HYPERAMMONAEMIA AND COGNITIVE IMPAIRMENT IN EPILEPSY PATIENTS TREATED WITH VALPROIC ACID - PRELIMINARY STUDY

OBJECTIVE

The aim: To determine whether VPA pharmacotherapy, mainly in the group of patients using subtherapeutic doses of VPA, could contribute to the occurrence of cognitive impairment.

PATIENTS AND METHODS

Materials and methods: The study involved 14 patients: six women and eight men, aged 24 - 77 years (mean SD ± - 52.36±13.71) diagnosed with epilepsy in accordance with the ILAE criteria (International League Against Epilepsy), in whom the main clinical complaint, in addition to poor control of epileptic seizures, were impaired concentration, attention and memory impairment.

RESULTS

Results: Mild cognitive impairment - MCI was diagnosed in 4 patients (28.57%) (3 with elevated ammonia levels, 1 without), in 1 patient (7.14%) there was a mild level of dementia. In only one MCI case, elevated serum concentrations of valproic acid were also recorded. It is very important to highlight that cognitive impairment has never been diagnosed before (prior to VPA therapy) in this group. Of these 5 patients, in four cases, after discontinuation of the drug, an improvement in the clinical condition was achieved. In a patient with mild level dementia, the termination of therapy did not give a similar effect. This proves the possibility of other mechanisms responsible for generating these sometimes irreversible disorders.

CONCLUSION

Conclusions: Regardless of the dose and concentration of ammonia in blood serum of patients diagnosed with epilepsy, VPA therapy may cause various, significant dysfunctions that significantly impair quality of life.

Valproate-associated hyperammonemic encephalopathy in subarachnoid hemorrhage: a diagnosis to consider

Objective: Subarachnoid hemorrhage is a prevalent disease with high morbidity and mortality. Numerous complications contribute to brain injury and defy the clinical practitioner on diagnosis and management. Valproate-associated hyperammonemic encephalopathy is a rare, underdiagnosed, serious and important entity to consider. We present a case of a patient with subarachnoid hemorrhage who received anticonvulsant prophylaxis with valproate and developed neuroworsening associated with high levels of ammoniemia and periodic discharge electroencephalographic patterns without other identifiable causes. Discontinuing valproic acid treatment and normalization of ammoniemia resulted in improvement in clinical and electroencephalographic neurological status.

[Hyperammonemic encephalopathy after treatment with modified FOLFOX6 regimen for recurrent gastric cancer:a case report]

A 64-year-old female received modified FOLFOX6 therapy with continuous administration of a high concentration of 5-fluorouracil (5-FU) for recurrence of peritoneal dissemination after total gastrectomy. Twenty-nine hours after the administration, there was the sudden onset of altered consciousness and hepatic dysfunction accompanied by hyperammonemia. The consciousness and hepatic function improved the following day after treatment with branched-chain amino acid formulation, lactulose, fresh frozen plasma, and continuous hemodiafiltration. Thus, the diagnosis was 5-FU-induced hyperammonemia. Improvement of dehydration and renal dysfunction would be important for avoiding the risk of developing the side effects. Because recurrent gastric cancer is often a progressive condition, post-treatment might be promptly transferred to the other posterior regimen without 5-FU as required.

[Successful Control of Hyperammonemia with BRTO of a Splenorenal Shunt Induced by CAPOX Therapy]

Among portosystemic shunts, splenorenal shunts can cause increased portal pressure, which in turn can bring about hyperammonemia, resulting in hepatic encephalopathy. In recent years, it has been reported that oxaliplatin(OX), a key chemotherapy drug in colorectal cancer, can precipitate splenorenal shunts due to sinusoidal injury. We report a case of hyperammonemia post oxaliplatin therapy. A 72-year-old male patient who had undergone surgical resection for(RS)rectal cancer with hepatic metastasis had been receiving capecitabine plus OX(CAPOX)as adjuvant chemotherapy. During his 7th course of treatment, he visited the outpatient clinic with complaints of weakness, dysarthria, and urinary incontinence. Laboratory findings showed an elevated NH3 level (200 μg/dL), and subsequent abdominal computed tomography revealed a splenorenal shunt, which was attributed to OX. Balloon-occluded retrograde transvenous obliteration(BRTO)was then performed. The patient has been routinely followed up in the outpatient clinic and has had no recurrence of hyperammonemia or cancer 14 months after the procedure. In retrospect, the splenorenal shunt was present on his first visit, therefore, hyperammonemia could have been prevented at the time of commencement of chemotherapy. We report our case, along with the relevant literature.

