Pharmacokinetics and Pharmacodynamics (complete) Flashcards

1
Q

What is pharmacology?

A

the science of looking at composition, effects, and uses of drugs

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2
Q

Drug classifications: classified by effects on…

A
  • particular body system
  • therapeutic use
  • chemical characteristics
  • can fall into multiple categories
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3
Q

What is a prototype?

A
  • usually the first medication in a class
  • standard in which other drugs are compared to in the class: better or the same?
    – morphine
    – fluoxetine (Prozac)
    – captopril
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4
Q

What is the generic name?

A
  • official name of the medication
  • never changes
  • must meet same FDA standards
  • helps indicate what class a drug falls into (“pril”, “olol’, “statin”

designated by lowercase letter

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5
Q

What is a trade or brand name?

A
  • decided and parented by the manufacturer
  • can be several different names
  • have FDA approven

Example:
- Prinivil and Zestril (lisinopril)
- Advil (ibuprofen)

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6
Q

What is pharmacodynamics?

A

Interaction between the living system (person) and the foreign chemicals

How a drug affects the body:
- replaces or acts as a substitute for missing chemicals (ex: insulin)
- increase or stimulate certain cellular activities (ex. beta agonists)
- depress or slow down certain activities (ex. beta blockers)
- interfere with the functioning of foreign cells like microorganisms or neoplasms (ex. antibiotics or chemo)

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7
Q

What are receptor sites?

A
  • receptor site reacts with specific chemicals to cause an effect on the cell
  • drugs act on specific areas on cell membrane proteins that each perform a specific function
    – lock and key
  • effect can be to increase or decrease cellular activity
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8
Q

What are agonists?

A

Occupy and activate receptors
Types:
- full agonist
- partial agonist

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9
Q

What is a full agonist?

A

Does not need all the sites to produce the desired effect
- can be as little as 10%

Example: morphine, albuterol

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10
Q

What is a partial agonist?

A

Fall in between - turn on some action, but not completely
- only stimulate some of the receptors (intrinsic activity)
- can act as both agonist and antagonist
– beta blockers with ISA do not lower HR as low as pure antagonists

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11
Q

What are antagonists?

A
  • occupy receptors, but do not stimulate them
  • keep the agonist from occupying the same spot and producing a response

Examples
- beta blocker
- charcoal
- naloxone

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12
Q

What is an agonist/antagonist?

A

Only stimulate some of the receptors and others are blocked

Example: suboxone

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13
Q

What is acute therapy?

A

usually the patient is very ill and needs immediate therapy

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14
Q

What is empiric therapy?

A

Medications given because of practical experience and known data

Example: antibiotics for a UTI because most UTI are either E. coli or staph saprophyticus

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15
Q

What is maintenance therapy?

A

maintains steady dose for chronic conditions that do not resolve

like hypertension

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16
Q

What is supportive therapy

A

Does not cure but maintains other function until the patient improves

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17
Q

What is palliative therapy

A

Used for end stage or terminal diseases to make person comfortable
- can be pain medication but also can be meds like chemotherapy

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18
Q

What is critical concentration

A

The amount of a drug that is needed to cause a therapeutic effect

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19
Q

What is loading dose?

A
  • some medications take a long time to reach a critical concentration
  • if the drug effect is needed quickly, a loading dose is given to reach the critical concentration
  • it is a higher dose than usually used for treatment
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20
Q

What is the onset of a drug

A

time it takes to reach a minimum effective concentration

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21
Q

What is the peak of a drug

A

Occurs when drug reaches its highest blood or plasma concentration

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22
Q

What is the duration of a drug

A

the length of time the drug has a pharmacologic effect

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23
Q

What is therapeutic drug monitoring

A

Defined as the use of assay procedures (labs) to determine drug concentration in the blood
- assesses toxic levels

Therapeutic index: margin of safety of drug
- low: narrow margin of safety
- high: less danger

Variation can occur based on pharmacokinetics, disease states, and possible drug interactions

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24
Q

What is the therapeutic range?

