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A 28-year-old female asked about a male:

How many hours does a dose of phenobarbital has effect? vch dosage is better-1 dose of 30mg/day at night or 2 doses of 15mg each/day?

1 doctor answer2 doctors weighed in
Dr. Andrew Reeves
Neurology 30 years experience
Loooong time: Phenobarbital takes a long time to be cleared from the body. It typically takes several days for the level to drop by half. (It has a very long half-life...about 60 hours) Because of this, most people can take it just once a day.

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Last updated Sep 23, 2017

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