A novel transflectance near infrared spectroscopy technique for monitoring hot melt extrusion.

A transflectance near infra red (NIR) spectroscopy approach has been used to simultaneously measure drug and plasticiser content of polymer melts with varying opacity during hot melt extrusion. A high temperature reflectance NIR probe was mounted in the extruder die directly opposed to a highly reflective surface. Carbamazepine (CBZ) was used as a model drug, with polyvinyl pyrollidone-vinyl acetate co-polymer (PVP-VA) as a matrix and polyethylene glycol (PEG) as a plasticiser. The opacity of the molten extrudate varied from transparent at low CBZ loading to opaque at high CBZ loading. Particulate amorphous API and voids formed around these particles were found to cause the opacity. The extrusion process was monitored in real time using transflectance NIR; calibration and validation runs were performed using a wide range of drug and plasticiser loadings. Once calibrated, the technique was used to simultaneously track drug and plasticiser content during applied step changes in feedstock material. Rheological and thermal characterisations were used to help understand the morphology of extruded material. The study has shown that it is possible to use a single NIR spectroscopy technique to monitor opaque and transparent melts during HME, and to simultaneously monitor two distinct components within a formulation.

Assessment of perineural infiltration and spread of oral squamous cell carcinoma: a clinicohistopathologic study.

BACKGROUND: As the tumor spreads through the pathway of least resistance, the present study was carried out to evaluate the presence of perineural infiltration and spread of oral squamous cell carcinoma (OSCC) along the perineural spaces in gingivobuccal sulcus tumors infiltrating into the mandible. AIMS AND OBJECTIVES: (1) To investigate the incidence of perineural invasion of OSCC along the inferior alveolar nerve and (2) to investigate the neurovascular bundle as a potential route of spread of OSCC. MATERIALS AND METHODS: Twenty-six patients with histopathologically proven OSCC of the gingivobuccal sulcus with radiographic infiltration of the mandible were included. The surgical specimens were decalcified and serially sectioned. Each section was stained with hematoxylin and eosin and was screened for the presence of perineural invasion and spread. Results : Twenty-five specimens showed perineural infiltration but none of the cases showed perineural spread along the inferior alveolar canal. Also, not all cases showed any neurologic deficit. Follow-up of these cases showed early recurrence (6-8 months) in the study group. CONCLUSION: Perineural infiltration is present in OSCC but perineural spread along the inferior alveolar canal is absent. It is a bad prognostic indicator.

Differential behavior of (25R)-5,6-epoxyspirostan-22 alpha-O-3 beta-ol and (25R)-5,6-epoxyspirostan-22 alpha-O-3 beta, 4 beta-diol toward Dowex.

The acid-catalyzed hydrolytic cleavage of the 5,6-epoxyspirostane derivatives by the cation exchange resin Dowex 50W X8 has been exploited with the goal of developing synthetic protocols toward 3,4,5,6-polyhydroxyspirostane analogs that can serve as intermediates to potential biologically active compounds. Whereas the diastereomers (25R)-5 alpha, 6 alpha-epoxyspirostan-22 alpha-O-3 beta-ol and (25R)-5 beta, 6 beta-epoxyspirostan-22 alpha-O-3 beta-ol yield two products, (25R)-6 beta-methoxyspirostan-22 alpha-O-3 beta, 5 alpha-diol and (25R)-spirostan-22 alpha-O-3 beta, 5 alpha, 6 beta-triol on Dowex treatment in water-methanol, the alpha- and beta-diastereomers of the 5,6-epoxy derivative of 3 beta, 4 beta-diol provide a single product, (25R)-3 beta, 6 beta-dihydroxy-5 alpha-spirostan-4-one, in good yields. The structures of these products have been confirmed using 1H NMR, 13C NMR, and 1H-1H J-correlated spectroscopies. Multifunctional product formation suggests tremendous utility of Dowex in steroid synthesis. The product formation has been rationalized on the basis of differential conformational constraints of the A/B rings of the different epoxides in directing the reaction course. The reaction shows an interesting example of stereoelectronic effect of a single hydroxy group in discriminating solvent participation.