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General Pharmacology > Drug Disposition I > Flashcards

Drug Disposition I Flashcards

1
Q

Processes by which drugs cross biological membrane: (3)

A

Passive diffusion lipid aqueous
Passive transport
Active Transport

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2
Q

The most common and important mechanism of drug movement is active lipid diffusion, in which the drug dissolves in the lipid membrane and diffuses across driven by a concentration gradient. True or false?

A

false, passive diffusion

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3
Q

Rate of passive lipid diffusion depends on (3)

A

concentration gradient (affected by blood flow)
surface area
lipophilicity

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4
Q

2 major classes of drug transporters: Most drugs transported by which one?

A

Uptake& Efflux

Efflux

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5
Q

SLC transporters co-transport solutes like sodium. What type of transporter is this?

A

uptake

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6
Q

ABC transporters use ATP is an example of what transporter?

A

efflux

pump things out of the cell

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7
Q

Most drugs are ____ electrolytes.

A

weak

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8
Q

Ionized forms of chemicals do penetrate lipid membranes. True or false?

A

false

do not

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9
Q

Degree of drug ionization: (2)

A

pKa–intrinisic property of drug

pH of surrounding medium

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10
Q

weak acids: mainly ionized at pH __ pKa. weak bases: mainly ionized at pH __ pKa

A

>

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11
Q

The nonionized form is free to be absorbed across the gastric epithelial cell layer. Once it reaches the plasma, it encounters a pH that is now above its pKa. Therefore, aspirin will now be mostly in the ionized form. The rapid ionization of aspirin in the plasma maintains the concentration gradient of the diffusible (nonionized) form of aspirin, and diffusion will continue until equilibrium is reached. Thus, the total amount of aspirin at equilibrium (which never occurs in reality, this is only a conceptual example) will be 8000-fold higher in the high pH compartment. This is known as ___ ____.

A

ion trapping

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12
Q

What type of tissue contains : tight junctions lipid diffusion only

A

gastrointestinal epithelium

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13
Q

Molecules cross ______ endothelial cell layer by: Transcellular diffusion Aqueous diffusion Receptor-mediated endocytosis/pinocytosis Bold = most common

A

capillaries

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14
Q

Most capillaries are ______: (porous regions within and between cells) admit water-soluble molecules up to 60 kDa via ______ transport.

A

fenestrated

paracellular

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15
Q

________ capillaries are very leaky and allow RBCs and WBCs to pass

A

Discontinuous

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16
Q

_______ capillaries have tight junctions (but differ in the degree of pinocytosis)

A

Continuous

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17
Q

______ is the main drug barrier in the brain.

A

BBB

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18
Q

In the placenta, the human trophoblast basement membrane is quite porous. Admits most drugs < ____ MW

A

600

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19
Q

Factors affecting oral absorption: (7)

A 
solubility			
stomach acid			
pH range			
tight junctions, 
lipid solubility			
surface area			
transport to liver via portal vein and first pass metabolism			
Intestinal motility, gastric emptying,
 blood flow
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20
Q

Enteral routes of drug administration: (3)

A

oral
sublingual (to avoid first pass metabolism and liver)
rectal

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21
Q

Parental routes of drug administration: (7)

A 
IV			
IM			
subcutaneous			
inhalation			
nasal			
transdermal			
topical
22
Q

Pulmonary administration of drugs: (4)

A

Gaseous anesthetics
Smoking
Aerosols for topical effects on lungs e.g. albuterol for asthma Aerosols for delivery to systemic circulation droplet or particle size is critical

23
Q

Gaseous diffusion of anesthetics depends on: (3)

A

solubility in blood
drug concentration
ventilation

24
Q

____ _____, not concentration, in blood determines delivery to CNS.

A

Partial pressure

25
Q

____ soluble anesthetics have faster rise in arterial partial pressure and equilibrate with tissues faster.

A

Less

26
Q

The fraction (percentage) of the administered dose that reaches the systemic circulation is called _____.

A

Bioavailability

27
Q

What factors affect bioavailability? (3)

A

Dissolution in gastrointestinal fluids Absorption

First pass metabolism in liver

28
Q

____ ____ can vastly affect drug distribution by binding to the drug.

A

Plasma proteins

29
Q

Apparent volume of drug distribution: Formula? Units?

A

amount of drug (mg) plasma concentration (mg/ml)
liters

30
Q

The apparent volume of drug distribution can be much lower than body volume if drug is sequestered in compartment other than blood. True or false?

A

false

higher than body volume

31
Q

KNOW! What is used to determine the dose required to achieve desired plasma concentration (single or loading dose)?

A

apparent volume of distribution

32
Q

Most drugs bind to ____ which is ____ ____.

A

albumin

plasma proteins

33
Q

Basic drugs tend to bind to ____-acid _______

A

alpha-1

glycoprotein

34
Q

What is an acute phase protein that rises in the blood during inflammation?

A

alpha-1 acid glycoprotein

35
Q

Which of the following is false regarding binding to plasma proteins? Only free drug crosses membrane and is pharmacologically active Slows onset of drug action: slows rate of equilibration with e/c fluids and can reduce amount of drug available for equilibration Tends to increase Vd (app)

A

tends to decrease Vd (app)

36
Q

What factors affect drug distribution (cellular reservoirs)? (3)

A

Fat–lipid-soluble drugs Bones/teeth–metals form insoluble phosphates
Increased Vd,
biological half-life

37
Q

Rapid anesthesia due to rapid entry into brain (2)

A

Blood flow Crosses bbb easily

38
Q

Three phases of propofol PK Redistribution phase (~___ min) Rapid metabolic clearance (~___ min) Slow phase (____ hr) elimination from poorly perfused tissues

A

3
45
3-4 hours

39
Q

Amount of drug excreted = glomerular filtration + ___________ - ___________

A

tubular secretion tubular reabsorption

40
Q

______ _______ (units of ____) is volume of plasma from which drug is fully removed per unit time

A

Renal clearance ml/min

41
Q

Only _____ drug (both non-ionized and ionized) is filtered

A

free

42
Q

Influenced by: plasma protein binding volume of distribution blood pressure and blood flow

A

GFR

43
Q

Tubular reabsorption of sodium, water, creates a _________ _____ of drug.

A

concentration gradient

44
Q

Drug reabsorption occurs via ______ diffusion, primarily in ______ _____ and _____ _____.

A

passive

distal tubule and collecting duct

45
Q

_____ soluble, less polar drugs (unmetabolized) are ______.

A

Lipid

reabsorbed

46
Q

______ drug is _____ in urine

A

Ionized

excreted

47
Q

______ _____ of pH of the renal filtrate in drug overdose toxicity acidic drugs: enhanced excretion in alkaline urine (NaHCO3)

A

Therapeutic modulation

48
Q

_____ transport of drug from the blood into the renal tubular filtrate

A

Active

49
Q

Specific acid and base transport systems occur in the ________ tubule

A

proximal

50
Q

Biliary and fecal excretion (2)

A

Enterohepaticcirculation Prolongs duration of drug action

General Pharmacology (24 decks)

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