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MyDeficiencies

Valproate

antiepileptic, fatty acid derivative, mood stabilizer

Also sold as Depakote, Depakote ER, Depakote Sprinkles, Depakene.

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Findings for this medication

Research about this medication, graded for how strongly each finding can be attributed to it. Nothing here describes your own levels.

Valproate is the textbook case in this entire series for a drug that is directly, mechanistically, and severely nutrient-depleting rather than merely correlated with a deficiency. Its own FDA prescribing information lists "decreased carnitine concentrations" as an identified postmarketing adverse reaction, and two independent drug-specific primary studies going back to 1982 document valproate-associated carnitine deficiency with resulting hyperammonemia in treated children, a finding replicated enough times, and mechanistically clear enough (valproate is conjugated to valproyl-CoA and valproylcarnitine esters, consuming free carnitine and separately suppressing urea-cycle enzyme activity), that L-carnitine measurement and, when indicated, repletion is established clinical practice rather than a fringe supplement claim. That single relationship is graded red here, with the mechanism, the boundary populations, and the honest caveat that not every patient on valproate becomes carnitine-deficient, all stated plainly rather than oversold.

antiepileptic, fatty acid derivative, mood stabilizer · ATC N03AG01 · also sold as Depakote and Depakote ER and Depakote Sprinkles and Depakene and divalproex sodium and valproic acid · reviewed 2026-09-29. This describes research about the medication. It does not say anything about your own levels or health.

How to read the evidence grades

These colours describe how strongly a finding can be attributed to the medication in the research. They are not a severity score and they say nothing about your own health.

Grades describe how strongly a finding can be attributed to Valproate in the research — not how common it is, how serious it would be, and not anything about you personally.

Red — Severe
Two or more independent Tier A sources, this drug in the cohort, the nutrient directly measured, consistent direction, clinically meaningful magnitude, a named mechanism, no substantial contradicting Tier A evidence.
Orange — Moderate
At least one Tier A source with this drug in the cohort showing a real but bounded deficit: an exposure window, a subgroup, low frequency, or a functional rather than circulating deficit.
Yellow — Low
Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction.
Not graded — disclosed evidence gap
Nothing has been measured here, so this finding cannot be graded. That does not establish either safety or harm, and it is not the same as a White result.Source definition: Not gradeable under the rules above because nothing has been measured. Published as a documented gap, never as reassurance that there is no effect.

What the research found

Carnitine

Red — Severe

See study details

Valproate is conjugated with free carnitine, consuming it and impairing mitochondrial fatty-acid oxidation and urea-cycle function; the drug's own FDA label and at least two independent drug-specific cohort studies document reduced carnitine and resulting hyperammonemia, and L-carnitine measurement and repletion are established clinical practice in symptomatic patients.

Full detail, limits and 1 references

What the grade means here: Two or more independent Tier A sources, this drug in the cohort, the nutrient directly measured, consistent direction, clinically meaningful magnitude, a named mechanism, no substantial contradicting Tier A evidence. red

Limits on what this shows

  • Key negative/null findings: Not every valproate-treated patient develops measurable hypocarnitinemia. Verrotti 1999's own comparison of monotherapy against polytherapy subgroups indicates the deficiency is concentrated rather than universal, consistent with this being a real but bounded-severity, subgroup-weighted effect rather than a uniform one across all patients.
  • At-risk subgroups: Pediatric patients, polytherapy with other carnitine-lowering anticonvulsants, valproate overdose or acute toxicity, patients with poor nutritional intake or pre-existing metabolic disease, and any patient presenting with unexplained lethargy or altered mental status, in whom hyperammonemic encephalopathy should be considered even at therapeutic valproate concentrations.
  • Counter-evidence on record: Rezaee and Abbasgholizadeh, J Appl Toxicol 2026, a systematic review of L-carnitine and acetyl-L-carnitine across drug poisonings broadly (not a valproate-exclusive cohort) found generally supportive but heterogeneous evidence across agents; this is noted as class-level supportive context and is not counted toward the two independent Tier A sources supporting this grade.

Regulatory status

Labeled. FDA postmarketing experience (section 6.4, endocrine) lists "decreased carnitine concentrations" as an identified adverse reaction. Warnings and Precautions separately address hyperammonemia, stating it "may be present despite normal liver function tests" and instructing measurement of ammonia in patients who develop unexplained lethargy, vomiting, or changes in mental status.

