Understanding intestinal cysteamine bitartrate absorption

A New and Rapid LC-MS/MS Method for the Determination of Cysteamine Plasma Levels in Cystinosis Patients

Cystinosis is a rare lysosomal storage disorder caused by autosomal recessive mutations in the CTNS gene that encodes for the cystine transporter cystinosin, which is expressed on the lysosomal membrane mediating the efflux of cystine. Cysteamine bitartrate is a cystine-depleting aminothiol agent approved for the treatment of cystinosis in children and adults. In this study, we developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of cysteamine levels in plasma samples. This LC-MS/MS method was validated according to the European Medicines Agency (EMA)'s guidelines for bioanalytical method validation. An ultra-performance liquid chromatograph (UPLC) coupled with a 6470 mass spectrometry system was used for cysteamine determination. Our validated method was applied to plasma samples from n = 8 cystinosis patients (median, interquartile range (IQR) = 20.5, 8.5-26.0 years). The samples were collected before cysteamine oral administration (pre-dose) and 1 h after (post-dose). Our bioanalytical method fulfilled the regulatory guidelines for method validation. The cysteamine plasma levels in pre-dose samples were 2.57 and 1.50-3.31 μM (median and IQR, respectively), whereas the post-dose samples reported a cysteamine median concentration of 28.00 μM (IQR: 17.60-36.61). Our method allows the rapid determination of cysteamine plasma levels. This method was successfully used in cystinosis patients and, therefore, could be a useful tool for the evaluation of therapy adherence and for future pharmacokinetic (PK) studies involving a higher number of subjects.

Cysteamine improves growth and the GH/IGF axis in gilthead sea bream (Sparus aurata): in vivo and in vitro approaches

Aquaculture is the fastest-growing food production sector and nowadays provides more food than extractive fishing. Studies focused on the understanding of how teleost growth is regulated are essential to improve fish production. Cysteamine (CSH) is a novel feed additive that can improve growth through the modulation of the GH/IGF axis; however, the underlying mechanisms and the interaction between tissues are not well understood. This study aimed to investigate the effects of CSH inclusion in diets at 1.65 g/kg of feed for 9 weeks and 1.65 g/kg or 3.3 g/kg for 9 weeks more, on growth performance and the GH/IGF-1 axis in plasma, liver, stomach, and white muscle in gilthead sea bream (Sparus aurata) fingerlings (1.8 ± 0.03 g) and juveniles (14.46 ± 0.68 g). Additionally, the effects of CSH stimulation in primary cultured muscle cells for 4 days on cell viability and GH/IGF axis relative gene expression were evaluated. Results showed that CSH-1.65 improved growth performance by 16% and 26.7% after 9 and 18 weeks, respectively, while CSH-3.3 improved 32.3% after 18 weeks compared to control diet (0 g/kg). However, no significant differences were found between both experimental doses. CSH reduced the plasma levels of GH after 18 weeks and increased the IGF-1 ones after 9 and 18 weeks. Gene expression analysis revealed a significant upregulation of the ghr-1, different igf-1 splice variants, igf-2 and the downregulation of the igf-1ra and b, depending on the tissue and dose. Myocytes stimulated with 200 µM of CSH showed higher cell viability and mRNA levels of ghr1, igf-1b, igf-2 and igf-1rb compared to control (0 µM) in a similar way to white muscle. Overall, CSH improves growth and modulates the GH/IGF-1 axis in vivo and in vitro toward an anabolic status through different synergic ways, revealing CSH as a feasible candidate to be included in fish feed.

Enteric-Coated Cysteamine Bitartrate in Cystinosis Patients

Cystinosis is a severe inherited metabolic storage disease caused by the lysosomal accumulation of cystine. Lifelong therapy with the drug cysteamine bitartrate is necessary. Cysteamine cleaves intralysosomal cystine, and thereafter, it can exit from the organelle. The need for frequent dosing every 6 h and the high prevalence of gastrointestinal side effects lead to poor therapy adherence. The purpose of our study was to improve cysteamine treatment by comparing the efficacy of two cysteamine formulas. This is highly relevant for the long-term outcome of cystinosis patients. The cystine and cysteamine levels of 17 patients taking immediate-release cysteamine (IR-cysteamine/Cystagon^®) and 6 patients taking encapsulated delayed-release cysteamine (EC-cysteamine) were analyzed. The EC-cysteamine levels showed a near-ideal pharmacokinetic profile indicative of delayed release (longer T_max and T_min), and the corresponding cystine levels showed few fluctuations. In addition, the C_max of IR-cysteamine was greater, which was responsible for unbearable side effects (e.g., nausea, vomiting, halitosis, lethargy). Treatment with EC-cysteamine improves the quality of life of cystinosis patients because the frequency of intake can be reduced to 2-3 times daily and it has a more favorable pharmacokinetic profile than IR-cysteamine. In particular, cystinosis patients with no access to the only approved delayed-release cysteamine Procysbi^® could benefit from a cost-effective alternative.

Hepatic lipid metabolism disorders and immunotoxicity induced by cysteamine in early developmental stages of zebrafish

Cysteamine, a sulfhydryl compound, is an intermediate in the metabolism of coenzyme A to taurine in living organisms. However, the potential side effects of cysteamine such as hepatotoxicity in pediatric patients have been reported in some studies. To evaluate the impact of cysteamine on infants and children, larval zebrafish (a vertebrate model) were exposed to 0.18, 0.36 and 0.54mM cysteamine from 72 hpf to 144 hpf. Alterations in general and pathological evaluation, biochemical parameters, cell proliferation, lipid metabolism factors, inflammatory factors and Wnt signaling pathway levels were examined. Increased liver area and lipid accumulation were observed in liver morphology, staining and histopathology in a dose-dependent manner with cysteamine exposure. In addition, the experimental cysteamine group exhibited higher alanine aminotransferase, aspartate aminotransferase, total triglyceride and total cholesterol levels than the control group. Meanwhile, the levels of lipogenesis-related factors ascended whereas lipid transport-related factors descended. Oxidative stress indicators such as reactive oxygen species, MDA and SOD were upregulated after cysteamine exposure. Afterwards, transcription assays revealed that biotinidase and Wnt pathway-related genes were upregulated in the exposed group, and inhibition of Wnt signaling partially rescued the abnormal liver development. The current study found that cysteamine-induced hepatotoxicity in larval zebrafish is due to inflammation and abnormal lipid metabolism, which is mediated by biotinidase (a potential pantetheinase isoenzyme) and Wnt signaling. This provides a perspective on the safety of cysteamine administration in children and identifies potential targets for protection against adverse reactions.

