No abstract

Conversion of liquid and semisolid lipids into free flowing powders is an advantageous technique, as the carriers display high surface area, strong adsorption capacity, ease of processing, and ability to generate lipid loaded free flowing powders which can be converted to solid dosage forms like tablets and capsules. A combination of density, adsorption capacity and desorption is found to be of importance in the selection of the right adsorbent. Adsorbents like magnesium aluminium silicates (MAS), granulated fumed silica (GFS) and mesoporous silica gel (MSG) were characterized by flow property measurements, particle size, scanning electron microscopy (SEM) and pore structure by mercury (Hg) intrusion study. SEM results reveal adsorbent morphology, whereas an intrusion-extrusion study reveal pore size distributions. Tablets and capsules of oil loaded adsorbents were prepared by conventional methods. Oil loaded adsorbents were evaluated for the ability to convert oil into powder, easy of processing into tablets and capsules, and release of the loaded oil (Vitamin E) or active (Glyburide). All adsorbents possess good flow property while MSG has higher density than GFS and MAS. This helps to deliver maximum active per unit volume. A wider pore size distribution of MAS was observed in comparison to MSG and GFS. MAS exhibited poor oil release from powder and its formulations, whereas GFS demonstrated closely similar release to MSG. Maximum 70% oil loaded MSG can be delivered in tablet dosage form and MSG can deliver the highest amount in limited volume capsules due to its high density. Hence, lower density and poor oil release from MAS limit its applications in solid oral drug delivery, while both MSG and GFS proved to be suitable.

Crystal Chemistry and Thermal Behavior in the La(Cr,Ni)O3 Perovskite System. -The rhombohedral perovskite LaNiO3 decomposes into La4Ni3O10 and NiO above 825 • C both in air and in oxygen; above 1196 • C ( air) or 1291 • C (O2) La2NiO4 is formed besides NiO. Orthorhombic LaCrO3 transforms at 271 • C into a rhombohedral high-temp. phase, which is stable up to 1550 • C. The La(Cr,Ni) O3 systems show no miscibility gap at room temp. as well as at higher temperature. Samples containing up to 60% LaNiO3 have the orthorhombic LaCrO3-type structure, while those containing ≥ 70 mol% LaNiO3 are rhombohedral. The orthorhombic-to-rhombohedral phase transition temp. of LaCrO3 increases with increasing substitution of Ni for Cr and reaches a maximum value of 346 • C at 20-30 mol% LaNiO3. The thermal expansion coefficients of the rhombohedral high-temp. phases are higher than those of the orthorhombic low-temp. phases. -(HOEFER, H. E.; KOCK, W. F.; J.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.