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Unit 1 > 9/23b Pharmacology (Biomedical Sciences) > Flashcards

9/23b Pharmacology (Biomedical Sciences) Flashcards

• To understand the basic principles of pharmacology so as to apply them as a clinician • To understand the fundamental concepts of pharmacodynamics, including mechanism of action and dose-responsive curve To understand the stages of pharmokinetics as the drug is processed in the body and factors affecting pharmokinetics

1
Q

Drug Nomenclature

A
  1. Chemical - the chemical structure of the drug
  2. Generic - abbreviated version of the chemical name
  3. Trade Names - Motrin = NSAID = Ibuprofen = Isobutyl propanoic phenolic acid
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2
Q

what is the process that takes a drug to be ready to be sold on the market?

A
  1. approval from FDA
  2. regulation
    - animal trials and human trials that last up to 20 years
    - data is sent to FDA after completed
    - the whole trial needs to be safe and effective
  3. classification
    - prescription (Rx) vs over the counter (OTC)
    - often Rx drugs can change to be over the counter drugs as more data is stored
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3
Q

Are PTs allowed to prescribe drugs?

A
  • NO, except for PTs in the military (they can prescribe analgesics)
  • it is important to use information about the drugs to educate your patients and understand the big picture of their treatment
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4
Q

Basic Concepts of Pharmacodynamics

A
  1. site of action = location where drug exerts its effect
  2. mechanism of action = how a drug produces its effects
  3. receptor site = site on a cell wall where a drug exerts its effects
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5
Q

what is the dose curve and maximal efficacy related to?

A

pharmacodynamics

response of a drug to a proportional dose

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6
Q

define pharmacodynamics

A

the relationship between how the body interacts with a drug

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7
Q

Dose

A
  • the exact amount of a drug administered to produce a specific effect
  • want doses that fall on a linear curve because they actually bring about a response within the threshold
  • doctors normally start with a small dose
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8
Q

threshold dose

A

lowest dose you see with an actual response

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9
Q

max effect/ceiling effect dose

A

when you increase the dose to a maximal amount, it plateaus and stops at the max/ceiling effect

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10
Q

Potency

A

measure of strength, or concentration of a drug required to produce a specific effect
–be able to determine how potent a drug is on a chart

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11
Q

Drug safety is determined by what?

A

the therapeutic index!! aka median effective and toxic doses

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12
Q

what is the therapeutic index?

A
  • the amount of drug that creates a toxic response (adverse/lethal side effects) for 50% of the people = median toxic dose
  • the amount of drug that creates a beneficial dose for 50% of the people = median beneficial dose
  • TI = median toxic dose (TD50)/Median beneficial dose (ED50)
  • the higher the therapeutic index, the safer the drug typically is
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13
Q

Examples of therapeutic index that is low, but still on the market

A
  • TI is low (~1) in antihistamines because the drowsy-ness side effects are prevalent for more people than the benefits
  • TI is reallllly low for chemotherapy, but if this drug isn’t approved, then a lot of people wouldn’t get these benefits
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14
Q

Drug selectivity

A
  • Selective: a 100% selective drug only reacts with a specific receptor in a specific kind of cell in a specific tissue
  • Non-selective: a drug that binds with every receptor in the body
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15
Q

give an example of a non-selective drug

A

aspirin based products, NSAIDS, bind with any receptor that is a cox receptor

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16
Q

New techniques for drug delivery

A
  1. controlled release preparations
  2. implanted drug delivery systems
  3. targeting drug delivery to specific cells and tissues
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17
Q

Controlled release preparations for drug delivery

A

coating on drugs so the liver takes care of the coating, but the drug is more slowly dispensed and more bioavailable in the system

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18
Q

Implanted drug delivery systems

A

patch that continuously releases

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19
Q

targeting drug delivery to specific cells and tissues for drug delivery

A

cell receptor senses it has been bound and the drug starts actioning right then

20
Q

Factors that affect pharmokinetics

A
  • genetics
  • disease (liver disease)
  • Drug interaction (additive = 2 sns drugs together OR nullifying = one drug cancels out another drug)
  • age (efficiency decreases as age increases = plasma levels stay higher longer)
  • diet
  • sex (women are more vulnerable to processing drugs)
  • other factors (alcoholism, smoking, pathology)
21
Q

Importance of drug interaction that affects pharmacokinetics

A

Drug interaction

  • additive = 2 sns drugs together
  • nullifying = one drug cancels out another drug
22
Q

Importance of diet on pharmacokinetics

A
  • MAO inhibitors for hypertension bind to the same receptors as grapefruit juice. SO, if you drink a lot of grapefruit juice when taking a MAO drug, it ends up being more bioavailable
  • wine and cheese with antidepressants can cause an adverse effect
23
Q

how does pathology affect pharmacokinetics

A

GI motility is affected by spinal cord injuries, so processing is not the same

24
Q

define pharmacokinetics

A

how the body processes drugs

25
Q

what are the different routes of administration for pharmacokinetics?

