title: Alteplase: stability and bioactivity after dilution in normal saline solution.
abstract: OBJECTIVE
  To characterize the biochemical stability and bioactivity of reconstituted alteplase when diluted to a concentration of 0.01 mg/mL in normal saline solution and stored at ambient temperature for as long as 24 hours in commercial saline solution bags.
  
  
  METHODS
  Two commercially available formulations of lyophilized alteplase (2-mg and 50-mg vials, respectively) were reconstituted with sterile water to a final concentration of 1 mg/mL. For each vial configuration, 5 mg of alteplase (5 mL) was added to a commercial 500-mL bag of normal saline solution to achieve a 0.01-mg/mL targeted concentration. Solutions were assayed for optical clarity, pH, protein concentration, and in-vitro clot lysis activity. Assays of the solutions were performed at time points of 0 (control), 4, 8, and 24 hours at ambient room temperature and compared to controls.
  
  
  RESULTS
  On visual inspection, aliquots of the diluted protein solutions in clear glass vials remained clear/colorless after 24 hours. Bioactivity (clot lysis assay) over the course of 24 hours at ambient temperature remained essentially unchanged relative to control (2-mg vial: mean of 98.3%, range of 93.7%-103.3%; 50-mg vial: mean of 103.1%, range of 100.6%-108.3%). The mean protein recovery rates (relative to targeted concentration) over a 24-hour period were 43% (range, 39%-46%) and 42% (range, 40%-45%) for the 2-mg and 50-mg vial configurations, respectively.
  
  
  CONCLUSIONS
  Alteplase diluted in normal saline solution at a concentration of 0.01 mg/mL is biochemically stable and active at ambient temperature for as long as 24 hours as assessed by in vitro clot lysis assays. Alteplase appears to have a bimodal solubility profile in normal saline solution and further studies are required to determine the activity and solubility of alteplase concentrations lower than 0.01 mg/mL.
authors.affiliation: Department of Vascular Medicine, BioTherapeutic Unit , Genentech, South San Francisco, CA 94080-4990, USA. cpsemba@gene.com
authors.forename: Charles P
authors.initials: CP
authors.lastname: Semba
authors.forename: Suzanne
authors.initials: S
authors.lastname: Weck
authors.forename: Thomas
authors.initials: T
authors.lastname: Patapoff
mesh_terms: D001681:Biological Assay; D004355:Drug Stability; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010960:Plasminogen Activators / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry*; D012996:Solutions; D013696:Temperature; D010959:Tissue Plasminogen Activator / Q000737:chemistry*
chemical_list: D012996:Solutions; D012965:Sodium Chloride; D010960:Plasminogen Activators; D010959:Tissue Plasminogen Activator