From the Guidelines
Valproic acid works primarily by enhancing the inhibitory effects of gamma-aminobutyric acid (GABA) in the brain, increasing GABA levels by inhibiting GABA transaminase and blocking voltage-gated sodium channels, as supported by the most recent study 1. The mechanism of action of valproic acid is complex and involves multiple pathways.
- It increases GABA levels by inhibiting GABA transaminase, the enzyme that breaks down GABA.
- It also blocks voltage-gated sodium channels, which helps prevent the rapid firing of neurons that occurs during seizures.
- Additionally, valproic acid affects signaling pathways by inhibiting histone deacetylase, which influences gene expression and may contribute to its mood-stabilizing effects. These multiple mechanisms explain why valproic acid is effective for various conditions, including epilepsy, bipolar disorder, and migraine prevention. The drug's broad spectrum of action on different neural pathways accounts for both its therapeutic versatility and its potential for side effects, which can include hepatotoxicity, pancreatitis, and teratogenicity. Regular monitoring of drug levels and liver function is necessary during treatment to ensure safety and efficacy, as noted in various studies 1. However, the most recent and highest quality study 1 provides the most relevant information on the mechanism of action of valproic acid. Key points to consider when using valproic acid include:
- Therapeutic range: typically 50-100 μg/mL
- Potential side effects: hepatotoxicity, pancreatitis, teratogenicity
- Monitoring requirements: regular monitoring of drug levels and liver function.
From the FDA Drug Label
The mechanisms by which valproate exerts its antiepileptic effects have not been established. It has been suggested that its activity in epilepsy is related to increased brain concentrations of gamma-aminobutyric acid (GABA)
The mechanism of action of valproic acid (Valproate) is not fully established, but it is suggested to be related to increased brain concentrations of gamma-aminobutyric acid (GABA) 2.
From the Research
Mechanism of Action of Valproic Acid
The mechanism of action of valproic acid (Valproate) involves several pathways, including:
- Increased gamma-aminobutyric acid (GABA)-ergic transmission 3, 4
- Reduced release and/or effects of excitatory amino acids 3, 4
- Blockade of voltage-gated sodium channels 3, 5
- Modulation of dopaminergic and serotoninergic transmission 3, 4
- Inhibition of histone deacetylases (HDACs) activity, leading to chromatin remodeling and regulation of gene expression 6
Biochemical and Molecular Mechanisms
Valproic acid's mechanism of action also involves biochemical and molecular pathways, including:
- Regulation of intracellular pathways and modulation of neurotransmission 6
- Effects on cell growth, differentiation, and apoptosis 6
- Involvement in complex behaviors, leading to its use as a psychotherapeutic agent 6
Non-GABAergic Hypotheses
Non-GABAergic hypotheses have also been proposed to explain the anti-epileptic action of valproic acid, including:
Mechanisms of Undesirable Effects
The possible mechanisms for the undesirable effects of valproic acid, such as hyperammonaemia, hepatotoxicity, and hypoglycaemia, have also been discussed, including:
- The role of beta- and omega-oxidation of valproic acid in explaining these effects 7