Cysteamine bitartrate delayed-release capsules control leukocyte cystine levels and promote statural growth and kidney health in an open-label study of treatment-naïve patients <6 years of age with nephropathic cystinosis

Nephropathic cystinosis is a rare autosomal recessive lysosomal storage disease that is characterized by accumulation of cysteine and formation of crystals within cells of different organs and tissues causing systemic manifestations in childhood that include poor linear growth, ocular involvement, hypothyroidism, and progressive kidney disease. This study was a long-term, prospective open-label evaluation of twice-daily delayed release (DR) cysteamine capsules in cystinosis patients <6 years of age who were naïve to any form of cysteamine treatment. Fifteen treatment-naïve patients <6 years old (mean age 2.2 ± 1.0 years, 53% male, 73% White) were enrolled and treated with DR-cysteamine capsules for up to 18 months. Patients had clinically meaningful decreases in WBC cysteine concentration during treatment (3.2 ± 3.0 nmol ½ cystine/mg protein at Day 1 to 0.8 ± 0.8 nmol ½ cystine/mg protein at study exit), and anthropometric data improvements were consistently observed in height, weight and body surface area. Additionally, estimated glomerular filtration rate increased from 55.93 ± 22.43 ml/min/1.73 m2 at baseline to 63.79 ± 21.44 ml/min/1.73 m2 at study exit. Pharmacokinetic/Pharmacodynamic results support the use of the same starting, escalation, and maintenance doses according to body surface for children aged <6 years that are currently recommended in adults and older children. All patients experienced ≥1 adverse event(s) with vomiting (80%) and upper respiratory tract infection (53%) most frequently reported. Based on our study, patients <6 years of age with nephropathic cystinosis without prior treatment can safely and effectively initiate treatment with DR-cysteamine, a delayed-release form of cysteamine bitartrate that can be given every 12 h.

A comparison of immediate release and delayed release cysteamine in 17 patients with nephropathic cystinosis

Background

Nephropathic cystinosis is a rare and severe metabolic disease leading to an accumulation of cystine in lysosomes which especially harms kidney function. A lifelong therapy with the aminothiol cysteamine can delay the development of end-stage renal disease and the necessity of kidney transplantation. The purpose of our study was to compare the effectiveness of immediate-release and delayed-release cysteamine on cystine and cysteamine levels as well as assessing the onset of adverse effects.

Methods

We retrospectively analysed cystine and cysteamine levels of 17 patients after a single dose of immediate-release cysteamine (Cystagon®, Mylan Pharmaceuticals, Canonsburg, PA and Recordati Pharma GmbH) as well as a single dose of delayed-release cysteamine (Procysbi®; Horizon Pharma USA and Chiesi Farmaceutici S.p.A., Parma, Italy) respectively. Data were collected during a period of three years in the context of optimizing the individual treatment regimens. The dose of DR-cysteamine was reduced to 70% of the equivalent dose of IR-cysteamine. The efficacy of both formulas in depleting white blood cells’ cystine levels and their side effects were compared.

Results

Immediate (IR)- and delayed-release (DR) cysteamine effectively decreased intracellular cystine levels under the target value of 0.5 nmol cystine/mg protein, while fewer side effects occurred under DR-cysteamine. Mean maximum levels of cysteamine were reached after 60 min with IR-cysteamine and after 180 min with DR-cysteamine.

Conclusion

A therapy with DR-cysteamine is as effective as IR-cysteamine while less side effects were reported. Our data show that DR-cysteamine should be dosed higher than 70% of the equivalent dose of IR-cysteamine in order to decrease cystine levels over an extended period of time. Moreover, our data suggest increasing the dosing scheme of Procysbi® to three times daily, to prevent a rapid decrease and achieve a steadier decline in cystine levels. Due to the more convenient dosing scheme, DR-cysteamine might ameliorate therapy adherence and improve patients’ quality of life.

Using naso- and oro-intestinal catheters in physiological research for intestinal delivery and sampling in vivo: practical and technical aspects to be considered

Intestinal catheters have been used for decades in human nutrition, physiology, pharmacokinetics, and gut microbiome research, facilitating the delivery of compounds directly into the intestinal lumen or the aspiration of intestinal fluids in human subjects. Such research provides insights about (local) dynamic metabolic and other intestinal luminal processes, but working with catheters might pose challenges to biomedical researchers and clinicians. Here, we provide an overview of practical and technical aspects of applying naso- and oro-intestinal catheters for delivery of compounds and sampling luminal fluids from the jejunum, ileum, and colon in vivo. The recent literature was extensively reviewed, and combined with experiences and insights we gained through our own clinical trials. We included 60 studies that involved a total of 720 healthy subjects and 42 patients. Most of the studies investigated multiple intestinal regions (24 studies), followed by studies investigating only the jejunum (21 studies), ileum (13 studies), or colon (2 studies). The ileum and colon used to be relatively inaccessible regions in vivo. Custom-made state-of-the-art catheters are available with numerous options for the design, such as multiple lumina, side holes, and inflatable balloons for catheter progression or isolation of intestinal segments. These allow for multiple controlled sampling and compound delivery options in different intestinal regions. Intestinal catheters were often used for delivery (23 studies), sampling (10 studies), or both (27 studies). Sampling speed decreased with increasing distance from the sampling syringe to the specific intestinal segment (i.e., speed highest in duodenum, lowest in ileum/colon). No serious adverse events were reported in the literature, and a dropout rate of around 10% was found for these types of studies. This review is highly relevant for researchers who are active in various research areas and want to expand their research with the use of intestinal catheters in humans in vivo.

