Phenobarbital causes a depression of the body's systems, mainly the
central and
peripheral nervous systems. Thus, the main characteristic of phenobarbital overdose is a "slowing" of bodily functions, including decreased
consciousness (even
coma),
bradycardia,
bradypnea,
hypothermia, and
hypotension (in massive overdoses). Overdose may also lead to
pulmonary edemaand
acute renal failure as a result of
shock, and can result in death.
The
electroencephalogram of a person with phenobarbital overdose may show a marked decrease in electrical activity, to the point of mimicking
brain death. This is due to profound depression of the central nervous system, and is usually reversible.
[32]
Treatment of phenobarbital overdose is supportive, and mainly consists of the maintenance of
airway patency (through
endotracheal intubation and
mechanical ventilation), correction of bradycardia and hypotension (with
intravenous fluids and
vasopressors, if necessary) and removal of as much drug as possible from the body. Depending on how much time has elapsed since ingestion of the drug, this may be accomplished through
gastric lavage (stomach pumping) or use of
activated charcoal.
Hemodialysis is effective in removing phenobarbital from the body, and may reduce its half-life by up to 90%.
[32] No specific antidote for barbiturate poisoning is available.
[33]
British veterinarian
Donald Sinclair, better known as "Siegfried Farnon" in the "All Creatures Great and Small" books of
James Herriot, committed suicide at the age of 84 by injecting himself with an overdose of phenobarbital. Activist
Abbie Hoffman also committed suicide by consuming phenobarbital, combined with alcohol, on April 12, 1989; the residue of around 150 pills was found in his body at autopsy.
[34] Also dying from an overdose in 1996 was actress/model
Margaux Hemingway. The Japanese officers aboard the
German submarine U-234 killed themselves with phenobarbital while the German crew members were on their way to the US to surrender (but before Japan had surrendered).
39 members of the
Heaven's Gate UFO religious group committed mass suicide in March 1997 by drinking a lethal dose of phenobarbital and vodka "and then lay down to die" hoping to enter an alien spacecraft.
[35]