Population evidence

Ohtani, Endo, Matsuda, J Pediatr 1982 (foundational primary report; children treated with valproic acid developed carnitine deficiency with hyperammonemia). Verrotti, Greco, Morgese, Chiarelli, Int J Clin Lab Res 1999 (cohort of children receiving valproic acid with and without other anticonvulsant drugs; carnitine deficiency and hyperammonemia documented in the valproate-exposed groups). Schiavo, Maldonado, Vazquez, Fagiolino, Troconiz, Ibarra, Eur J Pharm Sci 2023, extended in CPT Pharmacometrics Syst Pharmacol 2026 (quantitative systems pharmacology model built from pooled clinical data characterizing valproic-acid-induced hyperammonemia and the corrective effect of L-carnitine supplementation).

Mechanism

Named. Valproate is hepatically conjugated to valproyl-coenzyme A and valproylcarnitine esters, depleting the free-carnitine pool needed to shuttle medium- and long-chain fatty acids into mitochondria for beta-oxidation, and independently suppresses carbamoyl phosphate synthetase I activity in the urea cycle. The combined effect is reduced fatty-acid-derived ATP yield and impaired ammonia clearance, for which carnitine repletion is a mechanistically rational and clinically used countermeasure.

Counter-evidence held on record

L-carnitine has no NIH Office of Dietary Supplements tolerable upper intake level because it is not classified as an essential nutrient with an established Dietary Reference Intake. Documented clinical dosing for symptomatic valproate-induced hyperammonemia is prescriber- or toxicologist-directed based on severity and renal function, not a general consumer supplementation guideline, and routine prophylactic supplementation of every asymptomatic patient on valproate is not universally established practice. Never present this as a reason for self-directed high-dose carnitine supplementation. Acute valproate overdose or hyperammonemic encephalopathy requires emergency clinical management, not supplement-aisle dosing.

Folate, reduced with elevated homocysteine in one valproate-monotherapy pediatric cohort, bounded and mechanistically distinct from the pregnancy malformation signal

Orange — Moderate

See study details

A direct-measurement study in children on valproate monotherapy found reduced serum folate and elevated homocysteine; this sits alongside, but is mechanistically distinct from, the drug's separately labeled and far better documented neural-tube-defect risk in pregnancy, and is bounded here to a single located cohort.

Full detail, limits and 1 references

What the grade means here: At least one Tier A source with this drug in the cohort showing a real but bounded deficit: an exposure window, a subgroup, low frequency, or a functional rather than circulating deficit. orange

Limits on what this shows

  • Key negative/null findings: The FDA label's own malformation-risk language does not frame the neural-tube-defect signal as simply folate-preventable; standard prenatal folate dosing is not presented in the label as fully mitigating valproate-specific teratogenic risk, which is why this entry is bounded rather than extended into a pregnancy-safety claim.
  • At-risk subgroups: Children, per the Sharma cohort directly; separately and independently, any patient of reproductive potential for the teratogenicity dimension of valproate exposure.
  • Counter-evidence on record: Only one direct-measurement primary study was located in this review despite search; a second independent Tier A cohort measuring serum folate directly in valproate-treated patients was not found, which is why this entry is graded orange, bounded to a single cohort, rather than red.

Regulatory status

Labeled for teratogenicity, not for serum folate specifically. Valproate "can cause major congenital malformations, particularly neural tube defects," with a malformation rate reported at roughly four times higher than comparator antiepileptic drugs; contraindicated in pregnancy for migraine prophylaxis. The label's PK and interaction sections do not separately address serum folate depletion.

Population evidence

Sharma, Vardey, Sitaraman, Clin Lab 2015, "Evaluate the Effect of Valproate Monotherapy on the Serum Homocysteine, Folate and Vitamin B12 Levels in Epileptic Children": direct biochemical measurement in a valproate-monotherapy pediatric cohort.

Mechanism

Proposed: valproate interferes with folate-dependent one-carbon metabolism, lowering serum folate and raising homocysteine. This is mechanistically distinct from, though plausibly contributory to, the drug's independently documented direct teratogenic effect on neural tube closure.

