Products
Antiepileptic drugs are commercially available in the form of tablets, dispersible tablets, capsules, solutions, suspensions, syrups, as nasal sprays, enemas, and as injectables, among others.
Structure and properties
The antiepileptic drugs are structurally heterogeneous agents. Within the class, several groups can be identified (see below).
Effects
The agents have antiepileptic, anticonvulsant, and muscle relaxant properties. They stabilize hyperexcited nerves, inhibit repetitive discharges and synaptic propagation of excitatory impulses. Effects are often based on interaction with ion channels (e.g., sodium channels, calcium channels) and with neurotransmitter systems (e.g., GABA, glutamate). Antiepileptic drugs reduce or prevent the number and severity of epileptic seizures.
Indications
For the prevention and treatment of epilepsy and seizures. Furthermore, antiepileptic drugs are also used for the treatment of chronic pain and nerve pain, anxiety disorders, migraine prevention, and as mood stabilizers for the treatment of bipolar disorder.
Dosage
According to the prescribing information. Antiepileptic drugs are administered systemically. Usually peroral, but also intranasal, rectal, and parenteral. Treatment is started at a low dose and increased slowly (gradual dose titration). Discontinuation should be gradual.
Abuse
Some agents, for example, the benzodiazepines, can be abused as sedating intoxicants and become addictive.
Agents
The following is a selection of important antiepileptic drugs. Barbiturates:
- Phenobarbital (eg, aphenylbarbit).
- Primidone (Mysoline)
- Barbexaclon (Maliasin, out of commerce).
Hydantoins:
Succinimide:
- Ethosuximide (Petinimide).
- Mesuximide (petinutin)
Benzodiazepines:
- Clonazepam (Rivotril)
- Diazepam nasal spray
- Midazolam nasal spray
Carboxamides:
- Carbamazepine (Tegretol, generic).
- Oxcarbazepine (Trileptal)
- Eslicarbazepine (Zebinix)
- Rufinamide (Inovelon)
Racetame:
- Brivaracetam (Briviact)
- Levetiracetam (Keppra, generic).
Fatty acids:
- Valproic acid (Depakine, generic).
Derivatives of GABA (without GABA effect):
- Gabapentin (Neurontin, generic).
- Pregabalin (Lyrica)
- Vigabatrin (Sabril)
AMPA receptor antagonists:
- Perampanel (fycompa)
Phenyltriazines:
- Lamotrigine (Lamictal, generic).
Salts:
- Potassium bromide
Sulfonamide derivatives:
- Sultiam (Ospolot)
- Zonisamide (Zonegran)
Amide:
- Lacosamide (Vimpat)
Dicarbamate:
- Felbamate (Taloxa)
Sulfamate-substituted monosaccharides:
- Topiramate (Topamax, generic).
Off-label:
- Retigabine (Trobalt, out of trade).
- Tiagabine (gabitril, out of commerce)
Contraindications
Full precautions can be found in the drug label. They depend on active ingredient. Many antiepileptic drugs should not be taken during pregnancy or breastfeeding.
Interactions
Older antiepileptic drugs in particular, such as carbamazepine and phenytoin, are known inducers of CYP450 isoenzymes and may therefore reverse the effects of other agents. Some newer agents, for example, pregabalin or lamotrigine, have a lower potential for interactions. Centrally depressant drugs and alcohol may increase adverse effects.
Adverse effects
The most common potential adverse effects include:
