Combination of 5% cysteamine and 4% nicotinamide in melasma: Efficacy, tolerability, and safety

BACKGROUND

Melasma is a chronic dermatosis that impacts the patient's quality of life and can present considerable challenges in terms of effective treatment.

OBJECTIVE

To evaluate the effectiveness, tolerability, and safety of 5% cysteamine combined with 4% nicotinamide in female subjects with melasma.

METHODS

This single-center, single-arm, prospective, open-label study evaluated patients with melasma using a combination cream of 5% cysteamine and 4% nicotinamide in a progressive regimen (60 min in the first month, 120 min in the second month, and 180 min in the third month).

RESULTS

Overall, 35 treated subjects exhibited reduced modified Melasma Area and Severity Index (mMASI) (p < 0.001) and decreased MelasQoL scores (p < 0.001), accompanied by improved brightness, luminosity, homogeneity, and spot intensity (p < 0.001). Photographic and colorimetric analysis revealed smaller spots and improved homogeneity.

LIMITATIONS

Adherence to progressive daily treatment could not be evaluated long-term.

CONCLUSION

A combination cream comprising 5% cysteamine and 4% nicotinamide was effective, tolerable, and safe for treating melasma.

Cysteamine Isobionic-Amide Complex Versus Kligman's Formula for the Treatment of Melasma: Equal Efficacy and Rapid Onset of Action

BACKGROUND

Modified Kligman's formula (mKF) is the gold standard treatment for melasma; however, its prolonged use is not recommended due to side effects. Cysteamine is a potent, safe, and effective depigmenting agent. Here, we conducted a double-blind, randomized, and placebo-controlled clinical trial to assess the efficacy of cysteamine isobionic-amide -- a complex with enhanced depigmenting efficacy -- and compared it to mKF for the treatment of melasma.

METHODS

This study involved a total of 80 patients divided into 3 groups: cysteamine-isobionic amide, placebo, or mKF. The modified Melasma Area Severity Index (mMASI) score and spectrophotometric evaluation were conducted at baseline, week 4, week 8, and week 16. Dermatological assessment, patients’ feedback, and satisfaction including quality-of-life scores were also collected.

RESULTS

At week 4, cysteamine isobionic-amide and mKF groups showed an equivalent onset of action in terms of mMASI and skin pigmentation contrast reduction. The 2 groups significantly reduced melasma severity and improved the overall skin condition with a comparable efficacy at week 16. Quality of life of melasma patients was significantly improved in the cysteamine isobionic-amide group at week 8 and further at week 16 (P<0.001) compared to the mKF group. Patients’ feedback and satisfaction were higher with the cysteamine isobionic-amide product compared to mKF.

CONCLUSION

Cysteamine isobionic-amide provided a rapid onset of action and was as effective as the mKF for the treatment of melasma. The data suggest that cysteamine isobionic-amide could potentially be an acceptable alternative to mKF for the long-term treatment of melasma. J Drugs Dermatol. 2024;23(2):9-16.  doi:10.36849/JDD.7428.

The effects of transitioning from immediate release to extended release cysteamine therapy in Norwegian patients with nephropathic cystinosis: a retrospective study

BACKGROUND

Nephropathic cystinosis is a rare lysosomal storage disorder in which accumulation of cystine and formation of crystals particularly impair kidney function and gradually lead to multi-organ dysfunction. Lifelong therapy with the aminothiol cysteamine can delay the development of kidney failure and the need for transplant. The purpose of our long-term study was to explore the effects of transitioning from immediate release (IR) to extended release (ER) formulation in Norwegian patients in routine clinical care.

METHODS

We retrospectively analysed data on efficacy and safety in 10 paediatric and adult patients. Data were obtained from up to 6 years before and 6 years after transitioning from IR- to ER-cysteamine.

RESULTS

Mean white blood cell (WBC) cystine levels remained comparable between the different treatment periods (1.19 versus 1.38 nmol hemicystine/mg protein) although most patients under ER-cysteamine underwent dose reductions. For the non-transplanted patients, the mean estimated glomerular filtration rate (eGFR) change/year was more pronounced during ER-treatment (- 3.39 versus - 6.80 ml/min/1.73 m2/year) possibly influenced by individual events, such as tubulointerstitial nephritis and colitis. Growth measured by Z-height score tended to develop positively. Four of seven patients reported improvement of halitosis, one reported unchanged and two reported worsened symptoms. Most adverse drug reactions (ADRs) were of mild severity. One patient developed two serious ADRs and switched back to IR-formulation.

CONCLUSIONS

The results from this long-term retrospective study indicate that switching from IR- to ER-cysteamine was feasible and well tolerated under routine clinical practice. ER-cysteamine allowed satisfactory disease control over the long period considered. A higher resolution version of the Graphical abstract is available as Supplementary information.

[Cystinosis: From the gene identification to the first gene therapy clinical trial]

Cystinosis is an autosomal recessive metabolic disease characterized by lysosomal accumulation of cystine in all the cells of the body. Infantile cystinosis begins in infancy by a renal Fanconi syndrome and eventually leads to multi-organ failure, including the kidney, eye, thyroid, muscle, and pancreas, eventually causing premature death in early adulthood. The current treatment is the drug cysteamine that only delays the progression of the disease. We identified the gene involved, CTNS, and showed that the encoded protein, cystinosin, is a proton-driven cystine transporter. We generated a mouse model of cystinosis, the Ctns-/- mice, that recapitulates the main disease complications. The goal was next to develop a gene therapy approach for cystinosis. We used bone marrow stem cells as a vehicle to bring the healthy CTNS gene to tissues, and we showed that wild-type hematopoietic stem and progenitor cell (HSPC) transplantation led to abundant tissue integration of bone marrow-derived cells, significant decrease of tissue cystine accumulation and long-term kidney, eye and thyroid preservation. We then developed an autologous transplantation approach of HSPCs modified ex vivo using a lentiviral vector to introduce a functional CTNS cDNA, and showed its efficacy in Ctns-/- mice. We conducted the pharmacology/toxicology studies, developed the manufacturing process using human CD34+ cells, and design the clinical trial. We received Food and Drug Administration (FDA)-clearance to start a phase 1/2 clinical trial for cystinosis in December 2018. Six patients have been treated so far. In this review, we describe the path to go from the gene to a gene therapy approach for cystinosis.

Cystinosis: Status of research and treatment in India and the world

Cystinosis is an autosomally inherited rare genetic disorder in which cystine accumulates in the lysosome. The defect arises from a mutation in the lysosomal efflux pump, cystinosin (or CTNS). Despite the disease being known for more than a century, research, diagnosis, and treatment in India have been very minimal. In recent years, however, some research on cystinosis has been carried out on understanding the pathophysiology and in the development of a humanized yeast model for interrogating the CTNS protein. There has also been a greater awareness of the disease that has been facilitated by the formation of the Cystinosis Foundation of India just over a decade ago. Awareness among primary physicians is critical for early diagnosis, which in turn is critical for proper treatment. Eight different mutations have been observed in cystinosis patients in India, and the mutation spectrum seems different to what has been seen in the US and Europe. Despite these positive developments, there are immense hurdles still to be surmounted. This includes ensuring that the diagnosis is done sooner, making cysteamine more easily available, and, also for the future, to make accessible the promise of gene therapy to cystinosis patients.

