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PubMed1993

[Hepatotoxicity induced by valproic acid in adults. Report of 3 cases].

Valproic acid is a useful antiepileptic drug, with occasional gastrointestinal side effects. Hepatotoxicity is the most serious adverse reaction and, although rare, it can be fatal. Risk factors for hepatotoxicity are an age of less than two years, polytherapy and mental retardation; it has been rarely reported in adults. We report three mentally retarded adult patients receiving polytherapy, who developed valproic acid induced hepatotoxicity. Two patients had a symptomatic hepatitis with a concomitant paradoxical increase in seizure frequency and one an asymptomatic alteration of hepatic function tests. After discontinuing the drug, the hepatitis subsided. We conclude that hepatotoxicity must be considered as a possible side effect of valproic acid and we suggest some recommendations for its early detection.

Adolescent↗

PubMed1979

The effects of the anticonvulsant valproic acid on cerebral indole amine metabolism.

The effects of valproic acid (500 mg/kg, ip, 1 h prior to testing) on indole amine metabolism were studied in rats by measurement of the contents of tryptophan, 5-hydroxytryptophan (5-HTP), 5-hydroxytryptamine (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) in the cerebral hemisphere. Tryptophan and 5-HIAA levels were increased, whereas 5-HTP and 5-HT remained unchanged. Furthermore, valproic acid failed to alter the levels of 5-HTP and DOPA, 5-HT and DA, and 5-HIAA in animals pretreated, respectively, with 3-hydroxybenzyl hydrazine (a decarboxylase inhibitor), pargyline (a monoamine oxidase inhibitor), or probenecid (a compound which blocks 5-HIAA transport out of the brain and cerebrospinal fluid). These results militate against the possibility that valproic acid alters the rate of tryptophan hydroxylation or the synthesis of 5-HT. However they do support the concept that valproic acid increases brain 5-HIAA by inhibition of the transport mechanism which removes 5-HIAA from the brain.

5-Hydroxytryptophan↗

PubMed2006

The antiepileptic and anticancer agent, valproic acid, induces P-glycoprotein in human tumour cell lines and in rat liver.

BACKGROUND AND PURPOSE: The antiepileptic drug valproic acid, a histone deacetylase (HDAC) inhibitor, is currently being tested as an anticancer agent. However, HDAC inhibitors may interact with anticancer drugs through induction of P-glycoprotein (P-gp, MDR1) expression. In this study we assessed whether valproic acid induces P-gp function in tumour cells. We also investigated effects of valproic acid on the mRNA for P-gp and the cytochrome P450, CYP3A, in rat livers. EXPERIMENTAL APPROACH: Effects of valproic acid on P-gp were assessed in three tumour cell lines, SW620, KG1a and H4IIE. Accumulation of acetylated histone H3 in rats' livers treated for two or seven days with valproic acid was evaluated using a specific antibody. Hepatic expression of the P-gp genes, mdr1a, mdr1b and mdr2, was determined by real-time polymerase chain reaction. The effects of valproic acid on CYP3A were assessed by Northern blot analysis and CYP3A activity assays. KEY RESULTS: Valproic acid (0.5-2.0 mM) induced P-gp expression and function up to 4-fold in vitro. The effect of a series of valproic acid derivatives on P-gp expression in SW620 and KG1a cells correlated with their HDAC inhibition potencies. Treatment of rats with 1 mmol kg(-1) valproic acid for two and seven days increased hepatic histone acetylation (1.3- and 3.5-fold, respectively) and the expression of mdr1a and mdr2 (2.2-4.1-fold). Valpromide (0.5-2.0 mM) did not increase histone acetylation or P-gp expression in rat livers, but induced CYP3A expression. CONCLUSIONS: Valproic acid increased P-gp expression and function in human tumour cell lines and in rat liver. The clinical significance of this increase merits further investigation.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1981

Pharmacology of valproic acid in children with severe epilepsy: clearance and hepatotoxicity.

