Valproate (valproic acid, VPA, sodium valproate, or valproate semisodium) is a medication primarily used to treat epilepsy and as a mood stabilizer in the treatment of bipolar disorder. It is useful for the prevention of seizures in those with absence seizures, partial seizures, and generalized seizures. It can be given intravenously or by mouth, and the tablet forms exist in both long- and short-acting formulations.
Common side effects of valproate include nausea, vomiting, somnolence, and dry mouth. Serious side effects can include liver failure, and regular monitoring of liver function tests is therefore recommended. Other serious risks include pancreatitis and an increased suicide risk.
Valproate is known to cause serious abnormalities or birth defects in the fetus if taken during pregnancy, and is contra-indicated for women of childbearing age unless the drug is essential to their medical condition and the person is also prescribed a contraceptive. Reproductive warnings have also been issued for men using the drug.
Valproate has been in use in Japan for the prophylaxis of migraine since 2011. It is approved as an antimanic and antiseizure in Japan as well. In UK, valproate is approved for bipolar mania and epilepsy, and both valproate and divalproex are approved, although divalproex sodium is known as valproate semisodium.
Valproate was originally synthesized in 1881 and came into medical use in 1962. It is on the World Health Organization's List of Essential Medicines. It is available as a generic medication. In 2023, it was the 160th most commonly prescribed medication in the United States, with more than 3million prescriptions.
In the US, valproic acid is also prescribed as an anti-epileptic drug indicated for the treatment of manic episodes associated with bipolar disorder; monotherapy and adjunctive therapy of complex partial seizures and simple and complex absence seizures; adjunctive therapy in people with multiple seizure types that include absence seizures.
Psychiatric disorders
Valproate products are used to treat manic or mixed episodes of bipolar disorder.
There is limited evidence that adding valproate to antipsychotics may be effective for overall response and also for specific symptoms, especially in terms of excitement and aggression. Valproate was associated with a number of adverse events among which sedation and dizziness appeared more frequently than in the control groups.
Outcome
Findings in words
Findings in numbers
Quality of evidence
Global outcome
Clinically significant response
When added to antipsychotic drugs valproate probably increases the chance of improvement. Data are based on moderate quality evidence.
Valproate in combination with antipsychotics may slightly reduce the chance of leaving the study early, but the difference between the two treatments is not clear. Data supporting this finding are based on moderate quality evidence.
The combination of valproate and antipsychotic drugs may increase the chance of being given additional sedating medication, but, at present it is not possible to be confident about the difference between the two treatments and data supporting this finding are very limited.
On average, people receiving the valproate combination scored lower (better) than people treated with antipsychotics in combination with placebo or antipsychotic drugs alone. There was a clear difference between the groups, but the meaning of this in day-to-day care is unclear.
Adding valproate to antipsychotic drug treatment does not clearly cause liver problems. Data supporting this finding are based on moderate quality evidence.
Adding valproate to antipsychotic drugs probably causes little or no increase to the chance of feeling sick, but the difference between the two treatments is not clear. Data supporting this finding are based on moderate quality evidence.
Valproate is not commonly used to prevent or treat migraine headaches, but it may be prescribed if other medications are not effective.
The medication has been tested in the treatment of AIDS and cancer, owing to its histone-deacetylase-inhibiting effects. It has cardioprotective, kidney protective, antiinflammatory, and antimicrobial effects.
Contraindications
Contraindications include:
Pre-existing acute or chronic liver dysfunction or family history of severe liver inflammation (hepatitis), particularly medicine related.
Pregnancy 11% risk of birth defects and 30-40% risk of neuro-developmental disabilities which can be permanent
Known hypersensitivity to valproate or any of the ingredients used in the preparation
There is evidence that valproic acid may cause premature growth plate ossification in children and adolescents, resulting in decreased height. Valproic acid can also cause mydriasis, a dilation of the pupils. There is evidence that shows valproic acid may increase the chance of Polyendocrine metabolic ovarian syndrome (PMOS) in women with epilepsy or bipolar disorder. Studies have shown this risk of PMOS is higher in women with epilepsy compared to those with bipolar disorder. Weight gain is also possible. Valproic acid may decrease platelets in proportion to its dosage, particularly in women and the elderly.
Valproate is a teratogen. Teratogens can cause birth defects. Valproate is restricted for all women under age 55 in the United Kingdom and European Union. It has a black box warning for pregnancy in the United States.
