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Flashcards in PK/PD Deck (52)
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1
Q
  • Study of substances that interact w/ living systems
  • Beneficial therapeutic effect
  • Toxic effects (parasites infecting patient)
A

Pharmacology

2
Q

Deal w/ the undesirable effects of chemicals on living systems

A

Toxicology

3
Q

Study of the therapeutic uses and effects of drugs

A

Pharmacotherapeutics

4
Q

ADME

  • A: absorption
  • D: distribution
  • M: metabolism (biotransformation)
  • E: elimination of drugs
A

Pharmacokinetics (PK)

5
Q

What the body does to the drug

A

PK (pharmacokinetics)

6
Q

Study of the relationship between the concentration of a drug and the response obtained in a patient

A

Pharmacodynamics (PD)

7
Q

What the drug does to the body

A

PD (pharmacodynamics)

8
Q
  • What drug has an action/effect in the body.
  • Requires what 2 things?
A
  • “free drug”
  • Needs a therapeutic site/ or is free
9
Q

Fraction (F) of the administered dose that reaches the systemic circulation

A

Bioavailability

10
Q

Defined as 100% for intravenous administration

A

Bioavailability

11
Q

What is reduced after administration by other routes (less than 100%)?

A

Bioavailability

12
Q

By which 2 ways is bioavailability reduced?

A
  • Incomplete absorption (and in the intestine, expulsion of drug by intestinal transporters)
  • First-pass metabolism (and any distribution into other tissues that occurs before the drug enters the systemic circulation)
13
Q
  • Absorption pattern: absorption circumvented
  • Limitations/Precautions: increased risk of adverse effects

What is the route and %?

A

Intravenous 100%

14
Q
  • Absorption pattern: Prompt from aq solution. Slow and sustained from repository preparations
  • Limitations/Precautions: Not suitable for large volumes. Possible pain or necrosis from irritating substances

What is the route and %?

A

Subcutaneous 75 - 100%

15
Q
  • Absorption pattern: Prompt from aq solution. Slow and sustained from repository preparations.
  • Limitations/Precautions: Precluded during anticoagulant therapy. May interfere w/ interpretation of certain diagnostic tests (CK)

What is the route and %?

A

Intramuscular (IM) 75 - 100 %

16
Q
  • Absorption pattern: Variable, depends on many factors
  • Limitations/Precautions: Requires patient compliance. Bioavailability potentially erratic and incomplete.

What is the route and %?

A

Oral Ingestion 5- 100%

17
Q

Route of administration:

  • Offers maximal convenience
  • Absorption is often slower
  • Subject to first pass effect (significant amount of agent is metabolized in gut wall, portal circulation, and liver before reaching systemic circulation)
A

Oral (swallowed)

18
Q

Route of administration:

  • Direct absorption into systemic venous circulation (bypassing hepatic portal circuit and 1st pass metabolism)
A

Buccal and sublingual (not swallowed)

19
Q

Route of administration:

  • Offers delivery closest to respiratory tissues (asthma)
  • Usually very rapid absorption (for anesthetic gases)
A

Inhalation

20
Q

Route of administration:

  • Includes application to skin or mucous membrane of the eye, ear, nose, throat, airway, or vagina for local effect
A

Topical

21
Q

Route of administration:

  • Involves application to the skin for systemic effect.
  • Absorption usually occurs very slowly (due to thickness of skin)
  • First pass effect is avoided
A

Transdermal

22
Q

Give some examples of how factors may affect bioavailability of a drug with various routes of administration.

A
  • Some of the inhaled drug accidentally gets swallowed
  • Rubbing site after IM injection alters kinetics and causes vasodilation
  • Oral: first pass effect
  • IM injection in thigh of runner/athlete will alter absorption
23
Q

Which route of administration is increased substantially in newborns due to underdeveloped stratum corneum and increased skin hydration?

A

Skin/Topical

24
Q

***Which route of administration should NEVER be used in pediatric patients? Why?***

A

IM, bc/ drug absorption is impossible to predict

25
Q

What changes in absorption are seen in pregnancy? Route?

A

Oral:

  • N/V (pt can’t absorb drug if they vomit soon after taking it) –> should repeat dose within 1 hour if pt vomits
  • Delayed gastric emptying
  • Increase in gastric pH may affect the absorption of weak acids and bases
26
Q

Geriatric

Most drugs are absorbed via: ___

A

Passive diffusion

27
Q

Geriatric

Nutrients absorbed by ___.