Is cysteamine use effective in the treatment of melasma? A systematic review and meta-analysis

Melasma is a recurrent hypermelanosis disorder characterized by the appearance of brownish and symmetrical spots on the skin. It affects the quality of life and is resistant to available treatment approaches. Cysteamine has been reported as a promising depigmenting agent for melasma treatment and following formulation enhancement, its use is being reported. This review aimed to evaluate the efficacy of the use of depigmenting formulations containing 5% cysteamine in the treatment of patients with melasma. A systematic search was performed in PubMed, Science Direct, and Scielo databases until December 27, 2021, based on criteria selected by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Statistical analysis was performed with Review Manager 5.4 software. The risk of bias was assessed using the Cochrane Risk of Bias Tool for Randomized Trials. A total of six studies containing 120 melasma patients treated with 5% cysteamine were included in this meta-analysis. The meta-analysis demonstrated that 5% cysteamine is effective for the treatment of patients with melasma (MD 6.26 [95% CI 3.68-8.83], p < 0.0001, I²  = 86%). In this review, through meta-analysis allows concluding that 5% cysteamine is effective in the treatment of melasma and presents a low probability of side or adverse effects.

Oral cysteamine as an adjunct treatment in cystic fibrosis pulmonary exacerbations: An exploratory randomized clinical trial

BACKGROUND

Emerging data suggests a possible role for cysteamine as an adjunct treatment for pulmonary exacerbations of cystic fibrosis (CF) that continue to be a major clinical challenge. There are no studies investigating the use of cysteamine in pulmonary exacerbations of CF. This exploratory randomized clinical trial was conducted to answer the question: In future pivotal trials of cysteamine as an adjunct treatment in pulmonary exacerbations of CF, which candidate cysteamine dosing regimens should be tested and which are the most appropriate, clinically meaningful outcome measures to employ as endpoints?

METHODS AND FINDINGS

Multicentre double-blind randomized clinical trial. Adults experiencing a pulmonary exacerbation of CF being treated with standard care that included aminoglycoside therapy were randomized equally to a concomitant 14-day course of placebo, or one of 5 dosing regimens of cysteamine. Outcomes were recorded on days 0, 7, 14 and 21 and included sputum bacterial load and the patient reported outcome measures (PROMs): Chronic Respiratory Infection Symptom Score (CRISS), the Cystic Fibrosis Questionnaire-Revised (CFQ-R); FEV1, blood leukocyte count, and inflammatory markers. Eighty nine participants in fifteen US and EU centres were randomized, 78 completed the 14-day treatment period. Cysteamine had no significant effect on sputum bacterial load, however technical difficulties limited interpretation. The most consistent findings were for cysteamine 450mg twice daily that had effects additional to that observed with placebo, with improved symptoms, CRISS additional 9.85 points (95% CI 0.02, 19.7) p = 0.05, reduced blood leukocyte count by 2.46x109 /l (95% CI 0.11, 4.80), p = 0.041 and reduced CRP by geometric mean 2.57 nmol/l (95% CI 0.15, 0.99), p = 0.049.

CONCLUSION

In this exploratory study cysteamine appeared to be safe and well-tolerated. Future pivotal trials investigating the utility of cysteamine in pulmonary exacerbations of CF need to include the cysteamine 450mg doses and CRISS and blood leukocyte count as outcome measures.

CLINICAL TRIAL REGISTRATION

NCT03000348; www.clinicaltrials.gov.

Effect of Pithecellobium dulce (Roxb.) Benth. fruit extract on cysteamine induced duodenal ulcer in rats

The edible fruits of Pithecellobium dulce (Roxb.) Benth. are traditionally used for various gastric complications in India. Here, we investigated the antiulcer activity of hydroalcoholic fruit extract of P. dulce (HAEPD) by applying cysteamine induced duodenal ulcer model in rats. Duodenal ulcer was induced in male albino Wistar rats by oral administration of cysteamine @ 420 mg/kg body wt. as a single dose. The rats were pre-administered orally with HAEPD @ 200 mg/kg body wt. for 30 days prior to ulcer induction. Rats pre-administered with ranitidine @ 30 mg/kg body wt. served as reference drug control. Ulcer score, thiobarbituric acid reactive substances (TBARS), glycoproteins, superoxide dismutase, catalase and glutathione peroxidase and reduced glutathione levels were measured in the duodenum. Rats pre-administered with the HAEPD showed significantly reduced ulcer score comparable to that of ranitidine pretreated rats. The co-administration of HAEPD lowered the TBARS level and also restored the levels of glycoproteins, enzymatic and non-enzymatic antioxidants. Histopathological observations confirmed the presence of inflammation, necrosis and hemorrhagic spots in the duodenum of ulcer control rats which were significantly reduced due to HAEPD treatment. No abnormal alterations were observed in normal rats treated with HAEPD at the dosage studied. The results demonstrated antioxidant and cytoprotective nature of P. dulce, and thereby its significant anti ulcer property.

[Glycoproteins of mucus of gastric and duodenal wall surface during ulcerogenesis and the impact of fenugreek]

The comparative evaluation of qualitative and quantitative composition of glycoproteins of gastric and duodenal wall surface layer of protective mucus in the normal, at the modeling of ulcers in rats and at the introduction to animals with ulcerative lesions of fenugreek extract carried out. It was shown in control (normally) the general level of glycosylation of glycoproteins gastric mucus is 1.7 times more than the duodenum. Under acute stress model ulceration in the stomach mucus decrease in hexosamine (1.4 times), galactose (2.2 times), fucose (1.3-fold) and an increase in NANA (3.6 times) observed. Under cysteamine model ulceration in duodenal mucus increase galactose (2.7 times), NANA (2.4 times), fucose (1.8-fold) but significant decrease in the amount of hexosamines 3 times compared to the control occurred. It was proved the protective effect of fenugreek extract to the wall surface mucus of the stomach and duodenum mucosa under conditions modeling ulceration in rats.

Cysteamine: Ehlers-Danlos syndrome

Adverse effect on connective tissue linked to drug for a rare disease.

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.

The origin of halitosis in cystinotic patients due to cysteamine treatment

INTRODUCTION

Cystinosis is a rare autosomal recessive disorder characterized by the intralysosomal accumulation of cystine. Cysteamine removes cystine from the lysosome and slows down the progression of the disease. One of its side effects is the induction of halitosis, which can interfere with patients' willingness to comply with cysteamine treatment.

