An antiepileptic capsule for absence seizures and complex partial seizures, alone or with other seizure drugs. Its boxed warning covers fatal liver failure, pancreatitis, and serious harm to an unborn baby, so liver tests are checked and it is avoided in pregnancy unless nothing else works.
Exactly how valproic acid prevents seizures is not known. In the gut, it changes into valproate, the form that circulates in the body. It may work by raising levels of GABA, a natural chemical that calms brain activity. Levels in the fluid around the brain match the share of drug not bound to blood proteins, and that free share grows as blood levels rise.
The liver breaks down almost all of it, and its level falls by half in about 9 to 16 hours. Some other seizure medicines, such as carbamazepine, phenytoin, and phenobarbital, speed its removal, and it can push drugs like warfarin and phenytoin off blood proteins. Babies in their first two months clear it much more slowly than older children and adults. Stopping it suddenly can bring on a severe, long-lasting seizure that may be life-threatening.
Valproic acid is a seizure medicine. It treats complex partial seizures, which start in one part of the brain and affect awareness, either alone or alongside other seizure medicines. It also treats absence seizures, very brief spells of clouded or lost awareness, alone or with other medicines, and it is added for people who have several seizure types that include absence seizures. It can help control seizures but does not cure the condition.
For complex partial seizures, it is used in adults and in children 10 and older. Children under 2 have a much higher risk of fatal liver damage, so in them it is used only with extreme caution and as the only seizure medicine. The capsules are swallowed whole, and taking them with food can ease stomach upset. Because of the risk to an unborn baby, it is not used in women who are pregnant or could become pregnant unless other medicines have failed or are otherwise unacceptable.
Nausea, vomiting, stomach pain, headache, weakness, sleepiness, tremor, dizziness, blurred or double vision, and hair loss are common. The label's boxed warning treats liver failure, pancreatitis, and harm to an unborn baby, including birth defects and lower IQ, as the main dangers. It also warns about low platelets and bleeding, high ammonia that can cause confusion, low body temperature, serious allergic reactions, and suicidal thoughts.
A clinician may order these while someone is taking it.
This is the boxed warning, the warning the FDA label prints first.
Life-threatening adverse reactions. Hepatotoxicity, including fatal liver failure, usually in the first 6 months; children under 2 and patients with mitochondrial disorders are at higher risk, so check liver tests before and frequently during therapy. Fetal risk: neural tube defects, other major malformations, and decreased IQ. Pancreatitis, including fatal hemorrhagic cases.
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