  • Vitamin B12
  • Iron
  • Calcium
  • Magnesium
  • Leucine

(may have impaired absorption in older adults)

A

Active transport

28
Q

Geriatric

  • Evidence for a decreased first-pass effect on _____.
  • Results in ____ and higher plasma concentrations of drugs
  • (you can give smaller doses)
A
  • Decreased 1st pass effect on heptic or gut wall metabolism
  • Results in increased bioavailability
29
Q
  • Concentration of a drug is greatly reduced before it reaches the systemic circulation
  • Fraction (F) of lost drug during the process of absorption which is generally related to the _____.
  • Give an example
A
  • First-pass effect
  • Related to liver and gut wall
  • Propranolol (F) fraction of drug lose during absorption is about 25%
30
Q
A

First Pass Extraction

31
Q

Drug Movement: Distribution: PK

  • 2 forms of passive transport
A
  • Paracellular transport
  • Diffusion
32
Q

Drug Movement: Distribution: PK

  • 2 forms of active transport
A
  • Facilitated diffusion
  • Drug transporters
33
Q

PK: Distribution: Drug Movement

What are the 2 ion channel examples?

A
  • Voltage activated Na channel (depolarization/hyperpolarization)
  • Ligand gated Na channel (ACh)
34
Q
  • relates the amount of drug in the body to the serum concentration
  • determined by the physiologic volume of blood and tissues and how the drug binds in blood and tissues
  • used to calculate the loading dose of a drug that will immediately achieve a desired steady-state concentration
    • gentamicin
A

PK: Volume of Distribution

35
Q

Pediatric patients are made up of more ____. So what type of drugs do we give them?

A

Water, give them water loving drugs bc/ they distribute well.

36
Q

What drugs increase plasma levels? Be careful with dosing this medication if the patient is fluid overloaded.

A

Diuretics

37
Q
  • Largest protein in the body
  • Lots of drugs bind to it
  • ASA is 98 - 99% bound to this protein
  • At higher doses it becomes “extended release drug”
A

Albumin

38
Q

____ are not available to exert pharmacologic effects.

A

Protein-bound molecules

39
Q
  • Anticoagulant w/ narrow margin of safety/narrow therapeutic window (very small difference in doses can move from therapeutic to toxic range)
  • 98% protein bound
  • Addition of another highly protein bound drug such as ASA, competes for the protein which results in more free drug for both ___ and ASA through inhibition of clearance of ____.
A

Warfarin

40
Q

Pediatric patients ARE NOT LITTLE ADULTS

  • What are 4 difference in distribution in peds patients compared to adults?
  • Give examples
A
  • Increased total body water (as % of total body weight)
  • Increased extracellular fluid volume (is markedly different compared to adults)
  • Ex: Gentamicin distribution volumes is 0.48 L/kg in neonates / 0.20 L/kg in adults
  • Decreased binding of drugs to plasma proteins is decreased in newborn infants
  • Decreased amount of body fat is substantially lower in neonates than in adults
41
Q

What are 2 differences in distribution in pregnancy?

A
  • Increased body fat (volume of distribution of fat soluble drugs may increase)
  • Decreased plasma albumin concentration (increases volume of distribution of drugs that are highly protein bound)
42
Q
  • Decreased total body water
  • Decreased lean body mass
  • Increased body fat
  • No change or Decreased serum albumin
  • Increased alpha acid glycoprotein
  • Decreased CO (cardiac output)
A

PK: Distribution for Geriatric patients

43
Q

•specific molecules in a biologic system with which drugs interact to produce changes in the function of the system.

A

Receptors

44
Q

Which drugs bind to and activate the receptor in some fashion, which directly or indirectly brings about the effect?

A

Agonist drugs

45
Q

•binds to its receptor but produces a smaller effect at full dosage than a full agonist

A

Partial agonist

46
Q

Which drugs, by binding to a receptor, compete with and prevent binding by other molecules?

A

Antagonist drugs

47
Q

Which drugs bind to the same receptor molecule but do not prevent binding of the agonist?

  • may enhance or inhibit the action of the agonist molecule
  • not overcome by increasing the dose of agonist
A

Allosteric drugs

48
Q

•an antagonist that cannot be overcome by increasing the agonist

A

Irreversible antagonist

49
Q

Where does the drug action happen?

A

At the receptors

50
Q
A

Allosteric binding

A + C (enhances activity of A)

Ex: synergism (1+1=3)

51
Q

Drug has BTDT “been there and done that”

Now what happens?

A

Metabolism and excretion

52
Q
  • What is the most important organ for drug metabolism?
  • Which other organ plays an important role in metabolism of some drugs?
  • Which drugs are metabolized in many tissues (liver, blood, intestinal wall)? and why?
A
  • Liver (most important)
  • Kidney (some drugs)
  • Esters, bc/ wide distribution of their enzymes