Phenobarbital is used to control seizures, to relieve anxiety. It is also used to prevent withdrawal symptoms in people who are dependent on another barbiturate medication and are going to stop taking the medication. Phenobarbital is in a class of medications called barbiturates. It works by slowing activity in the brain. Available in both injection and Tablet forms. strengths available in 10mg, 15mg, 30mg, 50mg, 60mg 100mg Tablets and 40mg, 60mg, 100mg, 200mg in Ampoules packings under Brand name VERBITAL.