lecture 3 - pharmacokinetics Flashcards
(74 cards)
1
Q
define ‘pharmaceutical preparations’
A
drug product suitable for administration of a specific dose of a drug to a patient by particular route of administration
2
Q
what are the two routes of administration
A
local routes and systemic routes
3
Q
what are the factors determining the route of administration
A
- drug characteristics
- type of use
- patient condition
- age
- co-morbid diseass
- patient/ doctor choice
4
Q
define systemic routes of administration
A
where the drug reaches the blood and produces systemic effects throughout the body
5
Q
describe the enteral route of drug administration
A
administration of substances by the GI tract
5
Q
describe the parenteral route of drug administration
A
administration into an organism other than through the GI tract
6
Q
describe the advantages of oral routes of drug administration
A
- cheap
- self-administered
- convienient for repeat and long term use
- safe
- painless
7
Q
describe the disadvantages of oral drug administration
A
- slow onset
- unpalpable
- potential destruction of drugs by stomach acid
- can’t be given to unconscious
- not suitable for vomiting/ diarrhea
- susceptible to hepatic first pass effect
8
Q
A
9
Q
define the term “hepatic first pass effect”
A
drugs that go past liver, the liver metabolises the drug before it can go into the systematic circulation
10
Q
describe the term “bioavaliability”
A
fraction of drug that is unchanged after leaving systematic circulation
11
Q
what are the functions of enteric coating on tablets
A
- prevents gastric irritatin
- slows down absorption, and increase duration of action
- decrease dosing frequency
- protects drug from gastric acid
12
Q
describe the advantages of buccal and sublingual routes of drug administration
A
- rapid onset
- actions terminated by spitting drug
- bypass first pass metabolism
- self administration
13
Q
describe the disadvantages of buccal and sublingual routes of drug administration
A
- not suitable for irritant and lipid - insoluble drug
- not suitable for unpalpable drugs
- may be absorbed incompletely or erratically
14
Q
describe the advantages of rectal routes of drug administration
A
- local effect in required location
- systematic effect suitable for unconscious or vomiting patients
- suitable w those w restricted eating
- systematic effect avoid first pass metabolism if administered in lower rectal cavity
15
Q
describe the disadvantages of rectal routes of drug administration
A
- local effect may be irritant
- systematic effect susceptible to first pass metabolism if not administered correctly
- uncomfortable
16
Q
define the term ‘parenteral routes’
A
administration into organism other than through GI tract
17
Q
describe the advantages of parenteral routes of drug administration
A
- rapid onset
- suitable for unconscious/ uncooperative patients
- suitable for vomiting and diarrhoea
- suitable for irritant drugs
- drugs with high first pass metabolism can be given
18
Q
describe the disadvantages of parenteral routes of drug administration
A
- requires sterilisation and aseptic conditions
- invasive technique, painful
- can cause local tissue injury
- require technical experts
- expensive
19
Q
describe the advantages of inhalation routes of drug administration
A
- rapid onset
- localised target organ for respiratory drugs - minimise side effects and allows lower dose to be used
- dose regulation is possible
20
Q
describe the disadvantages of inhalation routes of drug administration
A
- can cause local irritation
- rapid termination of effect
21
Q
describe the advantages of transdermal routes of drug administration
A
- self administered
- good patient compliance
- prolonged action
- minimal side effects
- constant plasma concentration
22
Q
describe the disadvantages of transdermal routes of drug administration
A
- expensive formula
- local irritation
- patch may become dislodged if not applied correctly
23
Q
what are intradermal injections
A
injections into the dermal layer of skin
24
what are subcutaneous injections
injections into the subcutaneous tissue
25
describe the advantages of subcutaneous injections
can be self administered, depot preparations can be used
26
describe the disadvanatages of subcutaneous injections
unsuitable for irritants, slow onset, unsuitable for emergency
27
what are intramuscular injections
injections into large muscle groups
28
what are the advantages of intramuscular injections
faster onset compared to oral, good for gradual absorption
29
what are the disadvantages of intramuscular injections
requires aseptic conditions, painful, may lead to abscess, self administration not possible, local tissue injury can occur
30
what are the advantages of intravenous injections
100% bioavaliability, rapid onset, large volumes can be given, highly irritant drugs can be given, constant plasma levels are maintained
31
what are epidural injections are where are they located
injections into the spinal fluid (subarachnoid and outside of dural membrane)
31
what are the disadvantages of intravenous injections
once injected action cannot be stopped, may cause local irritation, strict aseptic conditions, self-administration not possible
32
what are intra-osseous injections
injections through the cortex of bone into the medullar space
33
what is the aim of a dosing regime
determine the frequency of drug administration and the amount administered
34
what are the types of dosing regimes
single dose, continuous dose and intermittent dosing regime
35
explain the continuous infusion dosing regime
IV dosing at a constant rate to maintain steady state
36
define the term 'pharmacokinetics'
study of movement of drugs within the body
37
why is pharmacokinetics important
drug development, drug prescribing, drug administration, drug interactions
38
what is the first step of pharmacokinetics