Counter-evidence held on record

The NIH Office of Dietary Supplements tolerable upper intake level for folate/folic acid from supplements and fortified foods is 1,000 mcg per day for adults 19 and older. High-dose prescription folic acid, commonly 4 to 5 mg per day, sometimes used in specialist-directed pre-conception planning for patients on valproate, exceeds this general-population upper limit and must only be undertaken under direct prescriber or obstetric supervision, never self-directed. This entry does not itself recommend a folate dose. Do not present folic acid supplementation as fully preventing valproate-associated neural tube defect risk; the label does not support that framing.

The five body-system areas

Each finding is counted once, in a single area. Where a study is mentioned in a second area it is context only.

Mitochondrial Burden

Each finding below is counted once, in this area only.

Mitochondrial burden, boxed-warning-level in POLG-mutation carriers and young children, confirmed mechanistically in vitro

Orange — Moderate

See study details

The FDA label contraindicates valproate in patients with known POLG-related mitochondrial disorders because of an increased risk of fatal valproate-induced acute liver failure, and an independent in vitro study confirms direct mitochondrial respiratory dysfunction; this is bounded to genetically or clinically defined susceptible subgroups rather than a general-population finding.

Full detail and limits

What the grade means here: At least one Tier A source with this drug in the cohort showing a real but bounded deficit: an exposure window, a subgroup, low frequency, or a functional rather than circulating deficit. orange

Limits on what this shows

  • Key negative/null findings: The general population, outside the POLG-mutation and early-childhood risk window, tolerates chronic valproate without overt clinical mitochondrial failure in the overwhelming majority of cases; hepatotoxicity of this severity is concentrated in the labeled risk window of the first six months of therapy, age under two, and polytherapy.
  • At-risk subgroups: POLG mutation carriers and patients with suspected Alpers-Huttenlocher syndrome, children under two (especially on polytherapy or with pre-existing metabolic or mitochondrial disease), and any patient with unexplained lethargy, vomiting, or acute hepatic decompensation early in therapy.
  • Counter-evidence on record: The Nakayama 2026 book chapter (secondary, mechanistic reference) frames this mechanism as established consensus rather than presenting contradicting data; no Tier A source located in this review shows preserved mitochondrial function under valproate exposure specifically in POLG-mutant tissue.

Regulatory status

Labeled, high severity. Valproate is contraindicated in patients known to have mitochondrial disorders caused by DNA polymerase gamma (POLG) mutations, and in children under two years of age clinically suspected of having a POLG-related disorder, because of an increased risk of valproate-induced acute liver failure.

Population evidence

Komulainen et al., Toxicology 2015, "Sodium valproate induces mitochondrial respiration dysfunction in HepG2 in vitro cell model" (drug-specific in vitro study). Zahedi, Sadr, Sanaeierad, Roghani, 2022 preprint, rat model in which valproate exposure altered mitochondrial membrane potential and biogenesis, changes partially reversed by acetyl-L-carnitine co-treatment.

Mechanism

Named. Valproate and its coenzyme A/carnitine-ester metabolites directly impair mitochondrial beta-oxidation and respiratory chain function; in POLG-mutant cells, an already reduced capacity for mitochondrial DNA replication compounds this burden, precipitating fulminant hepatic mitochondrial failure.

Counter-evidence held on record

This is not a general-population energy-deficiency claim. It is a defined, severe, subgroup-specific hepatotoxicity risk that is the clinical basis for genetic or metabolic screening before valproate use in young children with suspected mitochondrial disease, not a rationale for mitochondrial-support supplementation in typical patients.

Oxidative Stress

Each finding below is counted once, in this area only.

Oxidative stress, drug-specific animal and embryo-model evidence, human clinical data not independently verified in this review

Yellow — Low

See study details

Drug-specific animal and embryo-model studies show valproate increases reactive oxygen species and disrupts antioxidant pathways; a pediatric human study is referenced by title in secondary literature but could not be independently retrieved and confirmed during this review.

Full detail, limits and 1 references

What the grade means here: Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction. yellow

Limits on what this shows

  • Key negative/null findings: No Tier A human study directly measuring oxidative-stress markers (malondialdehyde, glutathione, total antioxidant capacity) in valproate-treated patients was independently retrieved and confirmed in this review. Wilmott, J Pediatr 2006, "Children treated with valproic acid have evidence of oxidative stress," is a named commentary referencing pediatric clinical findings, but repeated attempts to open the underlying primary data were blocked by proxy-level rate limiting during this review (see the source list and access note); its content is disclosed here but not scored as supporting evidence.
  • At-risk subgroups: Not established at the human level in this review. The animal and embryo data implicate first-trimester or organogenesis-window exposure specifically.
  • Counter-evidence on record: None located directly contradicting the animal-level finding; the human-evidence gap itself is the limiting factor holding this grade at yellow rather than orange or red.

