Polymorphic Generation through Solvent Selection: Ranitidine Hydrochloride

Ranitidine: A Proposed Mechanistic Rationale for NDMA Formation and a Potential Control Strategy

The formation of N-nitrosodimethylamine (NDMA) in ranitidine hydrochloride drug substance (DS) and drug products has attracted considerable attention over the last few years. The drug structure is unusual in that it contains a vinyl nitro moiety. Although a variety of studies have been carried out to understand how NDMA is formed in the DS solids, a mechanistic description of NDMA formation has remained elusive. A new mechanistic view of NDMA formation is detailed here. Autoxidation of ranitidine can rationalize nitrite ion and dimethylamine liberation from ranitidine. The subsequent nitrosation is argued to be due to conversion of nitrite ion to the gas phase nitrosating agent nitrosyl chloride, NOCl. Oxygen scavenging packaging systems should be able to stop the autoxidation, and thus shut down the nitrite release from ranitidine. Without nitrite release NDMA cannot form. This may provide a practical means to stabilize ranitidine DS and solid dosage formulations against NDMA formation.

Synthesis and structural elucidation of a novel polymorph of alcaftadine

In this study, we have synthesized and elucidated the structure of the H1 histamine antagonist, 2-(1-methylpiperidin-4-ylidene)-4,7-diazatricyclo[8.4.0.0((3,7))]tetradeca-1(14),3,5,10,12-pentaene-6-carbaldehyde in the solution and solid-state. We have also studied the thermal dilapidation of the compound. Solution structure analysis was achieved by employing NMR spectroscopy including 2D experiments NOESY, HSQC and HMBC, while solid state investigations were undertaken using SXRD, PXRD, TGA, DSC, and IR spectroscopy. For the first time the single crystal structure of alcaftadine has now been solved. Crystallographic data are as follows: monoclinic, Cc, a=11.5694(6)Å, b=14.5864(6)Å, c=10.2688(4)Å, α=90°, β=111.793(3)°, γ=90°, V=1609.07(13)Å(3), Z=4. The Hirshfeld surface analyses also have been performed using the crystal structure.

Quantifying Solid-State Mixtures of Crystalline Indomethacin by Raman Spectroscopy Comparison with Thermal Analysis

This paper investigates Raman spectroscopy as a quick and reliable method to quantify the alpha (α) and gamma (γ) polymorphic forms of indomethacin compared to differential scanning calorimetry (DSC). Binary mixtures with different ratios of α and γ indomethacin were prepared and analyzed by Raman and DSC. The Raman method was found to be more reliable and superior compared to DSC. The partial conversion of the alpha to gamma polymorphic form during the DSC measurement was the major limitation for the use of full DSC as a quantitative method and resulted in difference between the calculated and measured enthalpy of both polymorphic forms.