A

Drug concentration from minimum effective concentration to the minimum toxic concentration

refers to the range of blood concentrations representing the lower and upper boundaries of “desirable” blood concentrations of a drug
- lower limit is established so that enough drug is administered to attain therapeutic effect
- upper limit established to avoid or minimize toxicity

should serve as a guide
- not all patients respond the same
- want to treat the patient, not the lab value

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25
Q

What is the trough drug level

A
  • rate of elimination
  • typically drawn right before the dose is administered
  • lowest point of concentration
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26
Q

What is peak drug level

A
  • rate of absorption
  • usually several hours after taking; depends on the med
  • about an hour to peak according to professor but is determined by drug
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27
Q

What is pharmacokinetics and what are its 4 stages?

A

The study of how the body processes a drug; how it works and how it is processes

Four stages:
- absorption
- distribution
- metabolism
- excretion

28
Q

What is dynamic equilibrium?

A

The actual concentration that makes it to the body

29
Q

What does dynamic equilibrium depend on?

A
  • absorption form site of entry
  • distribution to the active site
  • biotransformation (metabolism in the liver)
  • excretion from the body
30
Q

What is absorption

A

Defined as what happens to the drug from the time it is introduced to the body until it reaches body fluids and tissues and can be used
- the rate of medication absorption determines how soon the medication will take effect
- the route of administration affects the rate and amount of absorption
- completeness of absorption can differ

31
Q

What are some barriers to first pass?

A

All oral medications go through first pass

Barriers:
- presence of food or drugs and how much
– certain foods can increase acidity: milk, alcohol, and proteins can increase breakdown of med
- acidity of stomach:
– food in the stomach increases the acidity and stomach empties slower so drug exposed to acid longer
- blood flow to the GI tract
- length of time in the stomach
– the longer the drug is in the stomach, the longer the absorption

32
Q

What are some factors affecting absorption?

A
  • intestinal interference
  • more blood = better absorption; quicker onset of activity
    – IM injection: blood flows faster in the deltoid than the gluteal muscle but gluteal can handle more volume
  • pain and stress response
    – decreased blood flow to GI tract
    – autonomic nervous system response
  • heavy high fat meals
33
Q

Routes of administration, their barriers, and their absorption pattern

A
34
Q

Routes of administration

A
  • oral
  • IV
    – full absorption into the bloodstream
    – most dangerous
  • IM and SubQ
  • Sublinigual/Buccal
    – can swallow before it is absorbed
    – allows the gastric acid to inactivate the med
    – absorbed quickly because mucous membranes are vascular
  • Rectal/vaginal
    – stool will interfere with absorption
    – increased vaginal secretions
  • Inhalation
    – inspiratory efforts are essential
    – typically rapid absorption through the alveolar capillaries
  • Transdermal Patches
  • Nose/Eye drops
35
Q

What is distribution?

A

Describes the process of dissemination of drug throughout the fluids and tissues of the body

36
Q

What factors can affect distribution?

A
  • drug’s lipid solubility (fat-soluble vs water-soluble)
    – water soluble preferred
  • many drugs cannot cross the blood-brain barrier
  • perfusion: if unable to reach the tissues, then systemic administration may not be effective
  • temperature
  • vasoconstriction vs vasodilation
    – vasodilation increasing blood flow
37
Q

What are protein bound drugs

A

Some drugs circulate in the bloodstream bound to a protein; others are unbound in the plasma

  • Drugs that are protein bound are inactive as the protein-drug complex is too big to enter the tissue
  • the free drug is small enough to pass through the capillary wall into the tissue fluid to exert its effect on the cell

Many drugs bind with albumin
- if albumin is low, there are fewer protein binding sites
- drug doses need to be decreases

highly-bound drugs increase risk for drug-drug interactions

38
Q

What are levels of protein binding

A

The part of the drug which is bound is unavailable for use; the rest is free drug

Highly protein-bound drug: 85-90% bound
– part that is bound is inactive
Not highly bound drug: 35-45% bound

Some released slowly; others bind more rapidly (loose bind)

39
Q

What are examples of highly protein-bound medications?