Regulatory status

Not labeled.

Population evidence

Tung and Winn, Mol Pharmacol 2011, "Valproic Acid Increases Formation of Reactive Oxygen Species and Induces Apoptosis in Postimplantation Embryos" (drug-specific animal/embryo model). Asghar et al., Toxicol Appl Pharmacol 2025, systematic review, meta-analysis, and network pharmacology of valproic-acid-induced oxidative stress in rodents (drug-specific but animal-only).

Mechanism

Proposed: impaired mitochondrial respiration (see Mitochondrial burden entry) generates excess reactive oxygen species; the Asghar 2025 network-pharmacology analysis implicates disrupted antioxidant-pathway targets specifically.

Counter-evidence held on record

No antioxidant-supplementation dose is supported by animal-only evidence. Do not present this as confirmed in humans, and do not use it to justify empiric antioxidant supplementation; no valproate-specific human interventional trial was located in this review.

Copper and Iron Balance

No entry in this dossier measured copper or iron status for this medication. Copper and iron are assessed separately, and nothing here stands in for either.

Gut Microbiome Risk

Each finding below is counted once, in this area only.

Gut microbiome risk, drug-specific rodent autism-model evidence for altered composition, no human compositional study located

Yellow — Low

See study details

A drug-specific rat study directly measuring gut microbiota composition alongside fecal metabolites in a valproic-acid-induced autism model found the two tightly correlated with the autism-like behavioral phenotype, with a second, title-confirmed drug-specific mouse study pointing the same direction; both are animal-only, and no human study measuring gut microbiome composition in valproate-treated patients was located in this review.

Full detail and limits

What the grade means here: Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction. yellow

Limits on what this shows

  • Key negative/null findings: No valproate-specific human study measuring gut microbiome composition (16S rRNA sequencing or equivalent) was located in this review. A family-matched 16S rRNA case-control study of temporal lobe epilepsy patients (Song, Li, Deng, He, Fan, BMC Neurol 2026) was located but does not stratify by drug regimen, so valproate's presence specifically in the studied cohort could not be confirmed; it fails the cohort test for this drug and is not counted as supporting evidence here. The drug's own well-documented, high-frequency GI adverse-effect profile is a symptom outcome, not a compositional microbiome measurement, and is not treated as equivalent to one.
  • At-risk subgroups: Not established in humans. The supporting rodent literature is concentrated in prenatal or early-life valproic-acid-exposure autism-model designs, not general adult epilepsy or bipolar maintenance dosing, so this finding should not be extended to typical adult valproate patients without qualification.
  • Counter-evidence on record: None located directly contradicting the animal-level finding. The absence of any human compositional study is itself the limiting factor holding this grade at yellow rather than orange or red.

Regulatory status

Not labeled for microbiome composition specifically. The FDA label does document high-frequency gastrointestinal adverse reactions: nausea (up to 48% adjunctive epilepsy), diarrhea (up to 23% monotherapy epilepsy), vomiting, abdominal pain, anorexia, and dyspepsia. These are labeled GI symptom findings, not a measured microbiome-composition finding, and per this protocol's rule against filing a clinical symptom as a nutrient/category finding, they are disclosed here as plausible context for altered gut transit and substrate availability, not scored as evidence toward this grade.

Population evidence

Gu, Han, Ren, Zhang, Zhao, Wang, Zhang, Qin, Behav Brain Res 2022;417:113580, "Correlation among gut microbiota, fecal metabolites and autism-like behavior in an adolescent valproic acid-induced rat autism model" (drug-specific animal study; direct 16S/fecal compositional measurement correlated with fecal metabolomics and autism-like behavior in VPA-exposed offspring). Li et al., Psychiatry Clin Psychopharmacol 2025;35(1):6-13, "The Impact of Valproic Acid on Microbiota in a Mouse Model of Autism Spectrum Disorder" (drug-specific animal study, title and venue confirmed via PubMed search-listing; full text and DOI not independently opened in this review, see Sources).