Challenges for cysteamine stabilization, quantification, and biological effects improvement

The aminothiol cysteamine, derived from coenzyme A degradation in mammalian cells, presents several biological applications. However, the bitter taste and sickening odor, chemical instability, hygroscopicity, and poor pharmacokinetic profile of cysteamine limit its efficacy. The use of encapsulation systems is a good methodology to overcome these undesirable properties and improve the pharmacokinetic behavior of cysteamine. Besides, the conjugation of cysteamine to the surface of nanoparticles is generally proposed to improve the intra-oral delivery of cyclodextrin-drug inclusion complexes, as well as to enhance the colorimetric detection of compounds by a gold nanoparticle aggregation method. On the other hand, the detection and quantification of cysteamine is a challenging mission due to the lack of a chromophore in its structure and its susceptibility to oxidation before or during the analysis. Derivatization agents are therefore applied for the quantification of this molecule. To our knowledge, the derivatization techniques and the encapsulation systems used for cysteamine delivery were not reviewed previously. Thus, this review aims to compile all the data on these methods as well as to provide an overview of the various biological applications of cysteamine focusing on its skin application.

Cysteamine inhibits lysosomal oxidation of low density lipoprotein in human macrophages and reduces atherosclerosis in mice

Background and aims

We have shown previously that low density lipoprotein (LDL) aggregated by vortexing is internalised by macrophages and oxidised by iron in lysosomes to form the advanced lipid/protein oxidation product ceroid. We have now used sphingomyelinase-aggregated LDL, a more pathophysiological form of aggregated LDL, to study lysosomal oxidation of LDL and its inhibition by antioxidants, including cysteamine (2-aminoethanethiol), which concentrates in lysosomes by several orders of magnitude. We have also investigated the effect of cysteamine on atherosclerosis in mice.

Methods

LDL was incubated with sphingomyelinase, which increased its average particle diameter from 26 to 170 nm, and was then incubated for up to 7 days with human monocyte-derived macrophages. LDL receptor-deficient mice were fed a Western diet (19–22 per group) and some given cysteamine in their drinking water at a dose equivalent to that used in cystinosis patients. The extent of atherosclerosis in the aortic root and the rest of the aorta was measured.

Results

Confocal microscopy revealed lipid accumulation in lysosomes in the cultured macrophages. Large amounts of ceroid were produced, which colocalised with the lysosomal marker LAMP2. The antioxidants cysteamine, butylated hydroxytoluene, amifostine and its active metabolite WR-1065, inhibited the production of ceroid. Cysteamine at concentrations well below those expected to be present in lysosomes inhibited the oxidation of LDL by iron ions at lysosomal pH (pH 4.5) for prolonged periods. Finally, we showed that the extent of atherosclerotic lesions in the aortic root and arch of mice was significantly reduced by cysteamine.

Conclusions

These results support our hypothesis that lysosomal oxidation of LDL is important in atherosclerosis and hence antioxidant drugs that concentrate in lysosomes might provide a novel therapy for this disease.

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The drug cysteamine, which accumulates in lysosomes, inhibited the oxidation of LDL by iron at pH 4.5 (the pH of lysosomes).

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Cysteamine inhibited the lysosomal oxidation of LDL inside cultured macrophages.

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Cysteamine reduced atherosclerosis in LDL receptor knockout mice.

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These results support our hypothesis that lysosomal oxidation of LDL is important in atherosclerosis.

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Antioxidant drugs that concentrate in lysosomes might provide a novel therapy for this disease.

Influence of supplemented coated-cysteamine on morphology, apoptosis and oxidative stress status of gastrointestinal tract

BACKGROUND

Cysteamine was coated to cover its odor and maintain the stability. However, coated cysteamine (CC) has not been clearly evaluated for its effects on the gastrointestinal mucosa status. We hypothesize that the appropriate CC supplementation in diet impacts the stomach and intestinal mucosa variously through regulating the morphology, apoptosis, and oxidative stress status in model of pigs.

RESULTS

The results showed that villus height increased (P < 0.05), and crypt depth decreased (P < 0.05) in the ileum when pigs were fed the diet with low cysteamine (LCS) compared with the control diet. The ileal lesion score in the LCS group was significantly (P < 0.01) lower than that in the control group, while the gastric lesion score in the CC group was significantly (P < 0.01) higher compared with that of the control group. It also showed that the activities of total superoxide dismutase (T-SOD) and diamine oxidase (DAO) were upregulated (P < 0.05) in the LCS group. In addition, Bax and caspase 3 immunore-activity increased (P < 0.01), and Bcl-2 immunoreactivity decreased (P < 0.01) in the gastric mucosa of pigs fed the diet with high cysteamine (HCS). The Bax and caspase 3 immunoreactivity decreased (P < 0.01), and Bcl-2 immunoreactivity increased (P < 0.01) in ileum mucosa of pigs fed the HCS diet.

CONCLUSIONS

Although moderate dietary coated cysteamine showed positive effects on GI mucosal morphology, apoptosis, and oxidative stress status, the excess coated cysteamine may cause apoptosis leading to GI damage in pigs.

A systematic literature review of cysteamine bitartrate in the treatment of nephropathic cystinosis

OBJECTIVES

To summarize available clinical evidence for cysteamine bitartrate preparations in the treatment of nephropathic cystinosis as identified through a systematic literature review (SLR).

METHODS

We searched MEDLINE, MEDLINE In-Process and Embase using Ovid with a predefined search strategy through 19 January 2016. All publicly available clinical reports on the use of delayed-release (DR) cysteamine bitartrate (Procysbi ¹ ) or immediate-release (IR) cysteamine bitartrate (Cystagon ² ) in patients with cystinosis were included.

