Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

pharmacology > pharmacokinetics II, lecture 6 > Flashcards

pharmacokinetics II, lecture 6 Flashcards

1
Q

bioavailability

A

amount of free and active unchanged drug that reaches systemic circulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the absorption after IV administration?

A

100%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do you calculate the Dose (IV) if you are given Dose (oral) and % bioavailability

A

DIV = Doral x [Bioabailability (%) / 100]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How do you calculate bioavailability (F) if you are given AUCoral and AUCIV

A

Bioavailability (F) = [AUCOral / AUCIV] x 100

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

this constant relates the amount of drug in the body to the amount of drug in the blood

A

volume of distribution (Vd)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

There are two ways to calculate Vd (volume of distribution). Give both

A
  1. Vd = [total amount of drug in the body]/[concentration in plasma]
  2. Vd= intravenous dose / plasma concentration of drug at time zeo (C0)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

drugs that distribute extensively and bind to peripheral tissues have a large or small Vd

A

large Vd

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Drugs that are highly concentrated in the plasma have a large or small Vd

A

small Vd

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Vd is affected by several factors. Name them

A
  • age
  • body weight
  • organ pathology
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

if a drug’s Vd lies in the 3-5 L range, where is it found in the body

A

plasma water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Warfarin has what Vd concentration

A

Vd = 3-5 L which means it is highly concentrated in the plasma water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

If a drug has a Vd that lies in 10-20 L range, where is it highly concentrated?

A

extracellular space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

If a drug has a Vd that lies in 22-40 L range, where is it highly concentrated

A

whole body water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

If a drug has a Vd that lies in >70 L range, where is it highly concentrated

A

Tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

When you make Vd calculations, what weight for the patient is assumed?

A

70 Kg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Ex: 200 mg of Drug A is administered IV. Plasma concentration was 5 mg/L at time zero. Calculate the Vd in an 80 Kg patient

A
  • Vd = DIV / C0
  • Vd= 200 mg / 5 mg/L = 40L
  • Determine Vd in a single Kg: 40L / 70 kg = 0.57 L/kg
  • multiply by weight of patient: 0.57 L/kg x 80 kg = 45 L
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what are biological storage depots

A

sites in the body that can accumulate drugs and acts as reservoirs; affecting distribution by decreasing plasma levels and prolonging half-lives

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What type of drugs accumulate in fat

A

highly lipid soluble drugs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What type of drugs accumulate in tissues

A

drugs that bind reversibly to cellular components

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What type of drugs accumulate in bone

A

drugs with chelating properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what type of drugs accumulate in transcellular reservoirs such as GI tract

A

drugs that are slowly absorbed or undergo enterohepatic circulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

drugs that have high plasma protein (albumin) binding have a high or low Vd

A
  • low Vd
  • these drugs accumulate in plasma and have prolonged half-lives
  • they are available but not active
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what type of drugs can be distributed between compartments (e.g. from plasma to muscle and adipose tissue).

A

lipid soluble drugs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what type of drugs will accumulate in breast milk? Why?

A
  • breast milk is more acidic than plasma
  • basic and lipid soluble drugs will accumulate
25
Q

what are the sites that drugs are often unable to penetrate

A
  • cerebrospinal fluid
  • ocular fluid
  • fetal fluid
  • pleural fluid
26
Q

what type of drugs can be transfered from pregnant mother to fetus. why?

A
  • fetus is acidic
  • basic drugs will get trapped (can be teratogenic)
27
Q

what is first order elimination

A

a certain percentage of the drug is eliminated per amount of time

28
Q

what is the rate limiting factor in first order elimination

A

plasma concentration

29
Q

what is the relationship between half life (t1/2) and Vd and CL (clearence)

A

t1/2 = (0.7 x Vd) / CL

30
Q

What is the relationship between t1/2 and Kel (elimination constant)

A

t1/2 = 0.7 / Kel

31
Q

What is the t1/2 of a drug with Vd = 40L and CL 5L/hr?

A
  • t1/2 = (0.7 x 40L) / 5L/hr = 5.6 hr
32
Q

what is the t1/2 if Vd= 0.57 L/Kg and CL of 5 L/hr in a 80 Kg man

A

t1/2 = (0.7 x 0.57 L/kg x 80 kg) / 5L/hr = 6.4 hr

33
Q

if first order elimination, how long does it take (in t1/2) to eliminate most of a drug? How long does it take to obtain Css plasma levels?