Mechanism

Proposed, not fully characterized in this review: valproic acid exposure in rodent models is associated with a shifted gut microbial community structure that correlates with altered fecal metabolite profiles and autism-like behavioral outcomes. A specific taxonomic direction (for example a named phylum or genus shift) was indicated in bibliographic metadata for the Gu 2022 study but could not be confirmed against the full text in this review, so no specific taxon-level claim is made here.

Counter-evidence held on record

No probiotic, prebiotic, or microbiome-support supplement claim or dose is supported by this entry. The evidence is animal-model-only and drawn from a prenatal-exposure autism research paradigm, not from valproate's ordinary adult indications, and should not be presented as a confirmed human dysbiosis finding.

Oxygen and ATP Output

Oxygen delivery and ATP production are assessed separately. Nothing here is counted twice.

ATP production, mechanistic extension of the carnitine and mitochondrial-respiration findings, no direct human ATP-flux measurement located

Yellow — Low

See study details

The same carnitine-conjugation and mitochondrial-respiration mechanisms supporting the Carnitine and Mitochondrial burden entries plausibly reduce ATP-yielding fatty-acid oxidation, but no study directly measuring ATP output or oxidative-phosphorylation flux in valproate-exposed human tissue was located in this review.

Full detail, limits and 1 references

What the grade means here: Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction. yellow

Limits on what this shows

  • Key negative/null findings: None identified specific to direct ATP-output measurement.
  • At-risk subgroups: The same populations flagged under Carnitine and Mitochondrial burden: children, polytherapy patients, and POLG-mutation carriers.
  • Counter-evidence on record: None located; see the Overlap map. This entry should not be read as independent confirmation beyond the Carnitine and Mitochondrial burden entries.

Regulatory status

Not labeled.

Population evidence

Komulainen 2015 (HepG2 mitochondrial respiration dysfunction; shared with the Mitochondrial burden entry, see Overlap map). Nakayama 2026 book chapter describes valproate's inhibition of medium-chain fatty-acid beta-oxidation as the operative mechanism reducing acetyl-coenzyme A flux into the tricarboxylic acid cycle and downstream ATP synthesis.

Mechanism

Indirect but named: reduced free carnitine limits fatty-acid entry into mitochondria; impaired respiratory chain function limits oxidative phosphorylation itself; both converge on reduced ATP yield, inferred from upstream measurements rather than a direct ATP-flux assay.

Counter-evidence held on record

No coenzyme Q10, "mitochondrial cocktail," or other ATP-support supplement dose is supported by this entry. The plausible mechanism is inferred from upstream carnitine and respiration data, not directly measured, and should not be presented as a confirmed cellular energy deficit.

Oxygen delivery/utilization, no nutrient-mediated deficiency located; the one documented hemoglobin effect is a pharmacodynamic mechanism clarification, not a deficiency

Yellow — Low

See study details

No valproate-specific study measuring reduced hemoglobin, hematocrit, or tissue oxygen delivery through a nutrient-mediated mechanism was located; the one well-documented valproate-hemoglobin interaction in the literature is a histone-deacetylase-inhibition-driven increase in fetal hemoglobin, a drug pharmacodynamic effect studied for sickle cell disease, not a deficiency, and it is disclosed here strictly as a mechanism clarification.

Full detail, limits and 1 references

What the grade means here: Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction. yellow

Limits on what this shows

  • Key negative/null findings: No reduction in hemoglobin or hematocrit tied to a nutrient-mediated mechanism (for example, iron-, B12-, or folate-driven anemia) specific to valproate was located in this review.
  • At-risk subgroups: Not established for a nutrient-mediated oxygen-delivery deficit.
  • Counter-evidence on record: None located.

Regulatory status

Labeled thrombocytopenia risk, trough-concentration-dependent (probability increases significantly above approximately 110 mcg per mL in females and 135 mcg per mL in males), and postmarketing "decreases in other cell lines and myelodysplasia." These are hematologic toxicity findings, not oxygen-delivery or nutrient findings, and are directed to the Monitoring panel rather than graded here, per this protocol's rule against filing a drug's own labeled toxicity as a nutrient-category finding.

Population evidence

Selby, Nisbet-Brown, Basran, Chang, Olivieri, Blood 1997, "Valproic Acid and Augmentation of Fetal Hemoglobin in Individuals With and Without Sickle Cell Disease" (drug-specific clinical study). Smith and Boots, Ann Neurol 1980, case report of valproate-associated bone marrow suppression with platelet autoantibodies and coagulopathy (hematologic toxicity, not oxygen-delivery-specific).

