Flashcards in Session 1 Deck (15):
How do you calculate steady state concentration in plasma?
CpSS = dose rate / clearance
How do you calculate loading dose?
Volume of distribution x CpSS
What is the difference between zero order and first order kinetics?
Zero (non-linear) = rate of elimination is constant. No half-life can be defined.
1st (linear) = rate of elimination is proportional to drug level. Constant fraction of drug is eliminated in unit time. Elimination becomes non-linear at higher levels.
What is clearance?
The volume of plasma that is completely cleared of the drug per unit time.
How do you calculate half life?
T1/2 = (0.693 x Vd)/clearance
Name CYP inhibitors
G- grapefruit juice
Name CYP inducers
Describe phase 1 and phase 2 of drug metabolism
1 = oxidation/reduction/hydrolysis via CYP 450
2 = conjugation with glucoronyls/sulphates/methyls/acetyles etc.
How do you calculate volume of distribution?
Total amount of drug in the body / plasma concentration of drug at time zero
What are the major fluid compartments of the body?
Plasma, extracellular and intracellular fluid.
What factors affect drug distribution?
Lipophilicity (moves from blood plasma to tissues)
Plasma binding reduces entry into tissues.
Amount of tissue and density of binding sites within that tissue.
How do you calculate bioavailability?
Amount of drug reaching systemic circulation / total amount of drug given
How do you calculate oral bioavailability?
The amount getting in orally / Total amount administered via IV.
What are parenterally delivered drugs?
Do not involve the GI tract. E.g. IV, subcutaneous, transdermal, intramuscular and intrathecal.