OBJECTIVE

To identify breath sulphur compounds causing halitosis induced by cysteamine therapy in patients with cystinosis.

STUDY DESIGN

After the ingestion of 15mg/kg cysteamine whole blood (n=4), urine (n=4) and breath (n=8) volatile sulphur compounds levels were measured every 60min over a 360min period by gas chromatography and the cysteamine plasma concentrations (n=4) were measured by high-performance liquid chromatography.

RESULTS

The expired air of cystinotic patients contained elevated concentrations of methanethiol (MT, median maximum value 0.5 (range 0-11)nmol/L) and, in particular, dimethylsulphide (DMS, median maximum value 15 (range 2-83)nmol/L). DMS concentrations higher than 0.65nmol/L are known to cause halitosis. Maximal plasma values of cysteamine (median 46 (range 30-52)micromol/L) preceded those of MT and DMS, confirming that cysteamine is converted to MT and DMS. Less than 3% of the amount of cysteamine ingested was excreted as MT and DMS via expired air and 0.002% via urine.

CONCLUSION

Halitosis induced by cysteamine intake is caused by DMS and to a lesser extent by MT, excreted via the expired air. Further studies should focus on the possibilities of reducing the formation of these volatile sulphur compounds or masking their odour, which would improve the rates of compliance with cysteamine treatment.

Effects of Cysteamine on Growth Performance, Digestive Enzyme Activities, and Metabolic Hormones in Broilers

A total of 600 avian male broilers at the age of 1 d were used to investigate the effects of cysteamine (CSH) on growth performance, digestive enzyme activities, and concentrations of serum hormones. The broilers received the same basal diets, with CSH added at 0 (control), 60, 90, 120, or 150 mg/kg. The feeding program consisted of a starter diet until 21 d and a grower diet until 42 d. The broilers with addition of CSH at 60 or 90 mg/kg had significantly higher growth rates during d 1 to 21 or d 21 to 42 compared with the control, respectively. However, adding 150 mg of CSH/kg significantly suppressed the growth of broilers. Adding 60 mg of CSH/kg significantly increased the activities of protease, amylase, and lipase in the pancreas and small intestinal contents during d 1 to 21, and the activities of protease and amylase in the small intestinal contents during d 21 to 42. Adding 90 mg of CSH/kg significantly increased the activities of lipase during d 1 to 21 and protease, amylase, and lipase during d 21 to 42 in small intestines. The activities of digestive enzymes during the whole period were suppressed by adding 150 mg of CSH/kg. The concentration of serum thyroxine was higher in the CSH-added birds during the whole period, whereas serum triiodothyronine was higher only during d 1 to 21 compared with the control. These findings indicate that low doses of dietary CSH may improve the growth performance and the activities of the digestive enzyme, but high doses of CSH appear to be detrimental to growth and digestion.

Esomeprazole therapy for gastric acid hypersecretion in children with cystinosis

Oral cysteamine therapy prevents natural disease progression in children with cystinosis, but it may cause severe gastrointestinal (GI) symptoms through gastric acid-hypersecretion. The purpose of this study was to assess the value of esomeprazole in controlling cysteamine-induced acid-hypersecretion and GI symptoms in children with cystinosis. Subjects underwent upper GI endoscopy and biopsy, serum gastrin and cysteamine measurements as well as acid secretion studies (basal, maximal and peak acid output, BAO, MAO, PAO) before and during esomeprazole therapy. A symptom score (maximum 14 points) was devised to monitor symptoms. Twelve children (mean age 5.8 years) were studied. Cysteamine ingestion resulted in mean MAO and PAO significantly higher than mean BAO, both before and during esomeprazole therapy. PAO was usually within 60 min of cysteamine ingestion. Esomeprazole therapy significantly reduced MAO (P<0.01) and PAO (P<0.01). The mean symptom score fell from 6.4 to 0.7 (P<0.0001) during esomeprazole therapy. The mean final dose of esomeprazole was 1.7 mg/kg per day (range 0.7 mg/kg per day to 2.75 mg/kg per day). Plasma cysteamine levels were not affected by acid-suppression therapy. One child had multi-nucleated parietal cells. Cysteamine-induced gastric acid-hypersecretion and GI symptoms are dramatically reduced with esomeprazole therapy. Esomeprazole does not alter cysteamine absorption and is very well tolerated in children.

Permanent-wave dermatitis: contact allergy to cysteamine hydrochloride

Cysteamine hydrochloride (CHC) is a newly recognized sensitizer found in permanent-wave solutions. We report the case of a hairdresser who was found to be allergic to CHC. Our allergic patient was patch-tested to various chemicals found in permanent-wave solutions, including CHC (1.0% in petrolatum). Patch-test reactions were positive to CHC, glyceryl thioglycolate, diglyceryl thioglycolate, p-phenylenediamine (PPD), and PPD through a piece of latex glove. Sixty-four controls to CHC (1.0% in petrolatum) had negative results. Household-weight latex gloves were protective against CHC allergy. Persons with CHC-waved hair were not allergic. CHC contained in "neutral" permanent-wave preparations has been used in American beauty salons since 1993. We briefly discuss the introduction and significance of CHC in permanent waves.

The evaluation and treatment of gastrointestinal disease in children with cystinosis receiving cysteamine

OBJECTIVES

Cysteamine prevents organ damage in children with cystinosis, but may cause gastrointestinal (GI) symptoms. In this study we evaluated the nature of GI disease, and the value of omeprazole in controlling GI symptoms in these children.

STUDY DESIGN

Upper GI disease was evaluated with endoscopy, gastrin levels, and acid secretion studies after oral administration of cysteamine, before and after 16 weeks of therapy with omeprazole. A symptom score was devised.

RESULTS

Eleven children (mean age, 5.7 years) were studied. After cysteamine ingestion, before and after omeprazole therapy, the mean maximum acid output was significantly higher than the mean basal acid output. The maximum acid output was measured within 60 minutes of cysteamine ingestion and was reduced by omeprazole therapy (P<.01). The mean peak gastrin level was 30 minutes postcysteamine and was higher than baseline (P<.01). The initial mean symptom score (maximum score, 14) was 6.9 and fell to 0.7 (P<.0001) after 16 weeks of omeprazole therapy. At endoscopy, two children had diffuse gastric nodularity, and nearly all had cystine crystal deposits.

CONCLUSIONS

GI symptoms in children with cystinosis receiving cysteamine are often acid-mediated and improve with omeprazole. Cystine crystals were detected in the GI tract and may signify inadequate treatment with cysteamine.

A multicentre randomised double masked clinical trial of a new formulation of topical cysteamine for the treatment of corneal cystine crystals in cystinosis

AIM

To evaluate the safety and efficacy of a new topical cysteamine formulation, stable at room temperature, for the treatment of corneal cystine crystals in cystinosis.

