Synthesis and pharmacological activity of two derivatives of the amide of valproic acid

Valproic acid (VPA), a synthetic branched-chain fatty acid, and its pro-drug the primary amide (VPD) are effective and widely used anti-epileptic agents. Although the use of VPA has grown in recent years, major side effects are still associated with this drug. We presume that it is possible, without loosing the VPD pharmacological profile, to obtain new compounds by undertaking substitutions in the CONH group. N,N'-bis-(2-propylpentanoyl)- 1,2-ethanediamine (3) and N,N'-bis-(2-propylpentanoyl)-1,3-propanediamine (4) were obtained from VPA (1) using a method reported in the literature. The chemical structures of the new compounds were demonstrated by elemental analysis, IR, and 1H NMR spectroscopy. Both compounds are less toxic and more effective in protecting the animals from death caused by PTZ than VPD after intraperitoneal administration to mice.     

Reversible dementia due to valproic acid therapy

A progressive dementia syndrome (DSM IV) with frontal-subcortical features developed in a 72-year-old woman during valproate therapy (Depakine). Discontinuation of valproate resulted in complete recovery. Drugs are a common cause of reversible dementia. The association of dementia with valproate therapy is rare. Features of a subcortical dementia are indicative of a reversible cause. In addition, the possible role of drugs should always be considered in patients with cognitive decline.     

Hemodialysis and hemoperfusion for treatment of valproic acid and gabapentin poisoning

OBJECTIVES: Genotoxic risk was evaluated for spray painters possibly exposed to polyester resins and acrylic enamel-based paints in automotive body repair shops. METHODS: DNA (deoxyribonucleic acid) strand breaks and alkali-labile sites were measured in peripheral mononuclear blood cells ex vivo using the alkaline elution method. Samples of venous blood were taken on Monday after a free weekend and again on Friday from 38 male and 1 female spray painters and compared with the blood samples from 36 male and 3 female referents. The elution rate of each DNA sample was standardized by dividing it by the elution rate obtained from simultaneously sampled untreated Chinese hamster V79 cells. RESULTS: The spray painters showed a significantly (P < 0.001) higher mean level of strand breaks and alkali-labile sites in the Friday samples [2.05 (SE 0.17)] compared with the Monday samples [1.38 (SE 0.07)]. The Monday results of the spray painters were not distinguishable from the referents' [1.41 (SE 0.10)]. The increase in DNA damage was numerically higher, but only weakly significant (use of masks, P < 0.05) or nonsignificant (use of spray booths), when fewer safety provisions were taken. CONCLUSIONS: A significant increase in DNA strand breaks and alkali-labile sites was found in spray painters after a week's work. However, DNA damage seems to be reversible. The use of modern safety equipment seems to affect DNA damage only marginally. There is an urgent need to identify the genotoxic chemicals in the occupational environment of spray painters and to develop corresponding satisfactory safety measures.     

Impaired fatty acid oxidation in children on valproic acid and the effect of L-carnitine

Fatty acid oxidation was studied in 12 patients (aged 3 to 19 years) receiving valproic acid (VPA), predominantly as monotherapy, before and after 1 month of L-carnitine supplementation (50 mg/kg/day po) in order to determine whether L-carnitine plays a role in preventing the hepatotoxic effects of this drug. Five of these patients were also studied prior to VPA treatment. Only one patient taking VPA had an abnormally low plasma free carnitine. Acyl-/free carnitine ratios were elevated in five patients on VPA and normalized after L-carnitine supplementation. Mean plasma concentrations of free fatty acids, beta-OH-butyrate, and cumulative excretion of 13CO2 after administration of 1-13C-octanoic acid were not changed by VPA or L-carnitine treatment. Urinary dicarboxylic acids, acylglycines, and octanoylcarnitine were elevated during VPA therapy and unaltered by L-carnitine. These results suggest that, in patients at low risk for VPA-induced hepatotoxicity (patients aged > 2 years and taking VPA as monotherapy), VPA causes metabolic abnormalities resembling those found in inborn errors of mitochondrial beta-oxidation which are not corrected by L-carnitine.     

