AAPS PharmSciTech

, 20:303 | Cite as

Effects of Drug Particle Size and Lipid Additives on Drug Release from Paraffin Wax Formulations Prepared by Spray Congealing Technique

  • Hongyi Ouyang
  • Chen Yee Ang
  • Paul Wan Sia Heng
  • Lai Wah ChanEmail author
Research Article


Paraffin wax is a hydrophobic meltable material that can be suitably used in spray congealing to develop drug-loaded microparticles for sustained release, taste-masking or stability enhancement of drugs. However, these functional properties may be impaired if the drug particles are not completely embedded. Moreover, highly viscous melts are unsuitable for spray dispersion. In this study, the effects of drug particle size and lipid additives, namely stearic acid (SA), cetyl alcohol (CA) and cetyl esters (CE), on melt viscosity and extent of drug particles embedment were investigated. Spray congealing was conducted on the formulations, and the resultant microparticles were analysed for their size, drug content, extent of drug particles embedment and drug release. The melt viscosity increased with smaller solid inclusions while lipid additives decreased the viscosity to varying extents. The spray-congealed microparticle size was largely dependent on the viscosity. The addition of lipid additives to paraffin wax enabled more complete embedment of the drug particles. CA produced microparticles with the lowest drug release, followed by SA and CE. The addition of CA and CE enhanced the drug release and showed potential for taste-masking. Judicious choice of drug particle size and matrix materials is important for successful spray congealing to produce microparticles with the desired characteristics.


paraffin wax spray congealing viscosity drug particle size lipid additives 


Funding Information

The authors received the financial support from GEA-NUS PPRL fund (N-148-000-008-001). Ouyang Hongyi is a recipient of the National University of Singapore Graduate Research Scholarship.

Supplementary material

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Copyright information

© American Association of Pharmaceutical Scientists 2019

Authors and Affiliations

  • Hongyi Ouyang
    • 1
  • Chen Yee Ang
    • 1
  • Paul Wan Sia Heng
    • 1
  • Lai Wah Chan
    • 1
    Email author
  1. 1.GEA-NUS Pharmaceutical Processing Research Laboratory, Department of PharmacyNational University of SingaporeSingaporeSingapore

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