METHODS

20 study subjects were enrolled in the safety study and 16 in the efficacy study. Both studies were randomised and double blind. The primary outcome for the safety study was the occurrence of predefined serious adverse reactions over 6 months and for the efficacy study the reduction of corneal cystine crystal score (CCCS) by 1.00 or more units on photographs graded by a reading centre using a standardised protocol.

RESULTS

No study subject developed any serious adverse reactions. In the efficacy study, 47% of eyes receiving the standard formulation experienced a reduction in the CCCS of >/=1.00 after 1 year, while 7% of eyes on the new formulation experienced such a decrease (p=0.04).

CONCLUSION

Although no serious adverse reactions were observed with either formulation, the new formulation was not as effective as the standard formulation.

Review article: transcription factors and growth factors in ulcer healing

This review is focused on recent investigations demonstrating a pharmacological and pathophysiologic role in gastroduodenal ulceration for growth factors such as basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF), as well as for transcription factors. Our experiments revealed accelerated healing, without decreased gastric acid secretion, of chronic cysteamine-induced duodenal ulcers in rats treated daily for 3 weeks with intragastric administration of bFGF, PDGF or VEGF. Our recent studies also indicate a pathophysiological role of endogenous growth factors in the natural history of experimental duodenal ulcer development and healing. More recently, we investigated the genetic regulation of these growth factors in experimental duodenal ulceration. Since gene expression is most effectively controlled by transcription factors, proteins that bind to cis-acting elements of DNA and guide the binding of polymerase II to start the transcription of specific mRNA, we tested the hypothesis that the expression of IEGs and their transcription factor products, such as Egr-1 and Sp1, might precede the increased synthesis of bFGF, PDGF and VEGF in duodenal ulcer healing. Indeed, the duodenal ulcerogen cysteamine, but not its nonulcerogen and toxic analogue ethanolamine, rapidly increased duodenal (but not gastric) mucosal levels of ET-1, which was followed by enhanced expression of Egr-1 and a decrease in Sp1 in the preulcerogenic stage of duodenal ulceration. These changes in levels of ET-1 and expression of transcription factors were also accompanied by increased expression of the CDK inhibitor p21. Thus, not only growth factors such as bFGF, PDGF and VEGF, but also transcription factors such as Egr-1 and Sp1 and the cell cycle regulator p21, may play a role in the natural history of experimental duodenal ulceration.

Cysteamine: new preparation. Chronic treatment of cystinosis

(1) Cysteamine bitartrate (also known as mercaptamine) is marketed for the treatment of cystinosis, a rare hereditary disease which, in its juvenile and infantile forms, progresses spontaneously to severe renal and ocular impairment, growth retardation with rickets, and involvement of many other organs. Only symptomatic treatments have been available until now. (2) The clinical file includes only non comparative trials. (3) Few children have been treated with cysteamine beyond the age of 10. Provided treatment is begun early, the main beneficial effects of cysteamine are maintenance of the growth curve and prevention of deterioration of renal lesions (an effect that varies from patient to patient). Oral cysteamine does not prevent the progression of ocular lesions. (4) Cysteamine has many potential adverse effects, some of which are serious (mainly gastrointestinal and neuropsychiatric disorders). Little is known of its long-term adverse effects. (5) The main disadvantage of this treatment is the need for four daily intakes (every 6 hours) and the sulphurous breath it causes. (6) Treatment with cysteamine is expensive.

Characterization of dopamine receptor subtypes involved in experimentally induced gastric and duodenal ulcers in rats

There are conflicting reports about the role of dopamine in gastric and duodenal ulcers. This investigation was undertaken to characterize the specific subtypes of dopamine receptor involved in gastric and duodenal ulceration. Administration of dopamine D1 agonist fenoldopam and dopamine D2 antagonist sulpiride elicited a significant decrease in acid secretion, total acid output, pepsin output and histamine content in the gastric juice, and reduced ulcer-index values, in pylorus-ligated rats. However, dopamine D1 receptor antagonist SCH 39166 ((-)-trans-6,7,7a,8,9,13b-hexahydro-3-chloro-2-hydroxy-N-methyl-5H -benzo (d) naptho -(2,1-b) azepine) and the D2 receptor agonist quinpirole led to significant augmentation of these parameters compared with respective controls. In the restraint plus water-immersion stress model the score for intraluminal bleeding and the cumulative gastric lesion length was significantly lower for rats treated with fenoldopam and sulpiride. The opposite effects were observed after pretreatment of rats with SCH 39166 and quinpirole. In the cysteamine-induced duodenal ulcer model the mean ulcer area and the score for intensity were significantly lower for fenoldopam and sulpiride and higher for SCH 39166 and quinpirole. Our data suggest that the dopamine D1 and D2 receptors have opposite effects on gastric and duodenal ulcers. Whereas stimulation of dopamine D1 receptors inhibits the formation of gastric and duodenal ulcers, stimulation of dopamine D2 receptors has a pro-ulcerogenic effect.

A study of the relative bioavailability of cysteamine hydrochloride, cysteamine bitartrate and phosphocysteamine in healthy adult male volunteers

AIMS

Cysteamine, the only drug available for the treatment of cystinosis in paediatric patients, is available as the hydrochloride, the bitartrate and as sodium phosphocysteamine salts. It has been suggested that cysteamine bitartrate and phosphocysteamine are better tolerated and may have a better bioavailability than cysteamine hydrochloride. This has, however, never been demonstrated.

METHODS

We compared the pharmacokinetics and tolerance of these three formulations of cysteamine in 18 healthy adult male volunteers in a double-blind, latin-square, three-period, single oral dose cross-over relative bioavailability study.

RESULTS

No statistical difference was found between relative bioavailabilities, AUC (0, infinity) (geometric mean and s.d. in micromol l(-1) h: 169+/-51, 158+/-46, 173+/-49 with cysteamine hydrochloride, phosphocysteamine and cysteamine bitartrate respectively), Cmax (geometric mean and s.d. in micromol l(-1); 66+/-25.5, 59+/-12, 63+/-20) and tmax (median and range in h: 0.88 (0.25-2), 1.25 (0.25-2), 0.88 (0.25-2)) with each of the three forms of cysteamine tested. Bioequivalence statistics (90% confidence intervals) showed non equivalence of Cmax of cysteamine base as the only non equivalence of pharmacokinetics between the three formulations: 90% CI for Cmax relative ratios to cysteamine hydrochloride were [75.6-105.81 for phosphocysteamine and [74.2-124.2] for cysteamine bitartrate. The only significant adverse event was vomiting whose frequency was inversely correlated with body weight (Spearman's r=-0.76, P<0.001). The nature of the salt tested did not influence vomiting.

CONCLUSIONS

While none of the three forms of cysteamine tested has a clear advantage over the others in terms of pharmacokinetics and tolerance profile, this should now however be addressed in patients treated for cystinosis during repeat administrations.

