Effects of Particle Size, Surface Nature and Crystal Type on Dissolution Rate

Major difference in particle size, minor difference in release profile: a case study of solid lipid nanoparticles

Solid lipid nanoparticles (SLN) have been widely used in a variety of drug delivery routes, which have the outstanding advantage of controlled drug release. The release of SLN is dominated by many factors, among which the particle size of SLN is a critical one. The aim of this project was to explore the relationship between drug release profile and particle size of SLN. SLN were synthesized via the hot high-pressure homogenization (HPH) method, budesonide (BUD) was used as the model drug, and BUD-SLN1-BUD-SLN4 with increasing particle size was obtained, i.e. 120, 240, 360, and 480 nm. The prepared SLN has good encapsulation efficiency, drug loading capacity, and stability. In vitro release behavior studies showed that the cumulative release of BUD-SLN in Tris-Maleate (Tris-M) media was negligible, while that in Tris-M plus pancreatin media or Tris-M-ethanol media obeyed Ritger-Peppas model or first-order kinetic model, respectively. Noticeably, the release behavior of SLN was to some extent related to the average particle size of SLN, but the correlation was insignificant when the intersection degree of particle size distribution was great. This study provides a new idea for the understanding of in vitro release of SLN and has a certain referencing value for the research and development of novel nanomedicines.

Shedding a light on the physical stability of suspensions micronised with intensified vibratory milling; A trend observed with decreasing particle size as a function of time

Intensified vibratory milling is a nanonisation and micronisation technology which can be used to enable the oral bioavailability of poorly soluble compounds. The generated nano- and microsuspensions entail a large surface area which enhances the compounds dissolution rate, yet this large surface area is thermodynamically unfavourable and hence spontaneous destabilisation may occur, i.e. physical instability. Stability studies on suspensions manufactured via intensified vibratory milling have, to the best of our knowledge, not been reported in the literature before. An extended stability study was, therefore, executed with 30 bedaquiline suspensions milled with the intensified vibratory mill under various process settings. The particle size distribution was measured immediately after production, after four weeks of storage at 5 °C and after eleven weeks of storage at 5 °C with laser diffraction and scanning electron microscopy. In addition, a caking test was applied to scrutinise the redispersibility of the prevailing sediments. One sample whose sediment proved to be redisperible, demonstrated a peculiar trend during storage where a narrowing of the particle size distribution and a general particle size reduction was detected which opposed the conventional stability tendencies, i.e. stability or Ostwald ripening. This enigmatic trend was further explored via a repetitive analysis with laser diffraction and in a further phase, with an orthogonal particle sizing technique. Still, no matter the frequency nor technique, a narrowing particle size distribution was observed. To the best of our knowledge, this article, for the first time in the pharmaceutical literature, reports a narrowing particle size distribution of a micronised suspension containing an organic compound. Inevitably, this trend might shed a fundamental new light on the stability trends, exposed by suspensions post-micronisation by high energy milling.

Novel Siwa propolis and colistin-integrated chitosan nanoparticles: elaboration; in vitro and in vivo appraisal

Aim: The present study aimed to formulate novel cremophore-decorated chitosan nanoparticles of colistin, integrated with Siwa propolis extract, to solve bacterial resistance to colistin. Materials & methods: The novel nanoformula was prepared using an incorporation method. Physicochemical assessment and in vivo studies of the selected nanoformulations were performed. Results: The nanoformulation exhibited a nanosize of 48.3 nm, high ζ potential (43.6 mV), high entrapment efficiency (75%) and complete bacterial growth eradication within 2 h (minimum inhibitory concentration = 6.25 μg/ml). Histological examination showed that incorporation of colistin into the nanoformulation could successfully prevent its nephrotoxicity. Conclusion: Tailoring of proper nanocarrier could successfully revert bacteria from being colistin-resistant to colistin-sensitive. The developed nanoformulation can be considered as a potential antibacterial agent in pneumonia treatment.