Drugs Flashcards
1
Q
What are the 4 basic factors that determine drug pharmacokinetics?
A
Absorption
Distribution
Metabolism
Elimination
2
Q
What is absorption?
A
Absorption is defined as the process of movement of unchanged drug from the site of administration to the systemic circulation
3
Q
To have a biological effect where does the drug have to enter?
A
The blood stream
4
Q
What does taken orally mean?
A
In the mouth
5
Q
What does administered intravenously mean?
A
Straight into the blood stream
6
Q
What does subcutaneous mean?
A
Under the tongue
7
Q
What does administered intramuscular mean?
A
Straight into the muscles
8
Q
Give an example of a drug you inhale?
A
Asthma subutanol
9
Q
Why is intravenous not absorbed?
A
As it just goes straight to the systemic circulation
10
Q
What is Tmax?
A
The time for the drug to reach peak concentration
11
Q
What is Cmax?
A
The peak concentration of the drug
12
Q
Give a factor that can affect absorption of drugs?
A
How much food you have eaten
13
Q
What is bioavailability?
A
The amount of drug that is available to achieve a certain effect
14
Q
What is the therapeutic range?
A
The range of conc. at which a drug is active
15
Q
If the drug is under the therapeutic range what happens?
A
There is no pharmalogical effect
16
Q
If the drug is over the therapeutic range what happens?
A
Toxicity occurs
17
Q
What is therapeutic index?
A
The range at which a drug is safe and active
18
Q
How much bioavailability does a drug given intravenously have?
A
100%
19
Q
What physical properties of a drug affect its absorption?
A
Particle size
Lipid solubility
pH and ionisation
20
Q
What does the drug need to pass to get to the blood stream?
A
The cell membrane
21
Q
Do ionised or un-ionised drugs cross the membrane?
A
Un-ionised
22
Q
What can alter the ionisation of a drug?
A
Small pH changes
23
Q
What happens to an ionised drug at the cell membrane?
A
Does not cross the membrane
May not be absorbed at all
24
Q
What happens to an un-ionised drug at the cell membrane?
A
Should distribute across the membrane until equilibrium is reached - will rapidly diffuse across the membrane
25
Does food enhance or impair the rate of drug absorption?
Can do either
26
What is first pass metabolism?
Metabolism of the drug prior to reaching system circulation. There can be a limit on this on oral routes for some drugs
27
What is intramuscular administration most commonly used for now?
Vaccinations
28
How will sublingual be absorbed?
Under the tongue
| Enters the circulation directly
29
Does sublingual bypass first past mechanism?
Yes - it is absorbed straight into the blood stream
30
What kind of agents is inhalation administration best for?
Better for volatile agents
31
Are substances well absorbed by transdermal route?
No - few substances are well absorbed this way
32
What does transdermal administration mean?
Absorbed through the skin
33
For a drug to be active where must it leave then enter?
Must leave the blood stream and enter the intercellular or intracellular spaces
34
What do many drugs bind to?
Plasma proteins
35
What drug is the active drug?
The drug that is not bound to plasma protein
36
Is the binding of a drug to a plasma protein reversible?
Yes
37
What is the clearance of a drug?
Defined as the theoretical volume of fluid from which a drug is completely removed over a period of time
38
What is clearance a measure of?
Elimination
39
What is the clearance of a drug dependent on?
How quickly the kidneys clear the drug
| The rate of metabolism
40
What is the half life of a drug?
The half life is defined as the time taken for the drug concentration in the blood to decline to half of the current value
41
If it takes 4 hours for the conc. of a drug in the blood stream to drop from 10mg to 5mg then what is the half life?
4 hours
42
What does half life depend on?
The volume of distribution and the rate of clearance
43
If the half life is prolonged what is the effect?
There is a reduction in the drugs clearance
44
What does drug elimination mean?
This means the removal of the drug from the body
45
What is drug elimination dependent on?
Drug metabolism
| Drug excretion
46
What is the primary organ for drug excretion?
The kidneys
47
What damage is important in causing drug toxicity?
Renal damage
48
Are most medicines taken once off or chronically?
Chronically
49
In theory what should the Vd be?
42L
50
What determines the drug delivery system we use?
The dose of drug to be given
The frequency of administration
The timing of administration
51
What do we refer to for finding out the recommended dose of a drug in adults?
BNF
52
What do we refer to for finding out the recommended dose of a drug in children?
BNFc
53
What two organs do we consider the function o in drug prescription?
Kidneys (renal function)
| Liver (hepatic function)
54
What is the most common form or drug administration?
Orally
| Oral medication
55
In what state are suspended drugs?
Liquid
56
Who are solutions and suspensions useful for?
The young and elderly with swallowing difficulties
57
How quickly are drugs in solution absorbed?
Extremely rapidly
58
What is a suspension of a drug?
Dispersions of coarse drug particle in a liquid phase
59
What is the rate limiting step in absorption in tablets and capsules?
The dissolution or tablet breakdown
60
Where are enteric coated tablet disintegrated?
The small intestine
61
Why are some tablets enteric coated?
To protect the dug from the stomach acid
| To protect the stomach from the drug
62
Give an example of a drug that if not enteric coated can harm the stomach?
Aspirin
63
What does prolonged release reduce the need for?
Frequent dosing
64
What does prolonged drug release maintain?
Drug levels within a therapeutic range
65
Why can't after stabilisation on one drug can you switch the patient straight over to another drug?
Because the interaction of the previous drug still in the system and the new introduced drug can produce acute severe toxicity
66
What is a pro drug?
