Phenobarbital [Phenobarbitone]

Generally prescribe lower dosages of phenobarbital for elderly, frail, or debilitated patients. These patients may be more sensitive to the pharmacologic actions of phenobarbital, particularly its respiratory depressant action, than are younger or healthier adult patients. Phenobarbital pharmacotherapy has been associated with deficits on neuropsychologic test scores, primarily as a result of impaired short-term memory and memory concentration tasks among children. Phenobarbital is available in a variety of injectable, oral, and rectal formulations that can be prescribed to meet the individual needs of patients who require phenobarbital pharmacotherapy for the prophylactic or symptomatic management of seizure disorders. The exact mechanism of phenobarbital’s anticonvulsant action has not been fully determined. Phenobarbital appears to act primarily at the level of the thalamus, where it interferes with impulse transmission to the cortex. Long-term phenobarbital pharmacotherapy, or regular personal use, may lead to addiction and habituation. Sudden discontinuation of long-term phenobarbital pharmacotherapy, or regular personal use, can result in the barbiturate withdrawal syndrome.