Abstract
The advent of new anticonvulsants, the resurgence of the ketogenic diet, and the currently available surgical techniques mean that practitioners have many options for long term prophylaxis of seizure recurrence. Unfortunately, breakthrough seizures still occur. In some situations, an additional dose of the patient’s maintenance medication, or adjustment of the daily dose, is the most appropriate course of action for the management of such breakthroughs. However, in some situations, the patient may be unwilling or unable to cooperate and so oral administration of anticonvulsants is not possible. Until recently, only benzodiazepines, phenytoin and phenobarbital (phenobarbitone) have been available for parenteral administration; however, alternative treatment options have been developed: diazepam gel for rectal administration, fosphenytoin (a phenytoin prodrug) and an intravenous formulation of valproic acid (sodium valproate).
An intravenous formulation of diazepam has been long used for seizure treatment and has shown good efficacy. The gel formulation showed >60% efficacy for preventing seizures over 12 to 24 hours in 2 controlled studies. No life-threatening adverse reactions were reported. Fosphenytoin is rapidly converted to phenytoin with a conversion half-life of 8 to 15 minutes following intravenous administration, and can be given in a variety of solutions. It may also be administered intramuscularly. Fosphenytoin infusion has not been associated with tissue necrosis and there have been fewer cardiac complications than are seen with intravenous infusion of phenytoin. Intravenous valproic acid shows linear pharmacokinetics, and administration by this route has been demonstrated to maintain therapeutic concentrations in patients and offers an alternative when patients cannot take the drug orally. Intravenous valproic acid has been shown to be well tolerated.
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Morton, L.D., Pellock, J.M. Treatment Options for Acute Seizure Care. CNS Drugs 10, 405–416 (1998). https://doi.org/10.2165/00023210-199810060-00002
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DOI: https://doi.org/10.2165/00023210-199810060-00002