There are also restrictions for men. Children fathered by men taking valproate have a higher risk of neurodevelopmental disorders. Valproate is restricted for men under age 55 in the United Kingdom and European Union. The restrictions require two specialists to agree that there is no other effective or tolerated treatment for the patient.
Elderly
Valproate may cause increased somnolence in the elderly. In a trial of valproate in elderly patients with dementia, a significantly higher portion of valproate patients had somnolence compared to placebo. In approximately one-half of such patients, there was associated reduced nutritional intake and weight loss.
Excessive amounts of valproic acid can result in somnolence, tremor, stupor, respiratory depression, coma, metabolic acidosis, and death. In general, serum or plasma valproic acid concentrations are in a range of 20–100mg/L during controlled therapy, but may reach 150–1500mg/L following acute poisoning. Monitoring of the serum level is often accomplished using commercial immunoassay techniques, although some laboratories employ gas or liquid chromatography.
In contrast to other antiepileptic drugs, at present there is little favorable evidence for salivary therapeutic drug monitoring. Salivary levels of valproic acid correlate poorly with serum levels, partly due to valproate's weak acid property (pKa of 4.9).
In severe intoxication, hemoperfusion or hemofiltration can be an effective means of hastening elimination of the drug from the body. Supportive therapy should be given to all patients experiencing an overdose and urine output should be monitored. Supplemental L-carnitine is indicated in patients having an acute overdose and also prophylactically in high risk patients. Acetyl-L-carnitine lowers hyperammonemia less markedly than L-carnitine.
Interactions
Valproate inhibits CYP2C9, glucuronyl transferase, and epoxide hydrolase and is highly protein bound and hence may interact with drugs that are substrates for any of these enzymes or are highly protein bound themselves. It may also potentiate the CNS depressant effects of alcohol. It should not be given in conjunction with other antiepileptics due to the potential for reduced clearance of other antiepileptics (including carbamazepine, lamotrigine, phenytoin and phenobarbital) and itself. It may also interact with:
Aspirin: may increase valproate concentrations. May also interfere with valproate's metabolism.
Benzodiazepines: may cause CNS depression and there are possible pharmacokinetic interactions.
Carbapenem antibiotics: reduce valproate levels, potentially leading to seizures.
Cimetidine: inhibits valproate's metabolism in the liver, leading to increased valproate concentrations.
Erythromycin: inhibits valproate's metabolism in the liver, leading to increased valproate concentrations.
Ethosuximide: valproate may increase ethosuximide concentrations and lead to toxicity.
Felbamate: may increase plasma concentrations of valproate.
Mefloquine: may increase valproate metabolism combined with the direct epileptogenic effects of mefloquine.
Primidone: may accelerate metabolism of valproate, leading to a decline of serum levels and potential breakthrough seizure.
Rifampicin: increases the clearance of valproate, leading to decreased valproate concentrations.
Warfarin: valproate may increase free warfarin concentration and prolong bleeding time.
Zidovudine: valproate may increase zidovudine serum concentration and lead to toxicity.
Pharmacology
Pharmacodynamics
Although the mechanism of action of valproate is not fully understood, traditionally, its anticonvulsant effect has been attributed to the blockade of voltage-gated sodium channels and increased brain levels of the inhibitory synaptic neurotransmitter gamma-aminobutyric acid (GABA). The GABAergic effect is also believed to contribute towards the anti-manic properties of valproate. In animals, sodium valproate raises cerebral and cerebellar levels of GABA, possibly by inhibiting GABA degradative enzymes, such as GABA transaminase, succinate-semialdehyde dehydrogenase and by inhibiting the re-uptake of GABA by neuronal cells.
Prevention of neurotransmitter-induced hyperexcitability of nerve cells via Kv7.2 channel and AKAP5 may also contribute to its mechanism. Valproate has been shown to protect against a seizure-induced reduction in phosphatidylinositol (3,4,5)-trisphosphate (PIP3) as a potential therapeutic mechanism.
