PK & Genomics Flashcards
Bioavailability definition
percent of drug absorbed from extravascular administration relative to IV admin
IV drugs all have a bioavailability of 1
Absolute bioavailability (F) equation
Characteristics of highly distributed drugs
Lipophilic
Low MW
Uncharged
Low protein binding
Serum level correction is needed for highly ________ drugs when the _____ is low
highly protein bound(> 90%)
serum albumin (< 3.5 g/dL)
Corrected calcium formula
Corrected phenytoin formula
Volume of distribution formula
Clearance formula using rate of elimination (Re)
Clearance formula using AUC
First order clearance rate changes per unit of time
constant percentage per unit of time
Zero order clearance rate with changing concentrations
constant amount of drug removed per unit of time
Michaelis-Menten Kinetics
Saturable
Non-linear
Increases in dose when saturated can lead to disproportionate increases in concentration
Drugs that follow non-linear kinetics
Phenytoin
Theophylline
Voriconazole
Michaelis-Menten constant
Km = concentration at 1/2 Vmax
Vmax
max rate of metabolism
Elimination rate constant formula
Half life formula
> 95% of a drug is eliminated after ___ half lives
5 half lives
95% of steady state is reached after ____ half lives
5 half lives
Loading dose formula
Genetic testing:
Abacavir (Ziagen)
+ combo products (Trumeq)
HLAB*5701
+ patients are at greater risk for hypersensitivity
do not use
Genetic testing:
Azathioprine
TPMT
Low activity -> increased risk of life-threatening myelosuppression
Carbamazepine (Tegretol) Genetic Testing
HLAB*1502
positive patients at greater risk of hypersensitivity
more prevalent in patients of Asian descent
Genetic testing:
Cetuximab (Erbitux)
Panitumumab (Vectibix)
KRAS
+ patients -> drug will not be effective
