LEC 23 Clinical Pharmacokinetics I Flashcards

1
Q

What is the significance of P-gp (MDR-1) in relation to drug absorption?

A
  • P-glycoprotein (P-gp) expels drugs from cells and organs, preventing penetration
  • Distributed in intestinal epithelium where it pumps drugs back into the lumen
  • Reduces the drug’s efficacy, bc the cells are trying to get it excreted
  • Present in both prokaryotes and eukaryotes
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2
Q

What do phase I metabolites of a drug generally contain and why is it important?

Substituent group added?

A

Usually involves the addition of hydroxyl groups to the drug in order to make it more water soluble for conjugation and secretion

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3
Q

What is the most important enzyme for catalyzing the phase I reactions in drug metabolism?

A

Cytochrome P450 (CYP)

Flavin-containing monooxygenases (FMOs) are also important

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4
Q

Which enzymes catalyze the phase II (transferase) reactions in drug metabolism?

A
  • Glutathione S-transferase
  • UDP-glucoronyltransferases
  • Sulfotransferases
  • N-acetyltransferases
  • Methyltransferses
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5
Q

Where in the cell are the enzymes that are inducible by drugs located?

A

Smooth ER

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6
Q

What is pharmacodymanics?

A

What the drug does to the body

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7
Q

What is pharmacokinetics?

A

What the body does to the drug

ADME

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8
Q

In order to calculate the half life of a two compartment model, what must be taken into account?

A

The distribution must reach equilibrium before your can calculate the half life

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9
Q

What is the equation for half-life?

A
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10
Q

Generally speaking, about how many half lifes does it take to eliminate a drug?

A

4-7 half lifes

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11
Q

What does the volume of distribution tell us?

A

Provides a quantitative measure of the extent of distribution of a drug out of the blood stream

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12
Q

Volume of distribution (Vd) is equal to the sum of what other volumes?

A

Vc (volume of central compartment) + Vp (volume of peripheral compartment)

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13
Q

How do you calculate Vd for an intravenous administration?

A

Lambda n is the slope of elimination curve

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14
Q

How do you calculate Vd for an oral administration?

A

Lambda n is the slope of elimination curve. F is bioavailability

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15
Q

How do you calculate the amount of drug in the body?

A

Plasma concentration x Vd

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