AAPS PharmSciTech

, Volume 19, Issue 3, pp 1426–1436 | Cite as

A Novel Approach for Dry Powder Coating of Pellets with Ethylcellulose. Part II: Evaluation of Caffeine Release

  • Beatrice Albertini
  • Cecilia Melegari
  • Serena Bertoni
  • Luisa Stella Dolci
  • Nadia Passerini
Research Article


The objective of this study was to assess the efficacy and the capability of a novel ethylcellulose-based dry-coating system to obtain prolonged and stable release profiles of caffeine-loaded pellets. Lauric and oleic acids at a suitable proportion were used to plasticize ethylcellulose. The effect of coating level, percentage of drug loading, inert core particle size, and composition of the coating formulation including the anti-sticking agent on the drug release profile were fully investigated. A coating level of 15% w/w was the maximum layered amount which could modify the drug release. The best controlled drug release was obtained by atomizing talc (2.5% w/w) together with the solid plasticizer during the dry powder-coating process. SEM pictures revealed a substantial drug re-crystallization on the pellet surface, and the release studies evidenced that caffeine diffused through the plasticized polymer acting as pore former. Therefore, the phenomenon of caffeine migration across the coating layer had a strong influence on the permeability of the coating membrane. Comparing dry powder-coated pellets to aqueous film-coated ones, drug migration happened during storage, though more sustained release profiles were obtained. The developed dry powder-coating process enabled the production of stable caffeine sustained release pellets. Surprisingly, the release properties of the dry-coated pellets were mainly influenced by the way of addition of talc into the dry powder-coating blend and by the drug nature and affinity to the coating components. It would be interesting to study the efficacy of novel coating system using a different API.


Ethylcellulose Dry powder coating of pellets Caffeine release Drug migration Pore former 


Compliance with Ethical Standards

Conflict of interest

The authors declare that they have no conflicts of interest.

Supplementary material

12249_2018_964_MOESM1_ESM.jpg (25 kb)
Fig. S1 Pictures of film coated pellets taken immediately after the film coating process (Fig. S1a) and after 1 month of storage at room conditions (Fig. S1b). (JPEG 24 kb)


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Copyright information

© American Association of Pharmaceutical Scientists 2018

Authors and Affiliations

  • Beatrice Albertini
    • 1
  • Cecilia Melegari
    • 1
  • Serena Bertoni
    • 1
  • Luisa Stella Dolci
    • 1
  • Nadia Passerini
    • 1
  1. 1.Department of Pharmacy and BioTechnologyUniversity of BolognaBolognaItaly

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