title: Validated spectrofluorimetric method for determination of two phosphodiesterase inhibitors tadalafil and vardenafil in pharmaceutical preparations and spiked human plasma.
abstract: A valid, sensitive and rapid spectrofluorimetric method has been developed and validated for determination of both tadalafil (TAD) and vardenafil (VAR) either in their pure form, in their tablet dosage forms or spiked in human plasma. This method is based on measurement of the native fluorescence of both drugs in acetonitrile at λem 330 and 470 nm after excitation at 280 and 275 nm for tadalafil and vardenafil, respectively. Linear relationships were obtained over the concentration range 4-40 and 10-250 ng/mL with a minimum detection of 1 and 3 ng/mL for tadalafil and vardenafil, respectively. Various experimental parameters affecting the fluorescence intensity were carefully studied and optimized. The developed method was applied successfully for the determination of tadalafil and vardenafil in bulk drugs and tablet dosage forms. Moreover, the high sensitivity of the proposed method permitted their determination in spiked human plasma. The developed method was validated in terms of specificity, linearity, lower limit of quantification (LOQ), lower limit of detection (LOD), precision and accuracy. The mean recoveries of the analytes in pharmaceutical preparations were in agreement with those obtained from the comparison methods, as revealed by statistical analysis of the obtained results using Student's t-test and the variance ratio F-test.
authors.affiliation: Department of Medicinal Chemistry, Faculty of Pharmacy, University of Mansoura, 35516, Mansoura, Egypt.
authors.forename: Mohammed Abu Bakr
authors.initials: MA
authors.lastname: Abu El-Enin
authors.affiliation: Department of Medicinal Chemistry, Faculty of Pharmacy, University of Mansoura, 35516, Mansoura, Egypt.
authors.forename: Mohammed El-Sayed Abd
authors.initials: Mel-S
authors.lastname: Al-Ghaffar Hammouda
authors.affiliation: Department of Medicinal Chemistry, Faculty of Pharmacy, University of Mansoura, 35516, Mansoura, Egypt.
authors.forename: Dina Tawfik
authors.initials: DT
authors.lastname: El-Sherbiny
authors.affiliation: Department of Medicinal Chemistry, Faculty of Pharmacy, University of Mansoura, 35516, Mansoura, Egypt.
authors.forename: Dalia Rashad
authors.initials: DR
authors.lastname: El-Wasseef
authors.affiliation: Department of Medicinal Chemistry, Faculty of Pharmacy, University of Mansoura, 35516, Mansoura, Egypt.
authors.forename: Saadia Mahmoud
authors.initials: SM
authors.lastname: El-Ashry
mesh_terms: D006801:Humans; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D010726:Phosphodiesterase Inhibitors / Q000032:analysis* / Q000097:blood*; D013050:Spectrometry, Fluorescence; D013501:Surface-Active Agents / Q000737:chemistry; D000068581:Tadalafil / Q000032:analysis* / Q000097:blood*; D000069058:Vardenafil Dihydrochloride / Q000032:analysis* / Q000097:blood*
chemical_list: D004364:Pharmaceutical Preparations; D010726:Phosphodiesterase Inhibitors; D013501:Surface-Active Agents; D000069058:Vardenafil Dihydrochloride; D000068581:Tadalafil
keywords: native fluorescence; spectrofluorimetric; spiked human plasma; tablets; tadalafil (TAD); vardenafil hydrochloride (VAR)