Pharmacokinetics Absorption/Distribution Flashcards

1
Q

Pharmacokinetics relationship between what 2 things?

A

dose-concentration

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2
Q

Biophase (PK-PD link) reflects what relationship?

A

plasma-effect site

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3
Q

Pharmacodynamics reflects what relationship?

A

concentration-effect

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4
Q

What does ADME stand for?

A

Absorption, Distribution, Metabolism, Excretion

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5
Q

Simply define pharmacokinetics.

A

what the body does to a drug.

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6
Q

Name 4 drug properties that affect absorption.

A

size, shape, degree of ionization(acidic/alkaline), lipid solubility

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7
Q

What conditions at the site affect absorption?

A

blood flow, surface area, membrane thickness, presence of other substances, metabolism (1st pass hepatic metabolism), GI motility, pH

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8
Q

The rate of diffusion is directly proportional to what?

A

concentration gradient, surface area

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9
Q

The rate of diffusion is inversely proportional to what?

A

membrane thickness

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10
Q

What’s Fick’s Law of Diffusion equation?

A

Rate of diffusion= conc. grad. * SA * Diffusion Coef / membrane thicknss

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11
Q

Define Bioavailability.

A

Fraction of unchanged drug that reaches the systemic circulation following administration by any route

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12
Q

Where is the principle route of absorption for oral route?

A

largest surface area of the small intestine

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13
Q

Name 4 medications highly susceptible to first pass hepatic metabolism.

A

Aspirin, levadopa, metoprolol, morphine

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14
Q

What common medication is hydrolyzed in the stomach?

A

penicillin

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15
Q

True/False: Transmucosal meds (SL/buccal/intranasal) are subject to 1st pass hepatic effect.

A

False

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16
Q

What percentage of body weight does water make up in men? women? infants?

A

60% men; 50% women; 70% infants

17
Q

How many L is total body water?

18
Q

How many L of fluid is intracellular? Extracellular?

19
Q

What % of CO is central compartment?

A

75%, peripheral comp. 25%

20
Q

What % of weight is central compartment

A

10%, peripheral comp. 90%

21
Q

Define Vd and it’s equation.

A

Vd relates the amount of drug given to plasma concentration. Vd=amount of drug/desired plasma conc.

22
Q

True/False: Small plasma concentration=large Vd.

23
Q

What kind of drugs have large Vd?

A

Lipid soluble drugs, lipophilic. Needs larger dose for effect. Propofol

24
Q

What kind of drugs have low Vd?

A

hydrophilic drugs, highly water soluble, higher plasma concentrations. Neuromuscular blocking drugs

25
True/False: Aqueous Diffusion involves lipophilic substances.
False, Hydrophilic substances. Driven by a concentration gradient, small molecular weight, assisted by osmotic or hydrostatic pressure.
26
True/False: Lipid Diffusion is most pertinent to anesthesia.
True. Lipid soluble drugs, cross phospholipid bilayers based on conc. gradient to aqueous side.
27
True/False: acidic drugs bind to alpha1-acid glycoprotein.
False. Acidic (thiopental) bind to albumin. Basic drugs (local anesthetics) bind to alpha1-acid glycoprotein.
28
Name things that decrease albumin thereby increasing amount of free drug in the body.
renal disease, liver disease, old age, malnutrition, 3rd trimester
29
What causes increased alpha1-acid glycoprotein (AAG) binding?
surgical stress, MI, chronic pain, RA, old age.
30
What causes decreased (AAG) binding?
Neonates, 3rd trimester
31
Vd of a drug is directly/inversely proportional to a drug?
inversely, but only when just looking at protein binding, there are many other factors.
32
A drug changes from 98% protein bound to 94% protein bound, by what percentage has the amount of free fraction increased?
started with 2% unbound to 6% unbound, amount doubles twice, increases 200%. In highly protein bound drugs small changes can make a big difference
33
Which are more lipid soluble? ionized or non-ionized?
non-ionized are 1000-10000 times more lipid soluble and rapidly diffuse across cell membranes. larger Vd.
34
Ionized molecules are hydrophilic/lipophilic?
hydrophilic, doesn't cross membranes
35
True/False: non-ionized molecules are negatively charged?
False, neutral charge.
36
What is the order of routes of administration from fastest to slowest to reach peak plasma concentration?
IV, tracheal, intercostal, caudal, paracervical, epidural, brachial plexus, sciatic/subarachnoid, subcutaneous. I Think I Can Please Everyone But Susie & Sally.