Pharmacodynamics

Question 1

Clearance of drugs via plasma include which routes? What does elimination affect?

Answer 1

all - renal, hepatic, biliary, pulmonary, salivary, mammary, skin
affects the time a drug remains in the body and the dosage required

Question 2

What is the primary site of drug excretion?

Answer 2

renal (volume of plasma that gets filtered of drug per unit time)

Question 3

What are the 3 processes of renal clearance? Provide an explanation for each.

Answer 3

glomerular filtration - filtration of smaller molecules, free drug will be filtered

tubular secretion - active, carrier mediated

tubular reabsorption - reabsorbs remaining drug, control rate of reabsorption by altering the pH of the urine

Question 4

List some factors that will demonstrate decreased drug clearance. (3)

Answer 4

elderly patients/newborns, kidney/cardiac disease, secretion inhibitors

Question 5

Describe hepatic and biliary excretion.

Answer 5

clearance through biotransformation to metabolite, is the volume of blood perfusing the liver that is cleared of the drug per unit of time, is effected by blood flow, protein binding, and activity of enzymes/transporters

drugs may be reabsorbed when passing through intestines from liver enterohepatic re-circulation

Question 6

Describe pulmonary excretion.

Answer 6

simple diffusion, rate of elimination not constant

Question 7

Describe salivary excretion.

Answer 7

alkaline pH, non-ionized and lipid-soluble drugs excreted passively

Question 8

Describe mammary excretion.

Answer 8

excretion of drugs in milk, non-ionized and lipid soluble drugs will diffuse passively

Question 9

Describe skin excretion.

Answer 9

e.x. alcohol, salicylic acid, heavy metals and can cause skin irritation

Question 10

What is formula to determine maintenance dosing.

Answer 10

dosing rate (mg/hr) = CLp (L/hr) x plasma concentration (mg/L)

Question 11

Define and describe plasma half-life.

Answer 11

time required for the concentration of a drug in the blood to decrease by 50%

Question 12

Define critical threshold.

Answer 12

min. concentration of drug needed for therapeutic effect

Question 13

Describe a local vs. systemic effects of aerosols.

Answer 13

local - upper/lower respiratory tract

systemic - absorbed and distributed via blood

Question 14

What is the formula for the L/T ratio? What does the L/T ratio represent?

Answer 14

lung availability/total systemic availability
efficiency of aerosol drug delivery to lung

*goal in treating respiratory disease is to INCREASE L/T ratio

Question 15

List some factors that will increase L/T ratio.

Answer 15

efficient delivery devices, inhaled drugs with high first pass metabolism, mouth washing

Question 16

How does the structure-activity relationship effect drug duration?

Answer 16

differences in chemical structure may lead to the same effect but have different durations due to metabolism

Question 17

Describe the drug-receptor interaction.

Answer 17

majority of drugs believed to exert their effects by combining with a specialized area on the cell or within the cell on receptors

drugs mimic natural molecules

Question 18

Describe the different drug-receptor conditions.

Answer 18

lipid soluble drugs and intracellular receptor activation, attachment to extracellular protein activating an enzyme system, attachment to surface receptor and opening of ion channels, attachment to a transmembrane receptor

Question 19

How does degree of specificity relate to drug side effects?

Answer 19

the greater the specificity for different molecules, the greater the degree of specificity the receptor has for a different drug, the fewer the undesirable effects and greater drug efficacy

Question 20

Describe the process of lipid soluble drugs and intracellular receptor activation.

Answer 20

drug crosses lipid bilayer to cell membrane, binds DNA sequences, nucleus sends out info via mRNA which will change how the cell reacts to a/w irritant, leads to altered transcription and cell response

Question 21

Describe the process of drug related ion channels.

Answer 21

drug binds to receptor on cell surface, receptor opens channel (increased conductance of ion)

Question 22

Describe the process of receptors linked to G proteins.

Answer 22

3 components:
drug receptor - polypeptide spanning cell membrane 7x
G protein - guanine nucleo peptide binding protein (GDP, GTP)
effector system - enzyme (second messenger), ion channel (outflow of K)

drug binds to receptor, receptor/protein complex undergoes structural changes, a subunit dissociates and regulates target proteins (stimulatory vs inhibitory)

Question 23

Describe agonists.