High-dose versus low-dose valproic acid as a prophylactic medication

Valproic acid has been shown to be effective in migraine prophylaxis. Its method of action is believed to be the inhibition of gamma-aminobutyric acid transaminase. The therapeutic dose needed to prevent migraine headaches has been examined in several studies, yet the optimum dose has not been found. In this case report, valproic acid was given to a 24-year-old woman with chronic headaches at 1000 mg per day. Her headaches resolved for 2 months. She tapered herself off of the medication, and her headaches returned. She was restarted at 500 mg per day of valproic acid and again, her headaches resolved. She preferred being on the lower dose which she found as effective as the higher dose. Her case makes two interesting points. The first is that lower dosages of valproic acid may be as effective as higher ones in headache prophylaxis. The second is that more studies looking at dose ranges are needed to correlate effectiveness with daily requirements.     

Mechanism of valproic acid uptake by isolated rat brain microvessels

In an effort to characterize putative transport systems of valproic acid (VPA) at the blood-brain barrier, the effects of various substrates and inhibitors of known anion transporters on the equilibrium vessel-to-medium concentration (vessel/medium) ratio of VPA were investigated using isolated rat brain microvessels. The equilibrium vessel/medium ratio of VPA was decreased by the presence of high millimolar concentration of unlabeled VPA, indicating that a saturable transport system was involved in VPA transport from medium to microvessels. Short-chain monocarboxylates such as propionic acid, pyruvic acid, and L-lactic acid did not alter the vessel/medium ratio, whereas medium-chain fatty acids and unsaturated metabolites of VPA significantly inhibited the net transport of VPA. Dicarboxylates, tricarboxylate, and p-aminohippuric acid did not affect VPA accumulation in the brain microvessels. Several anionic drugs including salicylic acid, penicillin G, cefazolin, and probenecid significantly reduced the vessel/medium ratio of VPA. In addition, disulfonate inhibitors of inorganic anion exchangers, SH-group modifying reagent, and metabolic inhibitor showed remarkable inhibitory effects on the net transport of VPA between brain microvessels and medium. These results suggest that VPA may be actively transported through the antiluminal membrane via a carrier-mediated system shared by other anionic drugs.     

No evidence for inhibition of human glutathione reductase by valproic acid

The human red blood cell enzyme glutathione reductase (GR) was reported to be inhibited by the anticonvulsant drug valproic acid (VPA) [Cotariu et al., Biochem Pharmacol 43: 425-429, 1992]. When attempting to reproduce and extend these experiments, we could not detect any significant effect of VPA on glutathione reductase in haemolysates from 20 healthy children and 10 children under VPA therapy, no matter which concentration of the drug (0.9 or 1.8 mM in a haemolysate diluted by a factor of 50 or 1.8 mM directly in the assay), which incubation time (0-60 min) and which assay system were chosen. An influence of VPA on FAD-free apoglutathione reductase was also excluded. GR-activities of 10 children under VPA therapy (1.08 +/- 0.14 U/mL blood or 7.57 +/- 0.94 U/g Hb) were almost identical with the activities of age- and sex-matched controls (1.04 +/- 0.17 U/mL or 7.79 +/- 1.32 U/g Hb). No correlation between erythrocyte GR activity and serum levels of VPA was observed. Finally, incubation of crystalline human GR with VPA did not lead to enzyme inhibition; rather, in most experiments the enzyme was stabilized by incubation with VPA. Possible explanations for the discrepancies between the results of Cotariu et al. and our data are discussed.     

Multiorgan dysfunction and disseminated intravascular coagulation in children receiving lamotrigine and valproic acid

Two children developed multiorgan dysfunction with disseminated intravascular coagulation 9 days after lamotrigine was added to their antiepileptic therapy, which included valproic acid. During the episodes, rhabdomyolysis was detected in one of them, while being seizure-free, suggesting that this adverse reaction may involve muscular tissue.     

