Electrostatic coated controlled porosity osmotic pump with ultrafine powders

Working Mechanisms and Experimental Research of Piezoelectric Pump with a Cardiac Valve-like Structure

In this study, based on the working principle of the cardiac valve structure that prevents blood from flowing back, a piezoelectric pump with a cardiac valve-like structure (PPCVLS) is designed. The operating principles of cardiac-valve-like structures (CVLSs) are introduced. Furthermore, the closure conditions of the CVLSs on both sides of the flow channel are explored. The principle behind the working-state conversion between "valve-based" and "valve-less" of PPCVLS is also analyzed. A high-speed dynamic microscopic image-analysis system was utilized to observe and verify the working-state conversion between "valve-based" and "valve-less" PPCVLSs. The resonant frequency of the piezoelectric pump was measured by Doppler laser vibrometer, and the optimal working frequency of the piezoelectric vibrator was determined as 22.35 Hz. The prototype piezoelectric pump was fabricated by the 3D printing technique, and the output performance of the piezoelectric pump was also evaluated. The experimental results show that the piezoelectric pump is valve-based when the driving voltage is greater than 140V, and the piezoelectric pump is valve-less when the driving voltage is less than 140 V. Furthermore, the maximum output pressure of the piezoelectric pump was 199 mm H₂O when driven by the applied voltage of 220 V at 7 Hz, while the maximum flow rate of the piezoelectric pump was 44.5 mL/min when driven by the applied voltage of 220 V at 11 Hz.

Osmotic-controlled release oral tablets: technology and functional insights

In recent years, oral osmotic tablets have sparked a therapeutic paradigm for controlled-release dosage forms due to their intrinsic insensitivity to physiological and physicochemical factors. Despite these benefits, the design of an optimal osmotic technology is precluded by various challenges. These limitations include manufacturing complexity, the lack of understanding of the functional mechanics, and inadequate optimization for the desired bio-performance. This paper systematically reviews the development of an osmotic-driven drug delivery system and the strategy for a zero-order release profile with an emphasis on swellable core technology. We discuss the applicability of the various types of osmotic tablets, their suitability to specific needs, and factors that drive the technology selection. Finally, we review the challenges, opportunities, and future perspectives associated with osmotic tablets.

An Update of Moisture Barrier Coating for Drug Delivery

Drug hydrolytic degradation, caused by atmospheric and inherent humidity, significantly reduces the therapeutic effect of pharmaceutical solid dosages. Moisture barrier film coating is one of the most appropriate and effective approaches to protect the active pharmaceutical ingredients (API) from hydrolytic degradation during the manufacturing process and storage. Coating formulation design and process control are the two most commonly used strategies to reduce water vapor permeability to achieve the moisture barrier function. The principles of formulation development include designing a coating formulation with non-hygroscopic/low water activity excipients, and formulating the film-forming polymers with the least amount of inherent moisture. The coating process involves spraying organic or aqueous coating solutions made of natural or synthetic polymers onto the surface of the dosage cores in a drum or a fluid bed coater. However, the aqueous coating process needs to be carefully controlled to prevent hydrolytic degradation of the drug due to the presence of water during the coating process. Recently, different strategies have been designed and developed to effectively decrease water vapor permeability and improve the moisture barrier function of the film. Those strategies include newly designed coating formulations containing polymers with optimized functionality of moisture barrier, and newly developed dry coating processes that eliminate the usage of organic solvent and water, and could potentially replace the current solvent and aqueous coatings. This review aims to summarize the recent advances and updates in moisture barrier coatings.

Comparative Study of the Performances of Al(OH)3 and BaSO4 in Ultrafine Powder Coatings

Ultrafine powder coatings are one of the development directions in the powder coating industry, as they can achieve thin coatings with good leveling and high surface smoothness comparable to liquid coatings. Compared to regular coatings, they experience a higher sensitivity to any incompatibilities, e.g., filler from coating components. The properties of fillers play a great role in the performance of coating films. Aluminum trihydrate (Al(OH)3) is a well-known filler in solvent-based coatings and other polymer industries. To study and evaluate the performances of Al(OH)3 in ultrafine powder coatings, a popular filler, barium sulfate (BaSO4) is used for comparison. Both fillers are added in ultrafine powder coatings based on two of the most commonly used resin systems (polyester-epoxy and polyester). The differences of physical and chemical properties between both fillers have significant influences on several properties of powder paints and coating films. The polar groups (hydrogen bond) in Al(OH)3 result in the strong interaction between inorganic filler and organic polymer matrix, thus decreasing the molecular network mobility and influencing the chain formation, which is verified by differential scanning calorimetric (DSC). The bed expansion ratio (BERs) of powder paints incorporated with Al(OH)3 are much higher than those with BaSO4, which indicate more uniform gas-solid contact during the spraying process. Samples with Al(OH)3 exhibit much lower specular gloss at 60°, which are expected to achieve remarkable matting effects. Superior corrosion resistances can be observed for almost all the coated panels incorporated with Al(OH)3 in contrast to those with BaSO4. Other aspects are slightly influenced by the difference between the two fillers, such as the angle of repose values (AORs) of powder paints, the impact resistance and flexibility of coating films.