Mechanism

Valproate's histone-deacetylase-inhibiting activity is an established research mechanism for inducing fetal hemoglobin through gamma-globin gene reactivation, studied therapeutically in hemoglobinopathies. This is a direct pharmacodynamic effect on a gene-expression target, not a nutrient-mediated pathway, so per this protocol's rule against filing a drug's intended or incidental pharmacologic effect as a nutrient finding, it is not graded as an oxygen-delivery deficiency or benefit.

Counter-evidence held on record

Do not present the fetal hemoglobin finding as a nutrient effect or as evidence of altered oxygen-carrying capacity relevant to typical valproate patients. It is a distinct, gene-expression-level pharmacologic effect studied specifically in hemoglobinopathy populations, unrelated to nutrient status, and no supplement claim attaches to it.

Claims checked and not supported

These circulate online for this medication. They are listed here only so they can be answered, never as findings, and they are not graded.

A claim with no supporting evidence is not necessarily disproven. Where evidence actually argues against a claim, that is stated below.

  • Vitamin D

    Where it comes from: General antiepileptic-drug depletion consumer content and supplement-retailer material listing "all anticonvulsants" as vitamin D depleters, extrapolated from the well-documented enzyme-inducing anticonvulsant literature (phenytoin, carbamazepine, phenobarbital, primidone).

    Why it fails: Valproate's own FDA label confirms it is not a hepatic enzyme inducer; it functions as a net metabolic inhibitor of other drugs through enzyme inhibition and protein-binding displacement, the opposite pharmacologic direction from the CYP-induction mechanism (accelerated hepatic vitamin D catabolism) that underlies the genuine vitamin D depletion signal for the enzyme-inducing anticonvulsants. The drug's own postmarketing surveillance does report decreased bone mineral density, osteopenia, and osteoporosis, but per this protocol a bone-density finding is never filed as a vitamin D deficiency claim without a corresponding measured vitamin D or parathyroid hormone change, and no valproate-specific serum vitamin D depletion study was located in this review to support that step. The claim as commonly stated, that valproate depletes vitamin D the way the older enzyme-inducing anticonvulsants do, fails on its own proposed mechanism. The narrower, genuinely unresolved bone-density question is disclosed in the Monitoring panel instead.

  • Antioxidant megadosing

    Where it comes from: Consumer content citing animal and rodent oxidative-stress data, of the kind graded yellow in this dossier, to recommend high-dose vitamin C, vitamin E, or N-acetylcysteine supplementation to "counteract" valproate-induced oxidative stress.

    Why it fails: The underlying oxidative-stress signal is itself graded yellow, animal and embryo-model evidence only, with no confirmed human measurement located in this review. No valproate-specific human interventional trial testing antioxidant supplementation against a placebo or untreated comparator was located at any tier. A mechanistic animal finding does not, on its own, support a specific supplementation claim or dose, which is why no dose appears anywhere in the Oxidative stress entry above.

