title: Mupirocin calcium microencapsulation via spray drying: feed solvent influence on microparticle properties, stability and antimicrobial activity.
abstract: OBJECTIVE
  The aim of this research was to design a controlled release, spray dried, mupirocin calcium-loaded microparticles (MP) with acrylic polymer and assess the influence of a feed solvent at preselected drug:polymer proportions (1:5 and 2:1 (w/w)) on the performance and stability of the prepared MP.
  
  
  METHODS
  Physicochemical properties of MP were assessed using modulated differential scanning calorimetry (MDSC), and thermogravimetric analyses (TGA), Fourier transformed infrared spectroscopy (FTIR) and X-ray analyses and were correlated with drug release. Morphology and particle size were determined using low-angle laser light scattering and a scanning electron microscope. A time-kill assay was conducted on two strains of Staphylococcus aureus to evaluate the antimicrobial activity of MP.
  
  
  CONCLUSIONS
  The MP formed solid dispersions without apparent drug crystallization. Drug-polymer miscibility, morphology, drug release and consequently antimicrobial activity were dependent on drug loading (DL) and the used solvent. The superior control of drug release from MP was achieved for the higher DL (2:1 (w/w) drug:polymer proportion) using solvents in the following order: methanol ≈ methanol:ethanol (50:50, w/w) > isopropanol:acetone (40:60, w/w). Moreover, a time-kill assay performed on S. aureus (ATCC 29213) and methicillin-resistant S. aureus strains confirmed the prolonged release and preservation of antimicrobial activity of the microencapsulated drug. The physical aging of the solid dispersion after 10 months of storage had negligible impact on the MP performance.
  
  
  CONCLUSIONS
  Acrylic-based MP were confirmed as suitable microcarriers for prolonged drug release using a well-established spray drying technique, while solvent influence was strongly related to the DL employed.
authors.affiliation: Pliva Croatia Ltd, Research and Development, Zagreb, Croatia.
authors.forename: Marjana
authors.initials: M
authors.lastname: Dürrigl
authors.forename: Maja Lusina
authors.initials: ML
authors.lastname: Kregar
authors.forename: Anita
authors.initials: A
authors.lastname: Hafner
authors.forename: Maja Šegvić
authors.initials: MŠ
authors.lastname: Klarić
authors.forename: Jelena
authors.initials: J
authors.lastname: Filipović-Grčić
mesh_terms: D000704:Analysis of Variance; D000900:Anti-Bacterial Agents / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D003692:Delayed-Action Preparations / Q000737:chemistry; D003890:Desiccation; D004339:Drug Compounding; D004355:Drug Stability; D016712:Mupirocin / Q000737:chemistry*; D009330:Nebulizers and Vaporizers; D010316:Particle Size; D011108:Polymers; D012995:Solubility; D012997:Solvents; D017550:Spectroscopy, Fourier Transform Infrared; D013818:Thermogravimetry
chemical_list: D000900:Anti-Bacterial Agents; D003692:Delayed-Action Preparations; D011108:Polymers; D012997:Solvents; D016712:Mupirocin