[A Case of Severe Hyperammonemic Encephalopathy in a Dialysis Patient Following mFOLFOX6 Therapy]

A 69-year-old man on hemodialysis for chronic renal failure was diagnosed with ascending colon cancer, and received surgical resection. Multiple liver metastases were detected after surgery. He was administered modified FOLFOX6 therapy (reducing the dose to 50%), and showed severe disturbance of consciousness due to hyperammonemia on treatment day 6. After treatment with daily hemodialysis, branched-chain amino acid solutions, lactulose and rifaximin, his conscious level improved on day 9. Intensive chemotherapy in dialysis patients should be carefully performed considering the serious adverse events including hyperammonemia.

Ammonia level as a proxy of asparaginase inactivation in children: A strategy for classification of infusion reactions

INTRODUCTION

Allergic hypersensitivity reactions related to enzyme asparaginase may occur during intravenous infusion of drugs and other adverse reactions (non-allergic hypersensitivity and hyperammonemia), which do not require discontinuation of therapy as the first case. It makes differential diagnoses between infusion reactions essential to assure the team regarding the right decision to make after the adverse event. This study evaluated a pharmacovigilance strategy of differentiating infusion reactions to asparaginase in pediatric patients, based on the measurement of serum ammonia and the classification of the reactions by clinical symptoms and severity.

METHODOLOGY

We included children, diagnosed with ALL, and treated with native Escherichia coli asparaginase in a university hospital. The professional team monitored and evaluated all asparaginase infusions for continuity of treatment (rechallenge), seeing the measurement of serum ammonia and classification of reactions for type and severity grade. Data from this monitoring was collected retrospectively. Chi-square and Mann-Whitney tests were used to compare the ratios between serum ammonia concentration posterior and before asparaginase infusion.

RESULTS

245 infusions in 32 patients were monitored, and 19 reactions were observed in 17 children (53%). Three children have hyperammonemia and continue their treatment. The variation of the serum ammonia levels before and after the infusion was statistically significant, comparing the groups with no reaction or hyperammonemia versus the group with the hypersensitivity reaction.

CONCLUSION

The pharmacovigilance strategy applied in the hospital investigated was a useful and inexpensive tool that supported clinical decision-making and enabled the maintenance of asparaginase therapy for three (9,4%) patients followed up.

Sunitinib-associated hyperammonemic encephalopathy successfully managed with higher intensity conventional hemodialysis: A case report

RATIONALE

Hyperammonemia encephalopathy is a rare but severe complication that has been reported in association with the use of sunitinib, a tyrosine kinase inhibitor. We report here a unique case of a patient with end stage renal disease that was initiated on sunitinib for metastatic renal cell carcinoma.

PATIENT CONCERNS

A 65-year-old man with end stage renal disease on maintenance conventional hemodialysis and had concomitant stable Child-Pugh class B liver cirrhosis consequent of hepatitis C infection was started on sunitinib for metastatic renal cell carcinoma. He developed confusion few weeks after starting therapy with no other indication of worsening liver dysfunction otherwise.

DIAGNOSIS

He was later diagnosed with hyperammonemia encephalopathy.

INTERVENTIONS

His treatment was discontinued and reinitiated at a lower dose after recovery and titrated according to tolerance. As ammonia is a very low molecular weight molecule and is cleared well with diffusive clearance, we intensified his dialysis regimen by increasing intensity for each session and frequency per week.

OUTCOMES

With this change in dialysis regimen, patient was able to continue treatment with sunitinib.

