PHARMACOKINETICS Flashcards
1
Q
- 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
2
Q
- 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
3
Q
- What is Pharmacodynamics (PD)?
A
- it is the study of how the drug affects the organism
4
Q
- What do both Pharmacodynamics and Pharmacokinetics influence?
A
- they influence the dosing of drugs
- the benefits of drugs
- the adverse effects of drugs
5
Q
- 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
6
Q
- What is Clinical Pharmacokinetics?
A
- it is the application of Pharmacokinetic principles of drugs in a patient
- these drugs are safely and therapeutically managed
7
Q
- What is a drug’s effect often related to?
A
- its concentration at the site of action
8
Q
- Which fluid is most sampled for determining drug concentration?
A
- blood
9
Q
- 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%)
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%
11
Q
- Can Drug Half-Lives vary from person to person?
A
- yes
- they are based on:
- the person’s weight
- their gender
- their health
12
Q
- What 10 Factors affect the Plasma-Half life?
A
- The Route of Administration
- Dosage Schedule
- Age of the Patient
- Dosage of the Drug
- Distribution
- Drug Biotransformation
- Genetic Factors
- Tissue Binding
- Plasma Protein Building of the Drug
- Excretion
13
Q
- 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
14
Q
- What can be said about drug Distribution?
A
- the more widely a drug is distributed
- the longer the half life
15
Q
- 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
16
Q
- 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)
17
Q
- 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
- 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
- What can be said about drug Excretion?
A
- the faster the excretion:
- the shorter the half life
20
Q
- Which drugs have a long half life?
A
- Digoxin
(1-5 days) - Digitoxin
(7 days) - Warfarin
(26 - 60 hours) - Diazepam
(40 - 50 hours)
21
Q
- Which drugs have a short half life?
A
- Dopamine
(2 minutes) - Aspirin
(15 minutes) - Insulin
(10 minutes) - Lidocaine
(2 hours) - Paracetamol
(1-4 hours) - Morphine
(2,5 hours)
22
Q
- What is the importance of the half life of a drug?
A
- it gives an idea about the PK and the PD of a drug
- it predicts the duration of the drug’s action
- it helps to formulate a dosage schedule
(this is the amount of drug and the interval frequency) - it handles a case of overdose of a drug
- it determines the time to achieve a steady state of
plasma concentration - 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
- 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
- What is the dosage recommendation for a drug with a short half life?
A
- the drug should be given repeatedly
25
Q
- What are the therapeutic disadvantages for a drug with a long half life?
A
- it cannot be given in an emergency situation
(by oral route) - it has a more cumulative effect
(it accumulates in the blood) - it has more drug interaction
- the chance of toxicity is more
(the drug is less rapidly metabolised or eliminated)
26
Q
- What are the therapeutic advantages for a drug with a long half life?
A
- there is a long duration of action
- there is less dose frequency
(the drug is taken less often) - better patient compliance
- can be used in prophylaxis
(taken to prevent diseases) - does not develop a tolerance
27
Q
- What are the therapeutic disadvantages for a drug with a short half life?
A
- there is a short duration of action
(it cannot be used as a prophylactic measure) - there is a more frequent dose
- the development of a tolerance to the drug is more
likely
(due to it being frequently used)
28
Q
- What are the therapeutic advantages for a drug with a short half life?
A
- it can be given in an emergency
(this prevents an acute attack) - it is rapidly excreted
(there is less chance of toxicity) - there is no accumulative effect
- there is no drug interaction
29
Q
- What is Paracetamol also known as?
A
- Acetaminophen
- APAP
30
Q
- In which forms is Paracetamol given over the counter?
A
- Panadol
- Tylenol
31
Q
- When is Paracetomal administered?
A
- when the patient experiences mild to moderate pain
- when they have a fever
32
Q
- What is the Route of administration for Paracetamol?
A
- oral
- rectal
- intravenously
33
Q
- What is the Half- Life of Paracetamol?
A
- 4 hours
34
Q
- What is the Daily dosage of Paracetamol?
A
- maximum 4g
(for healthy adults)
35
Q
- What can an overdose of Paracetamol result in?
A
- liver damage
- liver failure
- death
36
Q
- 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
- 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
- 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
- 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
- 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