Falsely elevated enzyme-multiplied immunoassay serum valproic acid results in 12 patients

A split sample study of 69 patients' serum for valproic acid analysis by enzyme-multiplied immunoassay technique (EMIT) and by gas-liquid chromatography revealed falsely elevated EMIT values in 12 patients. Of the 69 serum samples, 28 were also assayed by fluorescence polarization immunoassay and all results agreed with those of gas-liquid chromatography. Five of the 12 patients with elevated EMIT values were included in this subgroup. The unidentified interfering substance appears to be a heat-labile, high-molecular-weight compound, possibly a protein complex that can persist in blood for several months following discontinuation of the drug.     

Substitution of immediate-release valproic acid for divalproex sodium for adult psychiatric inpatients

In a prospective open-label study, the substitution of immediate-release valproic acid for divalproex sodium was evaluated in the treatment of 47 adult psychiatric inpatients who had been stabilized on divalproex for at least one month. After two weeks, no significant change in Clinical Global Impressions scale (CGI) scores or in seizure frequency occurred, and serum valproate concentrations decreased by 14.4 percent (p=.001). One patient was restarted on divalproex because of gastrointestinal complaints. Among the 19 patients remaining hospitalized at six months, mean CGI scores did not significantly change. Costs were reduced 83 percent; annual savings per patient was approximately $905. These preliminary results suggest that many chronic psychiatric inpatients stabilized on divalproex may be safely switched to valproic acid.     

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.     

纳米锰方硼石的合成与结构性能表征

通过溶胶?凝胶（Sol?Gel）法成功合成了纳米锰方硼石并对其进行了稀土Eu3+掺杂。使用X射线衍射、透射电子显微镜和高分辨透射电子显微镜等表征了锰方硼石晶体结构,并通过荧光光谱测试对其发光性能进行了研究。结果表明:合成纳米锰方硼石为粒径小于50 nm的球状颗粒,与天然锰方硼石的物相结构相同,属于斜方晶系,与尖晶石类似,（010）晶面的晶面间距为0.8565 nm。在490 nm激发光激发下,天然锰方硼石、合成锰方硼石和稀土Eu3+掺杂锰方硼石晶体中的Mn2+发光,其中发绿光的Mn2+在晶体中占据四面体格位中心,发红光的Mn2+在晶体占据八面体格位中心。合成的锰方硼石随激发波长变长,产生发射光谱的红移现象,有利于实现冷暖发光转换;在稀土Eu3+掺杂的纳米锰方硼石光谱的发光强度得到了提升。      

Synthesis, characterization and enhanced luminescence of terbium complexes with 2-pyrazinecarboxylic acid and butanedioic acid by inert-fluorescent lanthanide ions

Ten solid terbium complexes with 2-pyrazinecarboxylic acid (Hpyca) and butanedioic acid (BDAH) were synthesized via coprecipitation method and characterized by elemental, EDTA titration, inductively coupled plasma (ICP), thermogravimetry-differential scanning calorimetry (TG-DSC) and infrared (IR) analyses. The results showed that the complexes had the compositions of Tb(pyca)(BDA)·2H2O, Tb0.5Y0.5(pyca)(BDA)·2H2O, Tb0.5La0.5(pyca)(BDA)·3H2O, Tb0.5Gd0.5(pyca)(BDA)·2H2O, Tb0.7Y0.3(pyca)(BDA)·3H2O, Tb0.7La0.3(pyca)(BDA)·0.5H2O, Tb0.7Gd0.3(pyca)(BDA)·H2O, Tb0.6Y0.4(pyca)(BDA)·2.5H2O, Tb0.6La0.4 (pyca)(BDA)·2.5H2O and Tb0.6Gd0.4(pyca)(BDA)·3H2O. IR spectra indicated that the rare earth ions coordinated with the carboxylic oxygen atoms of Hpyca and BDAH. Luminescence spectra showed that the doped La3+, Y3+ or Gd3+ ions did not affect the luminescence emission peak positions, but remarkably increased the luminescent intensities of terbium complexes. Furthermore, the doped lanthanide complexes showed longer luminescence lifetimes and higher quantum yields than pure terbium complex. The enhanced luminescence efficiencies of Tb3+ ions in the doped complexes might result from the antenna effect of the two carboxylate ligands as well as the decrease of the self-quench of the Tb3+ ions induced by the doped lanthanide ions.     