Evaluation of the reproductive and developmental safety of cysteamine in the rat: effects on female reproduction and early embryonic development

Cystinosis is an autosomal recessive metabolic disease in which the amino acid cystine accumulates in lysosomes due to a defect in lysosomal cystine transport. Cystinosis in infancy is associated with poor growth, muscle wastage, and death at about age 10 due to kidney failure. Treatment with cysteamine and kidney transplantation enables cystinotic girls to reach reproductive age and to be healthy enough to permit pregnancy. It is not known whether exposure to cysteamine will have adverse effects on reproduction in the human. It is also possible that some of the complications seen in cystinotic children could be avoided if a pregnant woman carrying a cystinotic fetus were given cysteamine. However, this treatment is not likely to occur until therapeutic exposures to cysteamine are judged to present no increased risk to the human fetus. As part of a larger investigation assessing the reproductive and developmental safety of cysteamine (as phosphocysteamine) using the rat, the two studies reported herein were performed. The first, a dose-finding study, led to the selection of 150 mg/kg/day as the highest dose of cysteamine used for the second and primary focus of this report. The second study involved the exposure of female rats to cysteamine from premating through day 6.5 postconception and assessment of female fertility and early embryonic development. Cysteamine was administered orally in doses of 0, 37.5, 75, 100, or 150 mg/kg/day. There were no clinical signs of maternal toxicity during the exposures of 2 to 5 weeks before successful mating. Animals in the 150 mg/kg/day group experienced a nonsignificant decrease in body weight gain during pregnancy to day 6.5 postconception, a significant increase in liver and spleen weights, and a significant increase in days to coitus--suggesting that a low level of toxicity was manifested. However, there were no adverse effects on reproductive performance with respect to conception and early embryonic development.

Synthesis and antitumour effect of the melanogenesis-based antimelanoma agent N-propionyl-4-S-cysteaminylphenol

Chemotherapy of malignant melanoma is still a great challenge, as no effective drugs are available. The development of melanogenesis-based drugs is a promising area of research because melanogenesis is a unique biochemical pathway operating only in melanoma cells (and their normal counterparts) so that the tumour can be targeted. We have been using cysteinylphenol, a sulphur-containing analogue of tyrosine, and derivatives for that purpose. N-Acetyl-4-S-cysteaminylphenol was found to have the best antimelanoma effect in cell culture systems and in mice bearing B16 melanoma tumours. It also caused depigmentation of the skin, suggesting the possibility of use as a hypopigmenting agent. To improve the efficiency of the drug, we thought of replacing the acetyl group in N-acetyl-4-S-cysteaminylphenol with a propionyl group in the hope that increased hydrophobicity would increase the cellular uptake of the drug. N-Propionyl-4-S-cysteaminylphenol was synthesized by condensing 4-hydroxythiophenol with 2-ethyl-2-oxazoline. The drug showed both cytostatic and cytocidal effects in a human melanotic melanoma cell line. The drug was found to be a good depigmenting agent for the black hair follicles of C57 black mice when given s.c. for 14 days. A 10-day treatment with N-propionyl-4-S-cysteaminylphenol at 300 mg/kg body weight reduced the growth rate of B16 melanoma s.c. tumours in mice by 36%. The propionyl derivative was found to increase the life span of mice bearing melanoma more effectively than did the acetyl derivative.

The effects of cysteamine on the upper gastrointestinal tract of children with cystinosis

The purpose of this study was to evaluate the effects of cysteamine on gastric acid output and serum gastrin levels in children with nephropathic cystinosis. We studied four children with nephropathic cystinosis receiving a dose of free base cysteamine of 14.35 mg/kg four times a day (range 12.30-18.80 mg/kg). Gastric acid was measured for the hour before and after administration of the medication. Serum gastrin levels were obtained at 0, 30, 60, and 90 min following the medication. Gastrointestinal anatomy was evaluated by endoscopy and biopsy. Following administration of the medication, all subjects showed an increase in gastric acid output. Mean acid output increased from 0.79 to 2.22 mEq/h. Mean gastric acid output adjusted for body weight increased from 0.03 to 0.09 mEq/kg per hour. Following administration of the medication, all subjects showed an increase in serum gastrin. The mean increase above the base value was 38.3 pg/dl. Two of the four subjects demonstrated visual and histological evidence of inflammation. Cysteamine has a marked effect on gastric acid production and serum gastrin, even at the dose used in children with nephropathic cystinosis. The clinical effect of this acid production is unknown but may be significant.

Effect of quinacrine, a phospholipase A2 inhibitor on stress and chemically induced gastroduodenal ulcers

Quinacrine, a phospholipase A2 inhibitor, has been studied for its ability to inhibit gastric secretion and to protect the gastric and duodenal mucosa against chemically and stress-induced ulcers. Acid secretion studies were undertaken in pylorus-ligated rats with and without quinacrine treatment. Experimental gastric lesions were induced by water-immersion restraint stress, indomethacin and 80% ethanol in rats; whereas duodenal ulcers were produced by treatment of rats with cysteamine. The level of nonprotein sulfhydryl compounds and gastric wall mucus were also measured in the glandular stomach of the rats following ethanol-induced gastric lesions. The results of this study demonstrate that quinacrine produces a dose-dependent inhibition of gastric acid secretion in rats. Pretreatment with quinacrine significantly attenuated the formation of stress-, indomethacin- and ethanol-induced gastric lesions. Quinacrine also protected intestinal mucosa against cysteamine-induced duodenal ulcers. The antiulcer activity of quinacrine was associated with appreciable inhibition of ethanol-induced depletion of nonprotein sulfhydryls and gastric wall mucus. These findings point towards the mediation of sulfhydryls in quinacrine-induced gastrointestinal cytoprotection. In conclusion, this study demonstrates that quinacrine possesses significant antiulcer and cytoprotective activity against various experimentally induced gastroduodenal lesions. Although the mechanism of action of quinacrine requires further evaluation, the experimental observations derived from this study may have future clinical relevance and therefore deserve to be investigated thoroughly.

Intravenous cysteamine therapy for nephropathic cystinosis

A 4-y-old boy with nephropathic cystinosis and gastrointestinal dysmotility of unknown etiology was treated with i.v. cysteamine over a period of 10 mo. Thirty minutes after a dose of 10 mg/kg cysteamine free base, the leukocyte cystine value had fallen from 11.9 to 4.9 nmol of half-cystine/mg of protein. When cysteamine was given every 6 h, the leukocyte cystine concentration, measured 5-7 h after a dose, decreased with increasing cysteamine doses up to 17 mg/kg; at this dose the cystine value was 1.1 nmol of half-cystine/mg of protein, or 9% of the untreated value. Oral administration of approximately 16 mg/kg per dose every 6 h to this patient over the previous 3 y achieved similar leukocyte cystine depletion, to 1.2 nmol of half-cystine/mg of protein. The plasma cysteamine concentration 30 min after a dose of 10 mg/kg was 71 microM; 5-7 h after a dose of up to 20 mg/kg, the concentration was below 5 microM. Dimethylsulfide was elevated in the breath and urine of this boy after, but not before, the initiation of i.v. cysteamine therapy. Ten months after the start of therapy, the patient tolerated 250 mg (14 mg/kg) every 8 h. Adverse effects of this treatment included lethargy and increased nausea and vomiting when a schedule of therapy every 6 h was attempted. This investigation demonstrates that cysteamine given through a central venous catheter is effective in reducing leukocyte cystine levels.

