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DPT710A: Pharmacology > Session 2: Pharmacodynamics/Pharmacokinetics > Flashcards

Session 2: Pharmacodynamics/Pharmacokinetics Flashcards

1
Q

What is pharmacodynamics?

A

How a drug affects the body (time course and intensity of effect)

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2
Q

What is pharmacokinetics?

A

How the body affects the drug (absorption, distribution, metabolism and excretion)

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3
Q

Optimal therapy (therapeutic dose), lies between what two dosages?

A

Sub-therapeutic and Toxic

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4
Q

The more potent a drug, the MORE/LESS drug required for a specific response.

A

Less

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5
Q

True or False. Potency does not equal efficacy.

A

True.

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6
Q

What is efficacy?

A

A drug’s ability to produce a desired response

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7
Q

What is drug effectiveness?

A

Describes how useful the drug is (TI, ease of use).People are less likely to take a drug if it is painful, hard to take, etc.

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8
Q

What is maximal efficacy (the ceiling effect)? Give an example.

A

Increase in dose produces no greater response than a lower dosage.

Beta-blockers for blood pressure- at a certain concentration the drug has saturated all receptors and has its greatest response (lowest blood pressure)

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9
Q

How do sterics affect if a drug is effective?

A

A drug has to be the right shape in order to fit where it needs to.

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10
Q

How do electronics affect a drugs effectiveness?

A

Binding pockets of receptors are akin to magnets- they have to line up properly in order for the drug to attach. Increases selectivity because it won’t fit in most places.

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11
Q

What are 3 examples of enteral administration?

A

Oral, sublingual, rectal

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12
Q

What is the “first pass effect”? What type of administration does this affect?

A

Metabolism/destruction of drug molecule in liver before reaching its site of action.

Only affects oral administration. Although sublingual and rectal come through the GI tract, most is distributed into the blood before it reaches the liver.

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13
Q

Describe the 4 features of enteral administration.

A
  1. Easiest for self-administration
  2. Generally safe, controlled entry to system. 3. Absorbed by small intestine
  3. Drug may have high lipid solubility
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14
Q

What types of drug administration are paraenteral? (9)

A
  1. Injection
  2. IV,
  3. IA (intra-arterial)
  4. Sub-Q
  5. IM (intra-muscular)
  6. TD (transdermal)
  7. Topical
  8. Intrathecal
  9. Inhaled
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15
Q

Describe 4 features of paraenteral administration.

A
  1. Bypasses the GI system.
  2. More direct route to target site.
  3. More predictable quantity.
  4. Not subject to “First Pass Effect”
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16
Q

What are the advantages, disadvantages and examples of oral administration?

A

Advantage: easy, safe, convenient.

Disadvantages: Limited/erratic absorption of some drugs, subject to first pass effect

Example: Analgesics, sedative-hypnotics, many

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17
Q

What are the advantages, disadvantages and examples of sublingual administration?

A

Advantage: Rapid onset, not subject to first pass.

Disadvantage: Drug must be easily absorbed from oral mucosa

Example: nitroglycerin

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18
Q

What are the advantages, disadvantages and examples of rectal administration?

A

Advantages: Alternative to oral; local effect on rectal tissues

Disadvantages: Poor or incomplete absorption; chance of irritation

Example: Laxatives, suppository forms of other drugs

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19
Q

What are the advantages, disadvantages and examples of inhalation administration?

A

Advantages: rapid onset, direct application for respiratory disorders, large surface area for systemic absorption

Disadvantages: Chance of tissue irritation, patient compliance

Examples: General anesthetics, anti-asthmatic agents

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20
Q

What are the advantages, disadvantages and examples of injection administration?

A

Advantages: Provide more direct administration to target tissues, rapid onset

Disadvantages: Chance of infection

Examples: Insulin, antibiotics, anti-cancer, narcotic analgesics

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21
Q

What are the advantages, disadvantages and examples of topical administration?

A

Advantages: Local effects on surface of skin

Disadvantages: Only effective in treating outer layers of the skin

Examples: Antibiotic ointments, creams used to treat minor skin irritation and injury

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22
Q

What are the advantages, disadvantages and examples of transdermal administration?

A

Advantages: Introduces drug into body without breaking the skin; can provide a steady, prolonged delivery via medicated patch

Disadvantages: Drug must be able to pass through dermal layers intact

Examples: Nitroglycerin, motion sickness meds, drugs used with phonophoresis and iontophoresis.

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23
Q

What is bioavailability?

A

The percentage of drug administered that reaches the bloodstream

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24
Q

Bioavailability is dependent on what? (2)

A
  1. The route of administration and the drug’s ability to cross membrane barriers
  2. Extend of first pass metabolism
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25
Q

Choose the best answer.

