Why is luvox the only ssri that requires b.i.d. dosing when dose is above 100mg (per p.i.sheet) ?

It isn't: generally given at that high of a dose. BUT it is very sticky to the liver and therefore more of it gets metabolized in a shorter period of time. HOWEVER, this is 12 hr in young healthy people but 24 hr in older or sicker people for half of it to go away. Frankly, one could just go with once a day.

Fast metabolism: The half life of Luvox is 13-15 hours which means that half of the drug is metabolized and out of the system at that time. This is comparison to other ssri meds that are 26-72 hours. There is an extended release form of Luvox called Luvox-CR which may be an alternative for you.

Uncertain: Noticed that when taken in split dose that the higher dose should be taken at night. My guess is this may be because it causes CNS depression.