Hi, a few questions:

1) What's the LD50 of butalbital?

2) I know the half-life is 35 hours, but in general, for how long
does this drug have a noticeable physiological effect a person (e.g.,
slower respiration, etc.)?

3) In general, for how long does a therapeutic dose last? 6 hours? Or
do they just say to take it every 6 hours, because it is usually in
combination form with acetaminophen?

Thanks for any helpful input.