Formulas

Question 1

What is the formula for clearance

Answer 1

CL = (rate of  elimination of  drug)/(plasma drug concenctration) 
CL =  Vd x Ke  (elimination constant)

Question 2

What is the half life formula?

Answer 2

T(1/2) = (0.693xVd)/CL

Question 3

What is the loading dose formula?

Answer 3

Loading dose = (Cp x Vd)/F

Question 4

What is the maintenance dose formula?

Answer 4

Maintenance dose = (Cp x CL x tau)/F
Tau = dosage interval
Cp = target plasma concentration at steady state

Question 5

What is the high Vd characterized by?

Answer 5

All tissues including fat

Small lipophilic molecules, especially if bound to tissue protein

Question 6

What is the medium Vd characterized by?

Answer 6

ECF

Small hydrophilic molecules

Question 7

What is the low Vd characterized by?

Answer 7

Large/charged molecules; plasma protein bound

Question 8

What is the formula for cardiac output?

Answer 8

Cardiac output = (rate of O2 consumption)/(arterial O2 content - venous O2 content)

OR

Cardiac output = stroke volume x heart rate

Question 9

What is the formula for physiologic dead space?

Answer 9

Vd = Vt x (PaCO2-PeCO2)/(PaCO2)

Question 10

Alveolar gas equation

Answer 10

PAO2 = PI02 - PaCO2/R

Question 11

Henerson hasselbalch equation

Answer 11

pH = 6.1 + log [HCO3-]/(0.03 * PC02)

Question 12

Predicted respiratory compensation

Answer 12

PCO2 = 1.5 [HCO3-] + 8 +/- 2

Question 13

Wall stress

Answer 13

(pressure * radius)/(2* wall thickness)