Microscopic image analysis techniques for the morphological characterization of pharmaceutical particles: Influence of process variables

Tuning the Morphology of Protein-Inorganic Calcium-Phosphate Supraparticles via Directed Assembly

Understanding the phenomena that govern complex interfacial and directed assemblies is essential for both control and scale-up of particle syntheses. The present work describes an effort to understand, control, and tune the formation of protein-inorganic calcium-phosphate supraparticles that are produced at an oscillating air-water interface created by end-over-end rotation of the synthesis solution. Supraparticles were synthesized under an array of different conditions that varied reagent concentration, the presence of additives, tube size, and rotational speed. Paired with a fluid mechanics model of the end-over-end rotation and dimensional analysis, the sensitivity of the synthesis to physicochemical and mechanical parameters was determined. Surface tension and bubble formation were found to be important criteria for changing the size distribution of supraparticles. Thresholds for the values of the Froude, Iribarren, and rotational Reynolds numbers were identified for narrowing particle size distribution. These results both guide the specific protein-inorganic supraparticle synthesis described here and inform future manipulation and scale-up of other complex interfacial colloidal assemblies.

Supremacy of modern morphometry in typing renal oncocytoma and malignant look-alikes

In the era of tumour type-specific therapies, the correct typing of renal tumours is of prime importance. As immunotyping and genotyping approaches are laborious and fall short of standardization, we used whole-scale computer-assisted morphometry instead. Three different types of renal tumours with different prognoses and therapies, notoriously prone to mistyping, were analysed . The sample of 335 tumours included clear cell renal cell carcinoma, chromophobe renal cell carcinoma and renal oncocytoma. The sample was analysed using H&E stains of tissue microarrrays in combination with an image-scanning software. Nuclear and cytoplasmic features were registered with the aid of computer-assisted morphometry. Features included shape, texture, colour and colour intensity for different cell compartments, e.g. nuclei and cytoplasm. The software passed several training steps for final validation. Using morphometry, we were able to classify the three renal tumour types correctly, with a 100 % specificity compared to the WHO typing. Nuclear features dominated the typing of chromophobe renal cell carcinoma, whereas cytoplasmic features were the leading classificators for renal oncocytoma. The grading of clear cell renal cell carcinoma attained a specificity of 80 %. In conclusion, modern morphometry may serve as a tool for typing renal epithelial tumours and additionally draws the attention to future nuclear research in chromophobe renal cell carcinoma.

Bioadhesive emulsions for control release of progesterone resistant to vaginal fluids clearance

The aim of this study is to propose that mucoadhesive vaginal emulsions can be able to resist the clearance effect of vaginal fluid and to have an effective control release of progesterone. With this goal, silicon derivative, cyclomethicone pentamer, was selected as the bioadhesive and water resistant material. In order to obtain a system which is insensitive to the dilution of aqueous fluids, water in silicone (W/S) emulsions were prepared and different proportions of cyclomethicone as well as 8% or 15% w/w of progesterone were employed. The rheological, mechanical and mucoadhesive properties of emulsions were characterized and the drug release was measured for each formulation. Mucoadhesive behavior was determined and the influence of simulated vaginal fluid (SVF) at bioadhesion was assessed using three commercial mucoadhesive vaginal gels (Crinone(®), K-Y jelly(®) and Zidoval(®)) as the bioadhesive references. All assayed emulsions have good rheological and mechanical properties and their consistence and viscosity increase when the proportion of the internal phase increases. Related to mucoadhesion, in the absence of SVF, W/S emulsions showed similar bioadhesive levels like the commercial formulations. However, in the presence of SVF, W/S emulsions are able to keep their mucoadhesive properties while the marketed references drastically lose their consistency and adherence to the vaginal mucosa. Drug release profiles from W/S emulsion show that progesterone is released with pseudo-order zero kinetics and a constant release rate is maintained for at least two weeks. The results of the in vivo studies developed in rats show that after a single vaginal administration, bioadhesive W/S emulsions increase the uterine tissue progesterone levels in young and postmenopausal rats. Moreover in postmenopausal rats, they provide high uterine levels of progesterone compared to the bioadhesive-marketed gel used as a reference. Therefore, W/S emulsions have an interesting potential as bioadhesive vaginal delivery systems for drug administration.

Optical microscopy as a comparative analytical technique for single-particle dissolution studies

Novel, simple and cost effective methods are needed to replace advanced chemical analytical techniques, in small-scale dissolution studies. Optical microscopy of individual particles could provide such a method. The aim of the present work was to investigate and verify the applicability of optical microscopy as an analytical technique for drug dissolution studies. The evaluation was performed by comparing image and chemical analysis data of individual dissolving particles. It was shown that the data obtained by image analysis and UV-spectrophotometry produced practically identical dissolution curves, with average similarity and difference factors above 82 and below 4, respectively. The relative standard deviation for image analysis data, of the studied particle size range, varied between 1.9% and 3.8%. Consequently, it is proposed that image analysis can be used, on its own, as a viable analytical technique in single-particle dissolution studies. The possibility for significant reductions in sample preparation, operational cost, time and substance consumption gives optical detection a clear advantage over chemical analytical methods. Thus, image analysis could be an ideal and universal analytical technique for rapid small-scale dissolution studies.

Microscopic image analysis techniques for the morphological characterization of pharmaceutical particles: Influence of the software, and the factor algorithms used in the shape factor estimation

The present report highlights the difficulties of particle shape characterizations of multiparticulate systems obtained using different image analysis techniques. The report describes and discusses a number of shape factors that are widely used in pharmaceutical research. Using photographs of 16 pellets of different shapes, obtained by extrusion-spheronization, we investigated how shape factor estimates vary depending on method of calculation, and among different software packages. The results obtained indicate that the algorithms used (both for estimation of basic dimensions such as perimeter and maximum diameter, and for estimation of shape factors on the basis of these basic dimensions) have marked influences on the shape factor values obtained. These findings suggest that care is required when comparing results obtained using different image analysis programs.