A
  1. enteral

2. parenteral

26
Q

What is the enteral route of adminstration for pharmacokinetics?

A
  • involves the GI tract
  • taken orally (subject to first pass effect)
  • buccal: inside of the cheek
  • sub-lingual: under the tongue (nitroglycerin)
  • rectal: suppositories
  • positive aspect: can be administered when unconscious and conscious
  • negative aspect: some part of it is metabolized before it reaches the target tissue
27
Q

First pass effect

A
  • enteral drugs are subject to first pass effect
  • this means that they are immediately shunted to the liver where they get metabolized then sent into the system for distribution
  • that amount of the drug that was processed in the liver WON’T be bioavailable for absorption later
28
Q

what is the parenteral route of administration for pharmacokinetics?

A
  • inhalation
  • intranasal
  • injection (IV, IM, or intrathecal, epidural)
  • Topical
  • transdermal (across the skin)
  • positive aspect: no subject to first pass effect because it gets delivered directly to target tissue
  • negative aspect: need a vehicle to administer and the danger of overdose is much higher
29
Q

transdermal iontophoresis

A

drug administration across the skin using steroids and electricity to drive across the SKIN OR lotion driven across the skin in ultrasound

30
Q

3 main phases of pharmacokinetics?

A
  1. absorption/bioavailability
  2. distribution
  3. elimination
31
Q

Bioavailability

A

how much of the drug is able to have an effect once in the systemic blood pool
–dependent on administration

32
Q

absorption

A

cell membranes are lipid bilayers, so in order for drugs to enter the cell they have to be absorbed passively or actively OR through facilitated diffusion OR endocytosis/exocytosis

33
Q

Passive diffusion

A

almost all drugs are lipid soluble, so they can dissolve into the lipid bilayer and be transpoted from outside to inside the cell readily

34
Q

Active transport

A

water soluble drugs need to find a way across the cell membrane, so they most commonly enter through active transport

35
Q

Importance of distribution of drugs through pharmacokinetics

A
  • storage

- redistribution

36
Q

Storage of drugs in pharmacokinetics

A

some portion of a drug is typically stored before it is eliminated. Most common sites of storage:

  1. fat/adipose tissue
  2. bone/bone marrow
  3. muscle
  4. organs (liver/kidney)
37
Q

examples of drugs being stored in the body

A

anesthesia gets stored in the body’s fat tissue prior to elimination, deep breathing helps with elimination of anesthetics (second pass redistribution)

38
Q

Redistribution of drugs through pharmacokinetics

A

when a drug is stored and re-distributed after its use

39
Q

elimination processes for drugs

A
  1. metabolism - biotransformation
    - lipid soluble drugs can’t be excreted on their own, so they get broken down into water soluble chunks through biotransformation in the liver
  2. excretion - RENAL, in the kidneys through urine
    - respiratory, anesthesia
    - less commonly, GI (feces), sweat, saliva, and lactation
40
Q

drug elimination rates

A
  1. clearance

2. half life

41
Q

what is clearance

A
  • a form of drug elimination
  • the ability for the body to eliminate the drug
  • based on blood flow rate and efficiency of the liver and kidneys
42
Q

what is half-life

A
  • how long it takes to get 50% of the remaining drug out of the body
  • determines how often a drug is administered
43
Q

Healthy pateint took a typical dose of acetominaphin with a half-life of 4 hours. How long will it take for this drug to be 95% eliminated from the body?

A 
Between 16-20hrs 95% of the drug is eliminated
						◊ 4hrs - 50%
						◊ 8hrs - 25%
						◊ 12hrs - 12.5%
						◊ 16hrs - 6.25%
						◊ 20hrs - 3.125%
44
Q

Determining a dosing schedule

A
  • based on how typically blood is eliminated
  • dosing windows and therapeutic windows
  • as the therapist, you want to make sure that you are seeing the patient when they are in their therapeutic window
45
Q

Endogenous carriers

A
  • receptors and class of substance produced innately within the body
  • Endorphins are an example of a class substance that goes through one of the body’s natural endogenous carriers
46
Q

Endogenous barriers

A

Blood brain barrier - epithelial cells within are attached to each other with the tight junctions and things can only come through with active transport

47
Q

PT correlation with pharmacokinetics

A
  • What causes passive diffusion/perfusion/blood flow to the tissue – anything that causes heat
  • Exercise because the biproduct of motion = heat
  • Heat packs
  • Decrease of BF to tissue = cold

Unit 1 (28 decks)

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