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Alan's lecture - Pharmacology > Quantitative pharmacokinetics part 1 > Flashcards

Quantitative pharmacokinetics part 1 Flashcards

1
Q

What is volume distribution?

A

The volume of plasma that would be required to contain the drug dose at the concentration measured in plasma.

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2
Q

Volume distribution can be greater than total volume of a human due to tissue binding. TRUE OR FALSE?

A

TRUE

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3
Q

From desired C and knowing VD we can estimate the required dose. TRUE OR FALSE?

A

TRUE

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4
Q

What is clearance?

A

volume of plasma cleared of drug per unit time

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5
Q

What is clearance used to estimate?

A

Used to estimate rate of elimination of the drug

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6
Q

What is the equation for rate of elimination?

A

Rate of elimination = Cl x C

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7
Q

What is the equation for calculating dose?

A

Dose = Cl x AUC∞

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8
Q

By measuring AUC∞ we can calculate Cl. TRUE OR FALSE?

A

TRUE

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9
Q

How can clearance be measured?

A

By measuring the area under the curve

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10
Q

What is half life?

A

The time required for elimination of half of the absorbed drug

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11
Q

What is a first order process?

A

The Rate is proportional to one variable/ rate is dependent on drug

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12
Q

What is a zero order process?

A

It depends on zero variables/ Rate is constant and doesn’t change with [Drug]

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13
Q

What is extraction ratio?

A

Is the fraction of drug entering a tissue that is eliminated

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14
Q

What does C0 mean?

A

concentration of drug in plasma at t=0 (immediately after administration)

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15
Q

What is the equation fro exponential decay?

A

C=C0e-kt

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16
Q

What does K mean in the exponential decay equation?

A

elimination rate constant, fraction of drug eliminated per minute

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17
Q

What is the equation for calculating half life?

A

kt½ = ln 2

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18
Q

If know k, can calculate t½. TRUE OR FALSE?

A

TRUE

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19
Q

If you know Vd you can calculate the dose for any give n concentration. TRUE OR FALSE? and provide equation for this

A

TRUE

VD = Dose/C0

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20
Q

What is Intravenous Infusion?

A

Drug delivered over minutes-hours

21
Q

What are the reasons/benefits for having Iv infusion?

A
  • allows precise and controlled exposure
    – adjust concentration
    – stop if required
    – short infusion sometimes used to reduce Cmax and adverse events following rapid bolus injection
22
Q

What is the equation that helps to describe the relationship between clearance and elimination rate constant?

A

k = Cl/VD

23
Q

If clearance is big the half life will be small and vice versa. TRUE OR FALSE?

A

TRUE

24
Q

The half life is controlled by how much volume of the drug appears to be dissolved in and by what volume of plasma is cleared per unit time . TRUE OR FALSE?

A

TRUE

25
Q

What occurs when drug concentration increases to a plateau value Css? and what is the equation that describes this?

A

Rate of elimination is equal to rate of infusion

C = Css(1-e^-kt)

26
Q

What does this equation describe? C = Css(1-e^-kt)

A

Concentration in plasma gets exponentially closer to Css as time progresses but it never reaches it

27
Q

What is a loading dose useful for?

A

Useful to quickly reach Css

bolus iv dose

28
Q

What is the equation for required rate of infusion?

A

Rinf = Cl x Css

29
Q

What is the equation for loading dose?

A

Loading dose = Css * VD

30
Q

How many half life’s does it take to reach 90% of plateau?

A

3.3 t½

31
Q

Plateau concentration determined by infusion rate
and clearance
Increasing the infusion rate will increase the final Css. TRUE OR FALSE?

A

TRUE

32
Q

Time to reach plateau depends on the elimination
constant (or t1/2). Increasing the infusion rate will NOT REDUCE the time to reach Css because Css will be increased. TRUE OR FALSE?

A

TRUE

33
Q

What is Linear pharmacokinetics?

A

pharmacokinetic parameters don’t change with dose

– increasing dose increases exposure

34
Q

What is Non-linear pharmacokinetics?

A

– Pharmacokinetic parameters change with dose of drug

– increasing dose has a disproportionate effect on exposure

35
Q

Rate of increase of

drug in body = Rate of absorption - Rate of elimination . TRUE OR FALSE?

A

TRUE

36
Q

what is the difference in terms of Cmax and Tmax in P.o compared to I.v?

A

reduced Cmax

increased Tmax

37
Q

What is meant by “Absorption can become rate-limiting” in P.O administration?

A

Rate of absorption controls rate of elimination, only happens when absorption is slow and rate limiting

38
Q

What is Bioavailability?

A

Fraction of administered drug that reaches the systemic circulation

39
Q

In I.V administration all drug is not systemically available . TRUE OR FALSE?

A

FALSE

40
Q

Non i.v. – some drug may not reach systemic circulation. TRUE OR FALSE?

A

TRUE

41
Q

What equation can be used to calculate the amount of drug reaching systemic circulation?

A

F x Dose (Bioavailability * Dose)

42
Q

Why is bioavailability important ?

A

because we want to determine the dose of drug to give a patient, so we need to know the proportion that gets absorbed

43
Q

What equation is used to measure bioavailability for P.o?

A

Fpo = Doseiv * AUCpo/Dosepo * AUCiv

44
Q

How can Bioavailability be measured?

A

By measuring AUC we can determine F

45
Q

If the doses are equal, F is simply the ratio of the two AUC values. TRUE OR FALSE?

A

TRUE

46
Q

What is the constant steady state Css dependent upon?

A

Depends on dose & frequency

47
Q

What is the equation to calculate dose for P.o taking into consideration bioavailability?

A

Dose = t * Cl *Css, av/ F

48
Q

What is a loading dose?

A

An initial “high” dose of drug to quickly plasma drug
concentration to the desired level
– particularly important for drugs with large VD

49
Q

What is Maintenance dose?

A

Once desired plasma drug concentration is achieved, them maintenance dose compensates for drug elimination

Alan's lecture - Pharmacology (16 decks)

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