LESSONS

Clinicians prescribing sunitinib should be vigilant to monitor for this complication in patients receiving sunitinib, apart from the more usual presentation of hepatotoxicity. We found that a more intensive hemodialysis regimen consisting of 4× a week conventional high-flux hemodialysis (HD) can permit the continuation of treatment with sunitinib in an end stage renal disease (ESRD) patient with Child-Pugh class B liver cirrhosis.

[A Case of Metastatic Colorectal Cancer with Hyperammonemic Encephalopathy Induced by mFOLFOX6 and SOX Therapy]

A 77-year-old man was given a diagnosis of pT4aN0M1a(PUL2), stage Ⅳ, RAS mutant type, after the operation for advanced ascending colon cancer. He was administered mFOLFOX6 plus Bmab as first-line chemotherapy. He showed consciousness disturbance on the 2nd day during the 6 cycles. Because of head computed tomography and magnetic resonance imaging showing no abnormal findings, we diagnosed convulsive seizure. His consciousness level gradually improved after intravenous infusion. He showed consciousness disturbance on the 2nd day during the 7 cycles again. Because blood ammonia level were high at 400μg/dL, he was diagnosed as hyperammonemic encephalopathy. His consciousness level rapidly recovered after branched chain amino acid(BCAA)infusion. SOX plus Bmab therapy was started as a post-treatment, he developed hyperammonemia(NH3 288μg/dL)again, on the 4th day during the 3 cycles. After taking of oral administration of BCAA and lactulose, the recurrence of hyperammonemic encephalopathy was not found. Therefore, 3 cycles of SOX plus Bmab therapy and 12 cycles of IRIS plus Bmab therapy were administered.

[A Case of Disturbance of Consciousness Due to Hyperammonemia during Chemotherapy for Metastasis of Sigmoid Colon Cancer]

A 76-year-old woman had underwent 5-fluorouracil(5-FU), oxaliplatin(L-OHP)combination therapy(mFOLFOX6)as first-line chemotherapy for peritoneal recurrence after resection of sigmoid colon cancer. She showed severe general fatigue and disturbance of consciousness on the second day of the 12th course of chemotherapy. Computed tomography of the head detected no abnormal findings in the central nervous system. The laboratory results revealed a marked hyperammonemia. She was diagnosed as a disturbance of consciousness due to hyperammonemia and treated her with branched- chain amino acid solution. Then the disturbance of consciousness resolved on the following day. After changing the regimen of chemotherapy, the disturbance of consciousness was not found. Recently, it has been reported that high-dose 5-FU regimen such as mFOLFOX6 causes hyperammonemia as a rare adverse event. We should take hyperammonemia into account when disturbance of consciousness occurs during high-dose 5-FU chemotherapy.

[Hyperammonemia with Disturbance of Consciousness during 5-FU plus Nedaplatin Therapy for Esophageal Cancer-A Case Report]

Hyperammonemia is a rare adverse event of 5-FU. Here, we report a case of hyperammonemia with disturbance of consciousness during 5-FU plus nedaplatin therapy for esophageal cancer and present a literature review. A 69-year-old man was diagnosed with cT2N2M0, cStage Ⅲ esophageal cancer. He was administered with DCF therapy as the first-line neoadjuvant chemotherapy. After the first course, he showed renal dysfunction. Therefore, as the second-line neoadjuvant chemotherapy, he was administered with 5-FU plus nedaplatin. He vomited on treatment day 5 and suddenly presented with disturbance of consciousness on treatment day 6. Blood tests showed hyperammonemia(114 μg/dL). He was treated with rehydration and branched-chain amino acid solutions, resulting in a gradual improvement of symptoms. Hyperammonemia has been reported in patients with colorectal cancer but rarely in patients with esophageal cancer. A case of hyperammonemia during the 5-FU plus nedaplatin therapy has never been reported in Japan. We should be aware that 5-FU may cause hyperammonemia and resultant disturbance of consciousness during chemotherapy with 5-FU.

