[Interactions between cyclodextrins and triglycerides: from emulsion stabilisation to the emergence of a new drug delivery system called "beads"]. / Interactions entre les cyclodextrines et les triglycérides : de la stabilisation des émulsions à l'obtention d'un nouveau système galénique appelé << billes >>.

Natural cyclodextrins are cyclic oligosaccharides which can be modified to obtain more water soluble or insoluble derivatives. The main interest of cyclodextrins results from their ability to form an inclusion complex with hydrophobic molecules. Inclusion constitutes a true molecular encapsulation. This property is employed in pharmaceutical industry to facilitate the formulation of poorly water soluble and/or fragile drugs. A more recent application of cyclodextrins consists in their use in the preparation of dispersed systems such as micro- and nanoparticles or even liposomes. When incorporated in dispersed systems, cyclodextrin can enhance drug solubility, drug stability and drug loading. Interestingly, cyclodextrins themselves can also be employed to form or stabilise dispersed systems (material or emulsifying agent). For example, the interactions between cyclodextrins with components of the vegetable oils (more especially with triglycerides) allow to stabilise simple or multiple emulsions but also to form particles called "beads". Very rich in oil, this novel lipid carrier presents an important potential for the encapsulation of highly lipophilic compounds and their delivery by topical and oral routes. These two applications are more particularly developed in the present paper.

Formulation and characterisation of beads prepared from natural cyclodextrins and vegetable, mineral or synthetic oils.

A continuous external shaking for 2.5 days of a mixture composed of alpha-cyclodextrin (6%), soybean oil (19.6%) and water (74.4%) resulted in a calibrated lipid carrier namely bead with a high fabrication yield. The purpose of this work was to explore the possibility to substitute alpha-cyclodextrin by other natural cyclodextrins, i.e. beta- and gamma-cyclodextrin and then soybean oil by mineral (Primol) 352 and Marcol 82) or synthetic (Silicon 200) fluid 10, 50 or 100cSt) oils. Beads can be successfully prepared using Marcol 82 with alpha-cyclodextrin and Silicon 50 or 100cSt with gamma-cyclodextrin. The area inside oil/cyclodextrin/water ternary diagram corresponding to bead occurrence was superior for the Marcol 82/alpha-cyclodextrin couple compared to that observed with soybean oil/alpha-cyclodextrin couple. Only a few ratios of Silicon 50 and 100cSt/gamma-cyclodextrin/water led to beads. The combinations which did not induce bead occurrence gave either emulsions, two non-miscible liquids or a solid mixture. Whatever the materials used, beads exhibited similarities: presence of a crystalline organisation and viscoelastic properties. Manufacturing process of paraffin- and silicon-based beads need further optimisation to increase fabrication yield and later on, to take advantages from the high stability of both oils for the formulation of drugs with beads.

alpha-Cyclodextrin/oil beads: an innovative self-assembling system.

The aim of this work was to characterise a new type of particulate system, named beads, prepared by a straightforward technique starting from a mixture of alpha-cyclodextrin aqueous solution and soybean oil without the use of any organic solvent or surface-active agent. Mechanisms involved in bead formation were also investigated. Optimal ratio between alpha-cyclodextrin (6%, w/w), soybean oil (19.6%, w/w) and water (74.4%, w/w) led to homogeneous bead size (1.6 mm) with a fabrication yield superior to 80% after a continuous external shaking during 2.5 days. After freeze-drying, oil and alpha-cyclodextrin contents were estimated at 80% (w/w) and 20% (w/w), respectively. X-ray diffraction studies revealed that beads presented a crystalline organisation and microscopic techniques showed that their inner structure was constituted by a matrix containing oily compartments. Beads offer interesting prospects for the microencapsulation of lipophilic and poorly stable molecules. Due to their semi-solid consistency and their ability to be freeze-dried, these beads have great potentialities for pharmaceutical (oral and topical routes) and cosmetic applications.

In vivo evaluation of paclitaxel-loaded lipid nanocapsules after intravenous and oral administration on resistant tumor.

AIM & METHODS: The aim of the present work was to encapsulate paclitaxel (Ptx) in various lipid nanocapsules (LNCs) formulations and then to compare their pharmacokinetics and efficacy on a subcutaneous isograft model in rats. RESULTS: Three different Ptx formulations were obtained. Drug payloads ranged from 1.32 to 3.62 mg Ptx/g of formulation. After oral administration the area under concentration-time curve was higher (p < 0.05) if Ptx was encapsulated, (1,2 Distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(PEG)] (DSPE-PEG-NH2)) LNCs displaying the highest area under concentration-time curve (p < 0.05). Efficacy was better than control for standard LNCs after oral administration (p < 0.05) and for (DSPE-PEG-NH2) LNCs after intravenous administration. Despite good absorption, (DSPE-PEG-NH2) LNCs failed to remain efficient after oral route. CONCLUSION: This study highlights the importance of efficacy studies paired to pharmacokinetic studies for nanomedicines.

Elderly persons in old-age homes. A medical, psychiatric and social investigation.

A survey of 100 consecutive admissions to homes for elderly Whites in Cape Town showed that an interplay of social, physical and psychiatric factors was responsible for most of the referrals, although psychiatric factors contributed to more than 50% of them. The largest proportion (37%) suffered from confusional states, 31% were diagnosed as having a senile organic condition and 25% showed moderate to severe depression. These old people were physically very frail; 53% had incapacitating muscular weakness or stiff and painful joints, 35% had a significant degree of deafness, 25% had a visual defect and 23% were incontinent. The findings indicate that old-age homes deal with a considerable amount of physical and mental ill health, and they are therefore an essential part of health services. The residents of old-age homes were much older than elderly people in the community, as well as being more socially isolated and very disadvantaged in terms of income and family and social support.

The admission of the elderly to places of care: a socio-psychiatric community survey.

Elderly persons over the age of 60 who were admitted for psychiatric care were compared with a random sample of persons living in the same community in respect of psychiatric, medical and socio-economic variables. The group admitted to hospital for psychiatric reasons was very similar to the latter in general characteristics. However, those people admitted to old age homes, which are the other major resource of psychiatric illness, constitute a distinctly separate population, being older and having considerably more physical illnesses and socio-economic problems. Factors predicting admission to an old age home were largely irremediable age-related conditions (dementia, physical infirmity, etc.), but there were also adverse social circumstances, including marked isolation and a lack of social and emotional support. A comparative analysis of the many psychiatric, social and medical factors is presented, with particular reference to reasons for referral and prevention of admission.