pharmokinetics Flashcards

1
Q

what is clinical pharmacology

A

science of drugs and their use in humans

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2
Q

what is bioavailability

A

the proportion of administrated drug which reaches the systemic circulation unchanged

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3
Q

what type of drug administration achieves 100% bioavailability

A

intravenous injection

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4
Q

what is the most common route of drug administration

A

oral route

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5
Q

in the oral route what does absorption rate depend on

A

GI transit

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6
Q

what are the mucosal routes of drug administration

A

nasal, eye, vaginal, rectum,

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7
Q

what route of administration avoids first pass metabolism

A

inhalation, mucosal routes, transdermal, intravenous subcutaneous and intramuscular injections

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8
Q

what is pharmacokinetics

A

study of drug movement within the body

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9
Q

what is pharmacodynamics

A

study of drug effects and metabolism of action

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10
Q

what are the four stages of pharmacokinetics

A

absorption, distribution, metabolism, excretion

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11
Q

For an orally- administrated drug to reach

systemic arterial circulation intact, the drug must :

A
  • cross the GI tract

- avoid metabolism by the GI tract and liver

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12
Q

factors affecting GI drug absorption rates

A
  1. Surface area and blood flow
  2. Gastrointestinal motility
  3. Malabsorptive tates
  4. food type
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13
Q

what is first pass metabolism

A

the extent of metabolism occurring BEFORE the drug enters the systemic circulation. Occurs in gut lumen, gut wall and liver

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14
Q

after absorption orally-administrated drugs enter what system

A

portal system

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15
Q

rate and distribution of a drug are determined by

A
  • the ability of the drug to pass through membranes
  • lipid solubility Of the drug
  • Binding of the drug to plasma proteins
  • active transport across cell membranes
  • Presence of other drugs in the body
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16
Q

what is drug distribution

A

process by which drugs are transferred from systemic circulation to tIssues

17
Q

what is the volume of distribution, what is the effect on lipid solubility and protein-bound on VD? What are the impacts of high VD?

A

the amount of water h20 which the drug would have to be added to give the same concentration as in plasma

lipid solubility: increases VD
protein-bound: decreases VD

high VD , causes sequestration of fat cells = long half-life

18
Q

a high Vd can indicate what

A

sequestration in body fat and Long drug half- life

19
Q

what type of drug can transverse membranes to accesss cells and targets

A

non-protein bound

20
Q

do drugs bind reversibly or irreversible to plasma proteins

A

reversible without causing damage

21
Q

what are the criteria for protein binding to significantly affect drug distribution

A
  1. protein-bound proportion must constitute 90% Off total drug in the plasma
  2. extent Of the distribution of the drug to the tissues must be the same
  3. High protein binding can dramatically Increase half- Life
22
Q

what is causes protein displacement

A

co-adminstrating drugs

23
Q

protein displacement is very important to what

A

drug distribution, effect and quality

24
Q

what organ is a major site of drug metabolism

A

liver

25
Q

what happens during phase 1 of absorption

A

products produced tend to be more chemically reactive and often more toxic than the parent drug

26
Q

what happens during phase 2 of absorption

A

drug produces chemically polar products which are cleared by the kidney

27
Q

examples of factors affecting drug metabolism

A

Liver disease

  • genetic polymorphisms in drug metabolism
  • advancing age
  • genetic polymorphisms in drug metabolising enzymes
  • competition between different drugs for some metabolising enzymes
28
Q

what are the main routes of excretion

A

kidney via the urine

29
Q

what are elimination kinetics in the rate of elimination

A

amount of drug eliminated from the body/unit of time

30
Q

what are first-order kinetics in drug elimination, what is an important parameter to measure this?

A

drug concentration decreases exponentially over time. drug elimination half-life curve

31
Q

what can be determined from elimination curves

A

drug half-life

32
Q

what is half life

A

the time it takes for the plasma drug concentration to halve, determined by an elimination curve

33
Q

what enzymes are important in phase 1 absorption

A

cytochrome P450

34
Q

what is protein binding, what is the affect on half-life

A

reversible has no effect on drug function, protein-bound however cannot cross the membrane increasing half-life

35
Q

what is the half-life of paracetamol, atenolol, warfarin, chloroquine

A

2 hours

6 hours

2 days

6 weeks

36
Q

what is the effect of liver disease on bioavailability

A

patients have higher bioavailability because the drug is not metabolised within the lives. Drug doses and timing calculations will need to be altered.