Topiramate reduced sweat secretion and aquaporin-5 expression in sweat glands of mice

Involvement of aquaporin 5 and Na-K-2Cl cotransporter 1 in the pathogenesis of primary focal hyperhidrosis: evidence from the primary sweat gland cell culture

People with primary focal hyperhidrosis (PFH) usually have an overactive sympathetic nervous system, which can activate the sweat glands through the chemical messenger of acetylcholine. The role of aquaporin 5 (AQP5) and Na-K-2Cl cotransporter 1 (NKCC1) in PFH is still unknown. The relative mRNA and protein levels of AQP5 and NKCC1 in the sweat gland tissues of three subtypes of patients with PFH (primary palmar hyperhidrosis, PPH; primary axillary hyperhidrosis, PAH; and primary craniofacial hyperhidrosis, PCH) were detected with real-time PCR (qPCR) and Western blot. Primary sweat gland cells from healthy controls (NPFH-SG) were incubated with different concentrations of acetylcholine, and the relative mRNA and protein expression of AQP5 and NKCC1 were also detected. NPFH-SG cells were also transfected with si-AQP5 or shNKCC1, and acetylcholine stimulation-induced calcium transients were assayed with Fluo-3 AM calcium assay. Upregulated AQP5 and NKCC1 expression were observed in sweat gland tissues, and AQP5 demonstrated a positive Pearson correlation with NKCC1 in patients with PPH (r = 0.66, P < 0.001), patients with PAH (r = 0.71, P < 0.001), and patients with PCH (r = 0.62, P < 0.001). Upregulated AQP5 and NKCC1 expression were also detected in primary sweat gland cells derived from three subtypes of patients with PFH when compared with primary sweat gland cells derived from healthy control. Acetylcholine stimulation could induce the upregulated AQP5 and NKCC1 expression in NPFH-SG cells, and AQP5 or NKCC1 inhibitions attenuated the calcium transients induced by acetylcholine stimulation in NPFH-SG cells. The dependence of ACh-stimulated calcium transients on AQP5 and NKCC1 expression may be involved in the development of PFH.NEW & NOTEWORTHY The dependence of ACh-stimulated calcium transients on AQP5 and Na-K-2Cl cotransporter 1 (NKCC1) expression may be involved in the development of primary focal hyperhidrosis (PFH).

Aquaporins Are One of the Critical Factors in the Disruption of the Skin Barrier in Inflammatory Skin Diseases

The skin is the largest organ of the human body, serving as an effective mechanical barrier between the internal milieu and the external environment. The skin is widely considered the first-line defence of the body, with an essential function in rejecting pathogens and preventing mechanical, chemical, and physical damages. Keratinocytes are the predominant cells of the outer skin layer, the epidermis, which acts as a mechanical and water-permeability barrier. The epidermis is a permanently renewed tissue where undifferentiated keratinocytes located at the basal layer proliferate and migrate to the overlying layers. During this migration process, keratinocytes undertake a differentiation program known as keratinization process. Dysregulation of this differentiation process can result in a series of skin disorders. In this context, aquaporins (AQPs), a family of membrane channel proteins allowing the movement of water and small neutral solutes, are emerging as important players in skin physiology and skin diseases. Here, we review the role of AQPs in skin keratinization, hydration, keratinocytes proliferation, water retention, barrier repair, wound healing, and immune response activation. We also discuss the dysregulated involvement of AQPs in some common inflammatory dermatological diseases characterised by skin barrier disruption.

Pediatric adverse reactions to antiseizure medications - An analysis of data from the Italian spontaneous reporting system (2001-2019)

INTRODUCTION

Spontaneous reports of adverse drug reactions (ADRs) are a valuable supplement to clinical studies in informing about the safety of medications. This is especially relevant for pediatric populations, which are not often included in large-scale clinical trials.

OBJECTIVES

To evaluate patterns of pediatric ADRs to antiseizure medications (ASMs) reported to the Italian Spontaneous Reporting System (SRS) database during the period November 1, 2001─May 31, 2019.

