Identification and characterization of a new dapoxetine impurity by NMR: Transformation of N -oxide by Cope elimination

Synthesis of (±)-Setigerumine I: Biosynthetic Origins of the Elusive Racemic Papaveraceae Isoxazolidine Alkaloids*

The biosynthetic origins of the structurally related racemic isoxazolidine Papaveraceae alkaloids Setigerumine I, Dactylicapnosinine and Dactylicapnosine have remained elusive since their original isolation over two decades ago. Herein we report the first biosynthetic hypothesis for their formation and, inspired by it, the first synthesis of (±)-Setigerumine I with accompanying computational rationale. Based on the results, these isoxazolidine alkaloids arise from racemizing oxidative rearrangements of prominent isoquinoline alkaloids Noscapine and Hydrastine. The key steps featured in this synthesis are a room temperature Cope elimination and a domino oxidation/inverse-electron demand 1,3-dipolar cycloaddition of an axially chiral, yet configurationally unstable, intermediate. The work opens this previously inaccessible family of natural products for biological studies.

Compatibility investigation for a new antituberculotic fixed dose combination with an adequate drug delivery

The compatibility of formulation components is crucial for safe and high-quality medicines. To detect the potential for incompatibility and to assess formulation stability, it is beneficial to conduct a compatibility study during the drug development phase. The therapy of tuberculosis normally consists of two or more medicines taken together. Consequently, different antituberculotic fixed-dose combination (FDC) formulations have been developed. Isoniazid is first-line medicine and present in several FDCs. Low bioavailability due to the active substances' incompatibility in acidic medium was reported for some of these FDC forms. Rifabutin, also a first-line antituberculotic, is available in the market as a single component formulation. This study presents compatibility testing of these two active substances for a new FDC and evaluates the impact of the most common solid dosage forms' excipients on the stability of two active substances. The potential for interaction between the formulation components was analyzed by the UHPLC method. One degradation product and one interaction product were observed and further characterized by high-resolution mass spectrometry. Still, significant degradation of two active substances, such as reported in marketed FDC formulations was not detected for this combination. The stability and drug delivery of the proposed combination were confirmed by the dissolution test in acidic medium.