Biotransformation in vitro of the 22R and 22S epimers of budesonide by human liver, bronchus, colonic mucosa and skin

A full scale tracing study of "ghost peaks" encountered in impurity analysis of budesonide based on experimental operation inspection-LC/MS fingerprint- mechanism based stress studies integrated strategy

Budesonide is an active pharmaceutical ingredient used in various dosage forms of finished products for the treatment of asthma. During the process of drug development, unbiased analysis of related substances is of utmost significance for both pharmaceutical research and quality control purposes. In this work, official method documented in the United States Pharmacopoeia was selected to determine the related substances of budesonide considering the pros and cons of critical chromatographic parameters, compared to the European Pharmacopoeia. In doing so, several unpredictable interference peaks, namely "ghost peaks", were observed occasionally during analysis. A strategy which integrated information derived from experimental operation inspection, LC/MS fingerprint analysis and mechanism based stress studies was then proposed for comprehensively and quickly exploring those non-degradable and degradable peaks. Some ghost peaks were found to originate from nylon syringe filter, illumination and alkali borosilicate glass HPLC vials. Besides, degradation pathways under alkaline conditions were also unravelled through LC-MS qualitative analysis. Overall, an optimization of the analytical methodology based on the United States Pharmacopoeia for its application in impurity analysis of budesonide and corresponding formulations was carried out with design of experiments, by which "ghost peaks" could be suppressed or prevented. The results obtained herein are not only crucial to studies on budesonide's stability or degradation kinetics but also contribute to clarify the impurity research of other drugs. This article is protected by copyright. All rights reserved.

Identification and Quantification by NMR Spectroscopy of the 22R and 22S Epimers in Budesonide Pharmaceutical Forms

The authors developed four variants of the qNMR technique (¹H or ¹³C nucleus, DMSO-d6 or CDCl₃ solvent) for identification and quantification by NMR of 22R and 22S epimers in budesonide active pharmaceutical ingredient and budesonide drugs (sprays, capsules, tablets). The choice of the qNMR technique version depends on the drug excipients. The correlation of ¹H and ¹³C spectra signals to molecules of different budesonide epimers was carried out on the basis of a comprehensive analysis of experimental spectral NMR data (¹H-¹H gCOSY, ¹H-¹³C gHSQC, ¹H-¹³C gHMBC, ¹H-¹H ROESY). This technique makes it possible to identify budesonide epimers and determine their weight ratio directly, without constructing a calibration curve and using any standards. The results of measuring the 22S epimer content by qNMR are comparable with the results of measurements using the reference HPLC method.

Pharmacokinetics of budesonide (Entocort EC) capsules for Crohn's disease

This overview summarises available pharmacokinetic data on budesonide capsules (Entocort EC), approved for the treatment of mild-to-moderate active Crohn's disease involving the ileum and/or ascending colon and for prolongation of symptom control. Budesonide is a locally-acting glucocorticosteroid with an extensive, primarily hepatic, metabolism after oral administration. It is rapidly absorbed and biotransformed by cytochrome P450 (CYP) 3A to metabolites with negligible glucocorticoid activity. Entocort EC, a pH- and time-dependent oral formulation of budesonide, was developed to optimise drug delivery to the ileum and throughout the colon. Pharmaco-scintigraphic studies have confirmed that the Entocort EC formulation delays budesonide absorption and prolongs the rate of elimination but maintains complete absorption. This improves the delivery of budesonide to the intestinal lumen relative to a plain formulation. A low systemic availability of 9-21% indicates extensive first-pass elimination. Food appears to have little impact on the absorption of budesonide from Entocort EC capsules and the pharmacokinetics are dose-proportional between 3 and 15 mg. On average, systemic availability was 2.5-fold higher in patients with cirrhosis compared with healthy controls; however, mild liver impairment had little effect on systemic exposure. Pharmacokinetics appear unaffected by gender and age, although this has not been tested in younger children. Renal impairment is not expected to have an impact on the kinetics of Entocort EC. Budesonide is unlikely to inhibit the metabolism of other drugs, including CYP3A4 substrates, mainly because of the very low plasma concentrations obtained with the compound even after high doses of Entocort trade mark EC capsules. Strong CYP3A4 inhibitors, such as ketoconazole, will inhibit the metabolism of budesonide, resulting in several-fold increases in the area under the concentration-time curve of budesonide. Also, grapefruit juice intake may increase systemic availability of budesonide, probably by inhibition of intestinal CYP3A4 activity. Unlike prednisolone, oral contraceptives do not alter plasma budesonide concentrations. An increased pH obtained by gastric acid inhibitory drugs, such as omeprazole, does not affect the pharmacokinetics of budesonide. In summary, budesonide capsules (Entocort EC) possess many pharmacological features that make the formulation well adapted for a targeted treatment of inflammatory disorders, such as Crohn's disease involving the ileum and ascending colon.

Transport and local metabolism of budesonide and fluticasone propionate in a human bronchial epithelial cell line (Calu-3)

Calu-3 cells grown on microporous filters at an air interface for 16-18 days were incubated with the glucocorticosteroid (GCS) budesonide (BUD). Apparent permeability (P(app)) of BUD across Calu-3 cell monolayers was determined. Amount of BUD transported across Calu-3 cells was clearly concentration dependent, and no polarised transport was detected. When cells were loaded with BUD by incubation with drug solution (30 microM) for 2 h, 9.35 +/- 0.53% of the initial dose of BUD, corresponding to 5.5 microg BUD/mg cell protein was retained intracellularly, and released over a time period of 10 h. Apical release of BUD was significantly higher than release to the basolateral side of the monolayer. In comparison, when Calu-3 cells were loaded with fluticasone propionate (FP) solution (0.8 microM), about 20% of the initial dose of FP, corresponding to 0.3 microg FP/mg total cell protein content was detected intracellularly and released immediately (45 min). There was no difference in FP release between the apical and basolateral side of the cell layer. Mass spectrometry of cell extracts indicated the presence of fatty acid conjugates of BUD. We conclude that Calu-3 cells are able to store BUD by intracellular conjugation to fatty acids. We, therefore, suggest the use of the Calu-3 cell model as a tool for examination of local pharmacokinetics and metabolism of GCS at the bronchial epithelium.