In the stomach (pH 1-3), weak ACIDS/BASES can be absorbed from the gastrointestinal tract.

A

Bases

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26
Q

Choose the best answer.

In the stomach (pH 1-3), weak ACIDS/BASES CANNOT be absorbed from the gastrointestinal tract.

A

Acids

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27
Q

Choose the best answer.

In the duodenum (pH 5-7), weak ACIDS/BASES can be absorbed from the gastrointestinal tract.

A

Bases

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28
Q

What are the four ways substances can cross the cell membrane?Which require ATP?

A
  1. Passive Diffusion
  2. Active Transport
  3. Facilitated Diffusion
  4. Endocytosis

Active transport requires ATP

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29
Q

True or False. There are processes that both decrease and increase drug delivery to target tissues.

A

True.

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30
Q

What factors affect the bioavailability of a drug?

A
  1. Body membrane structure and function
  2. Drug movement across Membrane barriers
  3. Active Transport
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31
Q

What 4 factors affect the distribution of a drug (how it moves through the body)?

A
  1. Tissue Permeability
  2. Blood Flow
  3. Plasma Protein binding
  4. Subcellular Protein binding
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32
Q

True or False.

Highly lipid soluble molecules cross membranes more easily. .

A

True

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33
Q

Describe how tissue permeability affects the distribution of a drug. Give an example.

A

Tissue permeability determines how readily a substance is absorbed. This cannot be modified.

Example: A pill can dissolve but not make it out of the gut.

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34
Q

Describe how tissue permeability affects the distribution of a drug.

A

Bloodstream will carry drugs to highly-perfused organs. Can be affected by disease.

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35
Q

Chose the best answer.

Negative venule pressure moves a drug from TISSUES/BLOOD to the TISSUES/BLOOD.

A

Tissues

Blood

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36
Q

Chose the best answer.

Positive venule pressure moves a drug from TISSUES/BLOOD to the TISSUES/BLOOD.

A

Blood

Tissue

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37
Q

Describe how plasma protein binding affects the distribution of a drug.

A

Bound portion of a drug doesn’t have a therapeutic effect , and is not eliminated. Extensive protein binding slows drug elimination. This is a reversible process.

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38
Q

True or False.

A drug that is unbound (free) may distribute from blood to tissues and is unactive

A

False.

A drug that is unbound may distribute from blood to tissues and is active.

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39
Q

True or False.

A drug that is bound to a plasma protein cannot leave the blood to distribute into the tissue and is inactive.

A

True.

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40
Q

Describe how plasma proteins work as a reservoir.

A

Only free drugs can have an effect on the body. If attached to the protein it is basically just stored in the blood in a reservoir. As more is absorbed into the tissue, more is released from the protein.

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41
Q

How is volume of distribution calculated?

A

Amount of drug administered/Concentration of drug in plasma

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42
Q

If Vd = Total amount of body water, what is the distribution of the drug?

A

Uniform. Drug is evenly distributed throughout the body.

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43
Q

IF Vd > Total amount of body water, what is the distribution of the drug?

A

Drug is being concentrated in the tissues. It is sequestered in the body, not floating in high concentrations in the blood.

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44
Q

If Vd

A

Drug is retained in the bloodstream and not leeching into the tissues.This is can be due to plasma protein binding. Beneficial if you want the drug to treat something in the blood.

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45
Q

If you inject 100 mg of a drug into 100 mL of water, what is the concentration of drug in the plasma? How would you confirm?

A

100 mg/100 mL = 1.0 mg/ml.

Confirm by drawing 1.0 mL of water- will contain 1.0 mg of drug.

46
Q

Inject 100 mg of a drug into an unknown volume. If you draw 1.0 mL and find a concentration of 2. mg/mL, what is the volume of water? What is the volume of distribution?

A

100 mg/50mL = 2 mg/mL. Volume of water is 50 mL.

Volume of distribution is also 50 mL

47
Q

Place activated charcoal and 100 mg of a drug into 100 mL of water. Draw 1.0 mL from the box and they find 0.02 mg/mL, what is the apparent volume of distribution?

A

Apparent volume of distribution is 5,000 mL.

48
Q

Where can drugs be stored in the body?

A
  1. Adipose tissue
  2. Bone
  3. Muscle
  4. Organs
49
Q

What is the primary site of drug storage? Give an example

A

Adipose tissue.

Example: anesthetics

50
Q

What type of drug is stored in bone? Give an example

A

Toxic agents

Example: lead

51
Q

What type of drug is stored in muscle? Give an example.

A

Drugs that require long-term storage.

