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DEN 2026 - Pharmacology > Pharmacokinetics 1 > Flashcards

Pharmacokinetics 1 Flashcards

1
Q

What determines a drug response?

A

Concentration at its site of action, which is in equilibrium with the concentration obtained in blood

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2
Q

What is pharmacodyamics?

A

What the drug does to the body

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3
Q

What is pharmacokinetics?

A

What the body does to the drug

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4
Q

What two factors determine the route of drug administration?

A
  1. Speed of onset

2. Convenience

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5
Q

What does ADME stand for?

A

Absorption, distribution, metabolism, excretion

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6
Q

What is drug absorption?

A

Movement of drug from site of administration to site of measurement

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7
Q

What is drug distribution?

A

Reversible transfer of absorbed drug into and out of various tissues in the body from the bloodstream

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8
Q

What is drug metabolism?

A

Conversion of a drug to a usually more water soluble compound

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9
Q

What is drug excretion?

A

Loss of unchanged drug from the body in the urine or faeces including biliary excretion

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10
Q

What is drug elimination?

A

Metabolism and excretion of a drug (everything after the distribution equilibrium)

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11
Q

What is drug disposition?

A

Distribution and elimination of a drug (all process which occur after a drug has been absorbed)

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12
Q

What is first pass metabolism?

A

The metabolism of a drug before it reaches the systemic circulation after oral administration

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13
Q

What is bioavailability?

A

The amount of drug which reaches systemic circulation

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14
Q

What happens to orally administered drugs once swallowed?

A

Transport proteins absorb the drugs through the gut wall to the liver, where the drugs are metabolised

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15
Q

What occurs during the metabolism of a drug in the liver?

A

The liver usually adds a water soluble molecule to the drug as water soluble molecules are easier for the kidney to remove

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16
Q

What happens to lipid soluble or small drugs which are hard for the kidney to excrete?

A

Usually travel to tissue reservoirs e.g. muscle

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17
Q

What is the main reason a drug may not be orally administered?

A

Low oral bioavailability

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18
Q

What are 4 reasons a drug may have low oral bioavailability?

A
  1. Poorly absorbed due to low lipid solubility
  2. Destroyed by acid or enzymes
  3. Causes major gut adverse conditions
  4. Has a large first pass effect
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19
Q

What is a method of administration to avoid first pass effect?

A

Sublingual administration

20
Q

What 6 chemical properties determine the amount of drug in systemic circulation after oral administration?

A
  1. Stability to acid
  2. Stability to digestive enzymes
  3. Solubility in aqueous solution
  4. Lipid solubility
  5. Molecular weight
  6. pKₐ
21
Q

What 4 physiological variables determine the amount of drug in systemic circulation after oral administration?

A
  1. Presence and type of food
  2. Blood flow to GIT and liver
  3. Gastric motility
  4. pH of stomach and intestinal contents
22
Q

What is the greatest risk of pH on a drug?

A

Can cause the drug to become ionized, forming a charge on the drug making it harder to move through the phospholipid bilayer

23
Q

What is the volume of distribution of a drug?

A

A measure of how easily the drug leaves the bloodstream

24
Q

How does a drug stay in the blood stream if it is particularly acidic or alkaline?

A

Attach to proteins as proteins are large molecules so find it hard to pass out of the bloodstream

25
Q

What determines the extent and ease of a drug’s distribution?

A

The drugs physicochemical properties

26
Q

What plasma proteins do acidic drugs tend to bind to?

A

Albumin

27
Q

What plasma proteins do basic drugs tend to bind to?

A

a1-acid glycoprotein

28
Q

What 3 factors can affect plasma binding proteins?

A
  1. Age
  2. Inflammatory conditions
  3. Pathologic stress
29
Q

What is a free drug?

A

An active version of a drug, not bound to a plasma protein, which is able to distribute to tissues and exert pharmacological action

30
Q

What equation allows the calculation of the volume of distribution of a drug?

A

Amount in Body = Vd x [Plasma]

Vd = Amount in Body / [Plasma]

31
Q

What is the first step to make a lipid-soluble molecule water-soluble?

A

Phase I reactions uncover or add chemical reactive group by oxidation, reduction or hydrolysis

32
Q

What is the second step to make a lipid-soluble molecule water-soluble?

A

Phase II reactions involve attachment of an additional chemical group (conjugation) by glucuronidation, acetylation or sulphation

33
Q

What enzymes carry out Phase I Metabolism reactions?

A

Superfamily of enzymes Cytochrome P450 (CYP)

34
Q

What is the general equation for Phase I Metabolism reactions?

A

Drug-H + 0₂ (in presence of CYP) = Drug-OH

35
Q

What happens when pro-drugs are metabolised?

A

Metabolised to more active metabolites

36
Q

Give an example of the metabolism of a pro-drug?

A

Enalapril is metabolised to enalaprilat

37
Q

Where do Phase II Metabolism reactions mainly occur?

A

Liver

38
Q

How would Drug-glucuronide be excreted and why?

A

Bile or urine as it is inactive and polar

39
Q

What 5 things can cause interindividual differences in drug metabolism?

A
  1. Age
  2. Disease conditions
  3. Genetic variation
  4. Enzyme induction
  5. Enzyme inhibition
40
Q

What is the most common cause of drug interaction?

A

One drug can increase or decrease the metabolism of another drug

41
Q

What is enterohepatic recycling of a drug?

A

Drug conjugates excreted in bile are hydrolysed in lower intestine, releasing original drug for reabsorption into the bloodstream, so prolonging action

42
Q

What is the apparent volume of distribution?

A

The volume of plasma into which the drug appears to be dissolved

43
Q

What is the elimination half life?

A

Time taken for the amount of drug in the plasma to decrease by half

44
Q

What is clearance?

A

The volume of plasma cleared of drug per unit time e.g. litres/hour

45
Q

What is MTC?

A

Minimum toxic concentration

46
Q

What is MEC?

A

Minimum effective concentration

47
Q

What is the window between the MEC and MTC called?

A

Therapeutic window

DEN 2026 - Pharmacology (22 decks)

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