Anticonvulsants are a large group of medications used in the prevention of the occurrence of epileptic seizures. This group of medications is also known as anti-epileptics.
Although they were initially used only to treat epileptic episodes, today they are also seen as mood stabilizers. It has been proven that anticonvulsants can help in the treatment of bipolar disorder, formerly known as manic depression.
An epileptic attack is a consequence of the rapid and excessive firing of neurons that starts a seizure. Anticonvulsants prevent this process from starting, and thereby contain the spread of the seizure within the brain, as well as preventing possible brain damage. There are several possible mechanisms of action: some of these drugs block Sodium (Na+) channels and Calcium (Ca2+) channels, while others block AMPA receptors or NMDA receptors. Some anticonvulsants inhibit the metabolism of GABA or increase its release.
The anticonvulsants used most commonly are barbiturates and benzodiazepines. Instead of using only one drug, people often take two or more anticonvulsant medications to prevent seizures; possible drug interactions may cause several health problems.
Types of seizures treated with anticonvulsants
A seizure is a synchronized depolarization of brain cells. A seizure can affect only parts of the brain, or sometimes the whole cortex. The seizure mechanism is the only way the brain can defend itself against outer influences!
There are four different types of seizures, each with its own characteristic symptoms:
- Petit Mal
- Grand Mal (Generalized Tonic Clonic)
- Single Focal
- Partial Complex
Petit mal seizures are characterized by:
- Minimal or no movements
- The person will appear to have a blank stare
- A brief sudden loss of awareness or conscious activity
- Seizures that recur many times throughout childhood
- Decreased learning abilities
Grand mal seizures are characterized by:
- Generalized and violent muscle contractions
- Patients who emit a sudden cry
- Breathing stopping temporarily
- A loss of consciousness
- Weakness
- Stupor (loss of mental function)
- Headache
- Confusion
- Incontinence of urine
- Tongue or cheek biting
Single focal seizures are marked by:
- Muscle contractions of a specific body part
- Abnormal sensations
- Nausea
- Sweating
- Skin flushing
- Dilated pupils
- Other focal (localized) symptoms
Partial complex seizures are marked by:
- Automatism (uncontrolled movements or actions)
- Nausea
- Sweating
- Skin flushing
- Dilated pupils
- Loss of consciousness
- Changes in personality
The most commonly used anticonvulsants and their side effects include:
- Phenytoin (Dilantin®) and Hydantoin: Dizziness, drowsiness, confusion, Ataxia, nausea, gingival hyperplasia, megaloblastic anemia, leukopenia
- Carbamazepine, (Epitol®, Tegretol®), Tricyclic: Sedation, dizziness, fatigue, confusion, ataxia, nausea, blood, dyscrasias, hepatotoxicity
- Valproic acid (Depakene®, Depakote®), Carboxylic acid: Anorexia, diarrhea, nausea, drowsiness, ataxia, irritability, confusion, headache, leucopenia, thrombocytopenia, hepatotoxicity, prolonged bleeding time
- Ethosuximide (Zarontin®), Succinimide: Ataxia , sedation, dizziness, hallucinations, behavioral changes, headache, Stevens-Johnson syndrome, systemic lupus, erythematosus, nausea, anorexia
- Clonazepam (Klonopin®), Benzodiazepine: Tachycardia, drowsiness, fatigue, anxiety, ataxia, headache, dizziness, blurred vision, Xerostomia
- Primidone (Mysoline®), Barbiturate derivatives: Drowsiness, vertigo, ataxia, behavioral changes, headache, nausea
- Phenobarbital (Barbita®, Luminal®, Solfoton®), Barbiturates: Dizziness, lightheadedness, sedation, ataxia, impaired judgment, skin rashes
Anticonvulsants as mood stabilizers
Mood stabilizers are medications that are widely used to treat mood disorders, especially bipolar disorder. These drugs are used to treat the depressive part of this disorder (which also has a manic part, of course.)
Anticonvulsants that are also often used as mood stabilizers include valproic acid and carbamazepine. There are several theories regarding their mechanism of action, although nobody yet knows precisely how they work. The most probable theory is the one that claims they regulate the glutamate excitatory neurotransmission and GABA inhibitory neurotransmission.
Studies have shown that these drugs also have certain intracellular effects such as modulation of the activity of enzymes, ions, arachidonic acid turnover, G-protein coupled receptors, and intracellular pathways involved in synaptic plasticity and neuroprotection in the brain.
Common anticonvulsants and their side-effects
There are some side effects that are common to all anticonvulsants. Some of these also can be applied to mood stabilizers of other classes.
Lethargy and photosensitivity
Anticonvulsants may lead to lethargy and photosensitivity; if you want to sleep more, you simply must avoid prolonged exposure to strong sunlight, This side effect is practically unavoidable since it’s due to the specific nature of anticonvulsants. These drugs are made to slow down the brain’s impulse to fight mania or prevent seizures to happen; but in doing so, they also wind up slowing down the patient’s metabolism.
Weight gain
A number of patients have reported weight gain on these drugs, but only with four of the FDA-approved mood stabilizers: Lithium®, Depakote®, Seroquel® (quetiapine) , and Zyprexa® (olanzapine).
Impact on memory and cognitive processes
Most anticonvulsants will impact a patient’s memory and cognitive processes, but only at first. After a while, this side effect simply stops. This has been reported by a great majority of patients.
Changes in dreaming patterns
There is no exact rule about the extent of possible changes, but a patient’s dreams do change in some ways. Some report positive changes, and some experience nightmares.
Hormonal changes
Almost all anticonvulsants mess around with our hormones, both female and male. Women can expect menstrual cycles to be disrupted, for example. If a patient is taking birth control pills, she must discuss the interaction of these medications with a specialist. Anticonvulsants such as Tegretol® (carbamazepine USP) and valproates are believed to interfere with a normal metabolism of testosterone.
Interactions with Dietary Supplements
Biotin
Several controlled studies have shown that anticonvulsant treatment decreases blood levels of a vitamin called biotin. This can leave a great impact, especially on children; it can cause withdrawn behavior and a delay in mental development. Adults experience a loss of appetite, feelings of discomfort or uneasiness, mental depression, or hallucinations.
Calcium
Patients who are on long-term multiple anticonvulsant therapy may develop a condition called hypocalcaemia, characterized by below-normal blood levels of calcium.
Vitamin A
Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, possibly due to low blood levels of vitamin A.
Vitamin B6
Anticonvulsive medications may also cause reduced blood levels of vitamin B6. This condition has been associated with atherosclerosis and some other symptoms such as dizziness, fatigue, and mental depression.
Vitamin B12
Some anticonvulsants can even cause anemia. Such effects might be associated with a vitamin B12 deficiency.
Vitamin K
Babies born to women taking anticonvulsant drugs tend to have low blood levels of vitamin K. This vitamin is important in blood clotting, so the main symptom is usually the infant’s bleeding.