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RETRACTED ARTICLE: Study of the Transformations of Micro/Nano-crystalline Acetaminophen Polymorphs in Drug-Polymer Binary Mixtures


This study elucidates the physical properties of sono-crystallised micro/nano-sized acetaminophen/paracetamol (PMOL) and monitors its possible transformation from polymorphic form I (monoclinic) to form II (orthorhombic). Hydrophilic Plasdone® S630 copovidone (S630), N-vinyl-2-pyrrolidone and vinyl acetate copolymer, and methacrylate-based cationic copolymer, Eudragit® EPO (EPO), were used as polymeric carriers to prepare drug/polymer binary mixtures. Commercially available PMOL was crystallised under ultra sound sonication to produce micro/nano-sized (0.2–10 microns) crystals in monoclinic form. Homogeneous binary blends of drug-polymer mixtures at various drug concentrations were obtained via a thorough mixing. The analysis conducted via the single X-ray crystallography determined the detailed structure of the crystallised PMOL in its monoclinic form. The solid state and the morphology analyses of the PMOL in the binary blends evaluated via differential scanning calorimetry (DSC), modulated temperature DSC (MTDSC), scanning electron microscopy (SEM) and hot stage microscopy (HSM) revealed the crystalline existence of the drug within the amorphous polymeric matrices. The application of temperature controlled X-ray diffraction (VTXRPD) to study the polymorphism of PMOL showed that the most stable form I (monoclinic) was altered to its less stable form II (orthorhombic) at high temperature (>112°C) in the binary blends regardless of the drug amount. Thus, VTXRD was used as a useful tool to monitor polymorphic transformations of crystalline drug (e.g. PMOL) to assess their thermal stability in terms of pharmaceutical product development and research.

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Change history

  • 21 January 2020

    The Editors have retracted this article [1] because.


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Author information

Correspondence to Mohammed Maniruzzaman or Ali Nokhodchi.

Additional information

The Editors have retracted this article because:

• The top left panel of Figure 1a appears to be the same as Figure 1(ii) of [2]

• The bottom right panel of Figure 1a appears to be the same as Figure 1(iv) of [2]

The scanning electron microscopy data reported in this article are therefore unreliable. Mohammed Maniruzzaman, Ali Nokhodchi and Matthew Lam agree with this retraction. Carlos Molina has not responded to any correspondence from the Editors/publisher about this retraction.

Guest Editors: Dr. Z Ahmad and Prof. M Edirisinghe

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Maniruzzaman, M., Lam, M., Molina, C. et al. RETRACTED ARTICLE: Study of the Transformations of Micro/Nano-crystalline Acetaminophen Polymorphs in Drug-Polymer Binary Mixtures. AAPS PharmSciTech 18, 1428–1437 (2017). https://doi.org/10.1208/s12249-016-0596-x

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  • monoclinic
  • nano-sized crystals
  • orthorhombic
  • sono-crystallisation
  • variable temperature XRPD