Preparation and characterisation of spray-dried and crystallised trypsin: FT-Raman study to detect protein denaturation after thermal stress.

The production of stable protein formulations is difficult due to unique properties of proteins. Accordingly, spray drying and crystallisation techniques were assessed for their effects on trypsin, a model protein. Samples were investigated using polarising microscopy, thermogravimetry, differential scanning calorimetry (DSC), FT-Raman spectroscopy and enzymatic assay.

Can drug-bearing liposomes penetrate intact skin?

Using liposomes to deliver drugs to and through human skin is controversial, as their function varies with type and composition. Thus they may act as drug carriers controlling release of the medicinal agent. Alternatively, they may provide a localized depot in the skin so minimizing systemic effects or can be used for targeting delivery to skin appendages (hair follicles and sweat glands).

Stability of crystallised and spray-dried lysozyme.

Moisture and temperature promote protein degradation. The stabilities of commercial, crystallised and spray-dried lysozyme, a model protein, were assessed under these stresses to explore whether a crystalline protein had better storage stability than a conventionally produced one. Samples were maintained at different relative humidities (RH) and temperatures for 20 weeks and stabilities estimated in solid and aqueous states.

Electrically assisted skin delivery of liposomal estradiol; phospholipid as damage retardant.

This work investigated transdermal penetration of a model lipophilic drug (estradiol) through human epidermis from phosphatidylcholine (PC)-based liposomes and saturated aqueous estradiol solution (control). Representative examples of cholate-containing ultradeformable (Transfersomes), non-rigid (pure PC) and membrane-stabilized (cholesterol-containing) vesicles were used. The unilamellar vesicles' diameters and zeta potentials were determined.

Penetration enhancers.

One long-standing approach for improving transdermal drug delivery uses penetration enhancers (also called sorption promoters or accelerants) which penetrate into skin to reversibly decrease the barrier resistance. Numerous compounds have been evaluated for penetration enhancing activity, including sulphoxides (such as dimethylsulphoxide, DMSO), Azones (e.g.

Electroporation and ultradeformable liposomes; human skin barrier repair by phospholipid.

This work investigated the effect of electroporation on human epidermal penetration of a model neutral lipophilic compound (estradiol) from saturated aqueous solution and when encapsulated in ultradeformable liposomes. Total amount penetrated and skin deposition were compared with values obtained from passive diffusion. The effect of electrical pulsing on liposome size was investigated.

Human skin sandwich for assessing shunt route penetration during passive and iontophoretic drug and liposome delivery.

This work explored the role of skin appendages (shunt route) in passive and iontophoretic drug and liposome penetration. The technique used an epidermis and stratum corneum sandwich from the same skin donor with the additional stratum corneum forming the top layer of the sandwich. Penetration was monitored during occluded passive and iontophoretic (0.

Integrity of crystalline lysozyme exceeds that of a spray-dried form.

The development of proteins as therapeutic agents is challenging partly due to their inherent instabilities. Consequently, crystallisation and spray drying techniques were assessed to determine their effects on protein integrity using lysozyme as a model protein. Unprocessed, crystallised and spray-dried lysozyme were characterised by: thermal analysis using hot stage microscopy (HSM), differential scanning calorimetry (DSC), high sensitivity differential scanning calorimetry (HSDSC) and thermogravimetry (TGA); and spectroscopic analysis employing Fourier transform Raman (FT-Raman).

Iontophoretic estradiol skin delivery and tritium exchange in ultradeformable liposomes.

This work evaluated the in vitro transdermal iontophoretic delivery of tritiated estradiol from ultradeformable liposomes compared with saturated aqueous solution (control). Effects of current density and application time on tritium exchange with water were also determined. Penetration studies used three Protocols.