Top Gene Interactions
- Metabolism: Valproic acid is rapidly absorbed from gastrointestinal tract. Valproic acid is metabolized almost entirely by the liver. In adult patients on monotherapy, 30-50% of an administered dose appears in urine as a glucuronide conjugate. Mitochondrial oxidation is the other major metabolic pathway, typically accounting for over 40% of the dose. These products include 2-n-propylpent-2-enoic acid (delta 2,3 VPE) and several coenzyme A (CoA) derivatives including VPA-CoA, and delta 2,3 VPE-CoA. Usually, less than 15-20% of the dose is eliminated by other oxidative mechanisms. Less than 3% of an administered dose is excreted unchanged in urine (A308). Half Life: 9-16 hours (following oral administration of 250 mg to 1000 mg).
- Uses/Sources: For treatment and management of seizure disorders, mania, and prophylactic treatment of migraine headache. In epileptics, valproic acid is used to control absence seizures, tonic-clonic seizures (grand mal), complex partial seizures, and the seizures associated with Lennox-Gastaut syndrome (A308).
- Health Effects: Valproic acid causes hyperammonemia, which can lead to brain damage. Rarely, it can cause blood dyscrasia, impaired liver function, jaundice, thrombocytopenia, and prolonged coagulation times. In about 5% of pregnant users, valproic acid will cross the placenta and cause congenital anomalies. Valproic acid may also cause acute hematological toxicities, especially in children, including rare reports of myelodysplasia and acute leukemia-like syndrome (L1132). May cause a potentially dangerous rash that may develop into Stevens Johnson syndrome, an extremely rare but potentially fatal skin disease. Acute overdoses of VPA can lead to hypo/hyperthermia, tachycardia, hypotension, respiratory depression, coma, confusion, somnolence, dizziness, headaches and cerebral edema. Extended use of VPA can cause hepatotoxicity. Allopecia, anorexia, renal failure, tremors and miosis are also associated with chronic toxicity. VPA is a known teratogen (due to folate antagonism). The teratogenicity of VPA is mostly found at genetic and somatic levels, causing teratogenesis involving neural tube defects (NTDs), anencephaly, lumbosacral meningomyelocele, and leg dysfunction due to spina bifida aperta.
- Symptoms: Acute toxicity symptoms include hypo/hyperthermia, tachycardia, hepatic toxicity, hypotension, respiratory depression, coma, confusion, somnolence, dizziness, headaches and cerebral edema. Allopecia, anorexia, liver toxicity, renal failure, tremors and miosis are also associated with chronic toxicity.
- Treatment: In case of acute oral exposure, administer charcoal as a slurry. Consider gastric lavage after ingestion of a potentially life-threatening amount of the compound if it can be performed soon after ingestion (generally within 1 hour). Protect the patient’s airway by placement in Trendelenburg position (head down) and on their left side (left lateral decubitus position) or by endotracheal intubation. Control any seizures first. Some experimental and clinical data suggest that early intravenous supplementation with l-carnitine could improve survival in severe VPA-induced hepatotoxicity. Carnitine administration has been shown to speed the decrease of ammonemia in patients with VPA-induced encephalopathy. As it does not appear to be harmful, l-carnitine is commonly recommended in severe VPA poisoning, especially in children (A15080). In case of inhalation, move patient to fresh air, monitor for respiratory distress. If the exposure occurred via eye contact, irrigate exposed eyes with copious amounts of room temperature water for at least 15 minutes. Remove contaminated clothing and wash exposed area thoroughly with soap and water if the exposure occurred via dermal contact. (T36).
- Route of Exposure: Inhalation. Rapid absorption from gastrointestinal tract. Although the rate of valproate ion absorption may vary with the formulation administered (liquid, solid, or sprinkle), conditions of use (e.g., fasting or postprandial) and the method of administration (e.g., whether the contents of the capsule are sprinkled on food or the capsule is taken intact), these differences should be of minor clinical importance under the steady state conditions achieved in chronic use in the treatment of epilepsy. Food has a greater influence on the rate of absorption of the Depakote tablet (increases Tmax from 4 to 8 hours) than on the absorption of Depakote sprinkle capsules (increase Tmax from 3.3 to 4.8 hours). Furthermore, studies suggest that total daily systemic bioavailability (extent of absorption) is the primary determinant of seizure control.
- Toxicity: Oral, mouse: LD50 = 1098 mg/kg; Oral, rat: LD50 = 670 mg/kg. In general, serum or plasma valproic acid concentrations are in a range of 20–100 mg/l during controlled therapy, but may reach 150–1500 mg/l following acute poisoning.
Mechanism of Action
|Target Name||Mechanism of Action||References|
Histone deacetylase 6
Histone deacetylase 1
Cellular tumor antigen p53
Succinate-semialdehyde dehydrogenase, mitochondrial
Alcohol dehydrogenase [NADP(+)]
Histone deacetylase 2
Sodium channel protein
Histone deacetylase 3
2-oxoglutarate dehydrogenase, mitochondrial
Superoxide dismutase [Cu-Zn]
Histone deacetylase 5
Histone deacetylase 7
Histone deacetylase 4
NAD-dependent protein deacylase sirtuin-5, mitochondrial
Fas-binding factor 1
Short/branched chain specific acyl-CoA dehydrogenase, mitochondrial
Histone deacetylase 9
4-aminobutyrate aminotransferase, mitochondrial
|Valproic Acid binds to and inhibits GABA transaminase. The drug's anticonvulsant activity may be related to increased brain concentrations of gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter in the CNS, by inhibiting enzymes that catabolize GABA or block the reuptake of GABA into glia and nerve endings. Valproic Acid may also work by suppressing repetitive neuronal firing through inhibition of voltage-sensitive sodium channels.||