The effect of food and liquid pH on the integrity of enteric-coated beads from cysteamine bitartrate delayed-release capsules.

BACKGROUND: Cysteamine bitartrate delayed-release (DR) capsule (Procysbi®) is approved for treatment of nephropathic cystinosis in the USA, Canada, and the EU. The capsules contain cysteamine bitartrate beads that are enteric coated with acid-resistant Eudragit L 30 D-55, preventing drug release in the acidic stomach environment while allowing dissolution of the beads in the more alkaline environment of the small intestine. Patients who have difficulty swallowing capsules can open capsules, sprinkle beads onto 4 ounces of a suitable food or liquid, gently mix, and consume the entire content within 30 minutes. Foods found to be suitable for administration, and described in the Procysbi US labeling, include fruit juices (except grapefruit juice), applesauce, and berry jelly; there are minor variations in the foods and liquids recommended by regulatory authorities in other countries. This study aimed to assess the stability of enteric-coated beads exposed to additional foods at different conditions to expand the list of suitable foods for drug administration. METHODS: For each test condition, beads from eight opened 75 mg cysteamine bitartrate DR capsules were gently mixed with test food and maintained at a prespecified temperature and duration; remaining undissolved beads were then recovered from the food. The recovered beads were split into two portions: one assayed for remaining drug content and the other subjected to dissolution testing to assess the effect on the drug-release profile. RESULTS: The results show that bead integrity was maintained when mixed with foods at pH values <5.5 at all time points when refrigerated (2°C-8°C) and at room (20°C-22°C) and lukewarm (37°C-41°C) temperatures. Bead integrity was not maintained when mixed with foods at pH values of ≥5.5 at room temperature. CONCLUSION: The results from this in vitro dissolution study help in identifying additional foods that may be used for the administration of cysteamine bitartrate DR beads from opened capsules using the sprinkle method.

Overcoming the blood-brain barrier with high-dose enzyme replacement therapy in murine mucopolysaccharidosis VII.

Enzyme replacement therapy (ERT) effectively reverses storage in several lysosomal storage diseases. However, improvement in brain is limited by the blood-brain barrier except in the newborn period. In this study, we asked whether this barrier could be overcome by higher doses of enzyme than are used in conventional trials. We measured the distribution of recombinant human beta-glucuronidase (hGUS) and reduction in storage by weekly doses of 0.3-40 mg/kg administered i.v. over 1-13 weeks to mucopolysaccharidosis type VII mice immunotolerant to recombinant hGUS. Mice given up to 5 mg/kg enzyme weekly over 3 weeks had moderate reduction in meningeal storage but no change in neo-cortical neurons. Mice given 20-40 mg/kg three times over 1 week showed no reduction in storage in any area of the CNS except the meninges. In contrast, mice receiving 4 mg/kg per week for 13 weeks showed clearance not only in meninges but also in parietal neocortical and hippocampal neurons and glia. Mice given 20 mg/kg once weekly for 4 weeks also had decreased neuronal, glial, and meningeal storage and averaged 2.5% of wild-type hGUS activity in brain. These results indicate that therapeutic enzyme can be delivered across the blood-brain barrier in the adult mucopolysaccharidosis type VII mouse if administered at higher doses than are used in conventional ERT trials and if the larger dose of enzyme is administered over a sufficient period. These results may have important implications for ERT for lysosomal storage diseases with CNS involvement.

Lipoprotein receptor binding, cellular uptake, and lysosomal delivery of fusions between the receptor-associated protein (RAP) and alpha-L-iduronidase or acid alpha-glucosidase.

Enzyme replacement therapy for lysosomal storage disorders depends on efficient uptake of recombinant enzyme into the tissues of patients. This uptake is mediated by oligosaccharide receptors including the cation-independent mannose 6-phosphate receptor and the mannose receptor. We have sought to exploit alternative receptor systems that are independent of glycosylation but allow for efficient delivery to the lysosome. Fusions of the human lysosomal enzymes alpha-l-iduronidase or acid alpha-glucosidase with the receptor-associated protein were efficiently endocytosed by lysosomal storage disorder patient fibroblasts, rat C6 glioma cells, mouse C2C12 myoblasts, and recombinant Chinese hamster ovary cells expressing individual members of the low-density lipoprotein receptor family. Uptake of the fusions exceeded that of phosphorylated enzyme in all cases, often by an order of magnitude or greater. Uptake was specifically mediated by members of the low-density lipoprotein receptor protein family and was followed by delivery of the fusions to the lysosome. The advantages of the lipoprotein receptor system over oligosaccharide receptor systems include more efficient cellular delivery and the potential for transcytosis of ligands across tight endothelia, including the blood-brain barrier.