DD French equations Flashcards
Bioavailability equation
F = AUCoral/AUCiv
T or F: For most drugs, bioavailability is equivalent to the amount of drug in the plasma.
TRUE
What does Cp0 mean?
Drug plasma concentration at time of administration
Define volume of distribution.
?The size of compartment necessary to account for total drug in body if present at same concentration in body as in plasma (Cp).? Obviously, not all drug stays in the plasma and will distribute out to its tissue target. This typically happens very rapidly, so two compartment modeling is not significant.
What does Vd mean?
Volume of distribution
Vd equation
Vd (L) = Dose [mg] / Cp0 [mg/L]
Calculate Vd: Dose = 120 mg, Cp0 = 3 mg/L
Vd = 40 L
If Vd = 40 L, how would you describe its distribution?
Distributed though all the water in the body (plasma, interstitial, intracellular).
If Vd = 3 L, how would you describe its distribution?
Only in the plasma
If Vd = 12 L, how would you describe its distribution?
In the plasma and interstitial fluid (3 L and 9 L, respectively)
If Vd = 100 L, how would you describe its distribution?
Sequestered at tissue sites. More common for lipid soluble drugs.
Loading dose equation
Loading dose = Cp * Vd
T or F: A patient?s body weight (size) does not affect Vd.
FALSE
Name 4 factors that influence Vd (other than patient size).
1.) Sites requiring drug to pass through cells, not between. 2.) The pH of body compartment with the drug. 3.) Lipid solubility of the non-ionized form of the drug. 4.) Drug binding to plasma proteins.
T or F: Only free drug is diffusible.
TRUE