RESULTS

We identified a total of 103 publications and 10 trial records. Of these, 9 studies describe DR cysteamine bitartrate (n = 267 patients), 42 describe IR cysteamine bitartrate (n = 1,427 patients) and in 53 studies the exact preparation was not specified (n = 906 patients). The vast majority of the studies used a non-randomized study design, with randomized clinical trials (RCTs) being scarce (1 study comparing DR and IR formulation) and case reports (n = 49) being the most common study design representing 47% of the total.

CONCLUSION

A substantial evidence base for cysteamine bitartrate in the treatment of nephropathic cystinosis was identified. However, the majority of the evidence was of relatively low quality, with evidence levels of 3 or 4.

Cystinosis (ctns) zebrafish mutant shows pronephric glomerular and tubular dysfunction

The human ubiquitous protein cystinosin is responsible for transporting the disulphide amino acid cystine from the lysosomal compartment into the cytosol. In humans, Pathogenic mutations of CTNS lead to defective cystinosin function, intralysosomal cystine accumulation and the development of cystinosis. Kidneys are initially affected with generalized proximal tubular dysfunction (renal Fanconi syndrome), then the disease rapidly affects glomeruli and progresses towards end stage renal failure and multiple organ dysfunction. Animal models of cystinosis are limited, with only a Ctns knockout mouse reported, showing cystine accumulation and late signs of tubular dysfunction but lacking the glomerular phenotype. We established and characterized a mutant zebrafish model with a homozygous nonsense mutation (c.706 C > T; p.Q236X) in exon 8 of ctns. Cystinotic mutant larvae showed cystine accumulation, delayed development, and signs of pronephric glomerular and tubular dysfunction mimicking the early phenotype of human cystinotic patients. Furthermore, cystinotic larvae showed a significantly increased rate of apoptosis that could be ameliorated with cysteamine, the human cystine depleting therapy. Our data demonstrate that, ctns gene is essential for zebrafish pronephric podocyte and proximal tubular function and that the ctns-mutant can be used for studying the disease pathogenic mechanisms and for testing novel therapies for cystinosis.

Cystinosis: a new perspective

Cystinosis is a rare, autosomal recessive inherited lysosomal storage disease. It is the most frequent and potentially treatable cause of the inherited renal Fanconi syndrome. If left untreated, renal function rapidly deteriorates towards end-stage renal disease by the end of the first decade of life. Due to its rarity and non-specific presentation, the entity is often not promptly recognized resulting in delayed diagnosis. Two major milestones in cystinosis management, cystine-depleting therapy with cysteamine and renal allograft transplantation, have had a considerable impact on the natural history and prognosis of cystinosis patients. However, due to its significant side effects and a strict 6-hourly dosing regimen, non-adherence to the immediate release of cysteamine bitartrate formulation (Cystagon®) is a major issue that might affect long-term outcome. Recently, a new twice-daily administered delayed-release enteric-coated formula of cysteamine bitartrate (Procysbi(TM)) has been approved by the European Medical Agency for the treatment of cystinosis, and has been shown to be safe and effective. This delayed-release cysteamine has the potential to improve compliance and hence prognosis, through its better dosing regimen, positive impact on quality of life and possibly less side-effects, and is now tested in an ongoing long-term clinical trial. Longer survival of patients with cystinosis makes transition from pediatric to adult-oriented care another challenge in cystinosis management and requires an extended multidisciplinary approach.

Cystinosis: a review

Cystinosis is the most common hereditary cause of renal Fanconi syndrome in children. It is an autosomal recessive lysosomal storage disorder caused by mutations in the CTNS gene encoding for the carrier protein cystinosin, transporting cystine out of the lysosomal compartment. Defective cystinosin function leads to intra-lysosomal cystine accumulation in all body cells and organs. The kidneys are initially affected during the first year of life through proximal tubular damage followed by progressive glomerular damage and end stage renal failure during mid-childhood if not treated. Other affected organs include eyes, thyroid, pancreas, gonads, muscles and CNS. Leucocyte cystine assay is the cornerstone for both diagnosis and therapeutic monitoring of the disease. Several lines of treatment are available for cystinosis including the cystine depleting agent cysteamine, renal replacement therapy, hormonal therapy and others; however, no curative treatment is yet available. In the current review we will discuss the most important clinical features of the disease, advantages and disadvantages of the current diagnostic and therapeutic options and the main topics of future research in cystinosis.

Cysteamine modulates oxidative stress and blocks myofibroblast activity in CKD

Therapy to slow the relentless expansion of interstitial extracellular matrix that leads to renal functional decline in patients with CKD is currently lacking. Because chronic kidney injury increases tissue oxidative stress, we evaluated the antifibrotic efficacy of cysteamine bitartrate, an antioxidant therapy for patients with nephropathic cystinosis, in a mouse model of unilateral ureteral obstruction. Fresh cysteamine (600 mg/kg) was added to drinking water daily beginning on the day of surgery, and outcomes were assessed on days 7, 14, and 21 after surgery. Plasma cysteamine levels showed diurnal variation, with peak levels similar to those observed in patients with cystinosis. In cysteamine-treated mice, fibrosis severity decreased significantly at 14 and 21 days after unilateral ureteral obstruction, and renal oxidized protein levels decreased at each time point, suggesting reduced oxidative stress. Consistent with these results, treatment of cultured macrophages with cysteamine reduced cellular generation of reactive oxygen species. Furthermore, treatment with cysteamine reduced α-smooth muscle actin-positive interstitial myofibroblast proliferation and mRNA levels of extracellular matrix proteins in mice and attenuated myofibroblast differentiation and proliferation in vitro, but did not augment TGF-β signaling. In a study of renal ischemia reperfusion, cysteamine therapy initiated 10 days after injury and continued for 14 days decreased renal fibrosis by 40%. Taken together, these data suggest previously unrecognized antifibrotic actions of cysteamine via TGF-β-independent mechanisms that include oxidative stress reduction and attenuation of the myofibroblast response to kidney injury and support further investigation into the potential benefit of cysteamine therapy in the treatment of CKD.

