Dosing Flashcards
(17 cards)
What determines the route of administration?
Properties of drug and where the intended site of action is
What determines the length of time the drug will be administered?
Length of time needed to produce the desired effect
pharmacokinetics of dosage regimens determine what aspects?
Dosing frequency and dose size
Rate of availability affect what aspects of drug dosing?
Onset of action, apparent efficacy, duration of action
What factors affect rate of availability?
Dissolution of drug into absorbable drug & vascularity of tissue
How is the volume of distribution determined? (Formula)
Amount of drug in body / drug administered x % of bioavailable drug (Cp(0))
Factors that affect volume of distribution
Body weight
Body composition (adiposity, etc)
Age
Disease
How do you determine rate of clearance (formula)?
CL = rate of elimination / Cp
1st order elimination characteristics:
DELIVERY DEPENDENT (Cp)
0 order elimination characteristics:
Capacity limited (enzyme activity)
INDEPENDENT OF Cp
Factors affecting clearance:
Body weight
VASCULARITY OF TISSUES
Age
Disease
Maintenance Dosing formula:
Dm = Css x CL x dosing interval / F
AKA
Rate of elimination / bioavailability
Loading dose formula
Dl = Css x Vd / F (bioavailability)
How many doses does it take to achieve the plateau effect?
Steady state level aka Css reached in 4x5 doses
Effect of renal disease on dosing:
Decrease clearance
Prolong half life
Effect of hepatic disease on dosing
Decrease clearance
Prolong half life
Increase bioavailability
Increase free plasma concentration from low plasma proteins
Ionization of drugs affects what:
Absorption & distribution
Pharmacodynamics sometimes