Antiulcer activity of pentacaine and some of its derivatives: effect on experimentally induced gastric and duodenal lesions and on gastric acid secretion in rats

The antiulcer, gastroprotective, and antisecretory effects of selected carbanilates were tested in rats. The compounds K-1905 and K-2002 were found to have beneficial effects similar to those of pentacaine in phenylbutazone- and ethanol-induced gastric injury and in cysteamine-induced duodenal lesions; their antisecretory activity was also comparable to pentacaine in pylorus-ligated rats. Compounds P2 and P3 were generally less effective than pentacaine, and compound P1 was gastrotoxic. Thus pentyloxy-substitution on the benzene ring of the parent structure (K-1905 and K-2002) is more suitable for antiulcer and gastroprotective activity than methoxy-substitution on the meta-position (P3) or alkyloxy-substitution on the para-position (P2, P1). The results indicate that the two carbanilates K-1905 and K-2002 can be considered prospective antiulcer drugs.

Cysteamine gliopathy in situ: a cellular stress model for the biogenesis of astrocytic inclusions

In cultured astroglia, cysteamine induces the accumulation of peroxidase-positive cytoplasmic inclusions in the context of a generalized cellular stress response. In the present study, systemic cysteamine administration over a 3 week period induced HSP27, 72, 90, and GRP94 (stress proteins) in astrocytes and significantly increased numbers of peroxidase-positive astrocytic inclusions in the various brain regions relative to controls. Similar patterns of HSP expression were also observed at 24 hours following cysteamine treatment indicating that cellular stress may be a very proximal event in the biogenesis of the astrocytic inclusions. The topography of glial peroxidase activity may provide a "map" of central nervous system regions particularly prone to oxidative stress during normal aging and under pathologic conditions.

The gastrin/cholecystokinin-B receptor antagonist L-365,260 reduces basal acid secretion and prevents gastrointestinal damage induced by aspirin, ethanol and cysteamine in the rat

L-365,260, a nonpeptide antagonist of gastrin/CCK-B receptors, was evaluated in receptor binding, antisecretory and gastrointestinal damage assays. L-365,260 binds potently and stereo-selectively to gastrin and CCK-B sites in guinea pig tissue. In contrast, L-365,260 binds to the isolated canine parietal cell gastrin receptor weakly, and without stereoselectivity. In the pylorus-ligated rat, low doses of L-365,260, given i.v., attenuated pentagastrin-stimulated acid secretion, whereas higher doses were required to inhibit both histamine-stimulated and basal acid secretion. In an aspirin-induced gastric damage model, L-365,260 was 2.4-fold less potent than the standard histamine H2 antagonist cimetidine in preventing gastric damage when given i.v., and was 8.3-fold less potent than cimetidine when given p.o. Moreover, the ED50 value for L-365,260, given i.v., in prevention of aspirin-induced gastric damage (11.5 mg/kg) agreed well with its ED50 value for inhibition of basal acid secretion (12.6 mg/kg). At doses as great as 100 mg/kg p.o., neither L-365,260 nor cimetidine had an effect on ethanol-induced gastric damage. L-365,260, although p.o. less bioavailable relative to cimetidine in the aspirin gastric damage model, was as potent as cimetidine in the prevention of cysteamine-induced duodenal ulcers in the rat. We conclude that the gastrin/CCK-B receptor antagonist L-365,260, at doses supramaximal for the inhibition of pentagastrin-stimulated secretory responses in vivo, inhibits gastrointestinal damage in models of peptic ulcer disease by an antisecretory mechanism of action.

Phase I trial of Perrimustine, a new cysteamine (2-chloroethyl) nitrosourea: an intrapatient escalation scheme

The recently synthesized nitrosourea, N-[N'-chloro-2-ethyl-N'-nitrosocarbamoyl]-S-methyl cysteamine sulfoxide (Perrimustine), is water soluble and has a high alkylating activity, similar to that of the widely used nitrsoureas BCNU and CCNU, and a low carbamoylating activity. Preclinical studies with a broad spectrum of murine tumors indicate that this new compound may be clinically useful. The maximally efficient dose range (MEDR) in L1210 bearing mice was 45 mg/m2 (subcurative dose) to 67 mg/m2 (subtoxic dose). The present phase I trial used an intrapatient escalation schedule, so that each patient entering the study received a potentially active dose. The first dose injected was 1:100 of the MEDR suboptimal dose to check for anaphylactic sensitivity. Patients were then given increasing doses at increasing time intervals until toxicity was observed. The highest dose was given on day 150-230. The main toxic effect was myelosuppression [five out of the 24 patients evaluated: one grade 4 thrombocytopenia, two grade 3 thrombocytopenia; anemia and leucopenia were milder (grade 1 to 2 on OMS scale)]. Of the 19 patients evaluated for clinical response, one showed response after the 45 mg/m2 dose (disappearance of the cerebral metastasis with persistence of hepatic localizations in a patient with melanoma) and the disease was stabilized in two cases (a pleural mesothelioma and a renal carcinoma with lung metastases) after 26 and 37 weeks, with total cumulative doses per m2 of 232 and 196 mg, respectively.

Cysteamine induced-duodenal ulcers are associated with a selective depletion in gastric and duodenal calcitonin gene-related peptide-like immunoreactivity in rats

We have measured the endogenous levels of gastric and duodenal calcitonin gene-related peptide (CGRP)-, neurokinin A (NKA)-, galanin-vasoactive intestinal polypeptide (VIP)- and neuropeptide Y (NPY)-like immunoreactivity (li) in relation to cysteamine-induced gastric lesions and duodenal ulcers in rats. CGRP-li but not NKA-, galanin-, VIP- or NPY-li was decreased in gastric and duodenal samples following a single ulcerogenic dose of cysteamine (900 mg/kg p.o.). Temporal relationships of this phenomenon showed that CGRP-li was selectively decreased (stomach 45%, duodenum 68% as compared to controls, respectively after 24 h) concomitantly to the formation of acute gastric lesions and duodenal ulcers. Animals bearing healed ulcers 12 days after cysteamine, had gastroduodenal CGRP-li similar to control values. Pretreatment with the selective sensory neurotoxin capsaicin decreased gastroduodenal CGRP-li but not NKA-, galanin-, VIP- or NPY-li, showing that CGRP might be considered a marker of the afferent innervation of the gastroduodenal tract. The residual gastroduodenal CGRP-li levels in capsaicin-pretreated animals were not decreased by cysteamine administration, indicating that the effect of cysteamine is restricted to a peptide pool of primary afferent origin. Duodenal CGRP-li is selectively decreased by the duodenal ulcerogen cysteamine during the acute phase of ulcers formation and might be among the local mediators which afford protection against the ulcerogenic stimuli.