Pharmacokinetic Studies of Cysteamine Bitartrate Delayed-Release

A twice-daily microsphere formulation of cysteamine bitartrate has been developed for cystinosis and other potential applications. To date, there are no published pharmacokinetic data for cysteamine bitartrate delayed-release in healthy adults. Three randomized open-label, crossover studies to determine the effects of fasting, high fat, and carbohydrate meals on the bioavailability of cysteamine bitartrate delayed-release (600 mg) administered in capsule or sprinkle form to healthy adults. Adverse events were monitored. Fifty-eight adults were studied. Cysteamine absorption (AUC0-24 hours ) was the same for capsule and sprinkle forms during all meal/fasting states. The AUC0-24 hours for capsules while fasted, 30 and 120 minutes before a carbohydrate meal and during a high fat meal were 6,313 ± 329, 4,616 ± 878, 6,691 ± 669, 2,572 ± 295 minutes × µM, respectively, and the mean Cmax values were 29.4 ± 1.7, 20.7 ± 4.9, 31.6 ± 3.0, and 10.9 ± 1.7 µM, respectively. The mean Tmax following fasting and high fat meal were about 3 and 6 hours, respectively. Minor transient GI adverse events occurred. Cysteamine bitartrate delayed-release capsule and sprinkle forms are bioequivalent and optimal absorption occurs during fasting state. High fat diet reduces drug absorption, increases the Tmax and should be avoided at the time of drug ingestion. Cysteamine bitartrate delayed-release (RP103) is best ingested >30 minutes before a carbohydrate-rich meal.

Treatment of cystinosis with delayed-release cysteamine: 6-year follow-up

BACKGROUND

Patients with nephropathic cystinosis are required to take 6-hourly immediate-release cysteamine (Cystagon®) to reduce disease progression. This arduous regimen affects quality of life, disrupts sleep, and may result in non-compliance with therapy. Enteric-coated cysteamine bitartrate (EC-cysteamine) was developed as a "proof-of-concept" formulation for twice-daily ingestion. Previous reports have shown this therapy to be effective up to a mean of 14 months.

CASE-DIAGNOSIS/TREATMENT

Two subjects (aged 13 and 15 years) received EC-cysteamine for 5-6 years at 60-65 % of their previous total daily dose of immediate-release cysteamine given at 6-h intervals. White blood cell (WBC) cystine levels were monitored every 1-3 months.

CONCLUSION

The administration of EC-cysteamine did not result in any change in mean trough WBC cystine levels or any deterioration in the estimated glomerular filtration rate, thyroid, or liver function, suggesting that delayed-release, twice-daily EC-cysteamine is an effective long-term treatment alternative to immediate-release cysteamine given at 6-h intervals.

Pharmacokinetics of cysteamine bitartrate following intraduodenal delivery

Cysteamine is approved for the treatment of cystinosis and is being evaluated for Huntington's disease and non-alcoholic fatty liver disease. Little is known about the bioavailability and biodistribution of the drug. The aim was to determine plasma, cerebrospinal fluid (CSF), and tissue (liver, kidney, muscle) cysteamine levels following intraduodenal delivery of the drug in rats pretreated and naïve to cysteamine and to estimate the hepatic first-pass effect on cysteamine. Healthy male rats (n = 66) underwent intraduodenal and portal (PV) or jugular (JVC) venous catheterization. Half were pretreated with cysteamine, and half were naïve. Following intraduodenal cysteamine (20 mg/kg), serial blood samples were collected from the PV or the JVC. Animals were sacrificed at specific time points, and CSF and tissue were collected. Cysteamine levels were determined in plasma, CSF, and tissue. The Cmax was achieved in 5-10 min from PV and 5-22.5 min from JVC. The PV-Cmax (P = 0.08), PV-AUC0-t (P = 0.16), JVC-Cmax (P = 0.02) and JVC-AUC0-t (P = 0.03) were higher in naive than in pretreated animals. Plasma cysteamine levels returned to baseline in ≤120 min. The hepatic first-pass effect was estimated at 40%. Peak tissue and CSF cysteamine levels occurred ≤22.5 min, but returned to baseline levels ≤180 min. There was no difference in CSF and tissue cysteamine levels between naïve and pretreated groups, although cysteamine was more rapidly cleared in the pretreated group. Cysteamine is rapidly absorbed from the small intestine, undergoes significant hepatic first-pass metabolism, crosses the blood brain barrier, and is almost undetectable in plasma, CSF, and body tissues 2 h after ingestion. Sustained-release cysteamine may provide prolonged tissue exposure.

The effect of cysteamine bitartrate on adiponectin multimerization in non-alcoholic fatty liver disease and healthy subjects

OBJECTIVE

To determine the effects of cysteamine on adiponectin multimerization in sera of patients with nonalcoholic fatty liver disease (NAFLD).

STUDY DESIGN

Sera from 10 children with biopsy-proven NAFLD treated with cysteamine were assayed for adiponectin multimers at baseline, after 24 weeks of treatment, and again 16 weeks after discontinuing treatment. Pretreatment sera from subjects with NAFLD and from adult controls without NAFLD controls (n = 8) were incubated in cysteamine and multimers were measured 1 hour later. A cysteamine/adiponectin multimer dose-response curve was created.

RESULTS

Following 24 weeks of cysteamine therapy, the mean percentage increase for high, medium (MMW), and low (LMW) molecular weight multimers and total adiponectin from baseline was 53% (P = .02), 19% (P = .02), 29.4% (P = .03), and 49.3% (P = .05), respectively. Levels returned to baseline at 16 weeks after stopping therapy, unlike hepatic transaminase levels which remained low. Sera from 0 week, incubated in cysteamine for 1 hour, showed a significant mean percent increase in LMW adiponectin levels and a mean percent reduction in MMW levels compared with baseline in adults with and without NAFLD.

