Parenteral antiepileptic/anticonvulsant drugs.

A large number of drugs can be given parenterally for the control of acute seizures, although many of these compounds are associated with serious adverse effects. Phenobarbital, the first antiepileptic drug (AED), has long been available in an injectable formulation. The sodium salt of phenobarbital is water soluble, and its parenteral formulation can be given for maintenance therapy or treatment of acute seizures. The introduction of phenytoin in 1938, and its subsequent parenteral formulation, represented a significant advance in AED therapy owing to its relative absence of sedation. However, the risk of adverse effects necessitates that the rate of phenytoin administration usually be limited to 50 mg/min. I.v. valproate has been used extensively but has not been approved for use in the United States, and its value for treating acute seizures is unclear. Several benzodiazepines have been used as adjunctive drugs for the treatment of epilepsy; given parenterally, they provide rapid CNS entry and prompt control of seizures, but their effect is short lived. Agents that have more hypnotic anesthetic properties are often used when the benzodiazepines or phenytoin alone or in combination fails.