Exam 1 - Pharmacokinectics Flashcards Preview

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Flashcards in Exam 1 - Pharmacokinectics Deck (61):
1

A medicine or other substance which has a physiological effect when ingested or otherwise introduced into the body

Drug

2

The study of how a drug enters the body, circulates within the body, is changed by the body, and leaves the body

Pharmacokinetics

3

What are the 4 major pharmacokinetic steps of drug movement in the body

1. Absorption
2. Distribution
3. Metabolism
4. Excretion

4

The study of the biochemical and physiologic actions of drugs, and their mechanisms of drug action at the cell level and sub-cell level (what the drug does to the body)

Pharmacodynamics

5

What 4 characteristics of drug molecules influence whether a drug can cross a lipid membrane?

1. Lipid solubility
2. Degree of ionization (charge cannot cross)
3. Molecular Size
4. Shape

6

Weak acid in an acidic environment = ____
Weak acid in a basic environment =____
Weak base in acidic environment = ____
Weak base in a basic environment = ____

Lipid soluble
Water soluble (dissociates)
Water soluble (dissociates)
Lipid soluble

7

(lipid/water) soluble = non ionized (no charge)
(lipid/water) soluble = ionized (polar)

Lipid
Water

8

____ = drugs given by this route are placed directly into GI tract - ORAL/RECTAL

Enteral

9

____= administration bypasses the GI tract and includes various injection routes, inhalation, and topical drug administration

Parenteral

10

9 parenteral drug routes

1. Inhalation
2. Intravenous *** MOST RAPID/PREDICTABLE
3. Intramuscular - slow
4. Topical - local or systemic
5. Subcutaneous
6. Sublingual
7. Transdermal - patch. more concentrated
8. Intrathecal - epidural
9. Intraperiotoneal - dialysis

11

T/F rectal (enteral) drug administration is poorly/irregularly absorbed from rectum

True

12

Describe rate of onset for:
1. IV
2. IM
3. Patch
4. Sublingual
5. Subcutanerous
6. Inhalation:
7. Ointment/spray
8. Oral

1. Controlled rate/continuous/rapid/predictable
2. delivers large quantity, slow sustained due to high blood flow through skeletal muscles
3. continuous delivery, slow release
4. rapid delivery
5. slow onset
6. rapid
7. dose controlled
8. usually enteral, cheapest/easiest

13

4 ways molecules cross membranes

1. Diffusion - lipid soluble drugs/passive/high to low
2. Filtration - small molecules -> membrane pores
Specialized transport for large/ionized/water soluble molecules
3. Facilitated diffusion - carrier
4. Active transport - ATP

14

3 factors that influence rate of drug movement

1. Physiochemical factors
2. Solubility
3. Route of administration

15

T/F the closer the site of administration is to a blood vessel, the faster a drug can be absorbed

True

16

Drugs that are administered orally pass from the stomach to the intestine to the portal veins to liver

"first pass effect" of drug metabolism after oral absorption (metabolize drugs to inactive forms before they have the change to enter the systemic circulation

17

What type of drugs bypass the first pass effect?

drugs given parenterally - direct to bloodstream

18

____= the fraction of the administered drug that becomes available in the plasma. FREQUENTLY influenced by the "vehicle" of the drug (difference between generic/brand name drugs)

Bioavailability - only IV administration gives 100%

19

FDA mandates that generics must have ___% of the availability of the parent compound

90

20

2 forms in which drugs are in the blood

1. Bound to plasma proteins - no effect
2. Free - can pass cell membranes and exert desired effect

21

____= most drugs cross easily; lipid-soluble drugs cross most easily

Placenta

22

____= drugs that can cross this barrier are lipid-soluble, very small molecular weight/size, and exert effects on the CNS

Blood Brain Barrier

23

Drug Redistribution - movement of the drug from the site of ____ to nonspecific sites of ____. Duration of action can be affected by redistribution from one ____ to another. If redistribution occurs between specific sites and nonspecific sites, the drugs action will be ____. Example: An "____" agent is administered to induce sleep before anesthesia for surgery. After a few minutes, the action is terminated, bc the drug has been redistributed from the CNS via the plasma to skeletal muscle to finally ___ ___ in the body.

Action
Action
Organ
Terminated
Induction
Fat Deposits

24

_____= converts lipid soluble drugs to water soluble metabolites (so kidneys can easily excrete and metabolites are less likely to bind to plasma proteins or store in fat)

Biotransformation aka drug metabolism

25

Where does biotransformation mostly occur?

Liver - also in kidneys, lungs, nerves, plasma, intestines

26

What 4 things can alter liver drug metabolism and often require a does modification?

1. Increased age
2. Cirrhosis
3. Hepatitis
4. Damage from drugs

27

In the liver, where does most drug transformation take place?

Microsomes in hepatocytes

28

Active to inactive =_____
Inactive to active =_____
Active to active =______

Active to inactive = most common- formed from active parent drug
Inactive to active = converted to active after metabolism
Active to active = metabolite is active

29

What happens in the 2 phases of drug biotransformation?

Phase I - drug is modified through oxidation, reduction or hydrolysis
Phase II - drug molecule is modified by conjugation to a large polar endogenous molecule (adds bulky group) INACTIVE, prepares for excretion

30

When is microsomal oxidation enzyme system used?

Endoplasmic like intracellular organelles which possess the enzymes required for biotransformation of most drugs in liver hepatocytes

31

_____= known value describing excretion rates

clearance rates - all drugs in the blood are filtered by the kidneys

32

Salivary drug concentration mimics _____ concentration

plasma

33

Name 5 ways drugs are excreted from the body

1. urine
2. feces
3. sweat
4. saliva
5. lungs
6. breast milk

34

The amount of time needed for the plasma concentration of a drug to fall to 1/2 its blood level per unit of time is known as?
What is the time that most drugs are cleared by?

