Half Life Flashcards
What is half life
The rate in which drugs are eliminated from the body
Explain it further (half life)
The time it takes for the concentration of drug in the plasma in systemic blood flow to decrease by 50%of its initial value
What is the half life of gentomyvcin
2hrs of 8mg
What would the half life of gent be in its 3rd half life
1mg/ml
What cause short half life
Extensive tissue uptake,rapid metabolism
What cause long half life
Extensive plasma protein binding, slow metabolism, poor excretion
What is the half life if dioxin
36hrs
What is the half-life of aspirin
6hrs
How does half life come into play in continuous drug usage
The second dose of a drug will add to the previous dose causing gradual accumulation till stable concentration is maintained.
What happens is intervals between administration too low
The plasma concentration range falls below therapeutic range
What happens if intervals is too frequent
Plasma concentration rises above the therapeutic range and it leads to toxicity
What happens to the rate of accumulation between each doses
It lessens and lessens
What happens to plasma levels in stable state
The plasma levels rises and falls till it reaches a stable therapeutic range
What is a loading dose
A loading dose is twice the dose of the maintaince dose given without waiting for gradual accumulation.
Why can’t you do loading doses with drugs with long half life
It’s dangerous and can lead to toxicity.
