The effectiveness of various scavengers on the γ-irradiated, methanolic solution of medazepam

Efficient Construction of 5H-1,4-Benzodiazepine Derivatives by a Catalyst-Free Direct Aerobic Oxidative Annulation Strategy

A catalyst-free direct aerobic oxidative annulation reaction of 2-aminobenzylic amines and α-hydroxy ketones efficiently afforded versatile 5H-1,4-benzodiazepine derivatives by employing air as economic and green oxidant under mild conditions. Interestingly, solvent was found to be crucial to the reaction, so that by using acetic acid as the best solvent an efficient and practical method could be achieved, requiring no catalysts or additives at all. This method tolerates a wide range of 2-aminobenzylic amines and α-hydroxy ketones and could be scaled up to multigram synthesis and directly applied in one-step synthesis of the pharmaceutically active N-desmethylmedazepam derivatives, revealing the potential of this new method in the synthesis of 5H-1,4-benzodiazepine skeleton-based pharmaceuticals and chemicals.

Studies into radiolytic decomposition of fluorine-18 labeled radiopharmaceuticals for positron emission tomography

Radiolytic decomposition of high specific concentration radiopharmaceuticals is an undesired side-effect that can hamper development of novel PET tracers. This was particularly evident in a series of carbon-11 and fluorine-18 labeled mono- and dimethyl-substituted aryl amines, where rapid decomposition was observed in isolation and formulation steps. We tested a number of additives that inhibit radiolysis and can be safely added to the synthesis procedures (purification and isolation) and reformulation steps to provide suitable clinical formulations. Ethanol and sodium ascorbate are established anti-oxidant stabilizers that completely inhibit radiolytic decomposition and are amenable to human use. Herein, we also demonstrate for the first time that nitrones are non-toxic radical scavengers that are capable of inhibiting radiolysis.

Radiolysis characterization of cetostearyl alcohol by gas chromatography-mass spectrometry

Methods for sample preparation, assay test and impurity test were established. Degrees of cetostearyl alcohol (CSA) radiolyses in pure state, ointment base and in chloramphenicol eye ointment (CAPEO) were determined at doses of 25 and 50 kGy. Radiolyses of CSA occur in all cases. The degrees are directly proportional to the irradiation dose in each case. Forty-two impurities and radiolysis products were identified using gas chromatography-mass spectrometry. The radiolysis products were assigned to be n-alkane, n-aldehyde and 2-methyl-1-alcohol. Accordingly, the degradation pathways of cetosteary alcohol were elucidated. Radiolysis behaviors of CSA in pure state, eye ointment base and CAPEO were studied by assay and impurity analyses. The influence of eye ointment matrixes is modest and chloramphenicol molecule exhibits slight scavenger function for cetostearyl. Both qualitative and quantitative data confirm that the radiolysis products of CSA do not cause safety concerns for human use.

A review of the effects of gamma radiation on pharmaceutical materials

This review on the radiation effects on pharmaceutical materials, with a view to their sterilization by gamma radiation, attempts to cover all the pertinent literature published over the period 1975 to 1992.