One-compartment model - extravascular dosing

Question 1

If elimination half-life is doubled, ka should be _________ (doubled/halved/unchanged)

Answer 1

unchanged

Question 2

When dose is halved, Cmax should be ________ (doubled/halved/unchanged) and tmax should be _________ (doubled/halved/unchanged)

Answer 2

halved; unchanged

Question 3

Time to reach Cmax is determined by _________ and ________

Answer 3

ka (or MAT) and k (or t1/2 or MRT)

Question 4

If F, D, V and k remain unchanged, when ka decreases, tmax should _________ (increase/decrease/stay the same) and Cmax should __________

Answer 4

increase/decrease

Question 5

Elimination half-life (t1/2) has _________ (a direct/an inverse) relationship with elimination rate constant (k). Elimination rate constant has __________ (a direct/an inverse_ relationship with tmax.

Answer 5

an inverse; an inverse

Question 6

T/F - Following the oral administration of a drug, the apparent volume of distribution calculated was 45L, indicating the drug reached the intracellular space

Answer 6

False - 45L indicated the true V must be less than 45L. The exact value is unknown without the information on F. Therefore, there is insufficient information for us to determine the extent of drug distribution

Question 7

Method of residuals for 1C with 1st-order absorption and elimination (ka»k)

Answer 7

Step 1: use the last 2 C-t points to calculate k
Step 2: Calculate the extrapolated C at time 0 (Ce0)
Step 3: Calculate the extrapolated C at the first time point post-dose (Ce1)
Step 4: Calculate the residual C at the first time point post-dose (Cr1)
Step 5: Calculate the ka knowing that the extrapolated C at time 0 (Ce0) equals the residue C at time 0 (Cr0)

Question 8

Total clearance is a proportionality constant relating _______ to _______

Answer 8

elimination rate; plasma concentration

Question 9

Total concentration has _______ (a direct/an inverse/no) relationship with AUC. Volume of distribution has _______ (a direct/an inverse/no) relationship with AUC

Answer 9

an inverse; no

Question 10

When CL increases, MRTiv should ________ (increase/decrease/stay the same)

Answer 10

decrease (MRTiv = 1/k, k = CL/V. Therefore, MRTiv = V/CL. There is an inverse relationship between MRTiv and CL)

Question 11

When CL decreases, AUC should ________ (increase/decrease/stay the same)

Answer 11

increase (CL = F*D/AUC. There is an inverse relationship)

Question 12

CLr

Answer 12

renal clearance

Question 13

CLnr

Answer 13

non-renal clearance