MicroCoat™: Improved Drug Release Control For Sustained Release Multiparticulates

Kavil Patel, Valentyn Mohylyuk, Nathan Scott, Darragh Murnane, Craig Richardson, Fang Liu*

*Corresponding author for this work

Research output: Contribution to conferencePosterpeer-review


Achieving sustained release from drug-loaded microparticles, especially without the use of organic solvents, can be challenging due to the relatively large surface area which is exposed during dissolution.
A novel Microcoat technology was developed to eliminate particle agglomeration during coating of microparticles. The aim of this project was to investigate the effect of the MicroCoat technology on drug release from coated microparticles for the development of gliclazide oral sustained release liquid suspensions.
The Coating Process
Cellets 100 and Cellets 350 were layered with gliclazide and coated with aqueous Eudragit NM using a Mini Glatt fluid-bed coater. Polymer coating was performed with and without the use of the MicroCoat technology, the addition of dry powder processing aid, via an external port during coating.
The average particle sizes (D50) of coated particles using Cellets 100 and Cellets 350 as cores were 199±3 µm and 519±5 µm respectively.
Applying the MicroCoat technology improved the product yield of coating small particles (Cellets 100) from 72.1 to 99.8%, by decreasing particle cohesion and reducing agglomeration.
Drug Release Investigation
Drug release was determined using USP II apparatus with paddle speed of 100 rpm and 900 mL of pH 7.4 phosphate buffer solution at 37 ± 0.5°C. Drug release was compared to the marketed product
Optimal coating levels (% W.G) required for 15 hours sustained release were established with and without MicroCoat. Utilising MicroCoat reduced the required coating levels for Cellets 100 (from 50% to 30%) and for Cellets 350 (from 30% to 20% (Fig 1).
Micro-structure and permeability of the MicroCoat
The impact of MicroCoat on physiochemical structure/performance on polymer membranes was investigated using SEM-EDX (Fig 3) and media uptake/weight loss tests (Fig 4, Fig 5).
MicroCoat is shown to slow both the uptake of media (Fig 4) and the release of solids by diffusion (Fig 5) which can be used to explain the ability to sustain drug release at lower polymer weight gains.
Single Dose Oral Suspension Development
A single dose oral suspension (powder for reconstitution) was developed using xanthan gum and carboxymethylcellulose sodium as suspending agents.
The single dose suspension was reconstituted in 20 mL water within 30 s with gentle stirring and was able to provide 30 min sedimentation stability with minimal residual loss of less than 4% w/w after administration (Fig 6).
The use of the MicroCoat technology during fluid bed coating reduced the quantity of polymer required to achieve sustained release for both small and large sized multiparticulates.
This could greatly decrease the time and monetary costs of the coating process for large scale manufacturing. The coated particles were appropriate for incorporation into powder for reconstitution for the preparation of sustained release oral liquid medicines.
Original languageEnglish
Number of pages1
Publication statusPublished - 11 Sep 2019
Externally publishedYes
Event10th APS International PharmSci 2019 Conference - Venue University of Greenwich, London, United Kingdom
Duration: 11 Sep 201913 Sep 2019
Conference number: 10


Conference10th APS International PharmSci 2019 Conference
Abbreviated title APS PharmSci 2019
CountryUnited Kingdom
Internet address


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