Valproic acid concentrations correlate with dose in children when sampling times are consistent. Both interpatient variability and average clearance of valproic acid are inversely related to age. Young children usually need higher doses to achieve the same blood levels as other patients, but the levels that result from a dose are less predictable from one child to the next. Whereas valproic acid therapy had little effect on the serum glutamic oxaloacetic transaminase (SGOT), 12% of patients had abnormal SGOTs during an average of 14 months' therapy. The abnormal SGOTs from patients without serious hepatic dysfunction overlap many of the abnormal values in cases of fatal hepatic failure associated with valproic acid.

Adolescent↗

PubMed1996

Toxic effect of valproic acid on tryptophan binding to rat hepatic nuclei.

This study evaluated whether valproic acid, a branched-chain fatty acid which has been used in the treatment of seizures, would influence the binding Of L-tryptophan to rat hepatic nuclei. Previous studies have indicated that binding of L-tryptophan to hepatic nuclear envelope protein was saturable, stereospecific, and of high affinity. In this study, we investigated whether valproic acid, which under certain conditions is heptatoxic, would influence L-tryptophan binding to rat hepatic nuclei as assayed by in vitro L-(5-3H)tryptophan binding. Our results indicate that the addition of valproic acid to hepatic nuclei or nuclear envelopes in vitro has little influence on their L-(5-3H)tryptophan binding. On the other hand, when valproic acid (80 mg/100 g body weight) is tube-fed 2 h before killing, the isolated nuclei show decreased specific L-tryptophan binding (total binding minus non-specific binding using unlabeled L-tryptophan (10(-4)M), at 2000-fold excess) compared with controls. Other fatty acids (oleic, palmitic or linoleic acid at 10(-4)M) when added with excess, unlabeled L-tryptophan (10(-4)M) in vitro to hepatic nuclei revealed some (but less than with valproic acid) decreased specific binding compared with controls. At high doses, valproic acid (80 mg/100 g body weight) appears to decrease tryptophan-induced stimulation of hepatic protein synthesis, probably in a hepatotoxic manner.

Animals↗

PubMedDate not supplied

Vitamin B6 and valproic acid in treatment of infantile spasms.

Twenty patients with infantile spasms were treated with high doses of vitamin b6, valproic acid, or both. Three of 13 patients (23%) treated initially with high doses of vitamin B6 demonstrated a definite reduction in seizures; 2 patients had no improvement on electroencephalography. Vitamin B6 therapy alone was continued in a single patient (8%) who remained seizure-free during the 15-month follow-up period. Initial treatment with vitamin B6 and valproic acid improved the electroencephalogram significantly more (P less than 0.05) than initial vitamin B6 treatment alone. The group which had valproic acid added to vitamin B6 therapy had significantly fewer seizures (P less than 0.05) and better electroencephalograms (P less than 0.01) than did the group treated initially with vitamin B6 alone. There were no significant differences among the group treated initially with vitamin B6, the group treated initially with valproic acid, and the group in which valproic acid was substituted for vitamin B6. ACTH was more effective in abolishing seizures than was valproic acid or vitamin B6 and valproic acid. ACTH had an excellent effect on seizures in 86% of patients who did not respond well to vitamin B6, valproic acid, or both; however, many of these patients had later recurrence of infantile spasms. The combination of vitamin B6 and valproic acid is effective and safe in the treatment of infantile spasms.

Adrenocorticotropic Hormone↗

PubMed1984

Effects of anticonvulsants on learning: performance of pigeons under a repeated acquisition procedure when exposed to phenobarbital, clonazepam, valproic acid, ethosuximide and phenytoin.

