Functionalised particles using dry powder coating in pharmaceutical drug delivery:promises and challenges

Introduction: Production of functionalised particles using dry powder coating is a one-step, environmentally friendly process that paves the way for the development of particles with targeted properties and diverse functionalities. Areas covered: Applying the first principles in physical science for powders, fine guest particles can be homogeneously dispersed over the surface of larger host particles to develop functionalised particles. Multiple functionalities can be modified including: flowability, dispersibility, fluidisation, homogeneity, content uniformity and dissolution profile. The current publication seeks to understand the fundamental underpinning principles and science governing dry coating process, evaluate key technologies developed to produce functionalised particles along with outlining their advantages, limitations and applications and discusses in detail the resultant functionalities and their applications. Expert opinion: Dry particle coating is a promising solvent-free manufacturing technology to produce particles with targeted functionalities. Progress within this area requires the development of continuous processing devices that can overcome challenges encountered with current technologies such as heat generation and particle attrition. Growth within this field requires extensive research to further understand the impact of process design and material properties on resultant functionalities

Characterisation and surface-profiling techniques for composite particles produced by dry powder coating in pharmaceutical drug delivery

The production of composite particles using dry powder coating is a one-step, environmentally friendly, process for the fabrication of particles with targeted properties and favourable functionalities. Diverse functionalities, such flowability enhancement, content uniformity, and dissolution, can be developed from dry particle coating. In this review, we discuss the particle functionalities that can be tailored and the selection of characterisation techniques relevant to understanding their molecular basis. We address key features in the powder blend sampling process and explore the relevant characterisation techniques, focussing on the functionality delivered by dry coating and on surface profiling that explores the dynamics and surface characteristics of the composite blends. Dry particle coating is a solvent- and heat-free process that can be used to develop functionalised particles. However, assessment of the resultant functionality requires careful selection of sensitive analytical techniques that can distinguish particle surface changes within nano and/or micrometre ranges

Quality by Design (QbD) based process optimisation to develop functionalised particles with modified release properties using novel dry particle coating technique

Quality by Design (QbD), a current trend employed to develop and optimise various critical pharmaceutical processes, is a systematic approach based on the ethos that quality should be designed into the product itself, not just end tested after manufacture. The present work details a step-wise application of QbD principles to optimise process parameters for production of particles with modified functionalities, using dry particle coating technology. Initial risk assessment identified speed, air pressure, processing time and batch size (independent factors) as having high-to-medium impact on the dry coating process. A design of experiments (DOE) using MODDE software employed a D-optimal design to determine the effect of variations in these factors on identified responses (content uniformity, dissolution rate, particle size and intensity of Fourier transform infrared (FTIR) C = O spectrum). Results showed that batch size had the most significant effect on dissolution rate, particle size and FTIR; with an increase in batch size enhancing dissolution rate, decreasing particle size (depicting absence of coated particles) and increasing the FTIR intensity. While content uniformity was affected by various interaction terms, with speed and batch size having the highest negative effect. Optimal design space for producing functionalised particles with optimal properties required maximum air pressure (40psi), low batch size (6g), speed between 850 to 1500 rpm and processing times between 15 to 60 minutes. The validity and predictive ability of the revised model demonstrated reliability for all experiments. Overall, QbD was demonstrated to provide an expedient and cost effective tool for developing and optimising processes in the pharmaceutical industry

Microparticle surface layering through dry coating: impact of moisture content and process parameters on the properties of orally disintegrating tablets

Objectives: The aim of this study was to investigate the influence of process parameters during dry coating on particle and dosage form properties upon varying the surface adsorbed moisture of microcrystalline cellulose (MCC), a model filler/binder for orally disintegrating tablets (ODTs). Methods: The moisture content of MCC was optimised using the spray water method and analysed using thermogravimetric analysis. Microproperty/macro-property assessment was investigated using atomic force microscopy, nano-indentation, scanning electron microscopy, tablet hardness and disintegration testing. Key findings: The results showed that MCC demonstrated its best flowability at a moisture content of 11.2% w/w when compared to control, comprising of3.9% w/w moisture. The use of the composite powder coating process (without air) resulted in up to 80% increase in tablet hardness, when compared to the control. The study also demonstrated that surface adsorbed moisture can be displaced upon addition of excipients during dry processing circumventing the need for particle drying before tabletting. Conclusions: It was concluded that MCC with a moisture content of 11% w/w provides a good balance between powder flowability and favourable ODT characteristics

Formulation of sublingual promethazine hydrochloride tablets for rapid relief of motion sickness

The delivery of antihistaminic agents via the oral route is problematic, especially for elderly patients. This study aimed to develop a sublingual formulation of promethazine hydrochloride by direct compression, and to mask its intensely bitter taste. Promethazine hydrochloride (PMZ) sublingual tablets prepared by direct compression were optimized using Box-Behnken full factorial design. The effect of a taste-masking agent (Eudragit E 100, X1), superdisintegrant (crospovidone; CPV, X2) and lubricant (sodium stearyl fumarate; SSF, X3) on sublingual tablets’ attributes (responses, Y) was optimized. The prepared sublingual tablets were characterized for hardness (Y1), disintegration time (Y2), initial dissolution rate (IDR; Y3) and dissolution efficiency after 30 min (Dissolution Efficiency (DE); Y4). The obtained results showed a significant positive effect of the three independent factors on tablet hardness (P  0.05). Optimized formulation that was suggested by the software was composed of: Eudragit E 100 (X1) = 2.5% w/w, CPV (X2) = 4.13% w/w, and SSF (X3) = 1.0% w/w. The observed values of the optimized formula were found to be close to the predicted optimized values. The Differential Scanning Calorimetric (DSC) studies indicated no interaction between PMZ and tablet excipients