Synthesis, characterization, and biological properties of nano-rare earth complexes with L-glutamic acid and imidazole

Four nano-rare earth ternary complexes of L-glutamic acid and imidazole RE（Glu）3ImCl3·3H2O （RE=Ce^3＋, Pr^3＋, Sm^3＋, Dy^3＋, Glu= L-glutamic acid, and Im=imidazole） were synthesized. Their composition was characterized with elemental analysis, IR, and molar conductance. The TEM image indicated that the complexes were regular shaped and the length was about 30-60 nm. The antibacterial activity test showed that all these complexes exhibited better antibacterial ability against Escherichia coli, Staphylociccus aureus, and Candida albican （MIC were about 180, 100, and 310 μg/mi, respectively） and could be considered as broad-spectral antimicrobial. Their antitumor activity in vitro against leukemia K562 cells was measured using the MTr method. The results indicate that the four complexes possess strong inhibi- tion effect on leukemia K562 cells. An approximately linear relationship is discovered between the relative inhibition rate and concentration, with the correlation coefficients R〉0.7 and P〈0.05, which is considered statistically significant.     

Inhibition of carnitine biosynthesis by valproic acid in rats--the biochemical mechanism of inhibition

The anticonvulsive drug, valproic acid (VPA), inhibits the biosynthesis of carnitine, and may contribute in this way to carnitine deficiency associated with VPA therapy. The conversion of [3H]-butyrobetaine into [3H]-carnitine was determined 60 min following a single intraperitoneal (i.p.) dose of 1.2 mmol/kg VPA in rats. The fraction of radioactivity found in [3H]-carnitine in the liver decreased from 63.2 +/- 1.50% to 39.2 +/- 1.11% (mean +/- SEM). Total carnitine in the liver also decreased, whereas the precursor butyrobetaine increased from 5.01 +/- 0.71 nmol/g to 8.22 +/- 0.82 nmol/g (mean +/- SEM). VPA also exhibited a dramatic effect on the conversion of an unlabeled loading amount of butyrobetaine. The increment in total carnitine caused by butyrobetaine in liver was reduced from 161 +/- 15.4 nmol/g to 53.2 +/- 5.11 nmol/g (mean +/- SEM). These data prove that VPA reduces the flux through butyrobetaine hydroxylase (EC 1.14.11.1.). The drug in vitro, however, did not inhibit the enzyme directly. Searching for the mechanism of action, we found that VPA decreased the level of alpha-ketoglutarate (alpha-KG; a cofactor of butyrobetaine hydroxylase) from 73.5 +/- 2.90 nmol/g to 52.9 +/- 2.2 nmol/g (mean +/- SEM) in the liver. The level of 1-glutamate showed a rather dramatic decrease in the liver. Moreover, alpha-KG proved to have a protective role against VPA in the [3H]-butyrobetaine conversion experiment.     

Paradoxical response to valproic acid in a patient with a hypothalamic hamartoma

We investigated factors of daytime sleepiness in 22 middle-aged male patients with sleep apnea syndrome (SAS) using the Epworth sleepiness scale (ESS) and polysomnography. The subjects were classified into two groups according to ESS score as follows; low ESS group: ESS score < 10, and high ESS group; ESS score > or = 10. ESS score was significantly correlated with duration in which nocturnal oxygen saturation decreased below 90% (Time of SpO2 < 90%) (r = 0.54, p < 0.05). Time of SpO2 < 90% and percent of movement arousals at the termination of apnea/hypopnea (number of movement arousal/total number of apnea/hypopneas x 100) were significantly higher in high ESS group than in low ESS group. Our findings suggest that the severity of oxygen desaturation and sleep fragmentation caused by arousal response at the termination of apnea/hypopnea may be important factors of daytime sleepiness in patients with SAS.