Protective effect of Lactobacillus salivarius Li01 on thioacetamide-induced acute liver injury and hyperammonaemia

The gut microbiota plays pivotal roles in liver disease onset and progression. The protective effects of Lactobacillus salivarius Li01 on liver diseases have been reported. In this study, we aimed to detect the protective effect of L. salivarius Li01 on thioacetamide (TAA)-induced acute liver injury and hyperammonaemia. C57BL/6 mice were separated into three groups and given a gavage of L. salivarius Li01 or phosphate-buffered saline for 7 days. Acute liver injury and hyperammonaemia were induced with an intraperitoneal TAA injection. L. salivarius Li01 decreased mortality and serum transaminase levels and improved histological liver damage caused by TAA. Serum inflammatory cytokine and chemokine and lipopolysaccharide-binding protein (LBP) concentrations, nuclear factor κB (NFκB) pathway activation and macrophage and neutrophil infiltration into the liver were significantly alleviated by L. salivarius Li01. L. salivarius Li01 also reinforced gut barrier and reshaped the perturbed gut microbiota by upregulating Bacteroidetes and Akkermansia richness and downregulating Proteobacteria, Ruminococcaceae_UCG_014 and Helicobacter richness. Plasma and faecal ammonia levels declined noticeably in the Li01 group, accompanied by improvements in cognitive function, neuro-inflammation and relative brain-derived neurotrophic factor (BDNF) gene expression. Our results indicated that L. salivarius Li01 could be considered a potential probiotic in acute liver injury and hepatic encephalopathy (HE).

Successful management of hyperammonemia with hemodialysis on day 2 during 5-fluorouracil treatment in a patient with gastric cancer: a case report with 5-fluorouracil metabolite analyses

Purpose

Hyperammonemia is an important adverse event associated with 5-fluorouracil (5FU) from 5FU metabolite accumulation. We present a case of an advanced gastric cancer patient with chronic renal failure, who was treated with 5FU/leucovorin (LV) infusion chemotherapy (2-h infusion of LV and 5FU bolus followed by 46-h 5FU continuous infusion on day 1; repeated every 2 weeks) and developed hyperammonemia, with the aim of exploring an appropriate hemodialysis (HD) schedule to resolve its symptoms.

Methods

The blood concentrations of 5FU and its metabolites, α-fluoro-β-alanine (FBAL), and monofluoroacetate (FA) of a patient who had hyperammonemia from seven courses of palliative 5FU/LV therapy for gastric cancer were measured by liquid chromatography–mass spectrometry.

Results

On the third day of the first cycle, the patient presented with symptomatic hyperammonemia relieved by emergency HD. Thereafter, the 5FU dose was reduced; however, in cycles 2–4, the patient developed symptomatic hyperammonemia and underwent HD on day 3 for hyperammonemia management. In cycles 5–7, the timing of scheduled HD administration was changed from day 3 to day 2, preventing symptomatic hyperammonemia. The maximum ammonia and 5FU metabolite levels were significantly lower in cycles 5–7 than in cycles 2–4 (NH3 75 ± 38 vs 303 ± 119 μg/dL, FBAL 13.7 ± 2.5 vs 19.7 ± 2.0 μg/mL, FA 204.0 ± 91.6 vs 395.9 ± 12.6 ng/mL, mean ± standard deviation, all p < 0.05). After seven cycles, partial response was confirmed.

Conclusion

HD on day 2 instead of 3 may prevent hyperammonemia in 5FU/LV therapy.

Electronic supplementary material

The online version of this article (10.1007/s00280-020-04158-1) contains supplementary material, which is available to authorized users.

Disturbance of consciousness due to hyperammonemia and lactic acidosis during mFOLFOX6 regimen: Case report

INTRODUCTION

FOLFOX therapy is the main chemotherapy regimen for colorectal cancer. Peripheral neuropathy, hematotoxicity, and digestive symptoms are known to be the most frequent adverse events. Hyperammonemia and lactic acidosis rarely occur simultaneously during treatment with FOLFOX therapy; the number of case reports is limited worldwide. We report a case of disturbance of consciousness, considered to be caused by hyperammonemia and lactic acidosis that occurred during treatment with mFOLFOX6 therapy that was administered as postoperative adjuvant treatment for rectal cancer.

