AAPS PharmSciTech

, Volume 11, Issue 3, pp 1320–1327 | Cite as

Ultrasound-assisted powder-coating technique to improve content uniformity of low-dose solid dosage forms

  • Natalja Genina
  • Heikki Räikkönen
  • Osmo Antikainen
  • Jyrki Heinämäki
  • Jouko Yliruusi
Research Article


An ultrasound-assisted powder-coating technique was used to produce a homogeneous powder formulation of a low-dose active pharmaceutical ingredient (API). The powdered particles of microcrystalline cellulose (MCC; Avicel® PH-200) were coated with a 4% m/V aqueous solution of riboflavin sodium phosphate, producing a uniform drug layer on the particle surfaces. It was possible to regulate the amount of API in the treated powder. The thickness of the API layer on the surface of the MCC particles increased near linearly as the number of coating cycles increased, allowing a precise control of the drug content. The tablets (n = 950) prepared from the coated powder showed significantly improved weight and content uniformity in comparison with the reference tablets compressed from a physical binary powder mixture. This was due to the coated formulation remaining uniform during the entire tabletting process, whereas the physical mixture of the powders was subject to segregation. In conclusion, the ultrasound-assisted technique presented here is an effective tool for homogeneous drug coating of powders of irregular particle shape and broad particle size distribution, improving content uniformity of low-dose API in tablets, and consequently, ensuring the safe delivery of a potent active substance to patients.

Key words

content uniformity homogeneity low-dose API powder coating ultrasound 



The Estonian National Scholarship Fund is acknowledged for financial support. Juha Hatara is thanked for helping with the acquisition of the digital images. Student Andrea Lanzetti is acknowledged for technical assistance with the tablet analysis.


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Copyright information

© American Association of Pharmaceutical Scientists 2010

Authors and Affiliations

  • Natalja Genina
    • 1
    • 2
  • Heikki Räikkönen
    • 1
  • Osmo Antikainen
    • 1
  • Jyrki Heinämäki
    • 1
  • Jouko Yliruusi
    • 1
  1. 1.Division of Pharmaceutical Technology, Faculty of PharmacyUniversity of Helsinki, FinlandHelsinkiFinland
  2. 2.Department of Pharmacy, Faculty of MedicineUniversity of Tartu, EstoniaTartuEstonia

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