Effect of different particle size reduction techniques on the nefopam and aciclovir dispersity

Presents the results of application of different particle size reduction approaches to the drug substances - aciclovir and nefopam, namely, wet milling, ultrasonic (US) dispergation, US crystallization and US antisolvent precipitation. All ultrasonic experiments were performed at two operation frequencies - 22 and 44 kHz. It was shown that the crucial parameters in US processes were US output power and sonication time, while the US frequency had a minor effect within the studied power range. US antisolvent precipitation showed the best results among the applied techniques yielding micron-sized particles of aciclovir, which makes this method a very promising technique in nanocrystallization area. The obtained study results provide an opportunity to choose the optimal particle reduction technique depending on the necessary particle size of drug substance suitable for a particular dosage form

High-efficient microwave-assisted method for the preparation of foamed liquid glass granules

In the present work, feasibility and efficiency of microwave-assisted preparation of the foam glass granules intended for production of the blocked heat-insulating materials were studied, and the effect of MW irradiation on the quality of the prepared foamed granules was assessed. The high quality material was obtained using microwave irradiation at much lower temperature in comparison with the known thermal method. The optimal process parameters were properly elaborated and analyzed

A facile microwave-mediated drying process of thermally unstable / labile products

The drying behavior of (S)-N-acetylindoline-2-carboxylic acid, precipitated (1a, 17 wt %) and nonprecipitated (1b, 5 wt %), and N-acetyl-(S)-phenylalanine ((S)-2-acetamido-3-phenylpropanoic acid, 2), both pharmaceutical intermediates, and of cocarboxylase hydrochloride (thiamine pyrophosphate, 3), a coenzyme, a bioactive form of vitamin B1, being a thermolabile substance, has been determined in straightforward drying setups. The method of supplying energy to the system had a profound influence on the drying rate and on the internal temperature of the samples during drying. The drying time of (S)-N-acetylindoline-2-carboxylic acid (1b) with the low moisture content (5 wt %) could be reduced by a factor 4 using microwave irradiation instead of conventional heating, while keeping the sample temperature under 35 °C. N-Acetyl-(S)-phenylalanine (2) with a higher moisture content (22 wt %) demonstrated a decrease in drying time by a factor 2.5 to 4 depending on the applied microwave powers. A reduction in drying time of the precipitated (S)-N-acetylindoline-2-carboxylic acid (1a, 17 wt % moisture) by a factor 2 was demonstrated for drying at 150 W of microwave irradiation instead of using a water bath at 70 °C. A dramatically shorter drying time by a factor 10 was found for cocarboxylase hydrochloride (3, 15 wt % water) on lab-scale which could be reproduced on pilot-plant scale. To achieve with conventional heating similar drying times as under microwave irradiation for the four examples, extremely high energy inputs should be applied, necessitating extremely high temperature differences between the heating source and the sample. The results reveal that microwave irradiation is less energy-consuming and is particularly useful for effective drying of thermally unstable materials in short periods of time