PHARMACOKINETICS Flashcards

1
Q
  1. What is Pharmacokinetics (PK) ?
A
  • it is a branch of pharmacology
  • it is dedicated to determining the fate of the
    substances that are administered to a living organism
  • it is the study of how an organism affects a drug
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2
Q
  1. What does Pharmacokinetics (PK) attempt to do?
A
  • it attempts to analyse chemical metabolism
  • it attempts to discover the fate of the chemical
  • it begins to analyse the drug from the moment that it is
    administered
  • to the point at which it is completely eliminated from
    the body
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3
Q
  1. What is Pharmacodynamics (PD)?
A
  • it is the study of how the drug affects the organism
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4
Q
  1. What do both Pharmacodynamics and Pharmacokinetics influence?
A
  • they influence the dosing of drugs
  • the benefits of drugs
  • the adverse effects of drugs
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5
Q
  1. What are the 4 main focuses of Pharmacokinetics?
A
  • Absorption of the drug by the body
  • Distribution of the drug by the body
  • Metabolism
  • Elimination of the drug by the body
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6
Q
  1. What is Clinical Pharmacokinetics?
A
  • it is the application of Pharmacokinetic principles of drugs in a patient
  • these drugs are safely and therapeutically managed
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7
Q
  1. What is a drug’s effect often related to?
A
  • its concentration at the site of action
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8
Q
  1. Which fluid is most sampled for determining drug concentration?
A
  • blood
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9
Q
  1. What is the half-life of a drug?
A
  • the duration of action of a drug
  • (t½)
  • it is the period of time required for the concentration
    of the drug in the body to be reduced by one-half
    (from 100% to 50%)
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10
Q

10.What is the Plasma Half Time?

A
  • it is the time in which the concentration of the drug in
    plasma falls by 50%
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11
Q
  1. Can Drug Half-Lives vary from person to person?
A
  • yes
  • they are based on:
    • the person’s weight
    • their gender
    • their health
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12
Q
  1. What 10 Factors affect the Plasma-Half life?
A
  1. The Route of Administration
  2. Dosage Schedule
  3. Age of the Patient
  4. Dosage of the Drug
  5. Distribution
  6. Drug Biotransformation
  7. Genetic Factors
  8. Tissue Binding
  9. Plasma Protein Building of the Drug
  10. Excretion
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13
Q
  1. What are some various ways in which a drug can be administered?
A
  • orally
  • portal circulation
  • liver
  • first pass metabolism
  • intravenously
  • intramuscular
  • intrathecal
  • CSF
  • topical
  • local effect
  • inhalation
  • rapid
  • targeted
  • rectal
  • 50% first pass
  • sublingual
  • rapid
  • no first pass
  • transdermal
  • sustained effect
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14
Q
  1. What can be said about drug Distribution?
A
  • the more widely a drug is distributed
  • the longer the half life
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15
Q
  1. What can be said about Drug Biotransformation?
A
  • if a patient suffers from liver diseases and there is
    decreased drug biotransformation:
    - the half life of the drug increases
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16
Q
  1. What can be said about Genetic Factors?
A
  • they determine whether a person is a fast or slow acetylator

ACETYLATE= the detoxification of xenobiotics
(foreign substances found in the body)

