title: Hollow crystalline straws of diclofenac for high-dose and carrier-free dry powder inhaler formulations.
abstract: OBJECTIVE
  To crystallize diclofenac (DF) from diclofenac sodium (DFNa), to micronize DF and DFNa, and to evaluate in vitro aerodynamic performance of the jet-milled formulations
  
  
  METHODS
  From the acidic titration of aqueous DFNa, DF crystals were formed and were identified using thermal analysis, spectroscopy, and X-ray powder diffraction. Following the micronization of the DF and DFNa powders, the recovered samples were imaged, and their particle size distributions were evaluated. Samples before and after jet millings were characterized, and in vitro aerodynamic performance testing was performed on the DF sample before jet milling and the DF and DFNa samples following jet milling.
  
  
  CONCLUSIONS
  Hollow needles of DF were precipitated. With similar particle size distributions, the jet-milled DFNa sample from the collection bag, and the DF sample from the cyclone were used for further characterization. Despite different deposition patterns in the Next Generation Impactor, the DF hollow needles had a comparable respirable fraction percentage to the jet-milled DF and DFNa particles. However, the jet-milled DF formulation had the best in vitro aerodynamic performance.
  
  
  CONCLUSIONS
  Hollow, crystalline needles of DF were formed and possessed promising aerosol performance in comparison with the jet-milled powders.
authors.affiliation: Division of Pharmaceutics, College of Pharmacy, The University of Texas at Austin, PHR 4.214, 2409 University Ave, A1920, Austin, TX 78712-1119, USA. Electronic address: ashkan.k.yazdi@utexas.edu.
authors.forename: Ashkan K
authors.initials: AK
authors.lastname: Yazdi
authors.affiliation: Division of Pharmaceutics, College of Pharmacy, The University of Texas at Austin, PHR 4.214, 2409 University Ave, A1920, Austin, TX 78712-1119, USA.
authors.forename: Hugh D C
authors.initials: HD
authors.lastname: Smyth
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D003460:Crystallization; D004008:Diclofenac / Q000737:chemistry*; D016503:Drug Delivery Systems; D058995:Dry Powder Inhalers; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D033362:Powder Diffraction; D011208:Powders; D017550:Spectroscopy, Fourier Transform Infrared; D013678:Technology, Pharmaceutical; D014961:X-Ray Diffraction
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D011208:Powders; D004008:Diclofenac
keywords: Diclofenac; Diclofenac (PubChem CID: 3033); Diclofenac sodium; Diclofenac sodium (PubChem CID: 5018304); Dry powder inhaler; Jet milling; Next generation impactor; Precipitation; Sodium dodecyl sulfate (PubChem CID: 3423265; Tween 20 (PubChem CID: 443314)