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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 (

Aims Cysteamine is used to reduce tissue cystine content in patients suffering from nephropathic cystinosis. The objectives of the current study were to investigate pharmacokinetics and pharmacodynamics of cysteamine bitartrate in children and young adults with nephropathic cystinosis. Methods Cysteamine bitartrate was administered to 11 cystinosis patients at their regular dose level in a single-dose, open-label, steady-state study. Blood samples were collected and analysed for plasma cysteamine and white blood cell cystine content and pharmacokinetic and pharmacodynamic parameters estimated by NONMEM analysis using a linked pharmacokinetic–pharmacodynamic model. Results Cysteamine was rapidly cleared from the plasma (mean CL/F = 32.3 ml min−1 kg−1, range = 17.3–52.2), appeared to be extensively distributed (mean Vss/F = 15.1 l, range 2.7–32.3) and exhibited a mean Tmax of 1.4 h. White blood cell cystine content post-dosing was significantly decreased compared with pre- and post-dose values (average decrement approximately 47%). A counter-clockwise hysteresis was noted in all patients, suggestive of a lag time (mean Tlag = 0.44 h, range 0.22–0.92) between drug concentration and effect. Conclusions The results of this study establish that cysteamine is rapidly cleared from the plasma but that an every 6 h dosing interval adequately maintains white blood cell cystine content below the target of 1 nmol cystine per mg protein.

Fourteen families of children with infantile nephropathic cystinosis were evaluated using the Stanford-Binet Intelligence Scale, Fourth Edition [Thorndike et al., 1986: Stanford-Binet Intelligence Scale, Fourth Ed.]. The IQs of 15 children with cystinosis, their 23 sibs and 24 parents were compared in order to evaluate a potential effect of cystinosis on intelligence. Children with cystinosis had a significantly lower mean IQ than their sibs and their parents (P = .001). Thus, even though the mean IQ of the children with cystinosis (94.4 +/- 10) was within the average range, there is evidence that these children have a mild global intellectual deficit relative to their expected IQ based upon the IQs of other relatives. In addition, to a subset of the subjects we administered a measure of scholastic ability, the Wide Range Achievement Test-Revised [Jastak and Wilkinson, 1984: The Wide Range Achievement Test-Revised], which consists of spelling, reading, and arithmetic subtests. The 11 cystinosis subjects scored significantly lower (P = .01) than their 16 sibs and their 14 parents in the area of spelling, whereas they did not significantly differ in their performance in the areas of reading and arithmetic.

We have studied a child with cystic fibrosis (CF), nephropathic cystinosis, and manifestations of Bartter syndrome, a finding reported previously in both of these diseases (CF and cystinosis). The chance of an individual inheriting a mutant allele for both CF and cystinosis from each of his parents by independent segregation is very small. Therefore, other mechanisms of inheritance were investigated, including whether his diseases were caused by a chromosome deletion or rearrangement that caused defects in both genes, whether his phenotype was caused by a new mutation or variant of either disease, or whether both diseases were inherited together due to inheritance of 2 copies of the same chromosome from one of the parents (uniparental disomy). An investigation was made of whether having mutations for both CF and cystinosis resulted in a different phenotype for either disease and whether the child was a heterozygote rather than a homozygote for one of the mutations. The results suggest that neither disease influenced the expression of the defect in the other and that this child inherited a mutant allele for both diseases independently from each parent.

Boman, H. and Schneider, J. A. (Institute of Medical Genetics, University of Oslo, Oslo, Norway, and Department of Pediatrics, School of Medicine, University of California San Diego, La Jolla, California, USA). Prenatal diagnosis of nephropathic cystinosis: Pregnancy at risk ascertained through heterozygote diagnosis of parents. Acta Paediatr Scand, 70:389, 1981.–The biochemical diagnosis of cystinosis in a deceased girl was made indirectly through the demonstration of heterozygote values of free-cystine contents in leukocytes from both parents. Amniocentesis was performed on the mother in the 16th week of two subsequent pregnancies. Amniotic fluid cell lysate from the first fetus had 6–8 times normal levels of radioactivity in the cystine band determined by a 35S-cystine pulse labeling method followed by high voltage electrophoresis on paper. Values for the cystine contents in various organs of the affected fetus are given. The second fetus was found to be not affected, and this was subsequently confirmed by the birth of a healthy child. The results of the laboratory analyses in these two cases were available to the parents 21 and 23 days following amniocentesis, respectively. The interruption of the first pregnancy was performed in the 19th week. This was 4 and 6 weeks earlier, respectively, than in the two previously reported induced abortions of affected fetuses, and should increase the acceptability of the present method for prenatal diagnosis of nephrophatic cystinosis.

The prenatal diagnosis of cystinosis is currently based on the increased amount of free-cystine present in amniotic fluid cells. Amniocyte cultures must be grown for at least 2 weeks to obtain sufficient cells for such measurements. Thus, the diagnosis cannot be made until close to 20 weeks gestational age by this method. We report a case in which chorionic villi were used for direct cystine measurement resulting in the in utero diagnosis of cystinosis at 9 weeks gestational age. The diagnosis was confirmed by the study of cultured chorionic villus cells, and of the 10-week abortus.

The brain of a 17-month-old boy with infantile Gaucher's disease and oculomotor apraxia was studied by light and electron microscopy. Light microscopic examination showed large perivascular accumulations of Gaucher's cells in frontal lobe white matter, severe neuronal loss in the calcarine cortex and dentate nucleus of the cerebellum, and neuronophagia and microglial nodules in the brainstem. Electron microscopy demonstrated intraneuronal cytoplasmic inclusions containing twisted tubules characteristic of Gaucher's disease in both the oculomotor nucleus and a random sample of cortex.

The metabolic defect which results in the accumulation of cystine within tissues of children with the recessively inherited disease cystinosis has baffled investigators for almost half a century. Investigations by numerous laboratories have finally culminated in the delineation of the basic defect in this unusual disorder.