Inhibition of the solid state transformation of carbamazepine in aqueous solution: impact of polymeric properties.

The effects of polymers on the anhydrate-to-hydrate transformation of carbamazepine (CBZ) was investigated. The three types of polymers studied were polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA) and substituted celluloses which included hydroxypropyl methylcellulose (HPMC) and methylcellulose (MC). Anhydrous CBZ was added to dilute aqueous polymer solutions and Raman spectroscopy measurements were collected to monitor the kinetics of the solution-mediated transformation to CBZ dihydrate.

Influence of polymeric excipient properties on crystal hydrate formation kinetics of caffeine in aqueous slurries.

The influence of polymeric excipients on the hydrate transformation of caffeine (CAF) was studied. Anhydrous CAF was added to aqueous solutions containing different additives and the transformation to the hydrate form was monitored using in-line Raman spectroscopy. Various properties of two known inhibitors of CAF hydrate formation, polyacrylic acid (PAA) and polyvinyl alcohol (PVA), were investigated.

Manipulating hydrate formation during high shear wet granulation using polymeric excipients.

Active pharmaceutical ingredients (API) can undergo an anhydrate to hydrate transformation during wet granulation and this transformation may either result in mixed crystalline forms or an unwanted form in the final drug product. Previous studies have shown that it may be possible to inhibit this transformation with polymeric excipients. In this study, three model compounds, caffeine (CAF), carbamazepine (CBZ), and sulfaguanidine (SGN), were subjected to high shear wet granulation and phase transformations were monitored using in-line Raman spectroscopy.

Surface-enhanced Raman spectral measurements of 5-fluorouracil in saliva.

The ability of surface-enhanced Raman spectroscopy (SERS) to measure 5-fluorouracil (5-FU) in saliva is presented. The approach is based on the capacity of Raman spectroscopy to provide a unique spectral signature for virtually every chemical, and the ability of SERS to provide microg/mL sensitivity. A simple sampling method, that employed 1-mm glass capillaries filled with silver-doped sol-gels, was developed to isolate 5-FU from potential interfering chemical components of saliva and simultaneously provide SERSactivity.

Influence of polymeric excipients on crystal hydrate formation kinetics in aqueous slurries.

Crystalline anhydrous active pharmaceutical ingredients (APIs) can potentially transform to the hydrate form during manufacturing processes involving water. The ability to understand and manipulate these transformations is important to maintain control of the solid state form of the API. The influence of various polymeric excipients on the anhydrate to hydrate transformation of caffeine, carbamazepine, and sulfaguanidine was investigated in this study.

Hyphenation of Raman spectroscopy with gravimetric analysis to interrogate water-solid interactions in pharmaceutical systems.

A moisture sorption gravimetric analyzer has been combined with a Raman spectrometer to better understand the various modes of water-solid interactions relevant to pharmaceutical systems. A commercial automated moisture sorption balance was modified to allow non-contact monitoring of the sample properties by interfacing a Raman probe with the sample holder. This hybrid instrument allows for gravimetric and spectroscopic changes to be monitored simultaneously.

Surface-enhanced Raman spectra of VX and its hydrolysis products.

Detection of chemical agents as poisons in water supplies not only requires microg/L sensitivity, but also requires the ability to distinguish their hydrolysis products. We have been investigating the ability of surface-enhanced Raman spectroscopy (SERS) to detect chemical agents at these concentrations. Here we expand these studies and present the SERS spectra of the nerve agent VX (ethyl S-2-diisopropylamino ethyl methylphosphonothioate) and its hydrolysis products, ethyl S-2-diisopropylamino methylphosphonothioate, 2(diisopropylamino) ethanethiol, ethyl methylphosphonic acid, and methylphosphonic acid.