Universal ion chromatography method for anions in active pharmaceutical ingredients enabled by computer-assisted separation modeling

Ion Chromatography (IC) is one of the most widely used methods for analyzing ionic species in pharmaceutical samples. A universal IC method that can separate a wide range of different analytes is highly desired as it can save a lot of time for method development and validation processes. Herein we report the development of a universal method for anions in active pharmaceutical ingredients (APIs) using computer-assisted chromatography modeling tools. We have screened three different IC columns (Dionex IonPac AS28-Fast 4 µm, AS19 4 µm and AS11-HC 4 µm) to determine the best suitable column for universal IC method development. A universal IC method was then developed using an AS11-HC 4 µm column to separate 31 most common anionic substances in 36 mins. This method was optimized using LC Simulator and a model which precisely predicts the retention behavior of 31 anions was established. This model demonstrated an excellent match between predicted and experimental analyte retention time (R2 =0.999). To validate this universal IC method, we have studied the stability of sulfite and sulfide analytes in ambient conditions. The method was then validated for a subset of 29 anions using water and organic solvent/water binary solvents as diluents for commercial APIs. This universal IC method provides an efficient and simple way to separate and analyze common anions in APIs. In addition, the method development process combined with LC simulator modeling can be effectively used as a starting point during method development for other ions beyond those investigated in this study.

Biocatalytic cascade process of islatravir: Analytical and regulatory control strategy of minor enantiomer

Commercial process of islatravir (MK-8591, EFdA) utilizes biocatalytic cascade reactions to construct the ribose moiety of the molecule which bears three chiral centers. However, this biocatalytic process also brought analytical challenges where all stereoisomers and process related compounds are controlled in one isolated intermediate, the final drug substance. A chiral LC method was developed to resolve all those compounds from islatravir and its minor enantiomer by thorough column screening and careful optimization. Detail of designing key method validation components such as method linearity, precision and robustness is discussed, and their results were presented. The method was successfully validated to fulfill various expectation from each individual health authority including FDA, EMA, PMDA, and ANVISA.

Development of a Robust Manufacturing Route for Molnupiravir, an Antiviral for the Treatment of COVID-19

Herein is described the development of a large-scale manufacturing process for molnupiravir, an orally dosed antiviral that was recently demonstrated to be efficacious for the treatment of patients with COVID-19. The yield, robustness, and efficiency of each of the five steps were improved, ultimately culminating in a 1.6-fold improvement in overall yield and a dramatic increase in the overall throughput compared to the baseline process.

Subliminal and supraliminal processing of reward-related stimuli in anorexia nervosa

BACKGROUND

Previous studies have highlighted the role of the brain reward and cognitive control systems in the etiology of anorexia nervosa (AN). In an attempt to disentangle the relative contribution of these systems to the disorder, we used functional magnetic resonance imaging (fMRI) to investigate hemodynamic responses to reward-related stimuli presented both subliminally and supraliminally in acutely underweight AN patients and age-matched healthy controls (HC).

METHODS

fMRI data were collected from a total of 35 AN patients and 35 HC, while they passively viewed subliminally and supraliminally presented streams of food, positive social, and neutral stimuli. Activation patterns of the group × stimulation condition × stimulus type interaction were interrogated to investigate potential group differences in processing different stimulus types under the two stimulation conditions. Moreover, changes in functional connectivity were investigated using generalized psychophysiological interaction analysis.

RESULTS

AN patients showed a generally increased response to supraliminally presented stimuli in the inferior frontal junction (IFJ), but no alterations within the reward system. Increased activation during supraliminal stimulation with food stimuli was observed in the AN group in visual regions including superior occipital gyrus and the fusiform gyrus/parahippocampal gyrus. No group difference was found with respect to the subliminal stimulation condition and functional connectivity.

CONCLUSION

Increased IFJ activation in AN during supraliminal stimulation may indicate hyperactive cognitive control, which resonates with clinical presentation of excessive self-control in AN patients. Increased activation to food stimuli in visual regions may be interpreted in light of an attentional food bias in AN.

Ultrafast chiral separations for high throughput enantiopurity analysis

Ultrafast chiral chromatography enables high throughput enantiopurity analysis (over one thousand samples in an 8 h workday) for enantioselective synthesis investigations.

