title: Stability of sildenafil in combination with heparin and dopamine.
abstract: OBJECTIVE
  The stability of sildenafil in combination with heparin and dopamine was evaluated.
  
  
  METHODS
  A stability-indicating high-performance liquid chromatography method with ultraviolet detection was developed for sildenafil citrate and validated. The method was applied to the investigation of sildenafil alone, sildenafil with heparin, sildenafil with dopamine, and sildenafil with heparin and with dopamine, all in 5% dextrose injection at room temperature and under refrigeration for 30 days. Samples of 100 μL were pulled from each storage bottle on each sampling day, diluted in mobile phase, and assayed in duplicate. Samples were tested on days 0, 1, 2, 3, 4, 5, 7, 9, 12, 14, 21, and 30. Each preparation was visually inspected for precipitation and color change. The percent recovery in each study sample was determined by comparing the peak area of sildenafil in the sample with the peak area of sildenafil from a freshly prepared 100-μg/mL standard in mobile phase.
  
  
  RESULTS
  The sildenafil alone, sildenafil with heparin, and sildenafil with dopamine remained within 90-110% of the expected sildenafil potency for at least 30 days at both temperatures. The preparation of sildenafil with both heparin and dopamine fell below 90% potency after 3 days at room temperature and 21 days in the refrigerator.
  
  
  CONCLUSIONS
  Sildenafil prepared in 5% dextrose injection alone, with heparin, and with dopamine retained over 90% potency after 30 days of storage at room temperature and under refrigeration. Sildenafil prepared with both heparin and dopamine had a potency of <90% after 3 days of storage at room temperature and 21 days of storage under refrigeration.
authors.affiliation: Department of Pharmaceutical Sciences, Bill Gatton College of Pharmacy, East Tennessee State University, Johnson City, TN.
authors.forename: Yao
authors.initials: Y
authors.lastname: Luu
authors.affiliation: Department of Pharmacy Practice, Bill Gatton College of Pharmacy, East Tennessee State University, Johnson City, TN.
authors.forename: Jim
authors.initials: J
authors.lastname: Thigpen
authors.affiliation: Department of Pharmaceutical Sciences, Bill Gatton College of Pharmacy, East Tennessee State University, Johnson City, TN. browsd03@etsu.edu.
authors.forename: Stacy D
authors.initials: SD
authors.lastname: Brown
mesh_terms: D000925:Anticoagulants / Q000008:administration & dosage / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical; D002648:Child; D002851:Chromatography, High Pressure Liquid; D004298:Dopamine / Q000008:administration & dosage / Q000737:chemistry*; D004338:Drug Combinations; D004355:Drug Stability; D004356:Drug Storage / Q000379:methods; D005947:Glucose / Q000737:chemistry; D006493:Heparin / Q000008:administration & dosage / Q000737:chemistry*; D006801:Humans; D006976:Hypertension, Pulmonary / Q000188:drug therapy*; D007231:Infant, Newborn; D012034:Refrigeration; D000068677:Sildenafil Citrate / Q000008:administration & dosage / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors
chemical_list: D000925:Anticoagulants; D004338:Drug Combinations; D006493:Heparin; D000068677:Sildenafil Citrate; D005947:Glucose; D004298:Dopamine
keywords: HPLC; beyond-use date; dopamine; heparin; sildenafil; stability