The effects of phenobarbital, clonazepam, valproic acid, ethosuximide and phenytoin were examined in pigeons performing under a repeated acquisition procedure. Clonazepam (0.06-0.75 mg/kg), valproic acid (40-120 mg/kg), ethosuximide (40-160 mg/kg) and phenytoin (2.5-15 mg/kg) produced generally dose-dependent decreases in rate of responding, whereas phenobarbital (5-50 mg/kg) had little consistent effect on response rate across the dose range studied. Phenobarbital and clonazepam produced dose-dependent increases in error rates. Although valproic acid and phenytoin generally increased errors relative to control values, this effect was not directly dose-dependent or consistent across subjects. A within-session analysis of the distribution of drug-induced increases in errors revealed that the main effect of phenobarbital, clonazepam, valproic acid and phenytoin was to increase errors during early acquisition (i.e., before the procurement of 15 or fewer reinforcers). Later in the session, a similar number of errors per reinforcer was made during drug and control sessions. In contrast to the other anticonvulsants examined, ethosuximide had little effect on error rates. These results suggest that there are qualitative as well as quantitative differences in the effects of anticonvulsant drugs under the repeated acquisition procedure.

Animals↗

PubMed1981

Recurrent pancreatitis induced by valproic acid. A case report and review of the literature.

Valproic acid represents a new class of anticonvulsants that are widely employed in the management of many types of seizure disorders. Compared with other anticonvulsants, it has been considered relatively free of adverse effects. Recently, acute hepatic failure has been ascribed to valproic acid. Now experience is accumulating that implicates this agent in causing pancreatitis. Contributing to this evidence, the patient described herein had well-documented, recurrent pancreatitis while he was taking valproic acid. Nonspecific vomiting and abdominal pain frequently occur with valproic acid; however, pancreatitis must be considered whenever these symptoms are severe or protracted.

Adolescent↗

PubMed1995

Valproic acid treatment of chronic daily headache.

The efficacy of valproic acid in the treatment of intractable chronic daily headache, unresponsive to traditional prophylactic medications, was examined prospectively in 16 patients. Dosage of the medication was adjusted to maintain serum valproic acid levels between 50 and 100 micrograms/mL, provided there were no significant side effects at that level. Valproic acid prophylaxis was of some benefit in only 2 of 16 patients. One of these two patients discontinued therapy due to side effects. Eight of the 16 patients reported side effects which included nausea, diarrhea, anorexia, lethargy, sleepiness, confusion, blurred vision, and decreased libido. In conclusion, valproic acid was not effective in controlling chronic daily headache in the majority of patients in whom conventional therapy had failed, and 50% of patients reported side effects. There is a significant disparity in the reported efficacy of this drug in treating chronic daily headache. This disparity is most likely due to the poorly-defined nature of this variety of headache. It is, therefore, recommended that more stringent definition of this disorder be developed before therapeutic regimens are evaluated.

Adult↗

PubMed1996

Interaction of valproic acid with nonsteroidal antiinflammatory drugs mefenamic acid and fenoprofen in normal and uremic sera: lack of interaction in uremic sera due to the presence of endogenous factors.

Valproic acid is an anticonvulsant that is strongly bound to serum albumin. The nonsteroidal antiinflammatory drugs mefenamic acid and fenoprofen are also strongly bound to albumin. We observed significant displacement of valproic acid from protein binding by mefenamic acid and fenoprofen at both therapeutic and slightly above therapeutic concentrations. The concentration of free valproic acid was higher in the uremic serum, as expected, but we observed no further displacement of valproic acid in the presence of mefenamic acid and fenoprofen. Known uremic compounds, hippuric acid and indoxyl sulfate, did not inhibit the interactions between valproic acid and mefenamic acid or fenoprofen. Treatment of uremic serum with activated charcoal at pH 3.0 removes endogenous interfering factors and corrects the binding defect of uremic serum for valproic acid. We observed significant displacement of valproic acid from protein binding by both mefenamic acid and fenoprofen in uremic serum after charcoal treatment. We conclude that endogenous factors are present in uremic sera that block interaction of valproic acid with mefenamic acid and fenoprofen.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1996

Hemodialysis and hemoperfusion for treatment of valproic acid and gabapentin poisoning.

