2. Levothryoxine)
78
Q

Interactions involved with drug metabolism in the GI associated with microflora are confined to__________

A

First-pass metabolism

enterohepatic circulation

79
Q

Classic example of Microflora drug interaction: Ampicillin pretreatment leads to less bacterial azo reduction of ___________, leading to less efficacy in the tx of IBD

A

Sulfasalazine
[prodrug have DECREASED efficacy with antibiotics]
Decreased AUC

80
Q

Abx with slow and poor absorption that are given at high doses are likely precipitants of interfering with bacterial metabolism. Which three drugs/classes were mentioned as being these precipitants?

A
  1. erythromycin
  2. tetracycline
  3. ampicillin
81
Q

Abx interrupt this process, which can lead to OCP failure

A

Entero-hepatic circulation

82
Q

ESTROGEN in OCP’s undergo conjugation to form _________ and _________ metabolites, which are excreted into bile and undergo enterohepatic circulation

A

Sulfate

Glucuronide

83
Q

This antibiotic has the most issue with OCPs due to its induction of p450s

A

Rifampin

84
Q

T/F

Non-enzyme inducing oral abx cause OCP failure more often than the control population

A

False

85
Q

Ketoconazole + Omeprazole DDI

Who is the [object/victim] drug?

A

Ketoconazole

86
Q

Ketoconazole + Omeprazole DDI

Who is the [perpetrator/precipitant] drug?

A

Omeprazole

PCEUT 510 (12 decks)

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