Barbiturate and hypnosedative withdrawal by a multiple oral phenobarbital loading dose technique.

Although intravenous phenobarbital loading is effective in barbiturate withdrawal, controlled infusions of a drug are inconvenient. To develop a practical and more widely applicable method, oral loading doses of phenobarbital were given to 21 barbiturate addicts, whose estimated mean daily intake of barbiturates was 1 gm (range 0.5 to 4 gm). Twelve had a past or present history of barbiturate withdrawal seizures. Phenobarbital was given orally at a rate of 120 mg/hr until a predetermined clinical end point of phenobarbital effect was achieved. This end point was the presence of at least three of the following: nystagmus, drowsiness, ataxia, dysarthria, or emotional lability. The total phenobarbital loading dose (mean +/- SD) was 23.4 +/- 7.1 mg/kg, median phenobarbital concentration after loading was 35.9 mg/l (range 13.2 to 71.6 mg/l), and median half-life (t 1/2) of phenobarbital was 90 hr (range 38 to 240 hr). One patient with t 1/2 = 38 hr was given supplemental doses of phenobarbital. None developed seizures or other evidence of barbiturate withdrawal.