A 31-y-old epileptic man developed coma and shock after suicidally ingesting large amounts of valproic acid and gabapentin. His peak valproic acid, level was 1306.9 micrograms/mL (therapeutic range = 30-100 micrograms/mL). His peak gabapentin level was 60.0 micrograms/mL (therapeutic range = 2.0-8.0 micrograms/mL). His hypotension was refractory to crystalloid and pressor infusions, but resolved during concurrent hemoperfusion and hemodialysis to enhance elimination of valproic acid. Concurrent hemoperfusion and hemodialysis, in series, produced a maximum valproic acid plasma clearance of 55.4 mL/min versus a maximum reported intrinsic valproic acid plasma clearance of 10.6 mL/min. concurrent hemoperfusion and hemodialysis, in series, should be considered in hemodynamically unstable patients with valproic acid poisoning whose clinical condition is worsening in spite of aggressive supportive care.

Acetates↗

PubMed1985

Discriminative stimulus properties of valproic acid in the pigeon.

Pigeons were successfully trained to discriminate 60 mg/kg valproic acid from saline using a two-key drug discrimination procedure. When 5-80 mg/kg doses of valproic acid were administered during generalization tests the percentage of responses directed to the valproic acid-appropriate key varied directly with dose. The effects of administering the training dose of valproic acid at presession injection intervals ranging from 15 to 120 min were described by an inverted U-shaped function; the 30-min interval used during discrimination training engendered the largest percentage of valproic acid-appropriate responses. The discriminative stimulus properties of valproic acid failed to generalize to the anticonvulsant compounds phenobarbital (10, 20 mg/kg), phenytoin (2.5, 5 mg/kg), and ethosuximide (40, 80 mg/kg), indicating that not all anticonvulsant compounds share similar discriminative properties. Clonazepam (0.25, 0.50 mg/kg) and diazepam (1, 2 mg/kg), two benzodiazepines with anticonvulsant properties, produced quite different effects. The stimulus properties of valproic acid generalized to all doses of clonazepam, whereas intermediate generalization was evident with diazepam. Pentylenetetrazol (10, 20 mg/kg), chlorpromazine (5, 10 mg/kg), tripelennamine (2.5, 5.0 mg/kg), d-amphetamine (0.5, 1.0 mg/kg), morphine (1.25, 2.50 mg/kg), and imipramine (2.5, 5.0 mg/kg) induced only saline-like patterns of responding. The concomitant administration of pentylenetetrazol failed to antagonize the discriminative stimulus properties exerted by the training dose of valproic acid.

Animals↗

PubMed1998

Valproic acid use in psychiatry: issues in treating women of reproductive age.

Valproic acid, a well known anticonvulsant, is being used by psychiatrists increasingly to manage bipolar and other affective disorders. Because of the demographics of the population affected by such psychiatric conditions, more women of childbearing age are likely to be exposed to this teratogenic drug. Neural tube defects (NTD) are the most common of the major anomalies associated with in utero valproic acid exposure, and are estimated to occur in 1% to 2% of exposed fetuses. Other teratogenic effects include facial dysmorphism, congenital cardiac defects, limb reduction defects and other skeletal anomalies. Prenatal diagnosis, in particular maternal serum alpha-fetoprotein screening and targeted ultrasonography, should be offered to all pregnant women exposed to valproic acid and couples need to be aware of the prenatal diagnostic options available to them. Periconceptual prophylaxis with high doses of folic acid is recommended for all women on valproic acid and counselling should also emphasize planning pregnancy to optimize folic acid supplementation. Psychiatrists should be aware of the teratogenic potential of valproic acid and know how to counsel their patients of reproductive age.

Adult↗

PubMed1996

Characterization of thiol-conjugated metabolites of 2-propylpent-4-enoic acid (4-ene VPA), a toxic metabolite of valproic acid, by electrospray tandem mass spectrometry.

