Does nephrotoxicity exist in pediatric epileptic patients on valproate or carbamazepine therapy?

From Rare Disorders of Kidney Tubules to Acute Renal Injury: Progress and Prospective

Background

Acute kidney injury (AKI) is a severe condition marked by rapid renal function deterioration and elevated mortality, with traditional biomarkers lacking sensitivity and specificity. Rare tubulointerstitial diseases encompass a spectrum of disorders, primarily including monogenic diseases, immune-related conditions, and drug-induced tubulointerstitial diseases. The clinical manifestations vary from electrolyte and acid-base imbalances to kidney function insufficiency, which is associated with AKI in up to 20% of cases. Evidence indicated that rare tubulointerstitial diseases might provide new conceptual insights and perspectives for novel biomarkers and potential therapeutic strategies for AKI.

Summary

Autosomal dominant tubulointerstitial kidney disease (ADTKD) and Fanconi syndrome (FS) are rare tubulointerstitial diseases. In ADTKD, UMOD and REN are closely related to AKI by affecting oxidative stress and tubuloglomerular feedback, which provide potential new biomarkers for AKI. Both rare tubulointerstitial diseases and AKI share etiologies and treatment responses. From the mechanism standpoint, rare tubulointerstitial diseases and AKI involve tubular transporter injury, initially manifesting as tubular dysfunction in tubulointerstitial disorder and progressing to AKI because of the programmed cell death with apoptosis, pyroptosis, or necroptosis of proximal tubule cells. Additionally, mitochondrial dysfunction has been identified as a common mechanism in both tubulointerstitial diseases and AKI induced by drugs, pSS, or monoclonal diseases. In the end, both AKI and FS patients and animal models responded well to the therapy of the primary diseases.

Key Messages

In this review, we describe an overview of ADTKD and FS to identify their associations with AKI. Mitochondrial dysfunction contributes to rare tubulointerstitial diseases and AKI, which might provide a potential therapeutic target.

Kidney tubular injury induced by valproic acid: systematic literature review

BACKGROUND

Valproic acid is prescribed for epilepsy and as prophylaxis for bipolar disorder and migraine headaches. It has also been implicated as a cause of a kidney tubular injury.

METHODS

We undertook a review of the literature to characterize the biochemical and histopathological features of the overt kidney tubular injury and to evaluate the possible existence of a pauci-symptomatic injury. The pre-registered review (CRD42022360357) was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology. Searches were conducted in Excerpta Medica, the National Library of Medicine, and Web of Science. The gray literature was also considered.

RESULTS

For the final analysis, we retained 36 articles: 28 case reports documented 48 individuals with epilepsy on valproic acid for 7 months or more and presenting with features consistent with an overt kidney tubular injury. The following disturbances were noted: hypophosphatemia (N = 46), normoglycemic glycosuria (N = 46), total proteinuria (N = 45), metabolic acidosis (N = 36), hypouricemia (N = 27), tubular proteinuria (N = 27), hypokalemia (N = 23), and hypocalcemia (N = 8). A biopsy, obtained in six cases, disclosed altered proximal tubular cells with giant and dysmorphic mitochondria. Eight case series addressed the existence of a pauci- or even asymptomatic kidney injury. In the reported 285 subjects on valproic acid for 7 months or more, an isolated tubular proteinuria, mostly N-acetyl-β-glucosaminidase, was often noted.

CONCLUSIONS

Valproic acid may induce an overt kidney tubular injury, which is associated with a proximal tubular mitochondrial toxicity. Treatment for 7 months or more is often associated with a pauci- or oligosymptomatic kidney tubular injury. A higher resolution version of the Graphical abstract is available as Supplementary information.

Carbamazepine-induced renal toxicity may be associated with oxidative stress and apoptosis in male rat

Carbamazepine (CBZ) is the antiepileptic drug used in epilepsy and some psychiatric disorders. Besides its widely used, many adverse effects have been reported including hematotoxicity, hepatotoxicity, endocrine disorders, and testicular damages due to oxidative stress. However, the role of CBZ on renal toxicity is not fully known. In this study, we attempted to explain the connected mechanisms by focusing on the metabolism of CBZ-induced renal toxicity in rats. Twenty male Wistar-Albino rats were randomized into 2 groups (n = 10); control (1 mL/day distilled water, orally) and CBZ (25 mg/kg/day CBZ, orally) groups. After 60 days, TAS (total oxidant status) and TOS (total oxidant status) levels, histopathological features, some genes involved in apoptosis, 8-hydroxy-2-deoxyguanosine (8-OHdG) activity, and apoptotic cells were assessed of kidney tissue. The oxidative stress index (OSI) was measured from TAS and TOS levels. TOS levels and OSI significantly increased, while TAS levels decreased in the CBZ group relative to the control group. Histopathological observations, Caspase-3 (Casp3), Poly [ADP-ribose] polymerase-1 (PARP-1), 8-OHdG immunoreactivities, and apoptotic cells markedly raised in the CBZ group compared with the control group. Also, mRNA expression of Cytochrome c (Cytc) and CASP3 significantly increased in the CBZ group compared to the control group. In conclusion, long-term use of CBZ may promote renal damage in rats by inducing oxidative stress and apoptosis.

