Insulin nanoparticles: stability and aerosolization from pressurized metered dose inhalers.

Nanoparticles containing insulin have been produced by emulsification processes followed by freeze-drying. Purified nanoparticles were suspended in hydrofluoroalkane (HFA) 134a, using essential oils (cineole and citral) as suspension stabilizers to form pressurized metered dose inhaler (pMDI) formulations. The retention of insulin integrity after formulation processing was determined using high performance liquid chromatography (HPLC), size exclusion chromatography (SEC), circular dichroism (CD) and fluorescence spectroscopy.

The processing of nanoparticles containing protein for suspension in hydrofluoroalkane propellants.

Nanoparticles delivered from pressurized metered dose inhalers (pMDIs) potentially offer a means of efficiently delivering proteins to the lung. Nanoparticles containing the model protein lysozyme have been produced using microemulsion and nanoprecipitation methods. Freeze-drying water in oil emulsions, with chloroform as the organic solvent, followed by washing of excess surfactant (lecithin) led to the production of lactose nanoparticles having approximately 300 nm mean size.

An investigation into the influence of drug lipophilicity on the in vivo absorption profiles from subcutaneous microspheres and in situ forming depots.

Drug lipophilicity is known to have a major influence on in vivo drug absorption from intramuscularly and subcutaneously administered solutions. Indeed, chemical modification to increase drug lipophilicity is used to enable sustained drug release from solutions. In contrast to the wealth of knowledge on drug release from simple solutions, the influence of drug lipophilicity on its release from controlled release formulations, such as, microparticles and in situ forming depots, have not been systematically studied.

Combined surface pressure-interfacial shear rheology study of the effect of pH on the adsorption of proteins at the air-water interface.

The effect of pH on the adsorption of catalase and lysozyme at the air-water interface has been studied using a combined surface pressure-interfacial shear rheology technique. The results presented show that the rate of development of interfacial phenomena increases as the pH of the subphase approaches the isoelectric point of the protein under investigation. The development of the measured interfacial rheological parameters is due to an increased rate of cross-link formation within the resultant interfacial gel.

Combined surface pressure-interfacial shear rheology studies of the interaction of proteins with spread phospholipid monolayers at the air-water interface.

The adsorption of two model proteins, catalase and lysozyme, to phospholipid monolayers spread at the air-water interface has been studied using a combined surface pressure-interfacial shear rheology technique. Monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dipalmitoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DPPG) and DPPC:DPPG (7:3) were spread on a phosphate buffer air-water interface at pH 7.4.

Novel sustained release microspheres for pulmonary drug delivery.

A novel process for generating sustained release (SR) particles for pulmonary drug delivery is described. High purity nanoparticles of a hydrophilic, ionised drug are entrapped within hydrophobic microspheres using a spray-drying approach. Sustained release of the model drug, terbutaline sulphate (TS), from the microspheres was found to be proportional to drug loading and phospholipid content.

Surfactant solubility and aggregate orientation in hydrofluoroalkanes.

Purpose: To find surfactants soluble in the two hydrofluoroalkane (HFA) propellants, HFA-134a and HFA-227ea; to compare surfactant solubility in the two propellants with those in 2H,3H-decafluoropentane (DFP) in order to assess latter's suitability as a liquid model propellant and to investigate surfactant aggregation and aggregate orientation in HFAs.

Methods: To assess surfactant solubility, HFA was added to a known amount of surfactant until dissolution was visibly apparent. An iodine solubilization method was used to determine surfactant aggregation behaviour in DFP.

Peptide washout and permeability from glyceryl monooleate buccal delivery systems.

Simultaneous evaluation of the permeation and washout of a peptide from the mucoadhesive liquid crystalline phases of glyceryl monooleate (GMO) has been investigated using a donor compartment flow-through diffusion cell. [D-Ala2, D-Leu5]enkephalin (DADLE) was incorporated into the cubic and lamellar liquid crystalline phases of GMO and applied to excised porcine buccal mucosa mounted in the donor compartment flow-through cell. Phosphate-buffered saline pH 7.