The hepatotoxicity of the anticonvulsant drug valproic acid (VPA) is most likely associated with the bioactivation of its metabolite 2-propylpent-4-enoic acid (4-ene VPA), which is known to induce hepatic microvesicular steatosis in rats. This paper presents an on-line liquid chromatographic/tandem mass spectrometric (LC/MS/MS) identification of new glutathione (GSH)-related conjugates of the reactive metabolites of 4-ene VPA. Bile samples collected from male Sprague-Dawley rats dosed intraperitoneally with 4-ene VPA or its [2H7]-analogue (100 mg kg-1) were injected on to an ODS column interfaced to a LC/MS/MS instrument using electrospray ionization. LC was developed such that no overlapping of peaks occurred among those metabolites which may potentially produce common fragment ions of interest. Subsequent comparison of LC retention times and MS/MS full fragment ion spectra generated for putative metabolites with that of authentic reference compounds made available by chemical synthesis confirmed the presence of the GSH, cysteinylglycine, cysteine and N-acetylcysteine (NAC) conjugates of 2-(2'-carboxypentanyl)oxirane (4,5-epoxy VPA) and (E)-2-propylpenta-2,4-dienoic acid ((E)-2,4-diene VPA), respectively. Quantitatively, the biliary thiol conjugates accounted for 5% of the dose. This observation is novel for 4-ene VPA metabolism in terms of the degradation of GSH conjugates to the corresponding mercapturic acids possibly occurring within the liver as opposed to an inter-organ process which involves the kidney. In addition, the GSH- and NAC-glucuronide di-conjugates of (E)-2,4-diene VPA were also identified as the biliary metabolites with the GSH-glucuronide di-conjugate being 10% of the corresponding mono-GSH conjugate. Taken together, these data clearly indicate that reactive metabolites of VPA can react with hepatic GSH via several different metabolic pathways and may subsequently produce depletion of GSH that leads to toxic consequences.

Animals↗

PubMed1999

Valproic acid toxicokinetics: serial hemodialysis and hemoperfusion.

The toxicity and pharmacokinetic properties of a drug determine whether hemodialysis and/or hemoperfusion are indicated in acute intoxications. Valproic acid is considered unremovable by hemodialysis because of the high protein binding of 90%-95%. A 27-year-old male with a history of seizures was admitted to the emergency room because of coma, hypernatriemia, and respiratory failure caused by an intoxication with a large dose of valproic acid. At admission, the plasma valproic acid level was 1414 mg/L (9.9 mmol/L) (therapeutic range: 50-100 mg/L (350-700 micromol/ L). The anion gap was 26 mmol/L (normal <12-14 mmol/L) and corresponded fairly well with this valproic acid level. Because of the potential toxicity of this high valproic acid level serial hemodialysis and hemoperfusion was performed. The first session was done with a charcoal column and the second session with a resin column. The patient recovered during the course of treatment. The valproic acid plasma clearances during treatment were: 80 mL/min (hemodialysis); 40 mL/min (hemoperfusion by charcoal) and 80 mL/min (hemoperfusion by resin, only in the first hour). The protein binding of valproic acid in plasma was only 32% at the start and was 54% at the end of the two sessions. In this specific case of a severe valproic acid intoxication, saturated protein binding resulted in an increased fraction of unbound valproic acid. This made hemodialysis an effective treatment, while hemoperfusion was relatively less effective because of saturation of the column. In conclusion, the toxicokinetics of valproate are quite different from the pharmacokinetics at therapeutic levels. The anion gap and protein binding are important parameters in toxicokinetics.

Adult↗

PubMed1997

Acute effects of bromocriptine, cyproheptadine, and valproic acid on plasma adrenocorticotropin secretion in Nelson's syndrome.