Valproic acid restores the down-regulation of SDF-1 following kidney ischemia; experimental validation of a mathematical prediction

Background and purpose

Stromal-derived factor (SDF)-1, a chemokine recruiting leucocytes and stem cells, plays an essential role in tissue regeneration. In a previous study, we have unexpectedly found that the expression of this chemokine declines following kidney ischemia reperfusion (IR). To explain this observation, a mathematical model was constructed which proposed histone deacetylase (HDAC) as the main driver of SDF-1 down-regulation. To experimentally verify this prediction, the effect of valproic acid (VPA), a potent HDAC inhibitor, on the kinetics of kidney SDF-1 expression was here assessed.

Experimental approach

Adult mice were subjected to IR or sham operation and received VPA or vehicle. Next, SDF-1 expression as well as tissue repair indices were measured in a time course manner.

Findings / Results

The transcriptional expressions of Sdf-1 alpha, beta, and gamma isoforms were noisy in the sham groups but the fluctuations disappeared following IR where a continuous declining trend was observed. VPA induced the over-expression of gamma, but not alpha and beta mRNA in IR mice which was accompanied with protein upregulation. Remarkably, VPA deteriorated kidney injury.

Conclusion and implications

HDAC inhibition restores SDF-1 down-regulation following kidney IR. The present study is a classic example of the potential of computational modeling for the prediction of biomedical phenomena.

Renal dysfunctions/injury in adult epilepsy patients treated with carbamazepine or valproate

OBJECTIVES

Clinical and subclinical laboratory evidence of renal proximal tubular dysfunction had been reported in children with epilepsy as an adverse effect of some antiepileptic drugs (AEDs). This study aimed to determine kidney function in adult patients with monosymptomatic epilepsy of unknown etiology and treated with valproate (VPA) or carbamazepine (CBZ).

METHODS

This study included 60 patients [mean age of 33.97 ± 6.70 years and treated with VPA (n = 24) or CBZ (n = 36) for mean duration of treatment of 6.03 ± 2.81years. Measurements of serum creatinine (sCr), urinary creatinine, creatinine clearance (CrCl) and serum kidney injury molecule 1 (KIM-1), markers of renal dysfunction/injury were done.

RESULTS

Compared to controls, patients had higher sCr, KIM-1 and lower CrCl levels. Compared to patients on VPA, those on CBZ had relatively higher KIM-1 and lower CrCl levels. We reported only significant correlations between KIM-1 with sCr (r = 0.324, p = 0.001) and duration of treatment with AEDs (r = 0.301, p = 0.02).

CONCLUSION

Chronic VPA and CBZ therapy may be associated with subclinical renal glomerular and/or proximal tubular dysfunctions or injuries. The treating neurologist have to consider this while selection of AED on start treating patients or modifying the AED for patients at high risk of kidney injury.

The effect of antiepileptic drugs on the kidney function and structure

INTRODUCTION

Long-term use of antiepileptic drugs (AEDs) is associated with number of somatic conditions. Data from experimental, cross-sectional and prospective studies have evidence for the deleterious effect of some AEDs on the kidney. Areas covered: This review summarized the current knowledge of the effect of AEDs on the kidney including evidence and mechanisms. Fanconi syndrome was reported with valproate (VPA) therapy in severely disabled children with epilepsy. Renal tubular acidosis and urolithiasis were reported with acetazolamide, topirmate and zonisamide, drugs with carbonic anhydrase inhibition properties. Increased levels of urinary N-acetyl-beta-D-glucosaminidase (NAG) to urinary creatinine (U-NAG/UCr), urinary excretion of α1-micrglobulin, β-galactosidase activity; and urinary malondialdehyde to creatinine (MDA/Cr), markers of renal glomerular and tubular injury, were reported with chronic use of some AEDs (VPA, carbamazepine and phenytoin). The mechanism(s) of kidney dysfunction/injury induced by AEDs is unknown. Experimental and clinical studies have shown that VPA induces oxidative stress, mitochondrial deficits, carnitine deficiency and inflammation and fibrosis in renal tissue in mice and in vitro studies. Expert commentary: It seems reasonable to monitor kidney function during treating patients with epilepsy at high risk of kidney injury (e.g. on combined therapy with more than one AED, severely disabled children, etc).

Carbamazepine

This chapter includes the aspects of carbamazepine. The drug is synthesized by the use of 5H-dibenz[b,f]azepine and phosgene followed by subsequent reaction with ammonia. Carbamazepine is generally used for the treatment of seizure disorders and neuropathic pain, it is also important as off-label for a second-line treatment for bipolar disorder and in combination with an antipsychotic in some cases of schizophrenia when treatment with a conventional antipsychotic alone has failed. Other uses may include attention deficit hyperactivity disorder, schizophrenia, phantom limb syndrome, complex regional pain syndrome, borderline personality disorder, and posttraumatic stress disorder. The chapter discusses the drug metabolism and pharmacokinetics and presents various methods of analysis of this drug such electrochemical analysis, spectroscopic analysis, and chromatographic techniques of separation. It also discusses its physical properties such as solubility characteristics, X-ray powder diffraction pattern, and thermal methods of analysis. The chapter is concluded with a discussion on its biological properties such as activity, toxicity, and safety.