A
  • 5 t1/2
  • 5 t1/2
34
Q

in first order elimination, the time to reach Css is related to dose and/or t1/2?

A
  • only to t1/2, NOT dose
35
Q

if you are working with a first order kinetics drug, what changes to the dosing interval and the dose concentration will result in an increased steady state

A
  • shorten the dosing interval
  • increasing the dose
36
Q

How can you differentiate between a first order and zero order kinetics plot in a logarithmic form?

A
  • zero order: curved line
  • first order: straight line
37
Q

what is zero order elimination

A

constant amount eliminated over unit time

38
Q

what is the rate limiting factor in a zero-order reaction

A
  • biological system is the rate limiting factor
  • it is not dependent on plasma levels or dose
39
Q

in a zero order elimination, if you repeatedly give a high dose, will steady state levels develop? why or why not?

A
  • will NOT develop steady state levels
  • zero order kinetics is not dependent on plasma levels
40
Q

what happens if a first order elimination drug is given at higher doses then its elimination rate?

A

will accumulate in the body and produce excessive plasma levels and toxicity

41
Q

what is clearance (CL)

A

measure of body’s capacity to eliminate a drug

42
Q

What is the relationship between Vd and CL and Kel (elimination constant)

A

CL = Vd x Kel

43
Q

What is the equation between total systemic clearance

A

CL = CL renal + CL hepatic + CL lung + CL others

44
Q

what is the CL of a drug with Vd = 100 and t1/2 = 2 hr

A
  • T1/2 = (0.7 x Vd) / CL therefore CL = Vd x (0.7 / t1/2)
  • CL = 100L (0.7 / 2 hr) = 35 L/hr
45
Q

What is the CL if Vd=100L and t1/2= 2 hr in a 80 kg patient

A
  • Vd = 100L / 70 kg = 1.43 L/kg
  • CL = 1.43 L/kg x (0.7 / 2 hr) = 0.44 L/hr/Kg
  • CL = 0.5 L/hr/Kg x 80 Kg = 40 L/hr
46
Q

Css has what relationship to dose, bioavailability, t1/2, CL and Vd?

A
  • Css is directly proportional to dose, bioavailability, and t1/2
  • Css is inversely proportional to CL and Vd
47
Q

if drug infusion is stopped, how long does it take for your body to eliminate a drug

A

5 and 1/2 t1/2 to eliminate drug

48
Q

when drug infusion is started, how long does it take to reach concentration steady state

A

5 and 1/2 half lives

49
Q

what can be administered to achieve an immediate therapeutic plasma concentration

A

a loading dose

50
Q

what equation will allow you to determine LD (loading dose)

A

LD = Vd x TC (Css)

51
Q

once the loading dose is administered, what dose can be given to maintain steady state concentration

A

proper maintenance dose

52
Q

What is the loading dose if Vd = 100 L and TC = 5 mg/L

A

LD = 100 L x 5 mg/L = 500 mg

53
Q

what is the LD if Vd = 100 L and TC = 5 mg/L in a 60 Kg patient

A
  • Vd = 100L / 70 kg = 1.42 L/kg
  • LD = 1.42 L/kg x 5 mg/L x 60 kg = 426 mg
54
Q

how can you determine the maintenance dose?

A
  • maintenance dose = dosing rate x dosing interval
  • maintenance dose = (CL x TC / F) x dosing interval
55
Q

If you increase the dose and dosing interval by the same ratio, what happens to the Css

A

no change

56
Q

at concentration steady state, how can you determine the dosing rate using clearance, theraputic concentration and bioavailability of a drug

A
  • dosing rate = elimination rate = CL x TC / F
  • ** F = 1.0 if administration is IV
57
Q

determine the dosing rate for a drug that is infused and the desired TC is 100 mg/L. the CL is 2.0 L/hr

A

DR = (2.0 L/hr x 100 mg/L) / 1 = 200 mg/hr

58
Q

how long is a compound protected when it is first made

A

20 years, then companies can make generic form

pharmacology (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions