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Pathophys/Pharm > Pharmacokinetics > Flashcards

Pharmacokinetics Flashcards

1
Q

What does ADME stand for?

A

Absorption
Distribution
Metabolism
Excretion

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2
Q

What is the main role of absorption?

A

Getting the drug into systemic circulation

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3
Q

What is bioavailability %?

A

Amount of drug in circulation/amount of drug administered

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4
Q

What does the area under a bioavailability curve represent?

A

The amount of drug in circulation (more area under the curve = better drug)

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5
Q

What four things can effect absorption?

A
  1. Route of administration (IV, PO, Nasal)
  2. Blood flow
  3. Surface area
  4. Contact time
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6
Q

What is the Y-axis on the bioavailability graph?

A

Plasma drug concentration (how much drug is in the blood)
-Drugs give IV will have a peak concentration immediately because it is going directly into the blood and it will decrease with time

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7
Q

What is the X-axis on the bioavailability graph?

A

Time

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8
Q

What is the goal of absorption?

A

Maximize drug into circulation

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9
Q

What is the First-Pass Effect?

A

Oral drugs go to the liver (through the portal vein) and the liver metabolizes it before it goes into system circulation

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10
Q

What is the issue with the First-Pass Effect?

A

An orally administered drug will most likely not have 100% bioavailability (oral drug considered good between 40-60% bioavailability)
(First-Pass Effect is the inverse of bioavailability. If bio is 60% then first pass is 40%)

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11
Q

Oral drugs must be stable at a ___ pH because of stomach acid

A

Low

Stomach acid can degrade certain drugs

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12
Q

Oral drugs are best if _____ soluble

A

Lipid (tablet vs capsule)

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13
Q

Why might the oral mucous membrane route (sublingual or intranasal) be better than PO?

A
  • Faster absorption
  • No first pass effect (bypasses portal vein)
  • No exposure to GI HCl
  • IN drugs good if unconscious pt bc they cannot swallow
  • Sublingual drugs good if stomach acid would degrade the drug
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14
Q

What is the main role of distribution?

A

Move the drug from circulation (blood) to the target

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15
Q

Distribution is dependent on ______ to the organ

A

Blood flow/perfusion

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16
Q

What are 3 physical barriers to distribution?

A
  1. Blood brain barrier
  2. Placenta
  3. Testis and oocytes
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17
Q

Water soluble drugs _____

Fat soluble drugs ______

A

Stay in water (ex: UTI, want a water soluble drug because infection is in the bladder where liquid is)
Stay in fat (need a protein carrier in serum)

18
Q

Why might a toe with gangrene need to be amputated?

A

There is no blood flow to the toe –> drug cannot get to tissue –> amputation

19
Q

What is the process of altering a parent drug to different compounds?

A

Metabolism (biotransformation)

20
Q

Drugs must be ____ to be eliminated ?????

A

Polar

21
Q

What do phase I reactions do?

A

Convert the parent drug to a more polar metabolite (simple rxn, oxidation/reduction)

  • Enhances water solubility
  • May activate or inactivate
  • Prepares molecule for phase II
22
Q

What do phase II reactions do?

A

Adds a compound to the parent drug

  • Enhances water solubility
  • Almost always inactivates (failsafe way to inactive a drug)
  • Prepares molecule for elimination
23
Q

Which routes of drug administration have no first-pass effect?

A
  • Transdermal
  • IV
  • Sublingual
  • Rectal (very low first pass effect, if any)
24
Q

Transdermal route has a slow or fast onset?

A

Slow

25
Q

IV route has a slow or fast onset?

A

Fast

26
Q

Transdermal route has a short or long duration of absorption?

A

Long

27
Q

What two diseases dramatically alter drug dosing and kinetics?

A

Cirrhosis and Ascites

28
Q

What are the basic steps of metabolism?

A
  1. Drug becomes active
  2. Drug becomes inactive
  3. Drug becomes ready for excretion
29
Q

What is the role of CYP (cytochrome) P450?

A

Converts drugs to active or inactive

*almost every drug will go through CYP P450

30
Q

What is the primary site for drug metabolism?

A

Liver (but nearly all organ systems have metabolic enzymes)

31
Q

What is the GI tract’s role in metabolism?

A

Contributes to first pass

32
Q

What types of reactions does metabolism perform?

A
  • Oxidation/reduction
  • Hydroxylation, Dealkylation, Deamination, etc
  • Hydrolysis
  • Conjugation (phase II)
33
Q

Do all drugs get metabolized?

A

NO. Some have no metabolism at all and are eliminated in the same form as they came in

34
Q

Is CYP P450 involved in phase I or phase II reactions?

A

Phase I

35
Q

What enzymes are involved in phase II reactions?

A

Not CYP P450, but by “transferase” enzymes

36
Q

What are the common molecules added onto drugs in phase II reactions?

A

Molecules that increase the solubility for excretion

37
Q

What are the four main elimination systems?

A
  1. Renal
  2. Biliary
  3. Fecal
  4. Respiratory
38
Q

What is the most common elimination system?

A

Renal

39
Q

What type of drugs are eliminated via the renal system?

A

Hydrophilic drugs

40
Q

What is elimination due to in the renal system?

A
  • Blood flow
  • Filtration rate
  • Passive diffusion
  • Active secretion into tubule
  • Reabsorption back into blood
41
Q

What demographic of people is renal elimination an important consideration for?

A

The elderly

Pathophys/Pharm (9 decks)

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