A
  • diazepam
  • furosemide
  • ibuprofen
  • valproic acid
  • warfarin
40
Q

What is the blood-brain barrier

A
  • tightly controls substances that enter and leave the brain
  • keeps toxins and many medications away from the CNS; helps maintain homeostasis
  • high lipid soluble are more likely to get across the BBB and reach the CNS while non-lipid soluble drugs can NOT cross BBB
    — water soluble tend to not cross
  • very few antibiotics are lipid soluble: BBB altered by the infection so meds can get through
  • adverse effects are more indirect than direct on CNS tissue
41
Q

Placenta and breast milk and drugs

A
  • many drugs pass through the placenta (primarily by passive diffusion) and can affect the developing fetus
  • essentially, all drugs a mother takes have an effect on the fetus
  • breastfeeding can expose the baby to medications and possible adverse events
  • need to check if medication is safe if breastfeeding
42
Q

Old Pregnancy Categories

A
43
Q

New Pregnancy-Risk Categories (PLLR)

A

Aim:
- provide patients and healthcare providers with relevant information that allows for informed clinical interpretation and medical management
- all prescription drug labels must be updated as information on medication becomes outdated

Risk categories:
- pregnancy (including labor and delivery)
- lactation
- females and males of reproductive age

Newer FDA pregnancy system has written out information on safety

44
Q

What is metabolism (biotransformation)?

A

Liver is the primary site of drug metabolism
- drugs that become biotransformed; usually into a compound that is more water-soluble
- drug excreted into the bile with or without biotransformation

Kidney: drug eliminated into the urine for excretion

Concerns when patient has renal or hepatic impairment
– other factors include age and comorbidities

45
Q

Metabolism - Hepatic Enzyme System

A

Is a microsomal system
Phase 1: cytochrome P450 system
– inducers: increase metabolism (process more quickly)
– inhibitors: decrease metabolism (process more slowly)
Phase 2: readies the drug for the kidney

46
Q

What is the first pass effect?

A

When a drug is administered orally, it is metabolized by the liver
- a drug that is absorbed from the intestines is carried by blood flow to the liver
- during the drug’s first pass through liver, a large amount is metabolized
- once circulated through rest of body, about 30% is circulated through the liver again

intravenous and sublingual routes bypass the first pass effect

47
Q

What is the hepatic enzyme system?

A
  • accounts for metabolism of 70-80% of medications
  • are many hepatic enzymes responsible for metabolism: CYP450 enzymes
  • oxidizes (combine or become combined chemically with oxygen) medications
  • everyone’s CYP450 is different, based on genetics:
    – can alter function
    – increase or decrease plasma concentrations of medications

Inhibitors (slow):
- drug inhibits or slows the activity of the CYP enzyme often leading to HIGH DRUG LEVELS
- drug is slowly metabolized; hangs around
- example: grapefruit juice
- may need to lower dose

Inducers (fast):
- when a drug is able to increase the function of the CYP enzyme often causing SUB-THERAPEUTIC EFFECTS
- drug is metabolized too fast
- may need to increase dose

48
Q

What is pharmacogenetics?

