Development of Dexlansoprazole Delayed-Release Capsules, a Dual Delayed-Release Proton Pump Inhibitor.

Proton pump inhibitors (PPIs) are widely used for treating acid-related disorders. For an "ideal PPI," achieving maximal absorption and sustaining pharmacodynamic effects through the 24-h dosing cycle are critical features. Dexlansoprazole offers a relevant case study on how an improved PPI was developed capitalizing on the rational optimization of a precursor molecule-in this case, using lansoprazole as a starting point, leveraging its chemical properties on pharmacokinetics, and exploring optimized formulations. Dexlansoprazole is the R(+)-enantiomer of lansoprazole and shows stereoselective differences in absorption and metabolism compared with the racemic mixture of lansoprazole. The formulation was further refined to use pulsate-type granules with enteric coating to withstand acidic gastric conditions, while allowing prolonged absorption in the proximal and distal small intestine. As a result, the dual delayed-release formulation of dexlansoprazole has a plasma concentration-time profile characterized by 2 distinct peaks, leading to an extended duration of therapeutic plasma drug concentrations compared with the conventional delayed-release lansoprazole formulation. The dual delayed-release formulation maintains plasma drug concentrations longer than the lansoprazole delayed-release formulation at all doses.

Determination of S-(-)-lansoprazole in dexlansoprazole preparation by capillary zone electrophoresis.

Capillary zone electrophoresis was successfully applied to the enantiomeric purity determination of dexlansoprazole using sulfobutyl ether-ß-cyclodextrin and methyl-ß-cyclodextrin as chiral selectors. Separations were carried out in a 50 µm, 64/56 cm fused-silica capillary. The optimized conditions included 90 mM phosphate buffer, pH 6.0, containing 30 mM sulfobutyl ether-ß-cyclodextrin, 20 mM methyl-ß-cyclodextrin as background electrolyte, an applied voltage of 25 kV and a temperature of 16 °C, detection was at 280 nm. The assay was validated for the S-(-)-lansoprazole in the range of 0.2-1.0%. The limit of detection was 0.07%, the limit of quantitation was 0.20%, relative to a total concentration of 4.0 mg mL-1. Intra-day precision varied between 1.72 and 2.07%. Relative standard deviations of inter-day precision ranged between 1.62 and 1.96% for peak area ratio. The assay was applied for the determination of the chiral purity of dexlansoprazole capsules. Recovery in capsules was ranged between 101.7 and 103.1%.

Improving the solubility of dexlansoprazole by cocrystallization with isonicotinamide.

Cocrystallization of an active pharmaceutical ingredient (API) with a cocrystal former (co-former) is widely used to tailor the physicochemical properties of parent APIs. For proton-pump inhibitors (PPIs), the isolation of cocrystals has not been widely investigated. Here, a 1:1 cocrystal of a PPI molecule, dexlansoprazole (DLS), was obtained by solvent crystallization with isonicotinamide (INM). The product was characterized by X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), solid-state and liquid NMR, as well as Fourier transform infrared spectroscopy (FTIR) techniques. A two-point R2(2)(9) hetero-synthon was proposed to exist in the cocrystal, where intermolecular hydrogen bonding occurs between NH, SO groups of DLS and amide of INM. The dissolution profiles of DLS and DLS-INM in water were also collected, and the results demonstrate the cocrystal exhibits superior apparent maximum solubility relative to the pure drug.

Assessing the chiral switch: approval and use of single-enantiomer drugs, 2001 to 2011.

OBJECTIVES: A "chiral switch" occurs in the pharmaceutical market when a drug made up of 2 enantiomer forms is replaced with a purified single-enantiomer version, often in the context of a patent expiration. We studied the prevalence of chiral switching in the United States over the past decade, including trends in use of, and expenditures on, these products in Medicaid. STUDY DESIGN: Retrospective analysis. METHODS: We used US Adopted Names prefixes (lev/levo/ar/es/dex/dextro) to identify all single-enantiomer drugs approved from 2001 to 2011. From publicly available US Food and Drug Administration (FDA) approval documents, we extracted the characteristics of the pivotal premarket trials for the single enantiomers. Specifically, we evaluated whether the single enantiomer was directly compared with the precursor racemic drug and whether there was evidence of superior efficacy. We used quarterly drug expenditure data from each state Medicaid program to chart trends in use of, and spending on, the single-enantiomer products and their racemic precursors during the study period. RESULTS: From 2001 to 2011, the FDA approved 9 single-enantiomer products: dexlansoprazole, levoleucovorin, levocetirizine, armodafinil, arformoterol, eszopiclone, escitalopram, dexmethylphenidate, and esomeprazole. Of those 9 drugs, 3 had at least 1 pre-approval randomized trial that included the racemic precursor as a direct comparator, but there was no evidence of superiority of the single enantiomer over the racemic at comparable doses. Between 2001 and 2011, US Medicaid programs spent approximately $6.3 billion on these 9 single-enantiomer drugs. CONCLUSIONS: Recently approved single-enantiomer drugs showed no evidence of superior efficacy over the older racemic precursors in the pivotal trials leading to their approval, and in a majority of cases, they were not directly compared.