Scavengers of free radical oxygen affect the generation of low molecular weight DNA in stimulated lymphocytes from patients with systemic lupus erythematosus

Factors that potentially affect the generation of excess low molecular weight DNA (LMW-DNA) in cultured phytohemagglutinin (PHA)-stimulated lymphocytes of patients with systemic lupus erythematosus (SLE) were studied because this species of DNA is consistently found and this DNA may play a role in the pathogenesis of the disease. Superoxide dismutase (SOD; 0.05 mg/mL), a scavenger of free radical oxygen, decrease LMW-DNA formation in lymphocytes by 22%. Co-cultivation with cysteamine, a second scavenger of free radical oxygen and a sulfhydryl radioprotective agent, resulted in a 32% decrease in the generation of excess LMW-DNA at a concentration of 0.5 x 10(-3) mol/L and largely prevented its formation at 1.0 x 10(-3) mol/L. Other free radical scavengers (catalase, mannitol, vitamins C and E), cyclooxygenase inhibitors (ibuprofen and aspirin), a xanthine oxidase inhibitor (allopurinol), and an iron chelator (desferoxamine) did not affect excess LMW-DNA formation. Glutathione (1 x 10(-3) mol/L) had no effect and cysteine was toxic. Because scavengers of free radicals might be useful in the therapy of lupus, a trial of cysteamine (30 to 60 mg/kg/d) was administered to six acutely ill patients with SLE. A therapeutic benefit was not demonstrated, and some patients had exacerbation of disease. Lymphocyte cell growth from control and lupus subjects was stimulated when cysteamine, 1 x 10(-5) to 1 x 10(-4) mol/L was added to the media, but inhibited at concentrations of 2 x 10(-4) mol/L or greater. These studies suggest that the autooxidation and toxicity of high-dose cysteamine preclude its therapeutic use as a free radical scavenger.

In vivo cell kinetics studies of the duodenum during and after healing of cysteamine-induced duodenal ulcer in rats using bromodeoxyuridine incorporation

The present study investigated the defect of duodenal defence responsible for the tendency of recurrence of duodenal ulcer. Male Wistar rats were treated with cysteamine-HCl subcutaneously to induce duodenal ulcer, and bromodeoxyuridine (BrdU) was given intraperitoneally 1 h before laparotomy. Serial tissue sections and immunocytochemical staining of BrdU were done to study the cell kinetics during and after healing. Deep ulcers developed in the proximal part of the duodenum 24 h after cysteamine injection, and the ulcer was replaced by scar tissue 1 week later. BrdU-labelling index of normal duodenal mucosa in control rats was 30-34%. On the peripheral part of the regenerative mucosa, BrdU-labelling index increased from 1.5% to 26-27%, 1-4 weeks after injection and remained at this level thereafter. On the central part, except the most central area, the labelling index remained at 0% until 3 weeks, and was 15% 6 weeks after cysteamine treatment. It never achieved the level seen in control normal mucosa. The labelling rate of fibrous cells in scar tissue decreased from 28% to nearly 0% 1-4 weeks after the injection. It is concluded that both the ulcer scar and the regenerative mucosa do not achieve a mature state in the initial scarred stage; they need more time to reach a relatively mature condition. Moreover, the regenerative mucosa will be the weak, easily damaged part of the duodenum.

A comparison of the effectiveness of cysteamine and phosphocysteamine in elevating plasma cysteamine concentration and decreasing leukocyte free cystine in nephropathic cystinosis

Cysteamine (beta-mercaptoethylamine, MEA) is currently used to treat children with nephropathic cystinosis. In this study MEA was compared to phosphocysteamine (MEAP), a phosphorothioester that tastes and smells better than MEA, with respect to its ability to elevate plasma MEA and deplete leukocytes of cystine. Studies were performed in six children with nephropathic cystinosis ranging in age from 2 to 10 yr. After equimolar oral doses of either MEA or MEAP plasma cysteamine was determined at various times for 6 h. MEA was determined by sodium borohydride reduction followed by high-performance liquid chromatography separation and electrochemical detection. Leukocyte cystine was measured before and 1 and 6 h after drug administration. Peak plasma MEA was obtained 30 min to 1 h after a dose and was not significantly different when MEA (48.6 +/- 10.7, mean +/- SD) or MEAP (54.1 +/- 20.2) was given. Significant plasma MEA concentrations were seen as early as 15 min after an oral dose, indicating rapid absorption. Analysis of vomitus indicated that hydrolysis of the phosphate group of MEAP occurs in the stomach. The percent decrease in leukocyte cystine content obtained with MEA administration (61.9%) was not significantly different from the decrease observed when MEAP was administered (65.3%). MEA and MEAP appear to be equally effective in their cystine-depleting properties.

Cysteamine induces cataracts in newborn rats

Daily subcutaneous injections of cysteamine (CSH) administered to neonatal rats for 6 to 11 days cause dense bilateral cataracts that are evident at eye opening and that are permanent. CSH has been previously shown to induce protein cross-linking by the formation of abnormal disulfide bonds. It is hypothesized that the same mechanism underlies its cataractogenic effect; as such, CSH may be a useful agent in the study of models of senile cataract formation in humans.

Early myoelectrical activity changes during gastric or duodenal ulceration in dogs

Antroduodenal myoelectric activity and gastric transmural potential difference were recorded before and during fundic, antral, or duodenal ulceration in dogs. Gastric injury was obtained by electrocoagulation of the fundic or antral mucosa. Duodenal ulceration was induced by cysteamine injection which was accompanied by nausea or vomiting. Both antral electrocoagulation and cysteamine injection were also accompanied by antral dysrhythmia and a transient decrease of the gastric transmural potential difference. Effects of antral electrocoagulation were prevented by selective vagotomy. Since antral dysrhythmia disappeared as soon as the antral or duodenal ulcers became active, ie, within three days and 24 hr respectively, it is suggested that antral dysrhythmia is the result of antroduodenal stimulation and could thus not be assessed as a criterion of active ulceration.