Valproate is a weak or low-potencyhistone deacetylase inhibitor, specifically of the class I HDAC1, HDAC2, HDAC3, and HDAC8, but not of other HDACs. Earlier studies found a wide range of inhibitory potencies of valproate against HDACs, ranging from low micromolar to millimolar concentrations, but subsequent work with improved methodology has supported greater inhibitory potencies, with IC50Tooltip half-maximal inhibitory concentration values in the range of 36 to 219μM for the class I HDACs. For comparison, valproate was found to be 4- to 46-fold less potent in inhibiting the class I HDACs relative to butyric acid (butyrate). By inhibiting HDACs, valproate promotes more transcriptionally active chromatin structures, that is it exerts an epigenetic effect. This has been proven in mice: Valproic acid induced histone hyperacetylation had brain function effects on the next generation of mice through changes in sperm DNA methylation. Intermediate molecules include VEGF, BDNF, and GDNF.
Endocrine actions
Valproic acid has been found to be an antagonist of the androgen and progesterone receptors, and hence as a nonsteroidalantiandrogen and antiprogestogen, at concentrations much lower than therapeutic serum levels. In addition, the drug has been identified as a potent aromatase inhibitor, and suppresses estrogen concentrations. These actions are likely to be involved in the reproductive endocrine disturbances seen with valproic acid treatment.
Valproic acid has been found to directly stimulate androgen biosynthesis in the gonads via inhibition of histone deacetylases and has been associated with hyperandrogenism in women and increased 4-androstenedione levels in men. High rates of polycystic ovary syndrome and menstrual disorders have also been observed in women treated with valproic acid.
Taken by mouth, valproate is rapidly and virtually completely absorbed from the gut. When in the bloodstream, 80–90% of the substance are bound to plasma proteins, mainly albumin. Protein binding is saturable: it decreases with increasing valproate concentration, low albumin concentrations, the patient's age, additional use of other drugs such as aspirin, as well as liver and kidney impairment. Concentrations in the cerebrospinal fluid and in breast milk are 1 to 10% of blood plasma concentrations.
via omega oxidation: 5-hydroxyvalproic acid, 2-propyl-glutaric acid
some others: 3E-ene-valproic acid, 3Z-ene-valproic acid, 4-ene-valproic acid, 4-hydroxyvalproic acid
All in all, over 20 metabolites are known.
In adult patients taking valproate alone, 30–50% of an administered dose is excreted in urine as the glucuronide conjugate. The other major pathway in the metabolism of valproate is mitochondrial beta oxidation, which typically accounts for over 40% of an administered dose. Typically, less than 20% of an administered dose is eliminated by other oxidative mechanisms. Less than 3% of an administered dose of valproate is excreted unchanged (i.e., as valproate) in urine. Only a small amount is excreted via the faeces. Elimination half-life is 16±3 hours and can decrease to 4–9 hours when combined with enzyme inducers.
Valproic acid was first synthesized in 1882 by Beverly S. Burton as an analogue of valeric acid, found naturally in valerian. Valproic acid is a carboxylic acid, a clear liquid at room temperature. For many decades, its only use was in laboratories as a "metabolically inert" solvent for organic compounds. In 1962, the French researcher Pierre Eymard serendipitously discovered the anticonvulsant properties of valproic acid while using it as a vehicle for a number of other compounds that were being screened for antiseizure activity. He found it prevented pentylenetetrazol-induced convulsions in laboratory rats. It was approved as an antiepileptic drug in 1967 in France and has become the most widely prescribed antiepileptic drug worldwide. Valproic acid has also been used for migraine prophylaxis and bipolar disorder.
In 2024, for those under age 55, additional restrictions for valproate prescription have been imposed in the United Kingdom. Patients under 55 can still receive valproate, but need to obtain the permission of two specialists. The restrictions are, in women, due to the potential for birth defects in children born of women of childbearing age. In men, the restrictions are due to the potential for reversible male infertility, testicular problems, and the risks of neurodevelopmental conditions in children born to men taking valproate in the 3 months before conception. Similar restrictions have been imposed in the European Union for both women and men.
In February 2026, a French man, Jean-Marc Laurent, filed what has been described as the first legal complaint related to paternal exposure to valproate, alleging that his child developed neurodevelopmental disorders after he had been treated with the drug prior to conception.
Approval status
This section needs to be updated. Please help update this article to reflect recent events or newly available information.(February 2024)
Limited (depends on the seizure type; it can help with certain kinds of seizures: drug-resistant epilepsy, partial and absence seizures, can be used against glioblastoma and other tumors both to improve survival and treat seizures, and against tonic–clonic seizures and status epilepticus).
In 2012, pharmaceutical company Abbott paid $1.6 billion in fines to US federal and state governments for illegal promotion of off-label uses for Depakote, including the sedation of elderly nursing home residents.
