Anticonvulsant medications such as carbamazepine, lamotrigine, gabapentin, or valproate are prescribed primarily in cases of epilepsy. Some of them have also been shown to be effective in managing the symptoms of other psychological problems, such as bipolar disorder, anxiety, borderline personality disorder or neuropathic pain.
In this article we will describe the characteristics of the 7 main types of anticonvulsant or antiepileptic drugs : carboxamides, structural analogues of GABA, triazines, fatty acid derivatives, benzodiazepines, barbiturates and bromides. Some are currently used, while others have lost relevance.
What are anticonvulsants?
Anticonvulsant or antiepileptic drugs are a type of medication that is mainly used to treat seizures due to epilepsy or other causes . However, their uses are not limited exclusively to this symptom, but are increasingly prescribed to stabilize mood and to reduce neuropathic pain.
Since there are many different anticonvulsants, it is not possible to describe a single mechanism of action. However, a significant proportion of these drugs reduce the electrochemical activity of the brain through their interaction with receptors for neurotransmitters such as GABA and glutamate .
Other antiepileptic drugs block voltage-controlled sodium or calcium channels; this decreases the function of neurotransmitters associated with seizures. There are also several antiseizure drugs whose mechanism of action remains unknown today, despite their proven efficacy.
In the case of epilepsy, these effects reduce the frequency with which the neurons fire electrochemical signals, which prevents the neural dysfunctions that cause the seizures from spreading throughout the brain, significantly limiting the severity of the seizures .
Some anticonvulsants are used to stabilize the mood in different psychological disorders. In this sense, their use is popular in cases of bipolar disorder, which is characterized by alternating periods of depression and mania, and borderline personality disorder, in which there is instability of emotions and identity.
Types of anticonvulsant drugs
Many different types of anti-seizure drugs have been used since potassium bromide was first used to treat “hysterical epilepsy” in the mid-19th century. Today the use of these and other classic anticonvulsants, such as barbiturates and benzodiazepines, has been relegated to the background.
Currently the drugs of choice for the treatment of seizures include carbamazepine and oxcarbazepine, which belong to the class of carboxamides, the structural analogues of GABA such as gabapentin and some other drugs such as valproic acid and lamotrigine.
Carbamazepine and oxcarbazepine are two of the most widely used anticonvulsants today. In addition to treating epilepsy, carbamazepine is prescribed in cases of neuropathic pain, while oxcarbazepine is used as an adjuvant medication in bipolar disorder when symptoms do not remit with the drugs of choice.
These carboxamides are considered some of the safest treatments for seizures. Their side effects are usually few or mild, being limited to dizziness, nausea, vomiting, headaches or drowsiness; they rarely cause more serious adverse reactions.
2. Structural analogues of GABA
Drugs that act similarly to the inhibitory neurotransmitter GABA are called “structural analogues of GABA”. The two most common anticonvulsants in this class are gabapentin, which is used to treat epilepsy, neuropathic pain and restless leg syndrome, and pregabalin, used in anxiety disorders and fibromyalgia.
3. Fatty acid derivatives
Anticonvulsants derived from fatty acids, the most relevant of which is valproate or valproic acid, increase the availability of GABA in the nervous system or exert other agonist effects on it. They also block voltage-controlled sodium and calcium channels ; this results in an inhibition of brain activity.
This class of anti-epileptic drugs inhibits the release of excitatory neurotransmitters, mainly glutamate. Lamotrigine is part of this group and is used to treat bipolar disorder and different types of epileptic seizures: focal, tonic-clonic and those that appear as a consequence of the Lennox-Gastaut syndrome.
Benzodiazepines, a type of sedative, have for many decades been the most widely used psychodrugs to treat problems related to physiological and cognitive over-activation, such as anxiety, muscle tension and insomnia. Benzodiazepines used as anticonvulsants include clonazepam and clobazam.
In 1912, phenobarbital, a drug from the barbiturate class, was first used to prevent and treat the symptoms of epilepsy. Since then, many anticonvulsants have been discovered that have less intense and interfering sedative effects, although barbiturates are still sometimes used because of their rapid effect on seizure relief.
Sodium bromide was the first drug to be used to treat epilepsy . Its origin dates back to 1857, when Charles Locock suggested this application. They were replaced by barbiturates after the emergence of phenobarbital in 1912, but today bromides are still used as anticonvulsants in veterinary medicine, especially in dogs.