METHODS

Suspected ADRs ascribed to medications listed under ATC code N03, plus clobazam (code N05BA09), and affecting individuals below age 18 years were sourced from the Italian SRS database, categorized based on a modification of the MedDRA® high-level term, and analyzed using descriptive statistics.

RESULTS

A total of 956 reports listing a total of 1806 ADRs ascribed to one or more ASMs were received for individuals in pediatric age. The most commonly reported ADRs were skin rashes (24.0% of all reports), epileptic seizures (12.6%), gastrointestinal disturbances (11.8%), and somnolence (10.6%). A more detailed analysis was conducted on 675 reports listing a single ASM as suspected drug and occurring in patients with a specified or presumed diagnosis of epilepsy. Adverse drug reaction patterns differed widely across ASMs. Skin rashes were the most commonly reported ADR for lamotrigine (62.3%), carbamazepine (50.3%), phenobarbital (42.3%), and oxcarbazepine (33.0%). Other most commonly reported ADRs were gastrointestinal symptoms for ethosuximide (44%), irritability/aggression for levetiracetam (25.0%), epileptic seizures for valproic acid (16.1%), fever (often associated with hypohidrosis) for topiramate (17.9%), and utilization error (mostly accidental drug administration) for clonazepam (34.6%).

CONCLUSIONS

Patterns of spontaneous ADR reports are indicative of major differences in safety profile among individual ASMs. Most, but not all, frequently reported ADRs were in line with findings from clinical trials and observational studies.

Clear cell injury associated with reduced expression of carbonic anhydrase II in eccrine glands consistently occurs in patients with acquired idiopathic generalized anhidrosis

Acquired idiopathic generalized anhidrosis (AIGA) is characterized by anhidrosis/hypohidrosis without other autonomic and neurological dysfunctions. It has been believed that AIGA patients usually present no significant morphological alterations in the secretory portion of eccrine glands consisting of clear, dark and myoepithelial cells. However, we have recently revealed morphological damage of eccrine glands in AIGA patients by immunohistochemistry. Moreover, inhibitory side-effects against carbonic anhydrase II (CA II) by the antiepileptic reagent topiramate have been reported to cause heat intolerance mimicking AIGA. To determine the precise morphological changes and CA II expression in eccrine glands of AIGA patients, electron microscopic observation and immunohistochemistry were applied to skin of both anhidrotic (non-sweating) and normohidrotic (sweating-preserved) sites, taken from each patient clinically diagnosed with AIGA. We found consistent clear cell injury in eccrine glands in anhidrotic skin samples of AIGA patients. Electron micrographs demonstrated edematous, swollen and destructive damage in clear cells of eccrine glands from non-sweating areas of almost all AIGA patients. Immunohistochemically, clear cells showed reduced CA II expression that was heterogeneously distributed in non-sweating skin. Some areas showed almost complete loss of CA II expression in spite of preserved dark cells, and others showed mild or moderate loss of it. Selective destruction of clear cells resulting in heterogenous atrophy in AIGA patients may be important to elucidate its etiology.