Covalent functionalization of silica surface using "inert" poly(dimethylsiloxanes)

Methyl-terminated poly(dimethylsiloxanes) (PDMSs) are typically considered to be inert and not suitable for surface functionalization reactions because of the absence of readily hydrolyzable groups. Nevertheless, these siloxanes do react with silica and other oxides, producing chemically grafted organic surfaces. Known since the 1970s and then forgotten and recently rediscovered, this reaction provides a versatile yet simple method for the covalent functionalization of inorganic surfaces. In this work, we have explored the reactions of linear methyl-terminated and cyclic PDMS and bis-fluoroalkyl disiloxanes for the surface functionalization of mesoporous silica (Dpore ≈ 30-35 nm). The optimal reaction conditions included 24 h of contact of neat siloxane liquids and silica at 120-250 °C (depending on the siloxane). A study of the reactions of silicas with different extents of hydration demonstrated the critical role of water in facilitating the grafting of the siloxanes. The proposed reaction mechanism involved the hydrolysis of the adsorbed siloxanes by the Lewis acidic centers (presumably formed by water adsorbed onto surface defects) followed by the coupling of silanols to the surface to produce grafted siloxanes. For rigorously dehydrated silicas (calcination ∼1000 °C), an alternative pathway that did not require water and involved the reaction of the siloxanes with the strained siloxane rings was also plausible. According to FTIR and chemical analysis, the reactions of bis-fluoroalkyl disiloxanes and cyclic PDMS (D3-D5) produced covalently-attached monolayer surfaces, and the reactions of high-MM methyl-terminated PDMS produced polymeric grafted silicas with a PDMS mass content of up to 50%. As evidenced by the high contact angles of ∼130°/100° (adv/rec) and the negligible amount of water adsorption over the entire range of relative pressures, including saturation (p/p0 → 1), the siloxane-grafted porous silicas show uniform, high-quality hydrophobic surfaces. An overall comparison of siloxanes with classical silane coupling agents (i.e., silanes with readily hydrolyzable functionalities such as chloro, amino, etc.) demonstrated that the reactions of siloxanes produced surfaces of similar quality and, although requiring higher temperatures, used noncorrosive, less hazardous reagents, thereby providing an environmentally benign alternative to the chemical functionalization of metal oxide surfaces.

Combined nitrogen, hexane, and benzene adsorption characterization of pores and surfaces of lyophobic mesoporous silicas

For lyophobic porous surfaces, structural analysis by vapor adsorption is complicated due to weak adsorbate-adsorbent interactions and limited wetting of the pores (nonzero contact angles). To investigate further, adsorption isotherms of three distinct adsorbates (nitrogen - 77 K, n-hexane and benzene - 298 K) were studied for SBA-15 ordered mesoporous silica where the surface was functionalized with lyophobic perfluoroalkyl groups (C6F13 termini). The results demonstrated a clear advantage of the combined use of the adsorption isotherms of less surface sensitive (nitrogen) and more surface sensitive (hydrocarbons) adsorbates. The adsorption of nitrogen provided basic structural characteristics like surface area, pore volume, and pore size distribution, while the isotherms of benzene and n-hexane were used to characterize wetting (contact angles) and surface energy of the C6F13 surfaces within the pores. For the first time, the statistical film thickness for nitrogen, benzene, and n-hexane are being reported for the adsorption on fluorinated surfaces, thereby providing critical data for the pore size and the contact angle determination of the lyophobic materials.

Microscale HPLC enables a new paradigm for commercialization of complex chiral stationary phases

The small column size (0.3 mm i.d. x 15 cm) used in microscale HPLC contains only a small fraction (<1%) of the chromatographic packing material of a typical analytical HPLC column. Consequently, chromatographic stationary phases that are prohibitively expensive in conventional HPLC, owing either to synthetic complexity or costly starting materials, may become commercially viable in the microscale format. To illustrate this point, a previously described, synthetically complex, crown ether chiral stationary phase was prepared and evaluated in the microscale format, showing excellent separation of the enantiomers of underivatized amine analytes.

[Introduction of definite molecular weight heparan sulfate in a protocol of prevention of deep venous thrombosis in prosthetic orthopedic surgery]

Use of definite molecular weight heparan sulphate in a protocol for the prevention of deep venous thrombosis in the total joint replacement surgery. The authors propose a working protocol for the prevention of deep venous thrombosis in prosthetic orthopaedic surgery. It requires that integration of pharmacological, anaesthesiological, rheological and physiokinesitherapic measures, it has permitted a very good prevention of thromboembolic disease and it is well-tolerated and safe. The protocol requires: peripheral anaesthesia (sub-arachnoidal block), pre and post-operative pharmacological treatment with heparan-sulphate of a fixed molecular weight, haemodilution with maintenance of the haematocrit at no more than 30%, early physiokinesitherapy associated with the use of elastic stockings graduated tension. The fifty patients treated with this protocol were controlled during the pre-operative and post-operative stage and one month later and no thrombo-embolic complications resulted.