Answer 23

drug that has the ability to produce a desired therapeutic effect when bound to the receptor

produces same response as endogenous that binds to that specific receptor

Question 24

Describe antagonists.

Answer 24

drugs that produce no receptor response when bound to the receptor

can prevent endogenous chemicals or other drugs from having an effect, compete with agonists for receptor sites

Question 25

Describe competitive antagonists.

Answer 25

drugs that compete with agonist or endogenous molecule for a single site on the receptor, drug present in greatest number will bind, common for antidotes

Question 26

Describe non-competitive antagonists.

Answer 26

drug inactivates the receptor (partial vs complete) by binding (different site than agonist)

Question 27

Describe high affinity.

Answer 27

high rate or associating with a receptor then the rate of dissociating from a receptor *most drug-receptor binding is reversible

Question 28

Describe receptor saturability.

Answer 28

occurs when all available receptors are occupied, increasing the drug concentration will not increase therapeutic effect, receptor binding does not necessarily mean that effect will be stronger, will increase the risk of adverse effects

Question 29

Some drugs bind to enzymes and _____ their action on cells.

Answer 29

block

Question 30

Describe non-specific drug interactions.

Answer 30

no receptor action, interaction with microorganisms

Question 31

Define onset of drug action

Answer 31

the time is takes after the drug is administered to reach a concentration that produces a response

Question 32

Define duration of action.

Answer 32

the time during which the drug is present in a concentration large enough to produce a response

Question 33

Define maximal effect.

Answer 33

point at which the drug reaches its highest effective action

Question 34

Define trough level.

Answer 34

period immediately before.a drug is given in a repeated dosing regimen (lowest drug concentration)

Question 35

Define median effective dose.`

Answer 35

dose of a drug necessary to produce the desired intensity of effect in one half-life of all patients (ED50)

Question 36

Define lethal dose.

Answer 36

dose of a drug that elicits an undesirable toxic or lethal reaction in one half-life of all patients (LD50)

Question 37

Define therapeutic range.

Answer 37

plasma drug concentration between minimum and toxic concentrations

Question 38

Describe drugs with wide vs narrow therapeutic index. What is considered 'low or narrow' and what does this require?

Answer 38

wide therapeutic index - high safety margin, relatively safe, lethal dose in great excess of therapeutic dose narrow therapeutic index - more dangerous, small increased over normal doses may induce toxic reactions <2, requires close monitoring

Question 39

Define loading dose.

Answer 39

higher amount of drug given once or twice to achieve maximum effective dose quickly

Question 40

Define maintenance dose.

Answer 40

intermittent doses given to maintain plasma levels

Question 41

Define tolerance.

Answer 41

increased amount of a drug is needed to produce the same effect

Question 42

Define tachyphylaxis.

Answer 42

rapidly developing tolerance

Question 43

Define ADE.

Answer 43

adverse outcome to medication administration

Question 44

Define ADR.

Answer 44

unintended, undesirable, unpredictable drug effects

Question 45

Define adverse effects.

Answer 45

unwanted/unintended action that may occur during drug therapy

Question 46

Define side effects.

Answer 46

undesirable but mild pharmacological effects of a drug, predictable

Question 47

Define toxic effects.

Answer 47

life threatening, characteristic toxic effects, due to accumulation or intentional use

Question 48

Define teratogenic effects.

Answer 48

drug-induced birth defects which follow drug therapy in pregnant women

Question 49

Describe additive effects.

Answer 49

2 + similar effect drugs are combined, result = sum of individual agents, each drug is given in lower dose for an equal effect of either drug given separately * 1 + 1 = 2*

Question 50

Define synergism.

Answer 50

harmonious action of 2 unlike drugs producing an effect which is greater than the total effect of each drug acting by itself *1 + 1 = 3*

Question 51

Define potentiation.

Answer 51

one drug improves the performance of the other drug *1/2 + 1 = 2*

Question 52

Define idiosyncratic reactions.

Answer 52

unusual, unexpected reactions to a drug, which may have genetic cause, person may experience opposite reaction to the desired one

Question 53

True or false, reactions may decrease with repeated exposure to the drug.

Answer 53

F

Question 54

Define anaphylaxis.

Answer 54

systemic reaction - deem of a/w, severe hypotension, cardiac arrhythmia