A drug that requires to be metabolically activated after administration
67
What are the advantages of pro-drugs?
The prolonged duration of action of the drug
| The avoidance of the degradation of the drug in the gut
68
Where do sublingual drugs dissolve?
Under the tongue or in the buccal cavity
69
What sublingual drug treats angina?
GTN
70
Who might the rectal route be used for administration for?
For patients who cannot swallow tablets
71
Does rectal route bypass pre-systemic metabolism?
Yes
72
How is the rectal route administered?
As a suppository
73
How quickly do IV drugs work?
Immediately
74
How quickly can IV drugs produce toxicity?
Immediately
75
Does IV administration bypass first-pass metabolism?
Yes
76
How might drugs with a short half-life be administered?
Through IV administration
77
Why might a drug be given IV?
When a rapid onset of action is required
When careful control of plasma levels is required
When a drug has a short half-life
78
Where is an intramuscular injection given into?
Muscle mass
79
What is a disadvantage of IM injection?
They may be painful
80
What does subcutaneous injection bypass?
The need for venous access
81
Name a drug that is given by subcutaneous injection?
Insulin
82
Where are transdermal drugs delivered to?
The skin
83
With transdermal administration how does the drug cross the skin?
By diffusion
84
Do transdermal drugs achieve a local effect or a systemic effect?
Both
85
What do skin patches allow?
The release of a drug from a reservoir into the skin and systemic circulation
86
What drug is inhaled for systemic effect?
Anaesthetic
87
Where are inhaled drugs usually targeting?
Lung
88
What disease is treated through an inhaler?
Asthma
89
Is inhaled administration effect rapid?
Yes
90
Are large or small doses used for inhaled administration?
Small
91
What does a monoclonal antibodies deliver?
Toxins, cytokines or other active drug
92
How does a monoclonal Ab work?
It delivers straight to the site you want it to be active
They then release
Means the toxicity just affects the site directly
93
What does liposomal drug delivery exhibit a reduction of?
Toxicities
94
What does liposomal drug delivery exhibit and enhanced of?
Efficiency
95
What are nanoerythrosomes?
RBC that are transformed into drug delivery systems
96
What is an adverse drug reaction?
Any reaction to a drug which is harmful or unpleasant resulting from an intervention related to the use of a medicinal product
97
How many inpatients suffer form an ADR?
10-20%
98
How many hospital deaths occur as a result of ADR?
0.25-3%
99
How long is acute ADR onset?
Within 60 minutes
100
How long is sub-acute ADR onset?
1 to 24 hours
101
How long is latent ADR onset?
>2 days
102
Describe mild ADR?
Bothersome but no change to therapy
103
Describe moderate ADR
Requires change to therapy
| Requires additional treatment
104
Describe severe ADR
Disabling or life threatening
| Kidney Failure
105
What is the name given to Type A ADR?
Augmented
106
What is the name given to Type B ADR?
Bizarre
107
What is the name given to Type C ADR?
Chronic
108
What is the name given to type D ADR?
Delayed
109
What is the name given to Type E ADR?
End of treatment
110
What is the name given to type F ADR?
Failure of treatment
111
What gender is ADR more common in?
Women
112
What ages are ADR more common for?
Elderly and neonates
113
Problems with which 2 organs can affect drug metabolism and therefore their functioning has to be considered before drug administration?
Kidneys and liver
114
What are type A ADR?
Normal but augments response to a drug
115
Are type A ADR predictable?
Yes
116
What are type A ADR reactions due to?
Excess pharmacological action
117
How do type A ADR resolve?
By reducing or stopping the drug treatment
118
What factors affect absorption of a drug in pharmacokinetic variation?
Dose
Formulation
GI motility
First pass metabolism
119
What factors affect drug metabolism in pharmacokinetic variation?
Hepatic - enhanced/impaired
120
What factors affect drug elimination in pharmacokinetic variation?
Renal function
121
What type of drug metabolism is under genetic control?
Acetylation
122
What % of the population are slow metabolisers?
10%
123
What are slow metabolisers prone to?
Drug toxicity
124
Are most type A ADRS pharmacokinetic or pharmacodynamic in nature?
Pharmacokinetic
125
What are the characteristics of type B ADRs?
Bizarre
Unpredictable
Rare
126
What do type B ADRS cause?
Serious illness or death
127
Are type B ADRs related to the dose of the drug?
No
128
What causes the differences in response to drugs?
Genetics
| Immunological system
129
What is type C ADR related to?
The duration of the treatment
130
How predictable are Type C ADRs?
Semi-predictable
131
How quickly do Type D ADRs occur?
They occur some time after the treatment
132
Who do ADR type D occur in?
The children of the treated patients
| The patients themselves years after the treatment has stopped
133
What is Type E ADR?
Adverse effects which occur when a drug treatment is stopped especially suddenly
134
What commonly used substance can cause Type E ADR when stopped?
Alcohol - withdrawal symptoms
135
When does rebound phenomena occur?
When a drug is suddenly withdrawn
136
What does Type F ADR cause?
Failure of therapy
137
Are type F ADRs common?
Yes
138
What are type F ADRs related to?
Dose
139
Give examples of drugs that are commonly involved in ADRs?
Antibiotics
Cardiovascular drugs
Anticoagulants
Antineoplastics
140
Who are particularly at risk from ADR?
```
Young and old
Those on multiple medications
Those with altered physiology
Those with prior history of ADRs
Those with genetic predispositions
```
141
How do you report ADRs?
Using the yellow card scheme