Absorption - route of administration and absorbed into circulation
39
what are the types of drug transports in the body
passive diffusion, facilitated diffusion, active transport, filtration
40
what are the influences of absorption rate
physical state, particle size, disintegration time, dissolution time, lipid solubility, pH and ionisation, area and vascularity of absorbing surface, gastrointestinal motility, presence of food
41
What are the factors affecting drug absorption
blood supply, rate of gastric emptying, degree of peristaltic activity, presence of food/ digestive enzymes, absorptive surface, drug molecular size and solubility, active drug transport system
42
what is the second phase of pharmacokinetics
Distribution - drug is distributed to various tissue
43
what are the factors affecting drug distribution
lipid solubility, ionisation, vascularity, binding to plasma and cellular proteins
44
what is the function of the blood brain barrier
protects the brain from any noxious substances that may get into the bloodstream
45
What is the third step of pharmacokinetics
metabolism - chemical alterations of drugs in living organisms
46
describe the consequences of metabolism
1. active drug to inactive metabolite
2. active drug to active metabolite
3. inactive drug to active metabolite
47
what are the advantages of prodrug
increase bioavaliability, increased the duration of action, enhance taste, site specific drug delivery
48
Describe the phases of metabolism
1. phase 1 - chemical alteration of drug by oxidation, reduction or hydrolysis
2. phase 2 - conjugation reactions
49
what are the factors affecting drug metabolism
age, diet, diseases, pharmacogenetics
50
what is the third phase of pharmacokinetics
excretion - amount of drug removed from the body per unit of time
51
define the term 'half life'
time it takes for plasma concentration of drug in the body to be half
52
explain why half life is important in drug excretion
helps work out dosing intervals to maintain therapeutic concentration of drug over time
53
what is drug life a major determinant of
1. duration of ation of a drug after a single dose
2. time taken to reach a steady state concentration with ongoing dosing
3. maintain a concentration in therapeutic range
54
define the term 'steady state concentration'
when the rate of absorption is equal to the rate of elimination
55
define the term 'clinical pharmacology'
study of drug action in man providing the scientific basis for rationale, safe and effective prescribing
56
define the term 'therapeutics'
application of principles of pharmacology to the use of drugs as medicines to treat human diseases
57
define the term 'phamacoviligilance'
practice of monitoring the effects of medicines after they have been approved for use
58
describe the effects of drug distribution and drug action
plasma protein concentration, affinity for drug, body fluid levels, drug solubility, degree of ionisation
59
define the term 'pharmacogenetics'
study of individual variance in DNA sequence and how this can lead to variation in genes
60
define the term 'genetic polymorphism'
variations in DNA sequence occurs among individuals
61
define 'single nucleotide polymorphisms'
polymorphisms that arise from substitution of one nucleotide for another
62
describe the stages of drug metabolism
1. poor metabolism - little to no effect on enzyme activity
2. intermediate metabolisers - reduced enzyme activity
3. extensive metabolisers - normal activity
4. ultra-rapid metabolisers- increased enzyme activity
63
define the term 'adverse drug reactions'
any response to a drug that is noxious and unintended
64
Explain the patient related risk factors for adverse reactions
1. age - very young and elderly patients at higher risk
2. gender
3. existing conditions
4. allergies
65
explain the drug related factors for adverse reactions
1. polypharmacy
2. dose and duration
3. route of administration
66
explain the environment and lifestyle food factors in adverse reactions
1. diet - certain foods can interact with drugs
2. alcohol and tobacco - can alter drug metabolism and increase risk of ADRs
3. occupational exposure - exposure to chemicals can influence drug response
67
explain the severity based classifications of adverse drug reactions
1. mild - ADRs that are bothersome but don't require major interventions
2. moderate - require intervention or affect daily activities
3. severe - life threatening or cause significant disability/ hospitalisation
68
explain the mechanism based classification for adverse drug reactions
1. type A - predictable and dose dependant reactions based on known pharmacological action of drug
2. Type B - unpredictable and non dose dependant, often involve hypersensitivity reactions
3. Type C - reactions related to long term drug therapy
4. Type D - occur after a prolonged period following exposure
5. Type E - reactions occur upon withdrawal from drug
6. Type F - unexpected failure of therapy
69
explain the timing based classifications of adverse drug reactions
1. acute - occur within 60 mins of administration
2. Subacute - occur within 1-24hrs of administration
3. latent - occur after 2 or more days after administration
70
describe the types of drug reactions
drug-environment, drug-food, drug-drug
71
explain the classifications of drug-drug interactions
1. addictive effect - 2 drugs with similar pharmacological effect are combined which results in an additive effect
2. synergist effect - 2 drugs with different mechanisms of action produce a combined effect greater than the sum of their own individual effects
3. antagonist effects - one drug reduces or opposes the effect of another
72
explain the drug complications in elderly populations
1. financial consideration
2. complex regimes
3. lack of social support
4. depression and mental health
5. health literacy
6. side effects
7. healthcare system factors
