Myoclonic seizures drugs used

Valproic acid has become a major AED against several seizure types. It is highly effective against absence seizures and myoclonic seizures. In addition, valproic acid can be used either alone or in combination with other drugs for the treatment of generalized tonic-clonic epilepsy and for partial seizures with complex symptoms. 

Anticonvulsant Agents — Clonazepam (2f) was clinically useful in the treatment of akinetic and myoclonic seizures,22 intention myoclonus,23 tic douloureux24 and has been recorded as the drug of choice for status epilepticus.25... 

Phenobarbital has selective antiseizure activity at low doses and has a long half-life suitable for maintenance treatment in seizure disorders (for characteristics of barbiturates, see sedative-hypnotics). Clonazepam is usually a backup drug in absence and myoclonic seizures it causes marked sedation at anticonvulsant doses. IV lorazepam and diazepam are both used in status epilepticus. 

List the major drugs used for partial seizures, generalized tonic-clonic seizures, absence and myoclonic seizures, and status epilepticus. 

Absence seizures Ethosuximide and valproic acid are the preferred drugs since they cause minimal sedation. Ethosuximide is often used in uncomplicated absence seizures if patients can tolerate its gastrointestinal side effects. Valproic acid is particularly useful in patients who have concomitant generalized tonic-clonic or myoclonic seizures. Clonazepam is effective as an alternative drug but has the disadvantages of causing sedation and tolerance. 

Myoclonic syndromes Myoclonic seizure syndromes are usually treated with valproic acid. Clonazepam can be effective, but the high doses required cause drowsiness. Lamotrigine is also reported to be effective in myoclonic syndromes in children. Felbamate has been used adjunctively with the primary drugs but has hematotoxic and hepatotoxic potential. 

Drug of choice in myoclonic seizures Half-life is increased if used with phenobarbital Isoniazid (INH) decreases steady state blood levels of phenytoin Toxicity may occur with only small increments in dose... 

Carbamazepine was probably used at the start of treatment to prevent the automatisms (complex partial seizures) that were reportedly part of the patient s seizure repertoire. Carbamazepine is considered a drug of choice for this seizure type. When it became apparent that such seizures were actually infrequent in this patient, the drug was withdrawn. Carbamazepine has been reported to make absence (or myoclonic) seizures worse. 

Zonisamide is a sulfonamide derivative that is indicated as an adjunct for partial seizures in patients older than 16 years whose seizures are not controlled by first-line drugs. In Japan, it is used for myoclonic seizures as well. Apparently, it has more than one mechanism of action—all as yet unidentified. It is known to produce blockade of both sodium and T-type calcium channels (Fig. 20.2) (99,100). Because it also affects dopaminergic transmission, bipolar or schizoaffective disorder patients may improve. 

Benzodiazepines are the drugs of choice for status epilepticus (see above) however, development of tolerance renders them less suitable for long-term therapy. Clonazepam is used for myoclonic and atonic seizures. Clobazam, a 1,5-benzodiazepine exhibiting an increased anticonvulsant/seda-tive activity ratio, has a similar range of clinical uses. Personality changes and paradoxical excitement are potential side effects. 

Valproate is now the most commonly used antiepileptic drug worldwide. It is the drug of choice in primary generalized epilepsy, particularly in the treatment of generalized absence, myoclonus and tonic-clonic seizures. Valproate is the drug of first choice in atypical absence and atonic seizures, for Lennox-Gastaut syndrome and myoclonic epilepsy. 

The traditional treatment of tonic-clonic seizures is phenytoin or phenobarbital however, the use of carbamazepine and valproic acid is increasing because these AEDs have a lower incidence of side effects and equal efficacy. Valproic acid generally is considered the drug of first choice for atonic seizures and for juvenile myoclonic epilepsy. Lamotrigine and perhaps topiramate and zonisamide may be alternative agents for these seizure types. 

Clonazepam (Klonopin) was approved in 1975 for monotherapy or adjunctive treatment of akinetic (atonic), myoclonic, and absence variant seizures (64). Clonazepam also was found to be effective in controlling absence seizures, but because of the high incidence of side effects. It Is rated second to ethosuximide. It may be useful, however. In absence seizures when succinimide therapy has failed. It Is considered to be a third-line drug after 1) ethosuximide or valproate and 2) lamotrigine or valproate for the treatment of absence seizures. It is ineffective for treatment of generalized clonic-tonic seizures. 

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