The Effects of Relative Humidity on the Flowability and Dispersion Performance of Lactose Mixtures

Abstract

The flowability and dispersion behavior are two important physicochemical properties of pharmaceutical formulations for dry powder inhalers (DPIs). They are usually affected by the environmental conditions, such as temperature and relative humidity (RH). However, very few studies have been focused on the relationship between the two properties and their dependence on RH during storage. In this research, model pharmaceutical formulations were prepared using mixtures of coarse and fine lactose. The fractions of fines in the mixtures were 0%, 5%, 10%, and 20%, respectively. These blends were stored at four different RH levels, 0%, 30%, 58%, and 85%, for 48 h. The FT4 Powder Rheometer was used to evaluate the powder flowability, and the Malvern Spraytec® laser diffraction system was employed to assess the powder dispersion performance. The results indicated that both the flow and dispersion properties of lactose blends deteriorate after being stored at 85% RH, but improved after being conditioned at 58% RH. The fine particle fractions (FPFs) of the blends with 5% and 10% fine fractions and the as-received coarse lactose decreased when they were conditioned at 30% RH. For the blend with 20% fine fraction, a high RH during storage (i.e., 85% RH) affected the dispersion property, but had a limited influence on its flowability, while, for the coarse lactose powder, the different RH conditions affected its flowability, but not the dispersion results. A strong correlation between the powder flowability and its dispersion performance was found.

Pulmonary Targeting of Inhalable Moxifloxacin Microspheres for Effective Management of Tuberculosis

“…They are mostly influenced by the moisture content. The presence of free water (moisture) in powder formulations for inhalation can drastically affect the powder flow ability [ 45 ] and lead to poor aerosol performance. In this study, moisture content of the optimized MXF-PLGA-MS, determined by Karl Fischer volumetric titration technique, was found to be 4.24 ± 0.43%, which is acceptable for an inhalable microsphere DPI [ 46 ].…”

“…Good flow properties are desirable for dry inhalation powder (DPI) handling. Good flowability ensures the accuracy of the dose and, most importantly, allows the fluidization and release of drug powders from the delivery system [ 45 ]. In this study, flow properties of the optimized MXF-PLGA-MS were evaluated in terms of Carr’s index, Hausner’s ratio and angle of repose ( Table 2 ).…”

A review on the influence of water on food powder flowability

“…The main factors that affect liquid bridge strength are particle properties such as size, shape, and contact angle; powder chemical properties like solubility, hygroscopicity, and hygrocapacity; and liquid properties like viscosity and surface tension (Carpin et al, 2017; Jange & Ambrose, 2019; Salehi et al, 2021). Liquid resistance to particle movement (bridge strength) is stronger in the flowing state of the particles due to rheological properties during motion, such as viscosity, surface tension, and critical rupture distance (Enferad et al, 2021; Lu, Chen, Wu, Chan, & Freeman, 2017; Noren, Scanlon, & Arntfield, 2019). Additionally, an increase in water bridges viscosity can be observed due to the fine particles adsorption and their solubilization into the liquid bridge, and with further water desorption from the system.…”

Packaging and Delivery of Asthma Therapeutics

“…However, studies have shown that compliance with DPI inhalers is lower than pMDI, possibly due to annoyance at the required breath holds (3 s or more), and switching to pMDI from DPI reduced exacerbations in a Korean study population [105]. Furthermore, a study of 111 patients showed better control with pMDI, since the larger particle size of DPI dispensers may not allow for sufficient penetration into the deep lungs and reports have indicated that DPI dispensing precision relies on optimal humidity and electrostatic conditions [36,106,107].…”