PATIENT CONCERNS

This case was of a 71-year-old man who had been receiving oral treatment for chronic kidney disease and diabetes mellitus. Laparoscopic low anterior resection and artificial anal construction surgery were performed for stage III rectal cancer. As adjuvant postoperative therapy, mFOLFOX6 therapy was started but was followed by a disturbance of consciousness.

DIAGNOSES

Results of the blood tests revealed notable hyperammonemia (ammonia level, 1,163 μg/dl) and lactic acidosis (pH 7.207; lactate, 17.56 mmol/L); however, imaging diagnosis did not reveal intracranial lesions that could cause disturbance of consciousness.

INTERVENTIONS

For hyperammonemia, branched-chain amino acid agents and Ringers solution supplementation were administered. For acidosis, 7% sodium hydrogen carbonate was administered as treatment.

OUTCOMES

The disturbance of consciousness improved within 12 hours of initiating the treatment, and the patient was discharged with no sequelae on 7th day after hospitalization.

CONCLUSION

In patients with chronic kidney disease, FOLFOX regimen may confer risks of hyperammonemia and lactic acidosis.

Relapsing Hypoglycemia Associated with Hypocarnitinemia Following Treatment with Cefcapene Pivoxil in an Elderly Man

Pivoxil-containing cephalosporins can result in symptomatic hypocarnitinemia in children. We herein report a case of an 85-year-old man at risk of carnitine deficiency who developed relapsing symptomatic hypoglycemia after treatment with cefcapene pivoxil for urinary tract infection. On admission, laboratory tests showed low blood carnitine concentrations with low normal blood ketone levels. The patient was successfully treated by the oral administration of levocarnitine and dietary modification, including aggressive consumption of meat and dairy products, and remained symptom-free for nine months after the correction of carnitine concentrations. Healthcare providers should be cautious when prescribing pivoxil-containing antimicrobials to patients at high risk of hypocarnitinemia.

[A Case Altered Consciousness Due to 5-Fluorouracil-Induced Hyperammonemia in a Patient with Recurrent Colorectal Cancer]

We report a case of altered consciousness related to hyperammonemia due to FOLFIRI plus bevacizumab therapy in a patient with recurrent colorectal cancer and renal dysfunction.A 76-year-old man received third-line chemotherapy for left mediastinal lymph node metastasis.He complained of diarrhea on the evening of the same day, and mental confusion on day 3 of the first FOLFIRI therapy.He had a JCS of Ⅲ(200).The laboratory results revealed a marked hyperammonemia.5 - fluorouracil(5-FU)-induced hyperammonemia was diagnosed and the patient was ventilated and managed with branchedchain amino acid solutions, lactulose, and hemodialysis in the ICU.After hemodialysis, the blood ammonia level reduced to the normal limits, and the symptoms of encephalopathy resolved on the following day.He was discharged home on the 19th day of hospitalization.5 -FU-containing therapy should be carefully administered in patients with renal dysfunction.Herein, we report a case of 5-FU-induced hyperammonemia with literature considerations.

Long-term safety and efficacy of glycerol phenylbutyrate for the management of urea cycle disorder patients

INTRODUCTION

Glycerol phenylbutyrate (GPB) is currently approved for use in the US and Europe for patients of all ages with urea cycle disorders (UCD) who cannot be managed with protein restriction and/or amino acid supplementation alone. Currently available data on GPB is limited to 12 months exposure. Here, we present long-term experience with GPB.

METHODS

This was an open-label, long-term safety study of GPB conducted in the US (17 sites) and Canada (1 site) monitoring the use of GPB in UCD patients who had previously completed 12 months of treatment in the previous safety extension studies. Ninety patients completed the previous studies with 88 of these continuing into the long-term evaluation. The duration of therapy was open ended until GPB was commercially available. The primary endpoint was the rate of adverse events (AEs). Secondary endpoints were venous ammonia levels, number and causes of hyperammonemic crises (HACs) and neuropsychological testing.

