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PCEUT 510 > DDI-Gastrointestinal Absorption > Flashcards

DDI-Gastrointestinal Absorption Flashcards

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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
T/F | Oxybutynin will SLOW GI motility
True | Oxybutynin is anticholinergic used for urinary incontinence
26
T/F | Benztropine, trihexyphenidyl will SLOW GI motility
True | These are anticholinergic drugs used in Parkinson's disease
27
What is an agent that is used for motion sickness that will SLOW GI motility?
Scopolamine
28
This drug has an F~0.1%, poor mucosal permeability, absorption is limited by residence time in the small intestine
Desmopressin
29
Adding Loperamide to Desmopressin( poorly permeable drug) greatly [increases/decreases] the AUC of desmopressin?
INCREASES
30
Desmopressin + __________ greatly INCREASED its AUC/Concentration
Loperamide
31
Which is the OBJECT drug out of DDI of sotalol & cisapride?
Sotalol
32
Adding this prokinetic agent to sotalol lowered Sotalol's F by 30% [from 1.00 to 0.70]
cisapride
33
This oral cytotoxic antibiotic was shown to affect digoxin and methotrexate absorption
Neomycin
34
What is the mechanism of oral cytotoxic antibiotics and antineoplastic agents that leads to drug malabsorption?
Damage the intestinal microvilli
35
What two agents are responsible for decreasing oral drug bioavailability due to suppression of gastric acid production?
H2-antagonists PPI elevate fasting gastric pH to >3
36
Reduced acidity, caused by H2 antagonist/PPI use, will impede the dissolution of POORLY soluble [acidic/basic] drugs?
BASIC drugs | with pKa >3
37
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
D. is incorrect | Phenytoin is an example of an acidic drug
38
[Ketoconazole/itraconazole/Fluconazole] will NOT have its absorption significantly affected by H2 antagonists/PPIs?
Fluconazole
39
Sorafenib, axitinib & crizotinib are all ________ of tyrosine kinase inhibitors affected by reduced gastric acid production
Exceptions
40
Use of this substance counteracted omeprazole's effect on ketoconazole absorption
Coca-Cola
41
Omeprazole has no affect on the absorption of this antifungal
Fluconazole
42
What is the object drug out of ketoconazole and omeprazole in the presence of Coca-Cola?
Both would be considered the Object drug
43
How are the Cmax and AUC of tyrosine kinase inhibitors affected by PPIs?
Decreased
44
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?
Phenobarbital & Valproic acid | Decrease dissolution & absorption of very lipid soluble drugs like Griseofulvin
45
Direct Mechanisms Involve
1. Physicochemical interactions between TWO drugs | 2. Modulation of uptake and efflux transporter expression/activities at the intestinal mucosa
46
Physicochemical type interactions are ________ and USUALLY can be_______ by timing of the administration of the interacting medication.
Agent-specific | avoided/minimized
47
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
B is incorrect Neutralization of gastric acid is an INDIRECT mechanism D is partially correct in that Al3+ antacids = Constipation Mg2+ antacids = diarrhea
48
T/F | Antacids are not the same with respect to POTENTIAL and MAGNITUDE of interactions
``` 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
Which transporter at the intestinal mucosa will affect absorption?
Pg-P
50
Which antacid cation SLOWS gut motility? | [Al3+, Mg2+]
Al3+ | Constipation
51
Which antacid cation ACCELERATES gut motility? | [Al3+, Mg2+]
Mg2+ | Diarrhea
52
What is the effect on gut motility when you add Al3+ and Mg2+ together?
Nil effect
53
Which antacid cation has the most acid neutralizing capacity? [Ca2+, Na+, Mg2+, Al3+]
Ca2+
54
For BASIC drugs; Increases in gastric pH potentially leads to [increased/decreased] ionization which [slows/promotes] dissolution & [reduces/accelerate]________
``` Decreased ionization Slows dissolution Reduces Bioavailability example: Itraconazole-antacids ```
55
For ACIDIC drugs: Increases in gastric pH potentially leads to [increased/decreased] ionization which [slows/promotes] dissolution & [reduces/accelerate]________
``` Increased Ionization Promotes dissolution Accelerates Absorption example: Sulfonylurea antidiabetic drugs ```
56
Increased dissolution of _______ coating in a raised gastric pH patient will lead to premature drug release in the stomach
Enteric example: enteric-coated aspirin
57
Levothyroxine taken with Al3+ or Ca2+ containing antacids resulted in significant [increase/decrease] of bioavailability due to what two properties?