Targeting the pH Paradigm at the Bedside: A Practical Approach

The inversion of the pH gradient in malignant tumors, known as the pH paradigm, is increasingly becoming accepted by the scientific community as a hallmark of cancer. Accumulated evidence shows that this is not simply a metabolic consequence of a dysregulated behavior, but rather an essential process in the physiopathology of accelerated proliferation and invasion. From the over-simplification of increased lactate production as the cause of the paradigm, as initially proposed, basic science researchers have arrived at highly complex and far-reaching knowledge, that substantially modified that initial belief. These new developments show that the paradigm entails a different regulation of membrane transporters, electrolyte exchangers, cellular and membrane enzymes, water trafficking, specialized membrane structures, transcription factors, and metabolic changes that go far beyond fermentative glycolysis. This complex world of dysregulations is still shuttered behind the walls of experimental laboratories and has not yet reached bedside medicine. However, there are many known pharmaceuticals and nutraceuticals that are capable of targeting the pH paradigm. Most of these products are well known, have low toxicity, and are also inexpensive. They need to be repurposed, and this would entail shorter clinical studies and enormous cost savings if we compare them with the time and expense required for the development of a new molecule. Will targeting the pH paradigm solve the "cancer problem"? Absolutely not. However, reversing the pH inversion would strongly enhance standard treatments, rendering them more efficient, and in some cases permitting lower doses of toxic drugs. This article's goal is to describe how to reverse the pH gradient inversion with existing drugs and nutraceuticals that can easily be used in bedside medicine, without adding toxicity to established treatments. It also aims at increasing awareness among practicing physicians that targeting the pH paradigm would be able to improve the results of standard therapies. Some clinical cases will be presented as well, showing how the pH gradient inversion can be treated at the bedside in a simple manner with repurposed drugs.

Topiramate-related adverse events: Pattern and signals in the Korea Adverse Event Reporting System, 2010-2017

Despite safety concerns associated with topiramate use, the pattern of adverse events and signal analysis of antiepileptic drugs remain elusive.We aimed to determine patient demographics and characteristics of reported AEs of topiramate and to detect the associated signals by comparing those of other antiepileptics.We used the Korea Institute of Drug Safety & Risk Management-Korea Adverse Event Reporting System Database (KIDS-KD) from 2010 to 2017 to determine patient demographics and characteristics of reported AEs for topiramate and other antiepileptics. The proportional reporting ratio, reporting odds ratio, and information component were used in signal detection. Signals were compared against drug labels in Korea, the UK, the EU, and the US.A total of 1300 adverse events cases of topiramate were reported, and the number of topiramate-adverse event pairs was 1861. For topiramate, the proportion of women of childbearing age (20-39 years) with adverse events was more than double that for other antiepileptics. A majority of the 36 detected signals were of neuropsychiatric disorders such as cognitive disorders, concentration impaired, amnesia, hypoaesthesia. Patients with topiramate-induced adverse events were likely to be young and female. Also, adverse events related to carbonic anhydrase isoenzyme showed specifically great disproportionalities.Rigorous clinical management is needed to ensure proper and safe use of topiramate. Special precautions should be taken when prescribing in women of childbearing age.

Topiramate Pharmacotherapy for Alcohol Use Disorder and Other Addictions: A Narrative Review

: Topiramate is a non-benzodiazepine anticonvulsant medication with multi-faceted pharmacologic action. It has emerged as an efficacious pharmacotherapeutic option for the treatment of addiction, especially alcohol use disorder (AUD). We present a broad narrative review of the putative mechanism of action and clinical utility of topiramate with regard to AUD and other substance use disorders. Collective evidence suggests topiramate is an effective treatment option in AUD, with notable efficacy in reducing harmful drinking patterns in AUD. Though not currently approved by the United States Food and Drug Administration for the indication of AUD, topiramate should be considered as a pharmacological treatment option with high utility among AUD patients. Early pharmacogenetic studies raise the intriguing possibility of identifying patients likely to respond to topiramate using genetic testing, and initial studies show that topiramate may also be useful in treating cocaine use disorder, smoking cessation and behavioral addictions. However, further research is needed in all these areas.

Effect of topiramate on sweat chloride level while screening for cystic fibrosis

Cystic fibrosis is the most common life-limiting genetic condition in Caucasians caused by Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene mutations. Sweat chloride is the current gold standard for diagnosis where values >60 mmol/L are diagnostic and values >30 mmol/L are indeterminate. There is limited literature on the effect of medications on the sweat chloride values. We report a case of topiramate being responsible for false-positive testing which resulted in overutilisation of medical resources and psychosocial stress on the family. Topiramate should be considered during the interpretation of the gold standard testing as one of the cause of false-positive sweat tests.

