Equations

Question 1

Clearance of a drug

Answer 1

CL = 0.7 x Vd/ half-life

Question 2

Volume of distribution of a drug

Answer 2

V = D/C

Question 3

Loading dose

Answer 3

LD = Css x Vd

Question 4

Maintence dose

Answer 4

MD = Css x CL

Question 5

Renal clearance

Answer 5

Cx = UV/ P

U = urine concentration of X
V = urine flow rate
P = Plasma concentration

Question 6

Effective renal plasma flow

Answer 6

good going to glomeruli and tubules
Measured using para-aminohippuric acid (PAH)

eRPF= Upah x V/Ppah

eRPF underestimates true renal plasma flow

Question 7

Filtration fraction (kidneys)

Answer 7

portion of blood going to the kidney that is filtered through the glomerulus

FF= GFR/RR

Question 8

Excretion rate (kidneys)

Answer 8

Excretion Rate = V x U

Question 9

Mean Arterial Pressure

Answer 9

MAP = CO x TPR

MAP = 2/3 diastolic P + 1/3 systolic pressure

Question 10

pulse pressure

Answer 10

systolic pressure - diastolic pressure
* proportional to SV

• increase in pulse pressure in hypertension, aortic stiffening, obstructive sleep apnea, and exercise
• decrease with aortic stenosis, cariogenic shock, cardiac tamponade, advanced heart failure

Question 11

Stroke Volume

Answer 11

EDV- ESV

Question 12

Ejection fraction (heart)

Answer 12

EF = SV/EDV

normal: EF >= 55%

• EF decreases in systolic HF
• EF is normal in diastolic HF

Question 13

Renal Blood Flow

Answer 13

RBF= PAH clearance / (1- hematocrit)

PAH clearance = PAH secreted * urine flow/ plasma PAH

Refers to the volume of blood that flows through the kidney per unit time and can be calculated by dividing the renal plasma flow by (1- hematocrit)

Question 14

Renal Plasma flow

Answer 14

RBF * (1- hematocrit)

RPF is then used to calculate FF