Example: Anti-malarials

52
Q

What organs are most likely to store drugs? Give an example.

A

Drugs are often stored in the liver and kidneys.

Example: anti-microbials.

53
Q

What is controlled release? Give some examples.

A

Controlled release slows down drug absorption- avoids high peak concentration and quick drop off. Sustains dose throughout the night, resulting in a better control over a longer period. Also decreases the number of doses/day.

Example: beta blockers, analgesics, Parkinson’s Drugs

54
Q

Where are impacted reservoirs located? Give examples.

A

Located in the abdomen and spinal cord.

Examples: muscle relaxers, analgesics, anesthetic, hormones.

55
Q

What occurs with targeted cell and tissue drug delivery? Give examples.

A

Attaches antibodies to drugs. Allows them to target certain tissues.

Examples
Brentuximab vedotin for Hodgkin Lymphoma- want them to target the tumor.
Neurological- getting it to accumulate in the brain and not everywhere else.

56
Q

What are the three methods of drug elimination?

A
  1. Biotransformation
  2. Excretion
  3. Combination
57
Q

What is biotransformation?

A

Metabolism.

It is the chemical altering of a drug to a metabolite via enzymes to deactivate that drug.

58
Q

What form a drug is eliminated during excretion?

A

Excreting the active form of the drug

59
Q

What is involved in the combination method of drug elimination?

A

It is a combination of biotransformation and excretion.

60
Q

What are the four main biotransformation-cellular mechanisms?

A
  1. Oxidation
  2. Reduction
  3. Hydrolysis
  4. Conjugation
61
Q

Where are drugs metabolized? (5)

A
  1. Liver - primary location
  2. Lungs
  3. Kidneys
  4. GI
  5. Skin
62
Q

What factors can affect drug metabolism? (3)

A
  1. Tissue/organ damage
  2. Metabolic inhibitors
  3. Enzyme Induction
63
Q

What occurs in competitive inhibition of metabolism?

A

Inhibition of the enzyme that metabolizes drug B by drug A, therefore decreasing the metabolism of drug B.

64
Q

What occurs in irreversible inhibition of metabolism?

A

Inhibition of the enzyme that metabolism drug B by drug A. Decreases the metabolism of drug B and is irreversible.

65
Q

What occurs during induction of metabolism?

A

An inducer of the enzyme that metabolizes drug B by drug A increases the metabolism of drug B by increasing the enzyme quantity.

66
Q

Describe the steps of enzyme induction (circular)

A
  1. Prolonged use of drug
  2. Increased enzyme production or decreased degradation
  3. Increased rate of drug metabolism
  4. Decreased therapeutic effect
  5. Develop tolerance- need for increased doses of same drug to produce same effect
  6. Can extend effect to other drugs as well.
67
Q

Describe the pathway of a drug through the kidneys (7)

A
  1. Metabolized drug (metabolite) reaches nephron
  2. Filtration at the glomerulus
  3. Travels to the Proximal convoluted tubule
  4. Loop of henle
  5. Proximal convoluted tubule
  6. Collecting ducts
  7. Leaves body as urine
68
Q

What factors affect excretion? (2)

A
  1. Reabsorption

2. Polarity of metabolite

69
Q

Describe the difference in excretion for polar and non-polar drugs.

A

Polar/ionized drugs tend to be excreted.

Non-polar drugs tend to be reabsorbed into the body versus excreted.

70
Q

Where are nonpolar compound reabsorbed into the body?

A

In the proximal tubule of the nephron.

71
Q

What happens to polar metabolites in the kidney?

A

They remain trapped in the nephron and are eventually excreted.

72
Q

What is drug clearance (CL)?

A

Describes an organ or all organs ability to clear a drug.

73
Q

What is clearance dependent upon?

A

An organ’s ability to extract the drug from plasma and perfusion

74
Q

What is systemic clearance?

A

The sum of individual organ CLs

75
Q

What is the formula for drug clearance and what does each term mean?

A

CL = Q x ((Ci-Co)/Ci)

Q: Blood flow to organ
Ci-Co: Extraction ratio
Ci: Concentration

76
Q

What is extraction ratio?

A

The fraction of drug removed from the plasma as it passes through the organ

77
Q

What is half life?

A

Duration of activity of the compound in the body.

Refers to the amount of time required for 50% of the drug remaining in the body to be eliminated

78
Q

What is half life a function of? (2)

A

Clearance and Volume of Distribution

79
Q

What is the purpose of determining drug elimination rates?

A

Allows for proper dosing.

Parameters are used to indicate the rate at which a drug is usually eliminated so that dosages may be adjusted accordingly.

