Antiepileptic drugs status epilepticus

Refractory status epilepticus is seizure activity that is not controlled by first-fine and second-line therapies, including benzodiazepines and antiepileptic drugs. 

The brief duration of a single epileptic fit makes acute drug treatment unfeasible. Instead, antiepileptics are used to prevent seizures and therefore need to be given chronically. Only in the case of status epilepticus (a succession of several tonic-clonic seizures) is acute anticonvulsant therapy indicated — usually with benzodiazepines given i.v. or, if needed, rectally. 

Refractory status epilepticus that has failed to respond to one of these treatments, and has continued for more than 20-30 min, requires urgent action. The accepted strategy is to paralyze and ventilate the patient and administer an antiepileptic drug in sufficient dosage to suppress EEG evidence of seizure activity. The barbiturate anaesthetic thiopental (thiopentone), the benzodiazepine midazolam, and the anaesthetic propofol have all been used. What little comparative evidence there is remains inconclusive. Such treatment can only be carried out with facilities for artificial ventilation and intensive care, and effects can only be monitored by EEG recording. 

Status epilepticus can occasionally be fatal therefore, seizures should be treated aggressively. Seizures can be managed with antiepileptic medications such as carbamazepine. The common antiepileptic drug valproic acid is contraindicated because it depletes the body of carnitine, which may in fact exacerbate symptoms. The potential risk of stroke may be reduced using appropriate medication. The complications... 

Mazarati AM, Baldwin RA, Sankar R et al. (1998). Time-dependent decrease in the effectiveness of antiepileptic drugs during the course of self-sustaining status epilepticus. Brain Res, 814, 179— 185. 

Thomas P, Valton L, Genton P. Absence and myoclonic status epilepticus precipitated by antiepileptic drugs in idiopathic generalized epilepsy. Brain 2006 129 1281-1292. 

Status epilepticus is traditionally defined as a situation where there is continuous seizure activity for a period of 30 minutes or where there are a continuous series of seizures during which the sufferer does not regain consciousness. More recently, it has been suggested that any continuous seizure period of longer than 5 minutes should be classified as status epilepticus. In these situations the treatment employed may well consist of one of the previously indicated antiepileptic dmgs such as clonazepam (Fig. 13.15), phenobarbital and phenytoin (Fig. 13.15) or alternatively diazepam, fosphenytoin (a prodrug of phenytoin), loraze-pam, midazolam and paraldehyde (Fig. 13.16) may be employed. For the drugs used in the treatment of status epilepticus, the formulation and dose differ from conventional doses due to the situation and thus many of these will be administered by intravenous injection, intravenous infusion, buccal or rectal administration. 

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