Clinical Pharmacokinetics Flashcards
Can drugs meet an effective level before meeting their peak level?
Yes.
Reasons for loss of therapeutic effect:
drug drops below MEL, duration of action, duration is usually shorter than time to eliminate all drug from body, >90% of drug eliminated, determined by the rate of elimination (metabolism and excretion)
Why do some drug effects continue after drug drops below MEL?
Due to irreversible binding to receptors or proteins; example: aspiring irreversibly binds platelet cyclooxygenase
What equation describes therapeutic index (TI)
TD50/ED50; toxic dose/effective dose
What is the range of drug between minimum therapeutic effect and minimum for toxic effect?
Therapeutic range or therapeutic window
Equation to represent zero order kinetics:
V = Vm max rate
Another name for zero order kinetics
Saturation kinetics
You will see a exponential decline curve in what form of kinetics?
1st order elimination kinetics (small drug)
A constant fraction of drug is eliminated per unit time regardless of the amount of drug present in what type of kinetics?
1st order
What stands for the elimination rate constant?
Beta or Kel
Zero order elimination kinetics (large drug) have what type of curves?
Linear decline.
A constant amount of drug is eliminated per unit time in what kind of kinetics?
zero order, saturation
The time required to eliminate half of the drug from the body is referred to as:
Half life, T1/2
How many half lives does it take to eliminate >90% the drug from the body?
4-5 half lives under 1st order kinetics
Equation for half life:
t1/2 = .693/beta; where beta is the elimination rate constant (Kel)