80
Q

What are disadvantages of clearance calculations? (3)

A
  1. Units of mL/min suggest that drug is being removed from a specific volume of blood.
  2. Not a good physical description of what is happening.
  3. Clearance is a confusing concept of what is mathmatically useful.
81
Q

What is continuous administration?

A

Matching the rate of administration with the rate of drug elimination (clearance) once the desired plasma concentration is achieved

82
Q

What is interval administration?

A

Dosage is adjusted to provide an average plasma concentration over the dosing period.

83
Q

True or False.

During interval administration, dosing interval (time in hours) will affect size of dosage needed to maintain same relative plasma concentration.

A

True.

84
Q

What patient-related factors contribute to drug response variations? (7)

A
  1. Genetic factors
  2. Disease
  3. Drug interactions
  4. Age/sex
  5. Diet/nutrition
  6. Environment
  7. Smoking/alcohol
85
Q

What drug-related factors contribute to drug response variations? (6)

A
  1. Dose/dosing times
  2. Half-life
  3. Oral availability
  4. Routes of elimination
  5. Therapeutic index
  6. Interaciton mechanism
86
Q

What is a surface receptor?

A

A cellular component where a drug binds and initiates a chain of biochemical events.

Located on the outer cell membrane.

87
Q

What do surface receptors respond to?

A

Amino acid peptides

Amine compounds

88
Q

How do surface receptors recognize and effect change?(3)

A
  1. Ion channel/membrane permeability
  2. Enzymatic effects
  3. Regulatory Protein links
89
Q

Describe a receptor/ion channel using an example.

A

Acetylcholine.

ACH binds to receptor which activates opening pore in membrane allowing Na in

90
Q

Describe an enzyme/receptor using an example.

A

Protein tyrosine kinase.

Outer surface stimulation activates inner surface wall enzymatic process

91
Q

Describe a regulatory protein/receptor.

A

Proteins are located on inner surface of membrane. G-proteins when stimulated then activate enzymes or ion channels (2nd messenger system)

92
Q

Where are intracellular receptors located? What is their purpose? Give examples.

A

Located at cytoplasm and nucleus

Specific interaction mechanism for hormones. Generally control gene expression when activated.

Examples: thyroid hormones, steroids.

93
Q

Successful binding is affected by what? (4)

A
  1. Drug size
  2. Drug shape/fit: lock/key analogy
  3. Affinity
  4. Present of allosteric modulators
94
Q

What is affinity?

A

Electrostatic attraction between a drug and receptor. Related the drug amount required to bind to the unoccupied receptors (if affinity is low, higher concentrations may be needed)

95
Q

What are allosteric modulators?

A

Local modulators that affect affinity of receptor portion of bond

96
Q

True or False. Binding of a drug to a receptor causes a change in shape or configuration of receptor which starts a cascade of events.

A

True

97
Q

What is drug selectivity?

A

A drug affects only one type of cell or tissue and produces a specific physiologic response.

98
Q

Sub-typing of receptor populations is based on what? (3)

A
  1. Binding preferences
  2. Structure
  3. Function
99
Q

How many subtypes of histamine receptors are there?

A

4

100
Q

How many subtypes of muscarinic receptors are there?

A

5

101
Q

A dose response is proportional to what?

A

The number of receptors occupied by the drug (generally). Not always a linear relationship.

102
Q

Besides the # of receptors occupied by a drug, dose response can also be affected by what?

A
  1. Affinity

2. Receptor signal transmission

103
Q

What is an agonist drug class?

A

Drug capable of binding to a receptor and activating change in the cell’s function. Has both affinity and efficacy.

104
Q

What is a partial agonist?

A

Creates less than an optimal response even though they are are capable of occupying receptors.

105
Q

What is an antagonist?

A

Drug capable of binding to a receptor but unable to create change in the receptor’s function.

106
Q

Describe the characteristics of an antagonist (3). Give an example.

A
  1. Has affinity but not activity
  2. Occupy valuable receptor sites, thereby “blocking” agonists from binding
  3. Competitive or irriversible.

Example: beta blockers

107
Q

What are competitive antagonists?

A

Competitive agonists that can be displaced with higher concentrations of a drug agonist.

108
Q

What are irreversible atnagonists?

A

Form permanent bonds that prevent agonists from binding.

109
Q

What occurs with a prolonged increase in receptor stimulation?

A

A decrease in receptor function.

110
Q

What occurs with a decrease in receptor stimulation?

A

An increase in receptor #s or sensitivity.

111
Q

Increased stimulation of receptors results in what?

A

desensitization and down-regulation

112
Q

Decreased stimulation of receptors results in what?

A

Receptor supersensitivity

DPT710A: Pharmacology (2 decks)

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