The 'anticonvulsants', sometimes also called 'antiepileptics', belong to a diverse group of
pharmaceuticals used in prevention of the occurrence of
epileptic seizures. More and more, anticonvulsants are also finding ways into the treatment of
bipolar disorder, since many seem to act as
mood stabilizers. The goal of an anticonvulsant is to suppress the rapid and excessive firing of
neurons that start a seizure. Failing this, a good anticonvulsant would prevent the spread of the seizure within the brain and offer protection against possible
excitotoxic effects that may result in
brain damage.
Many anticonvulsants block
Sodium (Na+) channels,
Calcium (Ca2+) channels,
AMPA receptors or
NMDA receptors. Some anticonvulsants inhibit the metabolism of
GABA or increase its release.
In the following list, the dates in parentheses are the earliest approved use of the drug.
Aldehydes
''Main article:
Aldehydes''
★
Paraldehyde (1882). One of the earliest anticonvulsants. Still used to treat
status epilepticus, particularly where there are no resuscitation facilities.
Aromatic allylic alcohols
★
Stiripentol (2001 - limited availability). Indicated for the treatment of severe
myoclonic epilepsy in infancy (SMEI).
Barbiturates
''Main article:
Barbiturates''
Barbiturates are
drugs that act as central nervous system (CNS)
depressants, and by virtue of this they produce a wide spectrum of effects, from mild
sedation to
anesthesia. The following are
classified as anticonvulsants:
★
Phenobarbital (1912). See also the related drug
primidone.
★
Methylphenobarbital (1935). Known as mephobarbital in the US. No longer marketed in the UK
★
Metharbital (1952). No longer marketed in the UK or US.
★
Barbexaclone (1982). Only available in some European countries.
Phenobarbital was the main anticonvulsant from 1912 till the development of phenytoin in 1938. Today, phenobarbital is rarely used to treat epilepsy in new patients since there are other effective drugs that are less sedating. Phenobarbital sodium injection can be used to stop acute convulsions or
status epilepticus, but a benzodiazepine such as lorazepam, diazepam or midazolam is usually tried first. Other barbiturates only have an anticonvulsant effect at anaesthetic doses.
Benzodiazepines
''Main article:
Benzodiazepines''
The benzodiazepines are a class of
drugs with
hypnotic,
anxiolytic, anticonvulsive,
amnestic and
muscle relaxant properties. The relative strength of each of these properties in any given benzodiazepine varies greatly and influences the indications for which it is prescribed. Long-term use can be problematic due to the development of
tolerance and
dependency. Of the many drugs in this class, only a few are used to treat epilepsy:
★
Clobazam (1979). Notably used on a short-term basis around menstruation in women with catamenial epilepsy.
★
Clonazepam (1974).
★
Clorazepate (1972).
The following benzodiazepines are used to treat
status epilepticus:
★
Diazepam (1963). Can be given rectally by trained care-givers.
★
Midazolam (N/A). Increasingly being used as an alternative to diazepam. This water-soluble drug is squirted into the side of the mouth but not swallowed. It is rapidly absorbed by the
buccal mucosa.
★
Lorazepam (1972). Given by injection in hospital.
Bromides
''Main article:
Bromides''
★
Potassium bromide (1857). The earliest effective treatment for epilepsy. There would not be a better drug for epilepsy until phenobarbital in 1912. It is still used as an anticonvulsant for dogs and cats.
Carbamates
''Main article:
Carbamates''
★
Felbamate (1993). This effective anticonvulsant has had its usage severely restricted due to rare but life-threatening side effects.
Carboxamides
''Main article:
Carboxamides''
The following are carboxamides:
★
Carbamazepine (1965). A popular anticonvulsant that is available in generic formulations.
★
Oxcarbazepine (1990). A derivative of carbamazepine that has similar efficacy but is better tolerated.
Fatty acids
''Main article:
Fatty acids''
The following are fatty-acids:
★ The
valproates —
valproic acid,
sodium valproate, and
divalproex sodium (1978).
★
Vigabatrin (1989).
★
Progabide
★
Tiagabine (1997).
''Vigabatrin and progabide are also analogs of GABA.''
Fructose derivatives
''Main article:
Fructose''
★
Topiramate (1995).
Gaba analogs
★
Gabapentin (1993).
★
Pregabalin (2004).
Hydantoins
''Main article:
Hydantoins''
The following are hydantoins:
★
Ethotoin (1957).
★
Phenytoin (1938).
★
Mephenytoin
★
Fosphenytoin (1996).
Oxazolidinediones
''Main article:
Oxazolidinediones''
The following are oxazolidinediones:
★
Paramethadione
★
Trimethadione (1946).
★
Ethadione
Propionates
''Main article:
Propionates''
★
Beclamide
Pyrimidinediones
''Main article:
Pyrimidinediones''
★
Primidone (1952).
Pyrrolidines
''Main article:
Pyrrolidines''
★
Brivaracetam
★
Levetiracetam (1999).
★
Seletracetam
Succinimides
''Main article:
Succinimides''
The following are succinimides:
★
Ethosuximide (1955).
★
Phensuximide
★
Mesuximide
Sulfonamides
''Main article:
Sulfonamides''
★
Acetazolamide (1953).
★
Sulthiame
★
Methazolamide
★
Zonisamide (1990).
Triazines
''Main article:
Triazines''
★
Lamotrigine (1991).
Ureas
''Main article:
Ureas''
★
Pheneturide
★
Phenacemide
Valproylamides (amide derivatives of valproate)
''Main article:
Amides''
★
Valpromide
★
Valnoctamide
See also
★
ATC code N03
References
★
Drug Reference for FDA Approved Epilepsy Drugs
★
UK Anti-Epileptic Drugs List
External links
★
eMedicine: Antiepileptic Drugs: an overview
★
NINDS: Anticonvulsant Screening Program
★
Use of Anticonvulsants in Pharmacotherapy of Bronchial Asthma
★
MDNG: Anticonvulsants and Bone Health