Publications by authors named "Shane Tan"

In modern botanical pharmacopeial monographs, one measurement of content is the quantitation of relevant constituents as marker compounds. The use of suitable reference standards (RSs) to quantify multiple compounds by HPLC is recommended in the U.S.

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A new, simple and stability-indicating gas chromatography-flame ionization detection (GC-FID) method was developed and validated for the quantitative determination of busulfan and its organic impurities (OI) in drug substance without derivatization. The chromatographic attributes were achieved on a fused silica capillary column (0.53 mm × 30 m, 1.

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The current United States Pharmacopeia-National Formulary (USP-NF) and the British Pharmacopoeia phenoxybenzamine (PBA) hydrochloride drug substance and drug product monographs describe an HPLC procedure for the determination of a specified impurity "tertiary amine phenoxybenzamine" and use the resolution of an "unknown related substance" from PBA as a system suitability criterion; however, neither structural information of the "unknown related substance" is provided nor reference standards of the two impurities are available. The ambiguity in pharmacopeias poses difficulties in implementing the procedure for quality control. To clarify the degradation pathways, and incorporate the impurity profile of PBA into the USP monographs, the degradation of PBA was revisited.

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Aryloxypropanolamine is an essential structural scaffold for a variety of β-adrenergic receptor antagonists such as metoprolol. Molecules with such a structural motif tend to degrade into α, β-hydroxypropanolamine impurities via a radical-initiated oxidation pathway. These impurities are typically polar and nonchromophoric, and are thus often overlooked using traditional reversed phase chromatography and UV detection.

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Sulconazole has been reported to degrade into sulconazole sulfoxide via sulfur oxidation; however, structural characterization data was lacking and the potential formation of an -oxide or sulfone could not be excluded. To clarify the degradation pathways and incorporate the impurity profile of sulconazole into the () monographs, a multifaceted approach was utilized to confirm the identity of the degradant. The approach combines stress testing of sulconazole nitrate, chemical synthesis of the degradant via a hydrogen peroxide-mediated oxidation reaction, semi-preparative HPLC purification, and structural elucidation by LC-MS/MS and NMR spectroscopy.

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Introduction: This study evaluated delivery of immersive simulation-based training (SBT) by distance education. Newly graduated health professionals' experience of and learning outcomes from videoconference-enabled remotely facilitated (RF) were prospectively compared with a locally facilitated (LF) format within a course addressing management of the deteriorating patient.

Methods: Participants were exposed to both RF and LF formats in an intervention course (IC).

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The European Pharmacopeia (EP) metoprolol impurities M and N are polar, nonchromophoric α-hydroxyamines, which are poorly retained in a conventional reversed-phase chromatographic system and are invisible for UV detection. Impurities M and N are currently analyzed by TLC methods in the EP as specified impurities and in the United States Pharmacopeia-National Formulary (USP-NF) as unspecified impurities. In order to modernize the USP monographs of metoprolol drug substances and related drug products, a hydrophilic interaction chromatography (HILIC) method coupled with a charged aerosol detector (CAD) was explored for the analysis of the two impurities.

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The widespread application of stevia-based sweeteners in food products has resulted in the need for reliable analytical methods for measuring the purity and identity of high-purity steviol glycoside ingredients. The objective of this research was to develop and validate a new reversed-phase separation method capable of separating and quantifying nine steviol glycosides present in typical high-purity stevia extract ingredients. Results of the study established the linearity of the method at a correlation factor of 1.

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Background: Our objective was to compare the complication rates of two common breast reconstruction techniques performed at our hospital and the cost-effectiveness for each test group.

Methods: All patients who underwent deep inferior epigastric perforator (DIEP) flap and transverse rectus abdominis myocutaneous (TRAM) flap by the same surgeon were selected and matched according to age and mastectomy with or without axillary clearance. Patients from each resultant group were selected, with the patients matched chronologically.

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