CONCLUSIONS

Cysteamine impacts adiponectin multimerization. Long-term cysteamine therapy increases levels of all multimers, whereas, in vitro short-term exposure causes a rapid increase in LMW and reduction in MMW multimers in NAFLD and healthy controls. Cysteamine may be a potential therapeutic agent for conditions associated with insulin-resistance, oxidative stress, and depressed adiponectin levels.

A potential new method to estimate tissue cystine content in nephropathic cystinosis

OBJECTIVES

To evaluate intestinal mucosal cystine crystal (CC) load as a way to estimate tissue cystine content in children with cystinosis.

STUDY DESIGN

Intestinal mucosal biopsies were obtained endoscopically from children (ages 2-18 years) with cystinosis. Using a special processing technique, CC within histiocytes were easily visible and enumerable in the mucosal tissue. Mean CC counts, calculated from stomach and duodenum combined (CC-GD), were correlated with duration of cysteamine treatment, estimated glomerular filtration rate (eGFR), and mean white blood cells (WBC) cystine levels.

RESULTS

Seventeen subjects (6 male) were enrolled in 2 studies from 2001 and 2003. The CC-GD count (mean 12.5 ± 1.41 crystals/histiocyte) was lower than the colonic crystal count (mean 23.6 ± 3.38, P = .0031). Nine of 17 subjects underwent repeated endoscopy 2 years later and the trend for CC-GD was to decrease over time (P = .065). Biopsies, however, were never completely depleted of CC. In subjects who were diagnosed before age 18 months, the percent change from baseline of both eGFR and CC-GD were inversely correlated (P = .026). Mean WBC cystine levels were positively correlated with CC-GD (P = .023).

CONCLUSIONS

CC are easily visible in the intestinal mucosa. CC-GD counts appear to correlate with eGFR and may help monitor response to treatment. Even when mean WBC cystine levels are low, the mucosal CC are not depleted suggesting that tissue cysteamine levels may not achieve therapeutic efficacy.

A randomized controlled crossover trial with delayed-release cysteamine bitartrate in nephropathic cystinosis: effectiveness on white blood cell cystine levels and comparison of safety

BACKGROUND AND OBJECTIVES

Immediate-release cysteamine bitartrate (Cystagon; Mylan Pharmaceuticals, Canonsburg, PA) may prevent or delay kidney transplantation and other serious outcomes in patients with cystinosis, but has never been subjected to a prospective clinical trial. Cystagon efficacy requires strict lifelong dosing every 6 hours. Such a dosing schedule and Cystagon-associated side effects are often cited by patients as reasons for nonadherence.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This open-label, randomized, controlled, crossover trial was powered to show that a new delayed-release formulation of cysteamine bitartrate, RP103, taken every 12 hours, was noninferior to Cystagon for maintenance of white blood cell (WBC) cystine at levels associated with optimal outcomes in the disease.

RESULTS

Forty-three patients were randomized. Using a mixed-effects statistical analysis model, the least-squares mean peak value of WBC cystine level was 0.62±0.05 nmol 1/2 cystine/mg protein after 12 hours under RP103 and 0.54±0.05 nmol 1/2 cystine/mg protein after 6 hours under Cystagon, a difference of 0.08±0.04 nmol 1/2 cystine/mg protein (95.8% confidence interval, 0-0.16). The average steady-state total daily dose of RP103 was 82% of the incoming steady-state total daily dose of Cystagon. There were three-fold more gastrointestinal side effects compared with using Cystagon.

CONCLUSIONS

A new delayed-release Q12H formulation of cysteamine bitartrate is not inferior to the Q6H formulation (Cystagon) in maintaining low WBC cystine levels in patients with cystinosis but at a lower total daily dose.

Cysteamine suppresses invasion, metastasis and prolongs survival by inhibiting matrix metalloproteinases in a mouse model of human pancreatic cancer

Background

Cysteamine, an anti-oxidant aminothiol, is the treatment of choice for nephropathic cystinosis, a rare lysosomal storage disease. Cysteamine is a chemo-sensitization and radioprotection agent and its antitumor effects have been investigated in various tumor cell lines and chemical induced carcinogenesis. Here, we investigated whether cysteamine has anti-tumor and anti-metastatic effects in transplantable human pancreatic cancer, an aggressive metastatic disease.

Methodology/Principal Findings

Cysteamine's anti-invasion effects were studied by matrigel invasion and cell migration assays in 10 pancreatic cancer cell lines. To study mechanism of action, we examined cell viability and matrix metalloproteinases (MMPs) activity in the cysteamine-treated cells. We also examined cysteamine's anti-metastasis effect in two orthotopic murine models of human pancreatic cancer by measuring peritoneal metastasis and survival of animals. Cysteamine inhibited both migration and invasion of all ten pancreatic cancer cell lines at concentrations (<25 mM) that caused no toxicity to cells. It significantly decreased MMPs activity (IC₅₀ 38–460 µM) and zymographic gelatinase activity in a dose dependent manner in vitro and in vivo; while mRNA and protein levels of MMP-9, MMP-12 and MMP-14 were slightly increased using the highest cysteamine concentration. In vivo, cysteamine significantly decreased metastasis in two established pancreatic tumor models, although it did not affect the size of primary tumors. Additionally, cysteamine prolonged survival of mice in a dose-dependent manner without causing any toxicity. Similar to the in vitro results, MMP activity was significantly decreased in animal tumors treated with cysteamine. Cysteamine had no clinical or preclinical adverse effects in the host even at the highest dose.

Conclusions/Significance

Our results suggest that cysteamine, an agent with a proven safety profile, may be useful for inhibition of metastasis and prolonging the survival of a host with pancreatic cancer.

Pharmacokinetics of enteric-coated cysteamine bitartrate in healthy adults: a pilot study

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Cysteamine bitartrate is taken lifelong, every 6 h and for the treatment of cystinosis. Recent studies using cysteamine for for other diseases such as neurodegenerative disorders adopt the same dosing regimen for cysteamine. Regular cysteamine bitartrate (Cystagon) may cause upper gastrointestinal symptoms in some patients.