How the body handles this medication

Metabolism
Hepatic, through three parallel pathways: glucuronide conjugation (the major route), mitochondrial beta-oxidation, and a minor cytochrome P450-mediated omega-oxidation pathway that produces the hepatotoxic metabolite 4-ene-valproic acid. Aspirin co-administration measurably shifts the balance among these pathways.DailyMed, DEPAKOTE full prescribing information, AbbVie Inc., section 12.3
CYP450 / enzyme induction
Valproate is not a hepatic enzyme inducer. It acts predominantly as a metabolic inhibitor, reducing clearance of co-administered drugs such as diazepam, ethosuximide, lamotrigine, and phenytoin through enzyme inhibition and protein-binding displacement, the opposite pharmacologic direction from phenytoin, carbamazepine, and phenobarbital.DailyMed, DEPAKOTE full prescribing information, section 7.1
Elimination
Renal, predominantly as glucuronide and oxidative metabolites rather than unchanged parent drug. No specific renal tubular electrolyte-wasting mechanism is documented in the label.DailyMed, DEPAKOTE full prescribing information, section 12.3
Absorption and food effect
Well absorbed orally across formulations. Food delays time to peak concentration of the delayed-release tablet from about 4 to about 8 hours, a larger shift than for the sprinkle capsule formulation. No mineral-chelation, gastric-pH-dependent, or transporter-mediated absorption interaction is documented.DailyMed, DEPAKOTE full prescribing information, section 12.3
Protein binding
Concentration-dependent and nonlinear: the free (unbound) fraction rises from approximately 10% at 40 mcg per mL to approximately 18.5% at 130 mcg per mL. Binding is further reduced in elderly patients, chronic liver disease, renal impairment, and with concurrent aspirin.DailyMed, DEPAKOTE full prescribing information, section 12.3
Direct nutrient-relevant conjugation mechanism
Valproate is conjugated to valproyl-coenzyme A and valproylcarnitine esters, consuming the free-carnitine pool needed to shuttle fatty acids into mitochondria for beta-oxidation, and separately suppresses carbamoyl phosphate synthetase I activity in the urea cycle. This is the mechanistic basis, documented since 1982, for valproate-associated secondary carnitine deficiency and hyperammonemia, discussed in full in the Carnitine entry below.Ohtani et al., J Pediatr 1982; DailyMed postmarketing experience, section 6.4
All references used above
  1. DailyMed. DEPAKOTE (divalproex sodium) delayed-release tablets, full prescribing information, AbbVie Inc. — Regulatory label, Tier A. setid 08a65cf4-7749-4ceb-6895-8f4805e2b01f. Used for the full pharmacokinetic basis, hepatotoxicity, hyperammonemia, mitochondrial/POLG, teratogenicity, thrombocytopenia, and postmarketing carnitine and bone-density findings.
  2. WHO Collaborating Centre for Drug Statistics Methodology. ATC/DDD Index, N03AG01, valproic acid. — Regulatory classification reference, Tier A.
  3. Ohtani Y, Endo F, Matsuda I. Carnitine deficiency and hyperammonemia associated with valproic acid therapy. — J Pediatr 1982. DOI 10.1016/s0022-3476(82)80320-x. Tier A, drug-specific primary report, foundational reference for the Carnitine entry.
  4. Verrotti A, Greco R, Morgese G, Chiarelli F. Carnitine deficiency and hyperammonemia in children receiving valproic acid with and without other anticonvulsant drugs. — Int J Clin Lab Res 1999. DOI 10.1007/s005990050060. Tier A, drug-specific cohort, monotherapy versus polytherapy comparison.
  5. Maldonado C, Guevara N, Silveira A, Fagiolino P, Vazquez M. L-Carnitine supplementation to reverse hyperammonemia in a patient undergoing chronic valproic acid treatment: a case report. — J Int Med Res 2017. DOI 10.1177/0300060517703278. Tier B, drug-specific case report.
  6. Schiavo A, Maldonado C, Vazquez M, Fagiolino P, Troconiz IF, Ibarra M. Quantitative systems pharmacology model to characterize valproic acid-induced hyperammonemia and the effect of L-carnitine supplementation. — Eur J Pharm Sci 2023. DOI 10.1016/j.ejps.2023.106399. Tier B, drug-specific pharmacometric model; extended in a 2026 companion paper, CPT Pharmacometrics Syst Pharmacol, DOI 10.1002/psp4.70200.
  7. Coyne S, Das A. Hyperammonemia associated with low doses and concentrations of valproic acid in older adults with neurocognitive disorder. — Ment Health Clin 2026. DOI 10.9740/mhc.2026.06.163. Tier B, drug-specific.
  8. Schwarz ES, Thoelke M. Altered Mental Status and Hyperammonemia after Overdose of Valproic Acid with Therapeutic Valproic Acid Concentrations. — Int J Clin Med 2014. DOI 10.4236/ijcm.2014.510075. Tier B, drug-specific case report.
