Identification and characterization of potential impurities of donepezil

α-Functionalization of ketones promoted by sunlight and heterogeneous catalysis in the aqueous phase

Herein, a protocol that combines heterogeneous catalysis and solar photocatalysis for the regioselective α-substitution of asymmetric ketones with quinoxalinones has been reported. The result indicates that the reaction is more likely to occur on the α-carbon. This strategy provides a green and efficient way for the α-functionalization of ketones. A singlet oxygen involved mechanism is suggested for the transformation.

Prescribed drugs containing nitrogen heterocycles: an overview

Heteroatoms as well as heterocyclic scaffolds are frequently present as the common cores in a plethora of active pharmaceuticals natural products. Statistically, more than 85% of all biologically active compounds are heterocycles or comprise a heterocycle and most frequently, nitrogen heterocycles as a backbone in their complex structures. These facts disclose and emphasize the vital role of heterocycles in modern drug design and drug discovery. In this review, we try to present a comprehensive overview of top prescribed drugs containing nitrogen heterocycles, describing their pharmacological properties, medical applications and their selected synthetic pathways. It is worth mentioning that the reported examples are actually limited to current top selling drugs, being or containing N-heterocycles and their synthetic information has been extracted from both scientific journals and the wider patent literature.

Characterization of Five Oxidative Degradation Impurities and One Process Impurity of Suvorexant Drug Substance by LC-MS/MS, HR-MS and 1D, 2D NMR: Validation of Suvorexant Drug Substance and Process Impurities by HPLC and UPLC

During the oxidative (10% H2O2) degradation of suvorexant drug substance, around 1.0% of one impurity and less than 1.0% four impurities were found by a new high-performance liquid chromatography (HPLC) assay and related substance method. The mass numbers of 1.0% impurity was 469 [M + H]+, remaining four impurities were 172 [M + H]+, 467 [M + H]+, 483 [M + H]+ and 485 [M + H]+. The 469 [M + H]+, 485[M + H] and 172 [M + H]+ impurities were characterized by using the LC-MS/MS, HR-MS and 1D, 2D NMR spectroscopic data. The 172 [M + H]+ impurity was prepared synthetically and co-injected in HPLC. The retention time of synthesized 172 [M + H]+ impurity was matching with the unknown degradation impurity in HPLC. The developed mass compatible HPLC and ultra performance liquid chromatography methods were validated for drug substance and process impurities by following ICH Q2 (R1) guidelines.

Mn(ii)-catalysed alkylation of methylene ketones with alcohols: direct access to functionalised branched products

Manganese-catalysed alkylation of methylene ketones with alcohols is reported. This catalytic protocol enables the transformation in up to 84% yield and generates water as the byproduct.

Characterization of oral disintegrating film containing donepezil for Alzheimer disease

The aim of this study was to develop a taste-masked oral disintegrating film (ODF) containing donepezil, with fast disintegration time and suitable mechanical strength, for the treatment of Alzheimer's disease. Hydroxypropyl methylcellulose, corn starch, polyethylene glycol, lactose monohydrate and crosspovidone served as the hydrophilic polymeric bases of the ODF. The uniformity, in vitro disintegration time, drug release and the folding endurance of the ODF were examined. The in vitro results showed that 80% of donepezil hydrochloride was released within 5 minutes with mean disintegration time of 44 seconds. The result of the film flexibility test showed that the number of folding time to crack the film was 40 times, an indication of sufficient mechanical property for patient use. A single-dose, fasting, four-period, eight-treatment, double-blind study involving 16 healthy adult volunteers was performed to evaluate the in situ disintegration time and palatability of ODF. Five parameters, namely taste, aftertaste, mouthfeel, ease of handling and acceptance were evaluated. The mean in situ disintegration time of ODF was 49 seconds. ODF containing 7 mg of sucralose were more superior than saccharin and aspartame in terms of taste, aftertaste, mouthfeel and acceptance. Furthermore, the ODF was stable for at least 6 months when stored at 40°C and 75% relative humidity.

A new commercially viable synthetic route for donepezil hydrochloride: anti-Alzheimer's drug

An economical new process has been developed for the synthesis of donepezil hydrochloride (1) an anti-Alzheimer's drug. The process involves Darzen reaction of pyridine-4-carboxaldehyde and 2-bromo-5,6-dimethoxy indanone affording epoxide 5,6-dimethoxy-3-(pyridine-4-yl)spiro[indene-2,2'-oxiran]-1(3H)-one (4) as a key intermediate. The one-pot deoxygenation of 4 and hydrogenation of the aryl moiety in high yield improved the overall yield of the process.

Identification and characterization of potential impurities of amlodipine maleate

Six impurities ranging from 0.43 to 1.42% in amlodipine maleate were detected by a simple isocratic reverse-phase high performance liquid chromatography (HPLC). LC-MS was performed to identify the mass of the impurities. Based on the spectral data (IR, NMR and MS), the structures of these impurities were characterized as 3-ethyl 5-methyl 4-(2-chlorophenyl)-2-[2-(1,3-dioxo-2,3-dihydro-1H-2-isoindolyl)ethoxymethyl]-6-methyl-1,4-dihydro-3,5-pyridinedicarboxylate (impurity I); 5-ethyl 3-methyl 4-(2-chlorophenyl)-2-methyl-6-[2-(2-methylcarbamoylphenyl-carboxamido)ethoxymethyl]-1,4-dihydro-3,5-pyridinedicarboxylate (impurity II); besylate salt of 3-ethyl 5-methyl 2-(2-aminoethoxymethyl)-4-(2-chlorophenyl)-6-methyl-3,5-pyridinedicarboxylate (impurity III); dimethyl 2-(2-aminoethoxymethyl)-4-(2-chlorophenyl)-6-methyl-1,4-dihydro-3,5-pyridinecarboxylate (impurity IV); 3-ethyl 5-methyl 2-(2-aminoethoxymethyl)-4-(4-chlorophenyl)-6-methyl-1,4-dihydro-3,5-pyridinedicarboxylate (impurity V); diethyl 2-(2-aminoethoxymethyl)-4-(2-chlorophenyl)-6-methyl-1,4-dihydro-3,5-pyridinedicarboxylate (impurity VI).