Decreased bioavailability Due to: 1. absorption 2. elevation in gastric pH
58
These classes of antibiotics will chelate to Al3+ and Mg 2+ antacids, causing major bioavailability problems.
1. Tetracycline | 2. Quinolones
59
Which antacids show less/minimal problems when administered with quinolones? [Al3+, Mg2+, Ca2+]
Ca2+ | Separation of 2(before) or 4 (after) hours seems to help with all antacid associated issues
60
Ciprofloxacin + CaCO3 antacid [decreases/increases] AUC?
Decreased AUC
61
__ containing antacids can SLOW drug absorption and decrease efficacy if it depends on adequate peak concentration [Mg2+, Al3+, Ca2+]
Al3+ examples: isoniazid fenamate NSAIDs
62
Antacids with this cation can enhance absorption rate and bioavailability of sulfonylureas (glyburide) causing EXCESSIVE _________
Mg2+ | Hypoglycemia
63
Iron supplements can interfere with absorption of these antibiotics via chelation
1. Tetracycline | 2. quinolones
64
What are 4 direct-acting precipitants that DECREASE bioavailability?
1. Iron supplements 2. Sucralfate 3. Pepto-Bismol 4. Orlistat
65
This metal supplement will interfered with L-DOPA & Carbidopa bioavailability through what Two mechanisms?
Iron 1. Chelation 2. Fe-mediated redox-degradation
66
Sucralfate is salt of sulfated sucrose based on this cation? [Mg2+, Ca2+, Al3+]
Al3+
67
Sucralfate [decreases/increases] bioavailability of quinolones
Deceases
68
Pepto-Bismol will interfere with absorption of | [tetracycline, quinolones, both]
Tetracycline
69
This OTC drug reduces absorption of fat-soluble drugs
Orlistat example: 1. Cyclosporine 2. Lamotrigine 3. Amiodarone 4. Levothyroxine
70
T/F | Antacid interactions are unavoidable if the patient is taking antacids throughout the day?
True
71
Bile acid sequestrants are [cation/anion] exchange resins
anion
72
What types of drugs are: Cholestyramine, colestipol and colesevelam?
Bile acid sequestrants
73
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
Acid drugs 1. Warfarin 2. Thiazide diuretics 3. Gemfibrozil
74
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 _______
Lipophilic drug | 1. Diltiazem
75
Bile acid resins accelerate the clearance of drugs that undergo this maneuver
ENTERO-HEPATIC CIRCULATION
76
Mycophenolic acid undergoes entero-hepatic circulation, when combined with cholestyramine its AUC [increases/decreases] due to increased clearance
AUC Decreases
77
This phosphate binder interferes with the oral absorption of digoxin, enalapril, warfarin, iron, ciprofloxacin and quetiapine
Sevelamer (newer agent sucroferric oxyhydroxide interacts with: 1. Doxycycline 2. Levothryoxine)
78
Interactions involved with drug metabolism in the GI associated with microflora are confined to__________
First-pass metabolism | enterohepatic circulation
79
Classic example of Microflora drug interaction: Ampicillin pretreatment leads to less bacterial azo reduction of ___________, leading to less efficacy in the tx of IBD
Sulfasalazine [prodrug have DECREASED efficacy with antibiotics] Decreased AUC
80
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?
1. erythromycin 2. tetracycline 3. ampicillin
81
Abx interrupt this process, which can lead to OCP failure
Entero-hepatic circulation
82
ESTROGEN in OCP's undergo conjugation to form _________ and _________ metabolites, which are excreted into bile and undergo enterohepatic circulation
Sulfate | Glucuronide
83
This antibiotic has the most issue with OCPs due to its induction of p450s
Rifampin
84
T/F | Non-enzyme inducing oral abx cause OCP failure more often than the control population
False
85
Ketoconazole + Omeprazole DDI | Who is the [object/victim] drug?
Ketoconazole
86
Ketoconazole + Omeprazole DDI | Who is the [perpetrator/precipitant] drug?
Omeprazole

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