Some studies have suggested that valproate may reopen the critical period for learning absolute pitch and possibly other skills such as language.
Valproate exists in two main molecular variants: sodium valproate and valproic acid without sodium (often implied by simply valproate). A mixture between these two is termed semisodium valproate. It is unclear whether there is any difference in efficacy between these variants, except from the fact that about 10% more mass of sodium valproate is needed than valproic acid without sodium to compensate for the sodium itself. In Europe, the US, and many other countries three variants of valproate are sold: valproic acid, sodium valproate and valproate semisodium also known as divalproex sodium, the latter is believed to have fewer gastrointestinal side-effects. Divalproex sodium tablets are a formulation comprising valproate sodium and valproic acid in a 1:1 molar relationship.
Valproate is a negative ion. The conjugate acid of valproate is valproic acid (VPA). Valproic acid is fully ionized into valproate at the physiologic pH of the human body, and valproate is the active form of the drug. Sodium valproate is the sodium salt of valproic acid. Divalproex sodium is a coordination complex composed of equal parts of valproic acid and sodium valproate.
Depalept and Depalept Chrono (extended release tablets) are equivalent to Epilim and Epilim Chrono above. Manufactured and distributed by Sanofi-Aventis.
Mexico– Epival and Epival ER (extended release) by Abbott Laboratories
United Kingdom– Depakote (for psychiatric conditions) and Epilim (for epilepsy) by Sanofi-Aventis and generics
United States– Depakote and Depakote ER (extended release) by Abbott Laboratories and generics
India– Valance and Valance OD by Abbott Healthcare Pvt Ltd, Divalid ER by Linux laboratories Pvt Ltd, Valex ER by Sigmund Promedica, Dicorate by Sun Pharma
Germany– Ergenyl Chrono by Sanofi-Aventis and generics
Chile– Valcote and Valcote ER by Abbott Laboratories
France and other European countries– Depakote
Peru– Divalprax by AC Farma Laboratories
China– Diprate OD
Research
A 2023 systematic review of the literature identified only one study in which valproate was evaluated in the treatment of seizures in infants aged 1 to 36 months. In a randomized control trial, valproate alone was found to show poorer outcomes for infants than valproate plus levetiracetam in terms of reduction of seizures, freedom from seizures, daily living ability, quality of life, and cognitive abilities.
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12Wagner JM, Hackanson B, Lübbert M, Jung M (December 2010). "Histone deacetylase (HDAC) inhibitors in recent clinical trials for cancer therapy". Clinical Epigenetics. 1 (3–4): 117–136. doi:10.1007/s13148-010-0012-4. PMC3020651. PMID21258646. The structurally simplest class of HDACi are the short-chain fatty acids. Despite the low inhibitory potency of these inhibitors, also compounds from this class have been studied in the clinic. Valproic acid, which has been used as an antiepileptic drug for many years and still is used in this indication, has been shown to inhibit preferably class I HDACs in the high micromolar to millimolar range. [...] Even though the carboxylic acid valproate (VPA) is an HDACi with weak inhibitory potential, it is an interesting drug for clinical trials due to its well-characterized pharmacodynamic and pharmacokinetic profile (see Table 6).
12Lagace DC, O'Brien WT, Gurvich N, Nachtigal MW, Klein PS (2004). "Valproic acid: how it works. Or not". Clinical Neuroscience Research. 4 (3–4): 215–225. doi:10.1016/j.cnr.2004.09.013. Two laboratories have independently identified HDACs as direct targets of VPA [11,13]. [...] VPA inhibits HDAC1 with an IC50Z0.4–1.0 mM, which is within the clinical dose range (0.4–0.8 mM). VPA also inhibits HDACs 2–5 and 7 (but not HDAC6 or 10, see below), as well as the mixture of HDACs present in HeLa cell nuclear extracts [11–13]. VPA can also reduce HDAC activity by inducing the proteosome-dependent degradation of HDAC2 in cultured cells [81]. [...] VPA is a semiselective HDAC inhibitor, as it does not inhibit HDACs 6 and 10 [12], which have tandem HDAC-like domains and are structurally distinct from other HDACs. [...] The inability of VPA to inhibit HDAC6 may be a beneficial quality that distinguishes it from HDAC inhibitors of the hydroxamic acid class, such as trichostatin A (TSA) and suberoylanilide hydroxamic acid (SAHA).
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