Visualizing the conversion of carbamazepine in aqueous suspension with and without the presence of excipients: a single crystal study using SEM and Raman microscopy.

Visual observations of the hydration process of single carbamazepine (CBZ) crystals in water and in various excipient solutions [(1% w/v) - hydroxypropyl cellulose (HPC), poly(vinyl pyrrolidone) (PVP), sodium carboxymethylcellulose (CMC) at pH 7.5 and 3.0, and polyethylene glycol (PEG)] using scanning electron microscopy (SEM) are reported in this paper. Raman microscopy was used to confirm the chemical structures of the unconverted CBZ and the CBZ dihydrate (DH) needles. It was found that defect structures were a more important driving force than the nature of crystal faces for the initiation of the hydration, but face differences became obvious after 6 h immersion. The biggest crystal face grown from methanol, (100), was the slowest one to be covered with DH needles. A comparison of the molecular arrangements along the three crystal faces [(100), (010) and (001)] was carried out using crystal structure visualization software, and fewer polar groups exposed on the (100) face than on the (001) and (010) faces were found, explaining the comparatively weak interaction of the (100) face with water during hydration. Furthermore, investigation of the influence of excipients on the hydration of CBZ showed that both HPC and PVP strongly inhibited conversion, and no conversion of CBZ to DH was found after 18 h immersion in water. PEG and CMC (pH 7.5) were less potent inhibitors than HPC and PVP, and DH needles were observed on all the faces except the (100) face after 18 h immersion. No conversion was detected for the crystal immersed in CMC solution at pH 3.0. This is likely to be caused by the decreased polarity of CMC in water at pH 3.0 (pKa,cmc = 4.3), and thus a higher surface adsorption of CMC to the CBZ crystals in dispersion. The influence of excipients on the conversion of CBZ observed in this study agreed well with our previous quantitative studies using Raman spectroscopy. In this study, visual observation using electron microscopy has been demonstrated to be a unique and powerful tool to improve our understanding of polymorphic conversions of CBZ in aqueous suspension.

Risk factor characteristics in carers who physically abuse or neglect their elderly dependants.

This study investigates the prevalence of, and differences in, risk factor characteristics in a sample of two select populations of carers, one of which physically abused their elderly dependants and one of which neglected them. Nineteen carers (nine who had physically abused and 10 who had neglected their elderly relatives), who were referred to clinical psychology by either their general practitioner or their psychiatrist, were invited to take part in this study. A detailed history of risk factors was obtained, including history of alcohol dependency, type and history of mental ill health, history of maltreatment earlier in life, who they were caring for, how long they had been a carer and whether they felt isolated as a carer. Subjects were then given five assessments to determine whether there were any differences between the two groups. These were the Conflict Tactic Scale, Strain Scale, Beck Depression Inventory, Beck Anxiety Inventory and Cost of Care Index. An examination of the risk factors suggests that heavy alcohol consumption and past childhood abuse by fathers were likely to lead to physical abuse. Significantly higher conflict and depression scores were also present in the physical abuse group, while the neglect group had significantly higher anxiety scores. It is suggested that these findings should be incorporated into an assessment of future risk of abuse or neglect by the carer.