RESULTS

A total of 45 pediatric patients between the ages of 1 to 17 years (median 7 years) and 43 adult patients between the ages of 19 and 61 years (median 30 years) were enrolled. The treatment emergent adverse events (TEAE) reported in ≥10% of adult or pediatric patients were consistent with the TEAEs reported in the previous safety extension studies with no increase in the overall incidence of TEAEs and no new TEAEs that indicated a new safety signal. Mean ammonia levels remained stable and below the adult upper limit of normal (<35 µmol/L) through 24 months of treatment in both the pediatric and adult population. Over time, glutamine levels decreased in the overall population. The mean annualized rate of HACs (0.29) established in the previously reported 12-month follow-up study was maintained with continued GPB exposure.

CONCLUSION

Following the completion of 12-month follow-up studies with GPB treatment, UCD patients were followed for an additional median of 1.85 (range 0 to 5.86) years in the present study with continued maintenance of ammonia control, similar rates of adverse events, and no new adverse events identified.

[Valproic acid-induced hyperammonemic encephalopathy in a patient receiving valproic acid monotherapy]

A 79-year-old female was diagnosed with epilepsy because she experienced loss of consciousness twice in January and February and then had a seizure in June 2016. She was treated with 800 mg sodium valproate (sustained release). After 3 days, she experienced loss of appetite, and more than 3 days later, disturbance of consciousness. Serum valproic acid (VPA) concentration was 128.3 μg/ml and serum ammonia was 404 μmol/l. Cerebral edema and status epilepticus occurred. Severe neurological dysfunction remained, even after treatment with continuous hemodiafiltration and levocarnitine. VPA is widely used for the treatment of generalized epilepsy. VPA-induced hyperammonemic encephalopathy is a rare but serious adverse event of VPA. Thus, we must pay attention to serum ammonia levels when using VPA, even VPA monotherapy.

[Case of Hyperammonemia Induced by High-Dose Fluorouracil]

A case of hyperammonemia induced by chemotherapy, including high-dose fluorouracil(5-FU), for advanced unresectable large intestinal cancer has been reported. This case involved an 81-year-old female who was diagnosed with pT4bcN2M1 (multiple hepatic metastases; stage Ⅳ; KRAS: mutant)after emergency surgery for sigmoid colon cancer and diffuse peritonitis. Post-operation, the 4 courses of mFOLFOX6 plus Bmab therapy was started for advanced unresectable recurrent large intestinal cancer; 48 hours later, she developed consciousness disorder(JCS Ⅲ-300). The disorder promptly disappeared after discontinuation of high-dose 5-FU. Because high-dose 5-FU was inferred to be the main cause of hyperammonemia, XELOX plus Bmab therapy was started as a post-treatment. She did not develop hyperammonemia; therefore, 8 courses were administered. The patient is being followed-up now.

[A Case of Chemotherapy-Induced Hyperammonemic Encephalopathy in a Patient with Metastatic Colon Cancer]

A 70-year-old man was diagnosed with colon cancer with multiple liver metastases.He was administered modified FOLFOX6 plus panitumumab as first-line chemotherapy.He showed consciousness disturbance on the 3rd day during the 8 cycle and was hospitalized urgently.We diagnosed him with 5-FU-induced hyperammonemia.Administration of branchedchain amino acid preparation improved his consciousness disturbance.After changing the regimen of chemotherapy to another one containing oral fluoropyrimidine, the recurrence of hyperammonemic encephalopathy was not found.