WHAT THIS STUDY ADDS

This is the only study that provides pharmacokinetic data for cysteamine delivered in an enteric-release preparation in normal subjects. EC-cysteamine is very well tolerated and does not cause increased gastrin concentrations, even at relatively high doses. EC-cysteamine at the higher dose results in better drug uptake as measured by Cmax and AUC and is more likely to be effective.

AIMS

Cysteamine bitartrate (Cystagon) is the approved treatment for cystinosis. Poor compliance and patient outcome may occur because the drug needs to be taken every 6 h and in some patients causes gastrointestinal symptoms due to hypergastrinaemia. A formulation of cysteamine requiring twice daily ingestion would improve the quality of life for these patients. This study compares the pharmacokinetics and gastrin production following cysteamine bitartrate non-enteric-coated and cysteamine bitartrate enteric-coated in normal healthy subjects.

METHODS

Enteric-coated cysteamine was prepared. Following single doses of cysteamine bitartrate non-enteric-coated 450 mg and cysteamine bitartrate enteric-coated 450 mg and 900 mg, serial plasma cysteamine and gastrin concentrations were measured. Two subjects also received cysteamine bitartrate non-enteric-coated 900 mg. Gastrointestinal (GI) symptoms were recorded.

RESULTS

Six healthy adults (mean age 20.7 years, range 18-24 years; mean weight 59.3 kg) received drug. All post-dose gastrin concentrations were within the normal range (<100 pg ml(-1)). The tmax following cysteamine bitartrate non-enteric-coated (mean and SD is 75+/-19 min) was shorter than cysteamine bitartrate enteric-coated (220+/-74 min) (P=0.001), but only the Cmax and AUC estimates following 900 mg cysteamine bitartrate enteric-coated were significantly greater than any of the other preparations or doses (P<0.05). One patient had GI symptoms following both 900 mg cysteamine bitartrate non-enteric-coated and cysteamine bitartrate enteric-coated.

CONCLUSION

Although patient numbers were low, single high doses of cysteamine bitartrate enteric-coated were better tolerated than similar doses of cysteamine bitartrate non-enteric-coated in the healthy subjects and all had normal gastrin concentrations. The delayed tmax following cysteamine bitartrate enteric-coated suggested that the cysteamine was released enterically.

Long-term treatment of cystinosis in children with twice-daily cysteamine

OBJECTIVE

Cystinosis causes renal and other organ failure. Treatment with 6-hourly cysteamine bitartrate (Cystagon, Mylan, Morgantown, West Virginia) reduces intracellular cystine and the rate of organ deterioration. A recent study showed that an enteric-release cysteamine required less frequent daily dosing. This report describes the long-term use of enteric-coated (EC) cysteamine bitartrate (Cystagon) in children with cystinosis.

STUDY DESIGN

After a pharmacokinetic and pharmacodynamic study of EC-cysteamine in children with cystinosis, 5 patients remained on twice-daily treatment. White blood cell cystine levels were measured 12 hours after ingestion every 4 to 8 weeks. These levels were then compared with the patient's previous 6-h post-dose levels taken while on regular cysteamine bitartrate before entering the study. Blood chemistry was also measured.

RESULTS

Five children with cystinosis (mean age, 9 years; range, 8 to 17 years) who previously took cysteamine bitartrate (mean dose, 47 mg/kg body wt), received EC-cysteamine for 10 to 27 months (mean dose, 25 mg/kg body wt) and had mean white blood cell cystine levels of 0.77 and 0.71 nmol half-cystine/mg protein, respectively. During the study period, patients maintained adequate growth and there was no significant deterioration in renal or thyroid function. Two children were required to restart acid suppression after 6 months on EC-cysteamine therapy.

CONCLUSIONS

Long-term, twice-daily EC-cysteamine, given at approximately 60% of the previous daily dose of cysteamine bitartrate, was effective at maintaining white blood cell cystine levels within a satisfactory range. There was no significant deterioration in renal or thyroid function.

Twice-daily cysteamine bitartrate therapy for children with cystinosis

OBJECTIVE

Cystinosis causes renal and other organ failure. Regular 6-hourly cysteamine bitartrate (Cystagon; Mylan, Morgantown, West Virginia) reduces intracellular cystine and the rate of organ deterioration. A formulation of cysteamine requiring less frequent dosing may improve compliance and possibly patient outcome.

METHODS

Enteric-release cysteamine was prepared. For a period of 1 month, patients received their regular cysteamine dose every 6 hours (stage I). The patients then underwent pharmacokinetic and pharmacodynamic studies following washout periods using single-doses of cysteamine and enteric-release cysteamine (stage II). Finally, the patients commenced regular enteric-release cysteamine therapy (stage III). Weekly trough white blood cell (WBC) cystine levels were recorded.

RESULTS

Seven children with cystinosis (mean age, 11.8 years; range, 8-17 years) who received cysteamine and enteric-release cysteamine (mean dose, 45 and 28.8 mg/kg body weight/day, respectively) had mean WBC cystine levels of 0.7+/-0.3 and 0.41+/-0.22 nmol half-cystine/mg protein in study stages I and III, respectively. Study stage II showed that the mean time (T(max)) to reach the maximum plasma cysteamine level (C(max)) was longer for enteric-release cysteamine than for cysteamine (176 minutes vs 60 minutes; P=.001), but the mean C(max) at the same dose was similar. Mean serum gastrin levels were similar after ingestion of cysteamine and enteric-release cysteamine.

CONCLUSIONS

Twelve-hour enteric-release cysteamine, given at approximately 60% of the previous daily dose of cysteamine, was effective in maintaining trough WBC cystine levels within a satisfactory range.