"Half life"
4-5 half lives (conversely, it takes approximately 4-5 half lives for a drug to build up to a steady state level)

35

What concept is described as the amount of drug eliminated is dependent upon the amount of drug in the plasma at any given time?

First order drug elimination - a constant fraction of the drug is eliminated per unit time = clearance rate

36

What is being described; following administration of multiple therapeutic dosages of a drug at regular time intervals, a plateau level of drug accumulates?

Plasma steady state concentration

37

What does the plateau level indicate during the plasma steady state concentration?

A rate of drug administration that is equal to the rate of drug elimination

38

How is the steady state concentration achieved?

At a regular dosing frequency, the drug does not accumulate and a steady state or equilibrium is eventually reached

39

What are the 2 most common ways drugs bind with receptors?

Hydrogen and iconic (other less common ways include covalent, ionic, or hydrophobic)

40

The affinity of a drug for a particular receptor and the type of binding is intimately related to the drug's what?

Chemical structure
(Higher binding affinity to plasma proteins = remains in blood longer)

41

Drug binding occurs at _____ sites ( amino acid residues) on protein structure. Binding to one or more AA residue causes _____ ____ in the protein molecule (aka receptor) This results in a modification of the tertiary structure to bring other AA residues _____ to the drug, called "_____ ___". Drugs also bind to receptor proteins within the ____ structure. The receptor protein does not exist as an _____ substance external to the cell. Receptor protein may be a _____ or ____ component of the cell membrane (aka part of the cell membrane)

Multiple
Conformational change
CLOSER
Induced fit
Cell
Isolated
Structural
Enzymatic

42

In drug-receptor interaction, the receptor proteins recognize selected molecules at the ____ surface and transmit information ____ the cell. These receptor proteins exist naturally as receptors for _____, _______, and ____ ____.

External
Inside
Hormones
Neurotransmitters
Growth Factors

43

What type of protein receptor communicates with both sides of the cell membrane?

Membrane spanning

44

Molecule that binds to the receptor protein or receptor glycoprotein is called a?

Ligand - may be hormones, neurotransmitters, growth factors, or drug molecules

45

Name for when a ligand binds to a specific area of the receptor protein on the outer surface of the cell, or within the cell membrane, a CONFORMATIONAL CHANGE occurs in the receptor-protein molecule which is transmitted to the inner surface of the cell membrane.

Cell signaling - initiates the cells response to the binding for the ligand

46

What are 4 examples of cellular responses that occur following cell signaling.

1. Ion channel opening or closing
2. Formation of intracellular second messenger
3. Alteration in gene expression of the cell
4. Initiation or alterations in cell growth and differentiation

47

Ligand binding occurs directly to receptor at ____ site. Receptors are located on ___-___ channels and ___-___ channels. Bidning causes the channel to open, allowing for the ___ of ions. *Binding ____ cell membrane permeability to ___ and ___ which determines depolarization or _____ of nerve (aka the nerve firing)

Channel
ligand-gated
voltage-gated
influx
INCREASES
Sodium
Potassium
Hyperpolarization

48

What are the first messengers vs second messengers?

First messenger = ligand (receptors are located in cell membrane and transmit info from outside to inside cell.
Second messenger = pass the message from the inside of the cell to the effector organ (target site of action)

49

What are G-proteins and where are they located?

They are coupled with receptors which regulate the generation second messengers
Located at the internal portion of cell membranes

50

What are 3 results of effector activation?

1. Generate cAMP
2. Phospholipase C - phosphorylation of proteins
3. Change in membrane channel - change in ionic conductance

51

Term that is described as the amount of drug necessary to produce the effect

Drug potency
- Related to affinity of drug to its receptor

52

Term that is described as the degree of maximum intensity of the drug.

Efficacy
- max response produced by a drug
- related to receptor occupancy by drug molecules
- additional does produce no additional benefit "ceiling dose"

53

____ is dose, ____ is effect

Potency
Efficacy

54

____ drug produces SIMILAR EFFECTS as endogenous chemicals, it is able to bind to a receptor and produce an effect (think ligand)

Agonist

55

____ drug produces NO EFFECT. It binds to receptor but is unable to active it therefore it reduces/inhibits an effect. "blocker" drug

Antagonist

56

Who binds first, an agonist or an antagonist?

ALWAYS THE ANTAGONIST

57

A competitive antagonist competes with agonist for the same ____ ____, and blocks the receptor. But it is ______. Administering additional agonist will ____ the antagonist from the receptor, allowing the ____ to produce its effect.

Receptor site
REVERSIBLE
Displace
agonist

58

Noncompetitive antagonist binds _____ and cannot be displaced. Can bind to either the same receptor site as the agonist or a different site but both actions ___ the effect of the agonist. (think poisons)

IRREVERSIBLY
Inhibit

59

____ ____: activates pathways that oppose the action of the agonist. Agonist and antagonist act independently on 2 different receptors. Less desirable in medicine than receptor-specific antagonists.

Physiologic Antagonists

60

____ ____: Both agonist and antagonist compete for the same receptor site. Antagonist binds first. Prevents agonist from producing effect. Either competitive or non-competitive

Pharmacologic Antagonism

61

The RANGE of the doses (concentrations) of a drug that elicits a therapeutic response, without unacceptable side effects (toxicity) in a population of people is know as?

Therapeutic Window - Blood plasma levels of a drug with a small therapeutic window must be monitored closely!