The effect of film thickness on thermal aerosol generation.

PURPOSE: Rapid heating of thin films of pharmaceutical compounds can vaporize the molecules, which leads to formation of aerosol particles of optimal size for pulmonary drug delivery. The aim of this work was to assess the effect of coated film thickness on the purity of a thermally generated (condensation) drug aerosol. MATERIALS AND METHODS: Pharmaceuticals in their free base form were spray-coated onto stainless steel foils and subsequently heated and vaporized in airflow via a rapid resistive heating of the foil. Aerosol particles were collected on filters, extracted, and analyzed using reverse phase HPLC to assess the amount of degradation induced during the vaporization process. RESULTS: Condensation aerosols of five pharmaceuticals were formed from a wide range of film coating thicknesses. All five showed a roughly linear trend of increasing aerosol purity with decreasing film thickness, although with quite different slopes. These findings are consistent with a model based on general vaporization and degradation kinetics. Small non-uniformities in the film do not significantly alter aerosol purity. CONCLUSIONS: Rapid vaporization of pharmaceuticals coated as thin films on substrates is an efficient way of generating drug aerosols. By controlling the film thickness, the amount of aerosol decomposition can be minimized to produce high purity aerosols.

Cell surface expression of single chain antibodies with applications to imaging of gene expression in vivo.

Imaging of gene expression in vivo has many potential uses for biomedical research and drug discovery, ranging from the study of gene regulation and cancer to the non-invasive assessment of gene therapies. To streamline the development of imaging marker gene technologies for nuclear medicine, we propose a new approach to the design of reporter/probe pairs wherein the reporter is a cell surface-expressed single chain antibody variable fragment that has been raised against a low molecular weight imaging probe with optimized pharmacokinetic properties. Proof of concept of the approach was achieved using a single chain antibody variable fragment that binds with high affinity to fluorescein and an imaging probe consisting of fluorescein isothiocyanate coupled to the chelator diethylene triamine penta-acetic acid labeled with the gamma-emitter (111)In. We demonstrate specific high-affinity binding of this probe to the cell surface-expressed reporter in vitro and assess the in vivo biodistribution of the probe both in wild-type mice and in mice harboring tumor xenografts expressing the reporter. Specific uptake of the probe by, and in vivo imaging of, tumors expressing the reporter are shown. Since ScFvs with high affinities can be raised to almost any protein or small molecule, the proposed methodology may offer a new flexibility in the design of imaging tracer/reporter pairs wherein both probe pharmacokinetics and binding affinities can be readily optimized.

A new series of estrogen receptor modulators that display selectivity for estrogen receptor beta.

A series of 1,3,5-triazine-based estrogen receptor (ER) modulators that are modestly selective for the ERbeta subtype are reported. Compound 1, which displayed modest potency and selectivity for ERbeta vs ERalpha, was identified via high-throughput screening utilizing an ERbeta SPA-based binding assay. Subsequent analogue preparation resulted in the identification of compounds such as 21 and 43 that display 25- to 30-fold selectivity for ERbeta with potencies in the 10-30 nM range. These compounds profile as full antagonists at ERbeta and weak partial agonists at ERalpha in a cell-based reporter gene assay. In addition, the X-ray crystal structure of compound 15 complexed with the ligand binding domain of ERbeta has been solved and was utilized in the design of more conformationally restrained analogues such as 31 in an attempt to increase selectivity for the ERbeta subtype.