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 the inhibitory synaptic neurotransmitter, 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. Also, it has been shown to protect against a seizure-induced reduction in phosphatidylinositol (3,4,5)-trisphosphate (PIP3) as a potential therapeutic mechanism.It also has histone-deacetylase-inhibiting effects. The inhibition of histone deacetylase, by promoting more transcriptionally active chromatin structures, likely presents the epigenetic mechanism for regulation of many of the neuroprotective effects attributed to valproic acid. Intermediate molecules mediating these effects 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 nonsteroidal antiandrogen 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.
UK only
Capsules – Episenta prolonged release by Beacon
Sachets – Episenta prolonged release by Beacon
Intravenous solution for injection – Episenta solution for injection by Beacon

Germany, Switzerland, Norway, Finland, Sweden
Tablets – Orfiril by Desitin Pharmaceuticals
Intravenous injection – Orfiril IV by Desitin Pharmaceuticals

South Africa
Syrup – Convulex by Byk Madaus
Tablets – Epilim by Sanofi-synthelabo

Malaysia
Tablets – Epilim by Sanofi-Aventis

Romania
Companies are SANOFI-AVENTIS FRANCE, GEROT PHARMAZEUTIKA GMBH and DESITIN ARZNEIMITTEL GMBH
Types are Syrup, Extended release mini tablets, Gastric resistant coated tablets, Gastric resistant soft capsules, Extended release capsules, Extended release tablets and Extended release coated tablets

Canada
Intravenous injection – Epival or Epiject by Abbott Laboratories. Syrup – Depakene by Abbott Laboratories its generic formulations include Apo-Valproic and ratio-Valproic. Japan
Tablets – Depakene by Kyowa Hakko Kirin
Extended release tablets – Depakene-R by Kyowa Hakko Kogyo and Selenica-R by Kowa
Syrup – Depakene by Kyowa Hakko Kogyo

Europe
In much of Europe, Dépakine and Depakine Chrono (tablets) are equivalent to Epilim and Epilim Chrono above. Taiwan
Tablets (white round tablet) – Depakine (Chinese: 帝拔癲; pinyin: di-ba-dian) by Sanofi Winthrop Industrie (France)

Iran
Tablets – Epival 200 (enteric coated tablet) and Epival 500 (extended release tablet) by Iran Najo
Slow release tablets – Depakine Chrono by Sanofi Winthrop Industrie (France)

Israel
Depalept and Depalept Chrono (extended release tablets) are equivalent to Epilim and Epilim Chrono above. Manufactured and distributed by Sanofi-Aventis.