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17
Q
  1. What can be said about Tissue Binding?
A
  • the more the tissue binds to the drug:
    - the longer the half life of the drug
18
Q
  1. What can be said the Plasma Protein Binding of the
    drug?
A
  • the more the plasma protein binding:
    • the longer the half life of the drug
19
Q
  1. What can be said about drug Excretion?
A
  • the faster the excretion:
    - the shorter the half life
20
Q
  1. Which drugs have a long half life?
A
  1. Digoxin
    (1-5 days)
  2. Digitoxin
    (7 days)
  3. Warfarin
    (26 - 60 hours)
  4. Diazepam
    (40 - 50 hours)
21
Q
  1. Which drugs have a short half life?
A
  1. Dopamine
    (2 minutes)
  2. Aspirin
    (15 minutes)
  3. Insulin
    (10 minutes)
  4. Lidocaine
    (2 hours)
  5. Paracetamol
    (1-4 hours)
  6. Morphine
    (2,5 hours)
22
Q
  1. What is the importance of the half life of a drug?
A
  1. it gives an idea about the PK and the PD of a drug
  2. it predicts the duration of the drug’s action
  3. it helps to formulate a dosage schedule
    (this is the amount of drug and the interval frequency)
  4. it handles a case of overdose of a drug
  5. it determines the time to achieve a steady state of
    plasma concentration
  6. it gives us general knowledge about:
    - whether the drug is metabolised
    - whether the drug is eliminated
    - whether the drug is unchanged
    - whether the drug it active itself
    - whether the drug is converted into an active
    metabolite
    - if the drug has irreversible actions or not
    - the presence of the disease in the organ of
    metabolism or the organ of excretion
23
Q
  1. What is the dosage recommendation for a drug with a long half life?
A
  • the drug should be given one or twice a day
  • this prevents accumulation
24
Q
  1. What is the dosage recommendation for a drug with a short half life?
A
  • the drug should be given repeatedly
25
Q
  1. What are the therapeutic disadvantages for a drug with a long half life?
A
  1. it cannot be given in an emergency situation
    (by oral route)
  2. it has a more cumulative effect
    (it accumulates in the blood)
  3. it has more drug interaction
  4. the chance of toxicity is more
    (the drug is less rapidly metabolised or eliminated)
26
Q
  1. What are the therapeutic advantages for a drug with a long half life?
A
  1. there is a long duration of action
  2. there is less dose frequency
    (the drug is taken less often)
  3. better patient compliance
  4. can be used in prophylaxis
    (taken to prevent diseases)
  5. does not develop a tolerance
27
Q
  1. What are the therapeutic disadvantages for a drug with a short half life?
A
  1. there is a short duration of action
    (it cannot be used as a prophylactic measure)
  2. there is a more frequent dose
  3. the development of a tolerance to the drug is more
    likely
    (due to it being frequently used)
28
Q
  1. What are the therapeutic advantages for a drug with a short half life?
A
  1. it can be given in an emergency
    (this prevents an acute attack)
  2. it is rapidly excreted
    (there is less chance of toxicity)
  3. there is no accumulative effect
  4. there is no drug interaction
29
Q
  1. What is Paracetamol also known as?
A
  • Acetaminophen
  • APAP
30
Q
  1. In which forms is Paracetamol given over the counter?
A
  • Panadol
  • Tylenol
31
Q
  1. When is Paracetomal administered?
A
  • when the patient experiences mild to moderate pain
  • when they have a fever
32
Q
  1. What is the Route of administration for Paracetamol?
A
  • oral
  • rectal
  • intravenously
33
Q
  1. What is the Half- Life of Paracetamol?
A
  • 4 hours
34
Q
  1. What is the Daily dosage of Paracetamol?
A
  • maximum 4g
    (for healthy adults)
35
Q
  1. What can an overdose of Paracetamol result in?
A
  • liver damage
  • liver failure
  • death
36
Q
  1. Which medication is the most common taken in overdose?
A
  • Paracetamol
  • there is no prescription required for it
  • overdose can occur accidentally
  • it can also be a form of self harm
37
Q
  1. What are the immediate symptoms of a Paracetamol overdose?
    (within the first 24 hours)
A
  • there may be no symptoms
  • there could be nausea and vomiting
38
Q
  1. What are the symptoms of a Paracetamol overdose after 24 hours?
A
  • pain under the ribs
  • under the right side
  • where the liver is
  • jaundice
  • the yellowing of the whites of the eyes
  • yellowing of the skin
  • acute liver failure
  • death
39
Q
  1. What is the treatment for a Paracetamol overdose?
A

MAIN GOAL OF THE TREATMENT:
- prevent liver injury
- minimise liver injury

  • the treatment decision depends on the clinical scenario
  • this is influenced by the time after the overdose that
    the patient was presented to the doctors
  • the treatment is done intravenously
  • it uses a N- acetylcysteine (NAC) antidote
40
Q
  1. What does this curve help us to establish?
A
  • if the paracetamol levels are above a certain line
  • this indicates that the patient needs treatment
  • if the paracetamol levels are below a certain line
  • this indicates that the patient may not need treatment