A

The study of how a person’s unique genetic makeup (genome) influences his or her response to medications
- identification of genetic variants help to select most appropriate meds and limit adverse effects and maximize beneficial effects
- more than 200 drugs have label info regarding biomarkers; some measurable or identifiable info that can be used to individualize use of drugs

49
Q

What are liver function tests

A

simple blood draw
many meds require monitoring of liver function to ensure medication can be properly metabolized

50
Q

What is elimination

A

Kidneys are the major organ involved in drug excretion
- drugs are made water soluble in liver so they can be excreted

Other meds need active transport and will exchange an acid/HCO3 to do so (affects acid-base of urine)

Glomerular filtration

Can also occur via:
- skin
- lungs
- feces
- saliva
- bile

51
Q

Factors influencing drug effect

A
  • gender (muscle mass, pregnancy, weight differences)
  • physiological factors (diurnal rhythm, acid-base, hydration, electrolyte balance)
  • pathological factors (GI disease, vascular disease, hypotension, renal disease)
  • genetics (metabolism, mutations, genomind)
  • immunological (allergies)
  • psychological (attitude, placebo, trust, control of life)
  • environment (sedation/pain, temperature)
  • weight (most based on 150lb adult)
  • age (children and older adults: less absorption, fewer plasma proteins, less tissue perfusion, metabolism, kidney excretion, polypharmacy)
  • drug tolerance (resistance)
  • accumulation (too frequently, poor elimination, pt education)
  • interactions (adverse events, food)
  • additive effect: two meds given that do same thing at lower dose than one med at higher dose (decreases side effects)
  • potentiation (one drug makes another more potent)
52
Q

What is the additive effect

A

two meds given that do the same thing at a lower dose than one med at a higher dose
decreases side effects

53
Q

What is potentiation of a drug effect

A

One drug makes another more potent

54
Q

What is half-life?

A
  • time it takes for the concentration or amount of a drug to decrease by one-half of the peak level
    – when the drug is given on a regular schedule
  • takes about 5 half lives for the medication to be considered eliminated
    – short half-life: out quickly
    – long half-life: in body for long time
55
Q

What are variables that can impact half life?

A
  • age
  • circulation
  • diet
  • hydration status
  • gender
  • renal and hepatic function
  • smoking
  • genetics
  • comorbidities
56
Q

What is the steady state?

A
  • the amount of drug being absorbed EQUAL to the amount of drug being eliminated with continuous and/or repeated doses
  • rule of thumb is that steady state will be achieved after 5 half lives NOT 5 doses
  • does not always mean a person is at or in therapeutic range
57
Q

What are adverse effects?

A

undesired effects of meds
- effects other than therapeutic effects
- increased sensitivity
- action undesired effects
- too much or too little

58
Q

What is overdose?

A

adverse effect; too much effect
- anticoagulants
- pain medications
- blood pressure

59
Q

What is the secondary effect?

A

balance between the desired effect and the adverse effects
- change time to avoid side effects

60
Q

What is hypersensitivity

A

adverse effect - allergy, intolerance

61
Q

What is Steven Johnson Syndrome?

A
  • rare but severe skin reaction triggered by medications; adverse effect
  • commonly begins with fever and flulike symptoms
  • within few days, skin begins to blister and peel
  • typically seen on face and chest before spreading to other parts of body
  • also damages mucous membranes, urinary tract, eyes and genitals
  • considered to be life-threatening disease
62
Q

What is stomatitis?

A

inflammation of the mucous membranes; adverse effect
- common in chemo
- immune modulators

63
Q

What are superinfections?

A

adverse effect; bacteria protect us from other bacteria
- normal flora
- vaginal
- GI
- immunocompromised
(this slide didn’t seem very clear)

64
Q

What are anticholinergic effects?

A
  • block parasympathetic nervous system directly/indirectly
  • block cholinergic receptors

symptoms include: dry mouth (xerostomia), dizzy, taste change, paralytic ileus, urinary hesitancy/retention, blurred vision, headache, nasal congestion, dry skin

Examples: spiriva, antihistamines, antipsychotics, atropine, cold remedies

65
Q

What is Parkinson-like syndrome?

A
  • dopamine levels are affected directly or indirectly
    Examples: antipsychotics, neuroleptics, lithium, HTN meds (calcium channel blockers)

Symptoms: akinesia, dyskinesia, muscle tremors, drooling, change in gait, rigidity, restlessness

66
Q

Relationship between pharmacokinetics and pharmacodynamics (photo)

A