Half lives Flashcards
Half life definition
Time for concentration of a drug to fall to half its value
Number of half lives taken to reach steady state (without loading dose)
4-5
Number of half lives taken for drug to be 97% eliminated - taken to be fully eliminated
5
Half life of diazepam
20-100 hours
Half life of aripiprazole
75-90 hours
Aripiprazole time to steady state
2 weeks
Half life of olanzapine
30 hours
Olanzapine time to steady state
1 week
Half life of risperidone
20 hours
Risperidone time to steady state
2-3 days (oral)
6-8 weeks (depot)
Half life of clozapine
12-16 hours
Clozapine time to steady state
2-3 days
Half life of amisulpride
12 hours
Amisulpride time to steady state
2-3 days
Half life of quetiapine
6 hours
Quetiapine time to steady state
2-3 days
Half life of fluoxetine
4-6 days
However can inhibit its own clearance so displays non-linear pharmacokinetics
Reason half life does not correlate with duration of action for irreversible MAIOs
Because new MAO enzyme needs to be synthesised for normal action to resume which takes a minimum of 5-7 days
Half life of venlafaxine (normal release)
3.5 hours
Half life of venlafaxine (normal release)
3.5 hours
Half life of duloxetine
12 hours
Half life of buspirone
2-11 hours (hence given TDS)
Half life of mirtazapine
20-40 hours
Half life of lithium
18 hours initially
After chronic use 36 hours
