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Pharm 2024 > PPT 5 > Flashcards

PPT 5 Flashcards

1
Q

What are the 4 parameters affecting passive diffusion?

A

Molecular weight
pKa
Lipid solubility
Plasma protein binding

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2
Q

_____ of genes in genome encode for transporter proteins

A

7%

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3
Q

SLC transporters cross barriers via ______

A

Primarily passive transport (gradients)
Some active - exchanger and coupled transport

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4
Q

What do SLC proteins transport?

A

High substrate specificity - nutrients, ions, metabolites, and drugs

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5
Q

What are the 4 types of permeation?

A
  • Aqueous diffusion
  • Lipid diffusion
  • Endocytosis and exocytosis
  • Special carriers
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6
Q

What are special carriers? How do they work?

A

Membrane drug transporters; molecules bind to drugs and move across barriers
Primary function - transport endogenous substances

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7
Q

What is the main drug efflux transporter?

A

ATP-binding cassette (ABC) transporters

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8
Q

ABC transporters have ______ substrate specificity

A

broad

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9
Q

What do drug efflux pumps do?

A
  • Pump drug out of cell
  • Cell survival mechanism
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10
Q

What are nucleotide-binding domains?

A

ATP binds to NBD

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11
Q

What do ABC transporters have in common?

A
  1. Transmembrane spanning domains
  2. Nucleotide-binding domain (NBD)
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12
Q

ABC transporters are _____ specific

A

location - apical (top) vs basal (bottom)

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13
Q

What are the major drug efflux transporters?

A

ABC transporters - B, C, G

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14
Q

Which ABC transporter has the broadest substrate specificity?

A

ABCB1

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15
Q

_______ is critical in the maintenance of BBB

A

ABCB1

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16
Q

What are the drug interactions with ABCB1?

A

Drugs that inhibit ABCB1 - Cyclosporine A, Quinidine, Ritonavir

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17
Q

Digoxin is transported by ______

A

ABCB1

18
Q

What will happen if a patient is taking digoxin AND a drug that inhibits ABCB1?

A

Decreased intestinal removal and increased plasma levels (toxicity) of digoxin - arrhythmias

19
Q

Loperamide is transported by ______

A

ABCB1

20
Q

How does loperamide work as an antidiarrheal?

A

Although loperamide is an opioid, since it is transferred by ABCB1 in the gut, it stays in the gut – antidiarrheal
- No CNS effects: GI ABCB1

21
Q

How do people abuse loperamide?

A
  • When given with quinidine (ABCB1 inhibitor)
    - Systemic absorption
    - CNS effects (respiratory suppression)
22
Q

ABCC primarily transports _______

A

antineoplastic drugs

23
Q

ABCG transports ______

A
  • Breast cancer resistance protein (BCRP)
  • Antineoplastics, toxins, food-borne carcinogens
  • Folate transport
24
Q

The majority of drugs are absorbed through these barriers in ABC transporters

A

Intestines, liver, kidneys

25
Q

The majority of the drugs are pumped back out of these barriers via ABC transporters

A

Placenta, BBB, blood-CSF barrier

26
Q

_______, _______, and _______ prevent drugs from crossing the BBB

A

ABC transporters
The vascular epithelium
Other cells - astrocytes and podocytes - regulate how much drug reaches neurons

27
Q

ABC transporters in the GI tract are primarily on the ______ surface

A

apical - microvilli (increase surface area)

28
Q

Most of the ABC transporters are in the _____

A

gut and liver
Gut - most common – ABCG2 (BCRP), but has all types

29
Q

________ transport out glucuronides from hepatic metabolism back into the intestine

A

ABCC (MRPs)

30
Q

The liver facilitates xenobiotic metabolism, excretion into____

A

bile

31
Q

Types of transporters in the liver

A

SLC type (OATPs), ABCs (all)

32
Q

Lipophilic drugs can cross ____

A

barriers - BBB, placenta
nicotine, alcohol

33
Q

Transporter protein expression is upregulated by:

A

PXR, steroids, xenobiotics

34
Q

Transporter protein expression is downregulated by:

A
  • Endothelin
  • Partial agonist - antagonist function
35
Q

xenobiotics

A

chemical substances that are foreign to the biological system (made outside the body)

36
Q

Regulation of cholesterol in the cell is accomplished by ______

A

ABCA1 transporter

37
Q

Blood CSF barrier is not as ______ as the BBB

A

selective

38
Q

How is Tylenol metabolized when taken orally?

A

From intestine taken into the bloodstream where it undergoes first-pass effect in the liver. Tylenol metabolism is a phase II reaction of glucuronidation (a glucose molecule is attached to the Tylenol) it is now a non-toxic glucuronide. This is put into the bile that then returns to the intestine. It is now recognized by the ABC transporters because of the glucuronidation, it is transported to the intestine where it can be excreted via defecation.

39
Q

Drug transporter direction “flux” is determined by

A

Their location and what the function of the organ they are located on is

40
Q

The BBB is composed of _____

A

tight junctions

41
Q

Molecules that can cross the BBB include

A

Small, lipophilic molecules (O2, CO2, ehtanol, nicotine) - transcellular lipophilic pathway
Medium molecules (glucose, amino acids, nucleotides) - carrier protein-mediated pathway
Large molecules (insulin, IgG, albumin, histone) - endocytosis

Pharm 2024 (28 decks)

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