Respicelltm: An innovative dissolution apparatus for inhaled products

To overcome some of the shortfalls of the types of dissolution testing currently used for pulmonary products, a new custom-built dissolution apparatus has been developed. For inhalation products, the main in vitro characterisation required by pharmacopoeias is the deposition of the active pharmaceutical ingredient in an impactor to estimate the dose delivered to the target site, i.e., the lung. Hence, the collection of the respirable dose (<5 µm) also appears to be an essential requirement for the study of the dissolution rate of particles, because it results as being a relevant parameter for the pharmacological action of the powder. In this sense, dissolution studies could become a complementary test to the routine testing of inhaled formulation delivered dose and aerodynamic performance, providing a set of data significant for product quality, efficacy and/or equivalence. In order to achieve the above-mentioned objectives, an innovative dissolution apparatus (RespiCell™) suitable for the dissolution of the respirable fraction of API deposited on the filter of a fast screening impactor (FSI) (but also of the entire formulation if desirable) was designed at the University of Parma and tested. The purpose of the present work was to use the RespiCell dissolution apparatus to compare and discriminate the dissolution behaviour after aerosolisation of various APIs characterised by different physico-chemical properties (hydrophilic/lipophilic) and formulation strategies (excipients, mixing technology)

EPR of Gd3+ in a single crystal of Thorium disulfide (ThS2)

In this paper we report the experimental angular behaviour of the EPR spectra for a single crystal of Thorium disulfide (ThS2) doped with Gd3+ at very low concentration (of the order of 10 p.p.m.). The experimental data are interpreted in terms of a spin Hamiltonian which reflects the crystal field symmetry at the Th site, that is monoclinic Cs, and therefore shows that the doping ions enter substitutionally without lowering the site symmetry. The low symmetry and the unusually large values of the crystal field parameters b2 0 and b2 2 have made it necessary to use a numerical fitting procedure, starting from the exact numerical diagonalization of the energy matrix for any given direction of the static magnetic field

Mössbauer investigation of hematological diseases

Preliminary results on samples of human hemoglobin from patients with leukaemia or Hodgkin's lymphoma, studied by means of Mössbauer spectroscopy, are reported. © 1988 J.C. Baltzer A.G., Scientific Publishing Company