Pharmacology

Question 1

Volume of Distribution

Answer 1

Vd = Amount of Drug / Concentration of Drug

Question 2

Clearance

Answer 2

Clearance = Rate of elimination / Concentration of Drug
Clearance is additive
Ke x Vd

Question 3

Total body water

Answer 3

.6 L/Kg

Question 4

Extracellular Water

Answer 4

.2 L/Kg

Question 5

Blood

Answer 5

.08 L/Kg

Question 6

Plasma

Answer 6

.04 L/Kg

Question 7

Fat

Answer 7

.2-.35 L/Kg

Question 8

Bone

Answer 8

.07 L/Kg

Question 9

Three clinically active saturable drugs

Answer 9

Aspirin, Phenytoin, Ethanol

Question 10

0th order rate of elimination

Answer 10

RoE = (Vmax X C) / (Km+C)
At concentrations much higher than Km the bottom part of the equation is negligible and the concentration continuously decreases near Vmax

Question 11

Half Life

Answer 11

T1/2 = (.693 X Vd) / Clearance

Question 12

Accumulation Factor

Answer 12

AF = 1 / Fraction lost in one dosing cycle

Question 13

IV administration Characteristics

Answer 13

100 percent bioavailable

Most rapid onset

Question 14

Intramuscular administration characteristics

Answer 14

> 75% bioavailability
Large volumes feasible
May be painful

Question 15

Subcutaneous administration characteristics

Answer 15

> 75% bioavailability
Smaller volumes than IM
May be painful

Question 16

Oral (PO) administration characteristics

Answer 16

> 5% bioavailability
Most convenient
First pass effect can be significant

Question 17

Rectal (PR) administration characteristics

Answer 17

> 30% bioavailability

Less first pass effect than oral

Question 18

Inhalation administration characteristics

Answer 18

> 5% bioavailability

Often very rapid onset

Question 19

Transdermal administration characteristics

Answer 19

> 80% bioavailability
Very slow absorption
No first pass effect
Prolonged duration

Question 20

Extraction Ratio (First pass effect)

Answer 20

ER = CL (liver) / Q (hepatic bloodflow, 90L/hr in 90kg)

Question 21

Bioavailability of Drug

Answer 21

F = absorption X (1-ER)

Question 22

Dosing rate

Answer 22

Dosing rate = CL X TC

When bioavailability is less than 1 you must multiply dosing rate by the percentage bioavailability for that route

Question 23

Maintenance Dose

Answer 23

MD = Dosing Rate X Dosing Interval

Question 24

Loading Dose

Answer 24

LD = Vd X TC

Question 25

Loading Dose (for Peak Steady state concentration)

Answer 25

LD = Maintenance Dose X Accumulation Factor