Aquagenic palmar wrinkling induced by combined use of salazopyrin and indomethacin

Aquagenic palmar wrinkling (APW) is an uncommon dermatological condition, which manifests as asymptomatic or tender palmar papules and may cause discomfort and manual functional limitations during its flares. Despite some studies implying a relationship between cystic fibrosis (CF) and APW, there are also reports of APW cases without an accompanying CF. In this report we describe a 19-year-old ankylosing spondylitis patient, who developed APW lesions after the start of combined salazopyrin and indomethacin treatment. His palmar lesions were resistant to topical corticosteroid and aluminium hydroxide therapy and disappeared only after stopping the anti-inflammatory drugs. With this report, we aim to highlight and address this underrecognized dermatological condition and possible role of aquaporins in its pathogenesis.

Elevated sweat chloride concentration in children without cystic fibrosis who are receiving topiramate therapy

BACKGROUND

Topiramate, which is used as an anticonvulsant and for migraine prophylaxis in children, causes oligohydrosis as a side-effect, but its effect on sweat chloride concentrations has not been studied systematically.

METHODS

Twenty-one children receiving topiramate and 20 healthy controls with no signs or symptoms of pulmonary or gastrointestinal disease and a negative family history for cystic fibrosis (CF) underwent bilateral pilocarpine iontophoresis and sweat collection via Macroduct® system.

RESULTS

Adequate samples (>15 µl volume) were obtained from 17/19 topiramate subjects (89%), and 19/20 (95%) controls. The mean sweat chloride concentration was 37.7 ± 18.8 mmol/L for patients receiving topiramate, and 15.9 ± 6.9 mmol/L for controls (p = 0.0001). The mean sweat volume was 29.1 ± 17.4 µl for patients receiving topiramate, and 41.2 ± 17.5 µl for controls (p = 0.037). Overall 8/17 (47%) of patients on topiramate with a measurable sweat chloride had either an intermediate (>40 mmol/L but <60 mmol/L) or elevated (>60 mmol/L) sweat chloride test result, while 0/19 control subjects had elevated sweat chloride (p = 0.0008). Further analysis of the in vitro activity of topiramate on cultured human bronchial epithelial cells in modified Ussing chambers showed no differences in chloride conductance measured in cells exposed to 10 or 50 µg/ml of topiramate when compared to non-exposed cells.

CONCLUSIONS

This is the first report of a medication affecting sweat chloride values and shows that topiramate therapy can cause elevated sweat chloride concentrations in the absence of clinical manifestations of CF.

Hyperchlorhidrosis caused by homozygous mutation in CA12, encoding carbonic anhydrase XII

Excessive chloride secretion in sweat (hyperchlorhidrosis), leading to a positive sweat test, is most commonly indicative of cystic fibrosis yet is found also in conjunction with various metabolic, endocrine, and dermatological disorders. There is conflicting evidence regarding the existence of autosomal-recessive hyperchlorhidrosis. We now describe a consanguineous Israeli Bedouin kindred with autosomal-recessive hyperchlohidrosis whose sole symptoms are visible salt precipitates after sweating, a preponderance to hyponatremic dehydration, and poor feeding and slow weight gain at infancy. Through genome-wide linkage analysis, we demonstrate that the phenotype is due to a homozygous mutation in CA12, encoding carbonic anhydrase XII. The mutant (c.427G>A [p.Glu143Lys]) protein showed 71% activity of the wild-type enzyme for catalyzing the CO₂ hydration to bicarbonate and H(+), and it bound the clinically used sulfonamide inhibitor acetazolamide with high affinity (K(I) of 10 nM). Unlike the wild-type enzyme, which is not inhibited by chloride, bromide, or iodide (K(I)s of 73-215 mM), the mutant is inhibited in the submicromolar range by these anions (K(I)s of 0.37-0.73 mM).

Hypohidrosis-related symptoms in pediatric epileptic patients with topiramate

BACKGROUND

Topiramate is one of the most commonly prescribed newer antiepileptic drugs. However, we have encountered quite a few cases of pediatric epileptic patients on topiramate complaining about the symptoms related to hypohidrosis. The aim of this study was to determine the incidence and define the clinical characteristics of hypohidrosis-related symptoms with topiramate in pediatric patients.

