title: Stability of an extemporaneously prepared tadalafil suspension.
abstract: OBJECTIVE
  The stability of an extemporaneously prepared tadalafil oral suspension was studied.
  
  
  METHODS
  An oral suspension of tadalafil 5 mg/mL was prepared by thoroughly grinding 15 20-mg tadalafil tablets in a glass mortar. Thirty milliliters of Ora-Plus and 30 mL of Ora-Sweet were mixed and added to the powder to make a final volume of 60 mL. Three identical samples of the formulation were prepared and placed in 2-oz amber plastic bottles with child-resistant caps and stored at room temperature (23-25 °C). A 1-mL sample was withdrawn from each of the three bottles with a micropipette immediately after preparation and at 7, 14, 28, 57, and 91 days. After double dilution (1:10 and 0.1:5 v/v) to an expected concentration of 10 μg/mL with methanol and mobile phase, respectively, the samples were assayed in duplicate using stability-indicating high-performance liquid chromatography. The samples were visually examined for any color change and evaluated for pH changes on each day of analysis. Taste evaluation was performed at the beginning and end of the study. Stability was defined as the retention of at least 90% of the initial concentration.
  
  
  RESULTS
  At least 99% of the initial tadalafil concentration remained throughout the 91-day study period. There were no detectable changes in color, odor, taste, and pH, and no visible microbial growth was observed in any sample.
  
  
  CONCLUSIONS
  An extemporaneously prepared suspension of tadalafil 5 mg/mL in a 1:1 mixture of Ora-Plus and Ora-Sweet was stable for at least 91 days when stored in amber plastic bottles at room temperature.
authors.affiliation: Riley Hospital for Children, Indiana University Health, 705 Riley Hospital Drive, Indianapolis, IN 46202, USA. rpettit1@iuhealth.org
authors.forename: Rebecca S
authors.initials: RS
authors.lastname: Pettit
authors.forename: Cary E
authors.initials: CE
authors.lastname: Johnson
authors.forename: Regine L
authors.initials: RL
authors.lastname: Caruthers
mesh_terms: D002243:Carbolines / Q000032:analysis / Q000737:chemistry*; D004355:Drug Stability; D058986:Phosphodiesterase 5 Inhibitors / Q000737:chemistry*; D013535:Suspensions; D000068581:Tadalafil
chemical_list: D002243:Carbolines; D058986:Phosphodiesterase 5 Inhibitors; D013535:Suspensions; D000068581:Tadalafil