A symptom scoring tool for identifying pediatric patients with eosinophilic esophagitis and correlating symptoms with inflammation

BACKGROUND

Eosinophilic esophagitis (EE) is an increasingly recognized allergic disease entity that is difficult to distinguish clinically from other causes of esophagitis, especially gastroesophageal reflux disease (GERD). To our knowledge, there are no prospectively analyzed or validated symptom scoring tools for pediatric patients with EE and no prospective evaluation correlating symptoms with tissue inflammation.

OBJECTIVES

To prospectively analyze a symptom scoring tool's ability to distinguish pediatric patients with EE from those with GERD and from control patients with and without allergies and to correlate symptoms with tissue inflammation.

METHODS

A prospective study of a symptom scoring tool given to patients with EE (n = 35 not receiving EE targeted therapy), patients with GERD (n = 27 not undergoing acid suppression), allergic control patients (n = 24), and nonallergic control patients (n = 14) at an academic pediatric hospital. Histology and endoscopy scores were correlated with symptom complaints.

RESULTS

The total symptom score was higher among patients with EE (mean, 6.51; 95% confidence interval [CI], 5.50-7.53) and GERD (mean, 5.44; 95% CI, 4.64-6.25) than in allergic (mean, 0.92; 95% CI, 0.28-1.55) and nonallergic (mean, 1.00; 95% CI, 0.40-1.60) patients (P < .001). Patients with EE and GERD complained of more nausea/vomiting, abdominal pain, heartburn/regurgitation, and nocturnal awakening than control groups (P < .001). Only dysphagia (mean, 0.9 [95% CI, 0.7-1.2] in EE patients vs 0.4 [95% CI, 0.2-0.7] in GERD patients) and anorexia/early satiety (mean, 1.4 [95% CI, 1.2-1.6] in EE patients vs 0.8 [95% CI, 0.5-1.1] in GERD patients) discriminate EE from GERD (P < .01). These symptoms also correlated with the severity of histologic and endoscopic findings (P < .05).

CONCLUSION

Dysphagia and anorexia/early satiety identify pediatric patients with EE and correlate symptoms with tissue inflammation.

Nephropathic cystinosis: late complications of a multisystemic disease

Cystinosis is a rare autosomal recessive disorder due to impaired transport of cystine out of cellular lysosomes. Its estimated incidence is 1 in 100,000 live births. End-stage renal disease (ESRD) is the most prominent feature of cystinosis and, along with dehydration and electrolyte imbalance due to renal tubular Fanconi syndrome, has accounted for the bulk of deaths from this disorder. Prior to renal transplantation and cystine-depleting therapy with cysteamine for children with nephropathic cystinosis, their lifespan was approximately 10 years. Now, cystinotic patients have survived through their fifth decade, but the unremitting accumulation of cystine has created significant non-renal morbidity and mortality. In this article we review the classic presentation of nephropathic cystinosis and the natural history, diagnosis, and treatment of the disorder's systemic involvement. We also emphasize the role of oral cysteamine therapy in preventing the late complications of cystinosis.

Intravenous delivery of cysteamine for the treatment of cystinosis: association with hepatotoxicity

Nephropathic cystinosis is a lysosomal storage disorder, which, if untreated, results in renal failure by age 10 years. Oral cysteamine has been shown to preserve renal function in these patients. In this study, a 2-year-old girl with nephropathic cystinosis and severe gastrointestinal dysmotility was treated with intravenous (i.v.) administration of cysteamine hydrochloride (HCl). This is only the second report of long-term i.v. cysteamine therapy for nephropathic cystinosis. Unlike the treatment in the previous case, however, treatment in our patient was limited by liver toxicity.

Hematological manifestations of nephropathic cystinosis

Pancytopenia is an uncommon manifestation of cystinosis, a congenital lysosomal storage disease. We describe a 34-year-old patient with nephropathic cystinosis with multisystem involvement who developed progressive bone marrow failure after renal transplantation. Bone marrow examination demonstrated widespread deposition of cystine crystals in histiocytes and in the background. We review the literature on the hematologic manifestations of cystinosis and discuss the available treatment options for patients with bone marrow failure secondary to cystine accumulation. The availability of effective oral therapy and the limited activity of hematopoietic growth factors in these patients highlight the importance of bone marrow examination early in the evaluation of cystinosis patients with abnormal blood counts.

Pharmacokinetics of cysteamine bitartrate following gastrointestinal infusion

AIMS

Although cysteamine was first used in the treatment of cystinosis in 1976 and approved by the FDA as cysteamine bitartrate (Cystagon) in 1994, surprisingly little pharmacological data are available for this compound. Cysteamine and its related drugs are currently being evaluated for the treatment of Huntington's and Parkinson's disease. The aim of te study was to understand the pharmacokinetics of cysteamine bitartrate following gastrointestinal infusion.

METHOD

Cysteamine bitartrate was delivered through a naso-enteric catheter into the stomach (n = 8), small intestine (n = 8) and caecum (n = 4) of normal subjects. Plasma cysteamine concentrations were determined using LC-MS/MS.

RESULTS

The rate and extent of drug absorption were assessed by comparing AUC(0, infinity), C(max) and t(max), among the gastrointestinal infusion sites. Total cysteamine exposure, expressed as area under the curve (AUC(0, infinity)) was greatest when the drug was infused into the small intestine (4331.3 +/- 1907.6 min x microM) followed by stomach (3901.9 +/- 1591.9 min x microM) and caecum (3141.4 +/- 1627.6 min x microM). Cysteamine infusion into the small intestine resulted in the most rapid rise to maximal plasma concentrations (t(max) = 21 +/- 0.56 min); t(max) was delayed to 50 +/- 26 min and 64 +/- 26 min after gastric and caecal infusion, respectively. The maximum cysteamine plasma concentration (C(max)) was reached after infusion of the drug into the small intestine (51 +/- 21 microM), which was higher than plasma C(max) concentrations after gastric (39 +/- 16 microM) and caecal infusion (23 +/- 15 microM).

CONCLUSIONS

The pharmacokinetic data generated help extend our understanding of cysteamine.