METHODS

Data was collected prospectively on 264 patients diagnosed as having epilepsy and treated with topiramate at the Department of Pediatrics, Chonbuk National University Hospital between July 2004 and July 2006. The data were collected by direct interview after at least 3 months had elapsed from the initiation of the medication.

RESULTS

The study group was composed of 70 boys and 81 girls, with a mean age of 33.1 +/- 43.2 months. The mean duration of topiramate treatment was 13.4 +/- 15.0 months; 52 patients (34.4%) were treated with topiramate only and 99 patients (65.6%) were on polytherapy including topiramate; 59 out of 151 patients (39.1%) experienced hypohidrosis-related symptoms: such as facial flushing, lethargy, itching sensation, irritability with hyperthermia, heat sensation or heat intolerance. However, there were no patients complaining of hypohidrosis-related symptoms among those who were taking antiepileptic drugs other than topiramate.

CONCLUSIONS

Our results suggest that topiramate induces hypohidrosis-related symptoms more often than we expected, especially in pediatric patients. We recommend that pediatric epileptic patients taking topiramate should be warned to avoid hot and humid environments, especially during the hot summer season.

Evidences for pharmacokinetic interaction of riluzole and topiramate with pilocarpine in pilocarpine-induced seizures in rats

In this study we investigated the effectiveness of two antiepileptic drugs: riluzole and topiramate against pilocarpine-induced seizures, which are considered to be a model of intractable epilepsy commonly used to investigate the antiepileptic effect of drugs and mechanisms of epileptogenesis. Seizures and status epilepticus were induced by pilocarpine in adult male Wistar rats. Riluzole (1-4mg/kg) administered intraperitoneally before pilocarpine dose-dependently protected rats against seizures with the anticonvulsant ED(50) value (50% effective anticonvulsant dose) of 1.8 (1.3-2.6)mg/kg. In contrast, riluzole at 8 and 12mg/kg administered after the onset of pilocarpine-induced seizures affected neither status epilepticus nor mortality of rats. Topiramate significantly enhanced convulsive action of pilocarpine, lowering the convulsant CD(50) value (50% effective convulsant dose) of pilocarpine from 350.8 (329.2-373.8) to 246.4 (218.6-278.2)mg/kg. Riluzole (4mg/kg) lowered plasma and brain concentration of pilocarpine administered at a dose of 400mg/kg from 168.0+/-8.6 to 75.3+/-19.9microg/ml and from 193.7+/-6.6 to 97.0+/-26.1microg/g, respectively. Topiramate (200mg/kg) increased plasma and brain concentration of pilocarpine administered at a dose of 300mg/kg from 78.1+/-2.9 to 106.0+/-6.8microg/ml and from 138.4+/-5.0 to 155.2+/-5.1microg/g, respectively. It seems that both anticonvulsant effect exerted by riluzole and proconvulsant effect exerted by topiramate in pilocarpine model of seizures are due to a pharmacokinetic interaction. Therefore, we postulate that the concentration of pilocarpine should be measured routinely whenever the anticonvulsant effect of drugs is determined in the pilocarpine model of seizures.

Molecular pharmacodynamics, clinical therapeutics, and pharmacokinetics of topiramate

Topiramate (TPM; TOPAMAX) is a broad-spectrum antiepileptic drug (AED) that is approved in many world markets for preventing or reducing the frequency of epileptic seizures (as monotherapy or adjunctive therapy), and for the prophylaxis of migraine. TPM, a sulfamate derivative of the naturally occurring sugar D-fructose, possesses several pharmacodynamic properties that may contribute to its clinically useful attributes, and to its observed adverse effects. The sulfamate moiety is essential, but not sufficient, for its pharmacodynamic properties. In this review, we discuss the known pharmacodynamic and pharmacokinetic properties of TPM, as well as its various clinically beneficial and adverse effects.