[A Case of Recurrent Hyperammonemic Encephalopathy during Adjuvant Chemotherapy(Modified FOLFOX6)for Colorectal Cancer]

A 60-year-old woman was administered mFOLFOX6 therapy as postoperative adjuvant chemotherapy for fStage III a ascending colon cancer. The patient developed a disorder of consciousness(Japan Coma Scale[JCS]III-200)immediately after the completion of the therapy. Blood ammonia levels were high at 319 mg/dL, and a diagnosis of disturbance of consciousness due to hyperammonemia was made. The patient's state of consciousness improved on the following day as blood ammonia levels decreased due to treatment with branched chain amino acid(BCAA)formulation and oxygen. Two months later, mFOLFOX6 therapy was again administered with strengthening measures for side effects to nausea and vomiting and reducing 5-FU, but the patient again developed a disorder of consciousness(JCS III-200). The 5-FU administration rate was considered as a potential cause of hyperammonemia. Hyperammonemia induced by 5-FU is relatively rare, with a reported incidence of 5-9%; however, caution is required with high dosage regimens of 5-FU that are currently recommended for colorectal cancer therapy because hyperammonemia is an important side effect.

Lesson of the month 1: Sodium valproate-induced encephalopathy

A 69-year-old man developed reduced consciousness of sudden onset. Examination and parameters were normal, except for a Glasgow Coma Scale (GCS) score of six. Brain imaging and blood tests were also normal, except for high plasma ammonia. His past medical history included epilepsy, hypertension and colitis. He was taking multiple antiepileptic medications, including sodium valproate, with no recent dose alterations. Medical intervention led to the sodium valproate being stopped and naloxone being administered. The patient's level of responsiveness and ammonia levels gradually improved. The patient was also being treated with ciprofloxacin for a urinary tract infection and a newly developed syndrome of inappropriate antidiuretic hormone secretion treated with demeclocycline. There is an association between long-term sodium valproate use and low carnitine levels, especially in the setting of polypharmacy. This in turn precipitates hyperammonaemia and encephalopathy. This case highlights the importance of an adequate drug history and the awareness of serious but uncommon adverse effects.

Pharmacologic rescue of hyperammonemia-induced toxicity in zebrafish by inhibition of ornithine aminotransferase

Hyperammonemia is the common biochemical hallmark of urea cycle disorders, activating neurotoxic pathways. If untreated, affected individuals have a high risk of irreversible brain damage and mortality. Here we show that acute hyperammonemia strongly enhances transamination-dependent formation of osmolytic glutamine and excitatory glutamate, thereby inducing neurotoxicity and death in ammoniotelic zebrafish larvae via synergistically acting overactivation of NMDA receptors and bioenergetic impairment induced by depletion of 2-oxoglutarate. Intriguingly, specific and irreversible inhibition of ornithine aminotransferase (OAT) by 5-fluoromethylornithine rescues zebrafish from lethal concentrations of ammonium acetate and corrects hyperammonemia-induced biochemical alterations. Thus, OAT inhibition is a promising and effective therapeutic approach for preventing neurotoxicity and mortality in acute hyperammonemia.

[A Case of Hyperammonemia Induced by Chemotherapy with 5-Fluorouracil for Metastatic Colon Cancer]

Systemic chemotherapy based on 5-fluorouracil(5-FU)is a standard treatment for unresectable or recurrent colon cancers. Here, we report a case of hyperammonemia induced by chemotherapy using 5-FU for metastatic colon cancer. An 84-yearold male patient with past histories of liver cirrhosis related to hepatitis C virus and renal dysfunction underwent an operation for the rectosigmoid colon cancer 8 years ago. Three years after that operation, a local recurrence of the colon cancer was diagnosed, and chemotherapy using sLV5FU2 was initiated. The recurrence lesion reduced markedly by this chemotherapy, which was ceased 2 years ago. Two years after the cessation the recurrent tumor had been enlarged, and the chemotherapy using the same drugs at the same dose was performed. On the treatment day 3, he was emergently transported to our hospital due to the disturbance of consciousness. Since laboratory tests showed the high concentration of plasma ammonia and the progressed renal dysfunction with no other definite cause of obnubilation, he was diagnosed as the hyperammonemia induced by 5-FU. He was treated by administrating the branched-chain amino acids solutions combined with fluid therapy, which quickly recovered him from the encephalopathy. He is followed up without any chemotherapy because of his high age. When a patient treated with the chemotherapy using 5-FU is sent with the disturbance of consciousness, we should take hyperammonemia into consideration, especially when he or she has the hepatic or renal dysfunction.