Concentration, time & dose

Question 1

amount in body mg=

Answer 1

volume (l) x concentration (mg/l)

Question 2

initial concentration mg/l=

Answer 2

Dose (mg)/ volume (l)

Question 3

half life=

Answer 3

ln(2) V / CL

Question 4

constant rate infusion at steady state: concentration=

Answer 4

infusion rate/CL

Question 5

properties of the concentration-effect profile that are important determinants of the drug effect:

Answer 5

cmax-highest concentration
tmax- time highest concentration is achieved
area under the curve
threshold concentration
slope-absorption & elimination

Question 6

steady-state is?

Answer 6

where administration & elimination of a drug are in equilibrium
-reached at around 5 half-lives

Question 7

phenytoin?

Answer 7

anti-epileptic drug and it can be used in an emergency situation to stop epileptic seizures

Question 8

at what concentration is phenytoin efficacious at?

Answer 8

10-20 mg/L

Question 9

in an ideal scenario a steady-state concentration can be done in emergency situation but not ideal for?

Answer 9

chronic conditions because it is inconvenient

Question 10

how to calculate steady state? clearance-2L/hour
Vd= 70L

Answer 10

half life= ln(2) 70 / 2= 24 hours
24 x 5 - 120
so steady state is reached at around 120 hours

Question 11

to get a therapeutic concentration quickly we need to give?

Answer 11

a loading dose

Question 12

what is a loading dose?

Answer 12

an initial higher dose of a drug that may be given at the beginning of a course of treatment before dropping down to a lower maintenance dose

Question 13

when do we use a loading dose?

Answer 13

used when elimination is slow/ when there is a desire to reach therapeutic concentration quickly

Question 14

equation for first bolus dose:

Answer 14

concentration (mg/l) = dose (mg) / volume (l)

Question 15

equation for loading dose

Answer 15

dose= conc x volume

Question 16

vancomycin is?

Answer 16

an antibiotic with particular activity against gram positive bacterial infections

Question 17

clinicians will administer what type of doses to achieve steady state? from calculating mean concentration

Answer 17

intermittent drug doses

Question 18

intermittent dosing is favoured to giving a huge dose once a day as?

Answer 18

it avoids adverse effects

Question 19

why do oral drugs have lower availability than IV drugs?

Answer 19

takes longer to reach systemic circulation

Question 20

rosuvastatin is?

Answer 20

a statin that is used to lower cholesterol & prevent complications in patients with ischaemic heart disease

Question 21

Cpss

Answer 21

mean concentration at steady state

Question 22

F

Answer 22

bioavalabilty