The medical world's lexicon is constantly evolving, especially as our understanding of complex conditions like epilepsy grows. In the past, the most common term for a medication that prevents seizures was 'anticonvulsant.' However, as research revealed that not all seizures involve convulsions (involuntary muscle contractions), a shift towards more precise and encompassing terminology has occurred. This has led to the widespread adoption of 'antiepileptic drugs' (AEDs) and the most current, preferred term, 'antiseizure medications' (ASMs).
The Different Names for Antiseizure Drugs
Anticonvulsant
This term, still in common use by the public and occasionally in older medical contexts, emphasizes the prevention of convulsions. While historically relevant, it falls short in describing all seizure types. For example, absence seizures involve a brief loss of awareness or a 'staring spell' and do not involve convulsions. Using the term 'anticonvulsant' to describe a medication for this type of seizure would be medically inaccurate, which is why the term has become less favored in clinical practice.
Antiepileptic Drug (AED)
This was a significant improvement in terminology. An antiepileptic drug is specifically for treating epilepsy, a neurological disorder defined by recurrent, unprovoked seizures. The term acknowledges that the primary target is the epileptic condition, not just the convulsive symptom. However, some healthcare professionals still prefer the term 'antiseizure medication' to highlight the drug's effect of suppressing seizures, as it is important to remember that these drugs treat symptoms and do not cure the underlying condition.
Antiseizure Medication (ASM)
This is the most current and comprehensive term for drugs used to treat and prevent seizures. The shift towards this term by organizations like the International League Against Epilepsy (ILAE) reflects a better understanding of the diverse nature of seizure disorders. Using ASM avoids the inaccuracy of 'anticonvulsant' and provides a clear, universally understood description of the medication's function. The term encompasses drugs that manage all types of seizures, whether they involve convulsions or not.
How Antiseizure Medications Work
At the cellular level, seizures are caused by abnormal and excessive electrical activity in the brain's nerve cells, or neurons. Antiseizure medications work by influencing this electrical and chemical signaling to stabilize the brain's activity. While the precise mechanism can vary between different drugs, most function by either decreasing neuronal excitation or increasing inhibition.
Specific mechanisms include:
- Modulating Ion Channels: Many drugs, like phenytoin and lacosamide, work by blocking or altering the flow of ions (such as sodium and calcium) into neurons. By limiting these electrical currents, the rapid, uncontrolled firing of neurons that causes a seizure is reduced.
- Enhancing Neurotransmitters: Some ASMs increase the effect of gamma-aminobutyric acid (GABA), the brain's primary inhibitory neurotransmitter. For example, benzodiazepines like clonazepam enhance the calming effect of GABA, slowing down nerve signals.
- Blocking Excitatory Neurotransmitters: Other medications block the action of excitatory neurotransmitters like glutamate, which can trigger excessive electrical activity. Perampanel is an example of a drug that works via this mechanism.
Evolution and Generations of Antiseizure Drugs
The history of antiseizure drugs began with serendipitous discoveries and has evolved into a targeted, scientific process.
First-Generation Drugs
These are older medications that have been in use for many decades. They include phenobarbital (discovered in 1912) and phenytoin (discovered in 1938). While effective, they often come with more prominent side effects, significant sedative effects, and a higher risk of drug-drug interactions.
Newer Antiseizure Medications
Since the 1990s, many new antiseizure drugs have been developed through systematic screening programs. Examples include lamotrigine (Lamictal), levetiracetam (Keppra), and cenobamate (Xcopri). These newer drugs generally have more favorable side effect profiles, fewer drug interactions, and are better tolerated than their predecessors.
Comparison of Older vs. Newer Antiseizure Medications
| Feature | Older Generation Drugs | Newer Generation Drugs |
|---|---|---|
| Examples | Phenobarbital, Phenytoin, Carbamazepine, Valproate | Levetiracetam, Lamotrigine, Oxcarbazepine, Cenobamate |
| Common Side Effects | Higher incidence of sedative effects, dizziness, and cognitive impairment. | Generally better tolerated; side effects can be specific to the drug (e.g., mood changes with levetiracetam). |
| Drug Interactions | Significant potential for interacting with other medications by affecting liver enzymes. | Typically fewer and less significant interactions, making them safer for patients on polypharmacy. |
| Therapeutic Index | Often have a narrow therapeutic index, requiring close monitoring of blood levels. | Wider therapeutic index for many, with less need for routine blood level monitoring. |
| Cost | Generally more affordable due to availability as generics. | Often more expensive, though financial assistance programs exist. |
Other Therapeutic Uses of Antiseizure Medications
In addition to treating epilepsy, many antiseizure medications are prescribed for other conditions due to their effects on stabilizing nerve activity. These are often referred to as 'off-label' uses and include:
- Neuropathic Pain: Drugs like gabapentin (Neurontin) and pregabalin (Lyrica) are widely used to treat chronic pain caused by nerve damage from conditions like shingles or diabetic neuropathy.
- Mood Stabilization: Certain ASMs, including valproic acid and lamotrigine, are used as mood stabilizers to treat bipolar disorder.
- Migraine Prevention: Medications such as topiramate are effective in preventing migraine headaches.
Conclusion
While 'anticonvulsant' and 'antiepileptic drug' are still in use, the most accurate and preferred term in modern medicine is 'antiseizure medication.' The evolution of this terminology reflects a better clinical understanding of seizure disorders, recognizing that not all seizures present with convulsive symptoms. Newer generations of these medications offer improved side effect profiles and fewer drug interactions, expanding the options available for managing epilepsy and other neurological conditions. Choosing the right medication is a personalized process that requires careful consideration of the patient's seizure type, health profile, and potential side effects, always in consultation with a qualified healthcare provider. For more information and resources on epilepsy management, the Epilepsy Foundation provides comprehensive support for patients and their families.