Previous studies have found that bromocriptine, cyproheptadine, and valproic acid can reduce ACTH secretion in Nelson's syndrome, but none of these agents has achieved widespread use due to their failure to normalize ACTH in most patients. The current study was undertaken to determine whether these three agents, which act through different mechanisms, decrease plasma ACTH synergistically when administered together. Six adult female patients (mean age, 41 yr) with Nelson's syndrome were studied. ACTH was measured every 20 min for 8 h, 2 h before and 6 h after each of the following six treatments: placebo, bromocriptine (2.5 mg), cyproheptadine (8 mg), valproic acid (1 g), cyproheptadine plus valproic acid, and the combination of all three drugs. The sequence of treatments was determined randomly, and there was an interval of at least 2 days between each treatment. The hourly ACTH values were averaged, and the percent maximal suppression of plasma ACTH, relative to the baseline values before drug administration, was compared among the six treatments. Basal plasma ACTH levels in the six patients ranged from 40-3324 pmol/L (normal range, 1-8). The percent maximal suppression of ACTH after administration of placebo (6 +/- 11%), cyproheptadine (17 +/- 15%), valproic acid (37 +/- 10%) or the combination of cyproheptadine and valproic acid (19 +/- 14%) did not achieve statistical significance. Bromocriptine, on the other hand, caused a significant decrease in plasma ACTH (52 +/- 8%; P < 0.05), as did the combination of bromocriptine, cyproheptadine, and valproic acid (58 +/- 12%; P < 0.05). However, the combined effect of the three drugs did not significantly exceed the effect of bromocriptine alone. We conclude that at the doses studied, bromocriptine had the greatest acute effect in suppressing ACTH secretion in Nelson's syndrome, and that combined administration with valproic acid and cyproheptadine did not further increase this acute ACTH-suppressive effect.

Adrenocorticotropic Hormone↗

PubMed1996

Delayed peak serum valproic acid in massive divalproex overdose--treatment with charcoal hemoperfusion.

BACKGROUND: Increased clearance and apparent clinical improvement in valproic acid overdose has been reported following in-series hemodialysis/hemoperfusion therapy. We report a case of divalproex sodium and chlorpheniramine overdose treated with charcoal hemoperfusion and multiple-dose activated charcoal. CASE REPORT: A 32-year-old female presented alert three hours postingestion of her own medication. Serum valproic acid was 105 micrograms/mL. No anticholinergic toxicity was seen. Despite three doses of activated charcoal over 14 hours, serum valproic acid continued to rise. Whole bowel irrigation and multiple-dose activated charcoal were commenced 17 h postingestion when serum valproic acid was 1380 micrograms/mL. Charcoal hemoperfusion was instituted three hours later when serum valproic acid had not fallen and the patient remained obtunded. RESULTS: Initial extraction ratio of the hemoperfusion cartridge was 0.54 with plasma clearance of 54.5 mL/min. Valproic acid elimination half-life was 3 h during the 190 min hemoperfusion cycle. Posthemoperfusion elimination half-life was 4.8 h with continued multiple-dose activated charcoal dosing. The clinical condition improved during hemoperfusion. CONCLUSION: Enteric coated valproic acid preparations may cause delayed toxicity in overdose, particularly with coingested anticholinergic medications. In our case, charcoal hemoperfusion appeared to increase valproic acid clearance.

Adult↗

PubMed2006

Synergistic effects of valproic acid and mitomycin C in adenocarcinoma cell lines and fresh tumor cells of patients with colon cancer.

Valproic acid has been demonstrated to mediate cytotoxic effects against tumor cells by acting as a histone-deacetylase inhibitor. However, to date, there are only limited data on the effects of valproic acid in colon cancer. Moreover, information regarding combinations of the drug with chemotherapeutic agents is very limited. The latter is of interest as there is increasing evidence for synergism between so-called "molecular targeting drugs" and chemotherapy. We first demonstrated that valproic acid dose-dependently reduced the viability of adenocarcimona cell lines. After co-incubation with a variety of chemotherapeutic agents, only valproic acid in combination with mitomycin C consistently induced synergistic growth inhibition in all cell lines. To confirm these results in an ex vivo situation, five samples of fresh colon cancer cells were studied. Again, the effect of valproic acid on the viability of the fresh tumor cells was dose dependent. In four of five samples of freshly isolated colon cancer cells, the synergistic effect of valproic acid and mitomycin C on the inhibition of cell growth was confirmed by calculation of the combination index by multiple drug effect analysis. In conclusion, this is the first demonstration that valproic acid as a model substance for histone-deacetylase inhibitors is effective in tumor cells freshly isolated from patients with colon cancer and that the combination of mitomycin C and valproic acid synergistically decreases viability of colon cancer cells.

Adenocarcinoma↗