title: An in situ dissolution study of aspirin crystal planes (100) and (001) by atomic force microscopy.
abstract: OBJECTIVE
  To observe in situ and on individual aspirin crystal faces the comparative rates and processes of dissolution of the dominant faces.
  
  
  METHODS
  The kinetics of the dissolution rate of two aspirin crystal planes (001) and (100) under 0.05M HCl are studied in situ at room temperature using Atomic Force Microscopy. The dissolution process of each crystal plane was followed by observed changes in topographic features.
  
  
  RESULTS
  The results revealed that crystal plane (001) dissolves by receding step edges, and has a dissolution rate of 0.45 nm s(-1). Conversely. plane (100) displays crystal terrace sinking at an average rate of 2.93 nm s(-1). Calculated intrinsic dissolution values (g s(-1) cm(-2)) for planes (001) and (100) are 1.37 x 10(-7) gs(-1) cm(-2) and 8.36 x 10(-7) gs(-1) cm(-2), respectively.
  
  
  CONCLUSIONS
  These values indicate that the rate of flux of material from plane (100) is approximately six times greater than that from plane (001), under 0.05M HCl. Interpretation of the data, based upon intrinsic dissolution rates and dissolution rate velocities, correlate with reported variations in the dissolution behavior of commercial aspirin products. These observations illustrate the suitability of the technique for characterizing the dissolution behavior of crystalline drugs.
authors.affiliation: School of Pharmaceutical Sciences, The University of Nottingham, UK.
authors.forename: A
authors.initials: A
authors.lastname: Danesh
authors.forename: S D
authors.initials: SD
authors.lastname: Connell
authors.forename: M C
authors.initials: MC
authors.lastname: Davies
authors.forename: C J
authors.initials: CJ
authors.lastname: Roberts
authors.forename: S J
authors.initials: SJ
authors.lastname: Tendler
authors.forename: P M
authors.initials: PM
authors.lastname: Williams
authors.forename: M J
authors.initials: MJ
authors.lastname: Wilkins
mesh_terms: D001241:Aspirin / Q000737:chemistry*; D003460:Crystallization; D007700:Kinetics; D018625:Microscopy, Atomic Force; D012995:Solubility; D013499:Surface Properties
chemical_list: D001241:Aspirin