Cysteamine therapy for children with nephropathic cystinosis

We treated 93 children with nephropathic cystinosis with oral cysteamine (mean dose, 51.3 mg per kilogram of body weight per day) for up to 73 months. This agent is known to be effective in depleting cells of cystine. In our study, the mean cystine depletion from leukocytes was 82 percent. A historical control group of 55 children received either ascorbic acid (27 children) or placebo (28). At age six, 2 of 17 controls had a serum creatinine level less than 1.0 mg per deciliter, as compared with 17 of 27 patients treated with cysteamine for at least one year (odds ratio, 12.8; 95 percent confidence interval, 2.1 to 33.9). At the end of the study, creatinine clearance was higher in the cysteamine group than in the control group (38.5 vs. 29.7 ml per minute per 1.73 m2; 95 percent confidence limits on the difference, 1.8 and 15.8), even though the cysteamine group was on average 1.4 years older than the control group. Cysteamine also improved growth; those in the cysteamine group between two and three years of age grew at 93 percent of the normal velocity, as compared with 54 percent in the control group. Fourteen percent of the patients could not tolerate the taste and smell of cysteamine. Concurrent controls treated in a blinded fashion with a placebo were not included in this study. With this limitation in mind, we conclude that oral cysteamine, by depleting cells of cystine, helps maintain renal glomerular function, improves growth, and constitutes the current treatment of choice for nephropathic cystinosis.

[Cysteamine in the treatment of cystinosis in children. In vitro and in vivo studies]

The effect of cysteamine was studied in 6 children with nephropathic cystinosis. In 3 of them an in vitro study on fibroblasts was performed. The cystine content of fibroblasts was immediately diminished (about 90% of total cystine content) as soon as the concentration of cysteamine in the medium was greater than or equal to 0,1 mmole/l. In vivo, 50 to 89 mg/kg/day of cysteamine was administered for 9 to 37 months (mean 21,3). There was no adverse reaction. In all cases a dramatic decline in leukocyte cystine level was observed (in 5 cases the level was within the range seen in clinically unaffected heterozygotes). Growth was not improved. The renal function was stabilised in 3 cases. Photophobia which was present in 4 children decreased in 2 cases or disappeared in 2 cases.

Gastric cytoprotective properties of SCH 32651, a novel antiulcer agent

The antisecretory activity of SCH 32651 (3-amino-2-methyl-8-phenylmethoxyimidazo[1,2-a] pyrazine HCl . 1/3 H2O) has been described in a preceding paper. This report describes its gastric cytoprotective properties. SCH 32651 inhibited the gastric lesions due to ethanol in a dose-dependent manner (ID50 = 5 mg/kg p.o.) and exerted its maximal effect when given 30 min before ethanol and had a duration of at least 90 min at 30 mg/kg p.o. The activity of SCH 32651 against ethanol was unaffected by indomethacin pretreatment. Furthermore, SCH 32651 produced significant increases in gastric mucus release (10-100 mg/kg p.o.) and rapidly reversed ethanol-induced (30-100 mg/kg p.o.) fall in gastric potential difference (PD). SCH 32651 displayed significant antiulcer activity in indomethacin-(30-100 mg/kg p.o.), aspirin - (30-100 mg/kg p.o.), "aspirin + acid" - (10-100 mg/kg p.o.), reserpine - (10-100 mg/kg p.o.), stress - (30-100 mg/kg p.o.), and cysteamine (10-100 mg/kg p.o.) ulcers. The present data in conjunction with those reported in a preceding paper indicate that SCH 32651 is an orally effective novel antiulcer drug with both gastric antisecretory and cytoprotective properties.

Methionine and cysteamine in paracetamol (acetaminophen) overdose, prospective controlled trial of early therapy

We have studied forty patients who were at risk of hepatic, renal, pancreatic or myocardial injury as a consequence of severe paracetamol overdosage and who were admitted to hospital within 10 h of ingestion. These were sequentially randomized into three treatment groups, comprising intravenous cysteamine therapy (3.6 g over 20 h, n = 14), oral methionine (10 g over 16 h, n = 13) or supportive therapy only (intravenous 10% dextrose with vitamins, n=13). All groups were matched for age, ingestion-treatment interval and severity of poisoning as estimated by stated amount ingested and a logarithmic paracetamol blood level index.

One death occurred in the supportive therapy (S) group. Significant differences in peak serum aspartate aminotransferase levels were seen with geometric means in S of 1046 U/l, in cysteamine treatment of 96 U/l and in methionine treatment of 139 Ull (Wilcoxon sum of ranks p < 0.01 in favour of methionine, p < 0.002 in favour of cysteamine). Hepatic necrosis, as shown by ‘blind’ histological assessment, was significantly less frequent in actively treated patients (methionine p < 0.05, cysteamine p < 0.01). These differences in favour of cysteamine and methionine were also reflected in peak serum bilirubin and prothrombin ratio. No significant effects of active treatment were shown for serial plasma creatinine, serum amylase, myocardial enzymes or ECG changes.

We conclude that in the context of a prospective controlled trial of active agents:

A convincing hepatoprotective effect of early i.v. cysteamine and oral methionine has been demonstrated. No clear difference in efficacy of the two antidotes has been shown. Early methionine administration is associated with few, if any, undesirable side-effects.

Effects of cysteamine therapy in nephropathic cystinosis

We studied the effects of cysteamine in five children with nephropathic cystinosis who were treated for up to 30 months. Cysteamine caused a decline in leukocyte cystine levels to the range seen in clinically unaffected heterozygotes; both plasma and urinary cystine diminished by more than half. Therapy had no effect on progressively declining creatinine clearance in three patients, but improvement occurred in the other two. Phosphaturia, glycosuria, aminociduria, and organic aciduria did not improve in any of the patients. Both blood lactate and the lactate pyruvate ratio were diminished. Growth velocity, which was abnormal in four of the five children, did not improve. No major side effects were noted. Therapy with cysteamine caused a consistent, dose-related decline in levels of cystine in leukocytes and in extracellular fluid, caused no improvement so far in renal tubular function or growth velocity, and improved creatinine clearance in some patients.

The effect of cysteamine on the Brunner gland secretion in the rat

Cysteamine in a single subcutaneous administration induces release of gastrin, acid hypersecretion, and duodenal ulcer in rats. Pentagastrin-induced acid hypersecretion has no ulcerogenic effect. The Brunner glands in the proximal duodenum have previously been shown to be an important factor in the natural defence of the duodenal mucosa, and this study has been performed to determine the effect of cysteamine and pentagastrin on the Brunner glands in the rat. The proximal duodenum was isolated in situ and drained by a polyethylene tube. The secretion was studied for two 5-h periods after administration of cysteamine or pentagastrin, and then the Brunner glands were studied histologically. Pentagastrin did not affect spontaneous Brunner gland secretion, whereas cysteamine inhibited the output approximately 50%. After cysteamine the secretory cells were low and depleted of mucus, suggesting that cysteamine interferes with the synthesis of the secretory product. The depression of the Brunner gland secretion may be an important factor in the pathogenesis of cysteamine-induced duodenal ulceration.