A microstructural study of water effects in lipid-based pharmaceutical formulations for liquid filling of capsules.

Water is known to exhibit pronounced effects on lipid-based formulations (LBFs) and much research has focused on aqueous dispersion and dilution behavior regarding biopharmaceutical performance. From a product quality perspective, it is also critical to study a range of lower water amounts in formulations with respect to capsule filling. The present work addressed the need for a better understanding of LBF microstructure by taking percolation theory into account. The effects of increasing amounts of water on LBFs were analyzed by conductivity, water activity, time-domain nuclear magnetic resonance, and diffusing wave spectroscopy. Results were interpreted using percolation theory and preliminary mechanical tests were conducted on gelatin and hypromellose (HPMC) capsule shells. For both LBF systems, increasing water amounts led to marked changes in the microstructure of the formulations. Percolation laws could be fitted adequately to the data and thresholds were identified for the formation of continuous water channels (ϕwc~0.02-0.06). A new theoretical model was proposed for water activity. The preliminary shell material studies showed that the threshold for generating water channels in the formulation could be correlated to mechanical changes of the capsule shell that were relatively more pronounced in the case of gelatin. This mechanistic study demonstrated the importance of understanding and monitoring of microstructural changes occurring in LBFs with increasing amounts of water, which will help to design quality into the final dosage form.

Meta-analysis of oro-cecal transit time in fasting subjects.

PURPOSE: Computer simulations are utilized during pharmaceutical development in order to design appropriate formulation based on the absorption, distribution, metabolism, and excretion (ADME) and physicochemical properties of target compounds, so that adequate prescriptions are offered to patients. Oro-cecal transit time (OCTT) is an important factor affecting these simulations because the absorption of drug that administered orally and the resultant pharmacokinetic profile are expressed as a function of time. Given the large intra- and inter-individual variance in OCTT, it is unsurprising that an accurate model has not yet been proposed. METHODS: We conducted a meta-analysis using subject-level data to construct a statistical model that predicted OCTT. Literature that utilized lactulose to measure OCTT was identified and analyzed using a mixed-effects model. RESULTS: The OCTTs of fasting healthy subjects were expressed using a linear model, with the amount of lactulose as the single significant explanatory factor. We found that this model could statistically distinguish the OCTTs of subjects with altered physical status from those of healthy people. Specifically, cystic fibrosis and celiac disease most significantly affected OCTT. CONCLUSION: The OCTT models developed herein incorporate inter-subject variations and can contribute to providing more accurate predictions of drug pharmacokinetic profiles.

Detection of gender difference and epitope specificity of IgG antibody activity against IgA1 hinge portion in IgA nephropathy patients by using synthetic hinge peptide and glycopeptide probes.

BACKGROUND AND AIMS: There are many reports on the presence of an incompletely glycosylated O-linked oligosaccharide(s) on the IgA1 hinge region in some immunoglobulin (IgA) nephropathy patients. Furthermore, the production of an antibody against the naked hinge peptide portion was reported in an IgA nephropathy patient. In this report, characterization of the IgG antibody against the hinge portion was carried out by using synthetic hinge glycopeptide probes. METHODS AND RESULTS: The following synthetic hinge peptide and glycopeptides were prepared: 19mer peptide, V-P-S-T-P-P-T-P-S-P-S-T-P-P-T-P-S-P-S (designated HP), the peptide having a single alpha-linked GalNAc residue at positions 4, 7, 9, 11 and 15 (4 GN - 15 GN, respectively) and the same peptide having five GalNAc residues at all five positions (GN5). The mean value of the antibody activity against these probes was compared with each other. The highest activity against the naked hinge peptide (HP) and lowest activity against the fully glycosylated hinge peptide (GN5) were obvious. As attachment of GalNAc to position 4 or 11 on the peptide brought about a significant reduction of the activity against the naked hinge peptide, the P-S-T-P sequence included in both positions was thought to be the most probable site recognized by these antibodies. As an additional unexpected observation, a gender difference in this antibody activity against all the probes was found. The antibody activity in a female was significantly higher compared with that in a male. CONCLUSION: Because the frequency of incidence of IgA nephropathy is known to be slightly higher in males, this gender difference might indicate a protective meaning to remove aberrantly glycosylated molecules from the patient's serum.

Enzymatically deglycosylated human IgA1 molecules accumulate and induce inflammatory cell reaction in rat glomeruli.

BACKGROUND: Previously, we have been able to isolate IgA1 from IgA nephropathy (IgAN) patients, that could accumulate in rat glomeruli (glomerulophilic IgA1). The 'glomerulophilic IgA1' was determined to be under-O-glycosylated in its hinge region, suggesting that under-O-glycosylation in the IgA1 hinge region plays a role in its glomerular deposition in IgAN. To confirm this, the accumulation of enzymatically under-glycosylated IgA1 in rat kidney was examined. METHODS: Human IgA1 was isolated from healthy individuals by Jacalin-affinity chromatography. Desialylated (deS IgA1) or further degalactosylated IgA1 (deS/deGal IgA1) molecules were then prepared using neuraminidase and beta-galactosidase. Two or five mg of IgA1 were injected into the left renal artery of Wistar rats. The rats were sacrificed at various time intervals (3, 9, 24 h) and the perfused part of the renal cortex was removed for immunofluorescence and for light and electron microscopy. RESULTS: Distinct amounts of deS IgA1 and deS/deGal IgA1 were observed in rat glomeruli. On the other hand, untreated IgA1 molecules (native IgA1) did not show any obvious accumulation. In rats injected with under-glycosylated IgA1, accumulation of polymorphonuclear cells (PMN) was also observed. CONCLUSIONS: These results confirmed that under-glycosylation of IgA1 played an important role in the glomerular accumulation of IgA1, which was followed by infiltration of PMN into glomeruli.