  9. Rezaee H, Abbasgholizadeh F. L-Carnitine and Acetyl-L-Carnitine in Drug Poisonings: A Systematic Review of Clinical and Experimental Evidence. — J Appl Toxicol 2026. DOI 10.1002/jat.70095. Tier C for valproate specifically; a broader drug-poisoning systematic review, not a valproate-exclusive cohort. Used only as class-level supportive context, not counted toward the red-tier source requirement.
  10. Lheureux PE, Hantson P. Carnitine in the treatment of valproic acid-induced toxicity. — Clin Toxicol (Phila) 2009. Tier B, drug-specific review.Title, authors, and journal surfaced via a secondary Crossref citation context; the primary record was not independently opened in this review. Cited descriptively only, with this caveat disclosed, not relied on for any numeric claim.
  11. Komulainen T, et al. Sodium valproate induces mitochondrial respiration dysfunction in HepG2 in vitro cell model. — Toxicology 2015;331:47. DOI 10.1016/j.tox.2015.03.001. Tier B, drug-specific in vitro study.
  12. Zahedi E, Sadr SS, Sanaeierad A, Roghani M. Acetyl-L-Carnitine and Valproate-Induced Autism. — 2022, rat model. DOI 10.2139/ssrn.4249935. Tier B, drug-specific animal study.Hosted as an SSRN preprint; not confirmed in this review as having completed peer review at time of citation, flagged accordingly.
  13. Nakayama N. Carnitine Deficiency Due to Sodium Valproate. — Book chapter, 2026. DOI 10.1007/978-981-95-7797-2_12. Tier B/C, secondary mechanistic reference.
  14. Tung EWY, Winn LM. Valproic Acid Increases Formation of Reactive Oxygen Species and Induces Apoptosis in Postimplantation Embryos. — Mol Pharmacol 2011;80(6):979-987. DOI 10.1124/mol.111.072314. Tier B, drug-specific animal/embryo model.
  15. Asghar MA, Tang S, Wan B, Chen Y, Zhang X, Zhao Q. Valproic acid-induced oxidative stress: systematic review, meta-analysis and network pharmacology highlights disruption in antioxidant pathways in rodents. — Toxicol Appl Pharmacol 2025;494:117160. DOI 10.1016/j.taap.2024.117160. Tier B, drug-specific but animal-only systematic review and meta-analysis.
  16. Wilmott RW. Children treated with valproic acid have evidence of oxidative stress. — J Pediatr 2006;149(5):A1. DOI 10.1016/j.jpeds.2006.10.002.Referenced by title, authorship, and citation metadata only. Repeated attempts to open the primary content were blocked by proxy-level rate limiting on the relevant literature-search channels during this review; not scored as supporting evidence, disclosed instead as a named but unverified lead in the Oxidative stress entry.
  17. Sharma T, Vardey S, Sitaraman S. Evaluate the Effect of Valproate Monotherapy on the Serum Homocysteine, Folate and Vitamin B12 Levels in Epileptic Children. — Clin Lab 2015. DOI 10.7754/clin.lab.2015.141230. Tier A, drug-specific monotherapy cohort.
  18. Smith FR, Boots M. Sodium valproate and bone marrow suppression. — Ann Neurol 1980. DOI 10.1002/ana.410080213. Tier B, drug-specific case report.
  19. Selby R, Nisbet-Brown E, Basran RK, Chang L, Olivieri NF. Valproic Acid and Augmentation of Fetal Hemoglobin in Individuals With and Without Sickle Cell Disease. — Blood 1997. DOI 10.1182/blood.v90.2.891. Tier A, drug-specific clinical study.
  20. NIH Office of Dietary Supplements. Folate, Health Professional Fact Sheet. — Reference source for the tolerable upper intake level cited in the Folate entry.
  21. Gu Y, Han Y, Ren S, Zhang B, Zhao Y, Wang X, Zhang S, Qin J. Correlation among gut microbiota, fecal metabolites and autism-like behavior in an adolescent valproic acid-induced rat autism model. — Behav Brain Res 2022;417:113580. DOI 10.1016/j.bbr.2021.113580. PMID 34555431. Tier B, drug-specific rat model, direct gut microbiota/fecal metabolite measurement. Primary source for the Gut microbiome risk entry, added in this revision.Bibliographic record (title, authors, journal, year, DOI, PMID) confirmed independently via Crossref and OpenAlex, and a partial abstract fragment was visible on the PubMed search-listing page; the full text and complete abstract were not reachable in this session (Elsevier host returned no extractable content and Unpaywall confirms no open-access copy exists). No specific taxon-level or diversity-index figures are claimed in the entry above for this reason.
  22. Li B, et al. The Impact of Valproic Acid on Microbiota in a Mouse Model of Autism Spectrum Disorder. — Psychiatry Clin Psychopharmacol 2025;35(1):6-13. Tier B, drug-specific mouse model, title indicates direct microbiota measurement.Title, author initial, journal, volume, issue, and pages surfaced via a PubMed search-listing page opened directly in this session; the individual PubMed record page, Crossref, OpenAlex, and Semantic Scholar were all blocked on retry before the DOI or abstract could be independently confirmed. Cited descriptively as corroborating context only, not relied on for any specific numeric or directional claim.