Thermal Analysis in the Evaluation of Solid Lipid Microparticles in the Form of Aqueous Dispersion and Fine Powder

In the presented study, an attempt was made to investigate the most important attributes of solid lipid microparticles (SLM) using thermal analysis (DSC/TG) in order to determine the importance of this technique in the research and development of lipid microparticles. Particularly interesting in our studies were drug–lipid interactions and modifications of the SLM matrix structure induced by the production method (the hot emulsification method) and further processing (e.g., spray drying), as well as changes occurring during the stability studies. Cyclosporine A, indomethacin and spironolactone were used as model active substances incorporated into SLM. The conducted research demonstrated the significant potential of DSC/TG, especially for the analysis of SLM in the form of fine powder. The method of sample preparation, consisting of evaporation of water at room temperature, turned out to be crucial for the DSC/TG analysis of SLM dispersion. In the case of the tested SLM, the basic and usually the only observed thermal transformation in the DSC spectrum was the endothermic peak associated with the lipid forming a microsphere matrix. This peak is the main source of information about the properties and stability of the tested SLM. The obtained results show that glyceryl behenate (Compritol) is a significantly better lipid for forming lipid microparticles than stearic acid. Although thermal transformations of the incorporated drug substances are not directly visible in the DSC spectra, their impact on the SLM properties can be assessed indirectly, based on changes in the lipid melting point and the shape of the DSC and TG peaks and curves. DSC/TG studies confirmed the lack of an effect of the spray drying process on the properties of drug-loaded SLM with Compritol. Studies have also shown up to a 2-year stability of SLM with CsA

Comparative study on the rheological properties and tablettability of various APIs and their composites with titanate nanotubes

The present study aimed to investigate the processability of API-titanate nanotube composites into direct compressed tablets and therefore to reveal the benefits of the composite formation provided in tablet manufacturing. Diltiazem hydrochloride, diclofenac sodium, atenolol, hydrochlorothiazide and their 1:1 ratio composites formed with titanate nanotubes (TNTs) were used for the comparative investigations focusing on flowability, compaction behaviour and post-compressional property measurements. The flowability was studied by measuring the flow time, the angle of repose, the Hausner Ratio and the Compressibility Index, while the compaction properties were estimated by the use of out-of-the-die method applying Kawakita and Walker models. The tablet properties were described by determining the apparent tablet density, the breaking strength and the disintegration time. Based on the experimental results, the composites have superior flowability and display better compactibility and compressibility than the pure APIs. These findings were supported by the more favourable post-compressional properties shown by the composite containing tablets. However, the measurements also revealed that the advantageous effect of TNTs on drug tablettability depends on the efficiency of the incorporation process. © 2017 Elsevier B.V