title: Determination of sildenafil citrate in plasma by high-performance liquid chromatography and a case for the potential interaction of grapefruit juice with sildenafil citrate.
abstract: This study was designed to establish a simple and reliable assay method that could be routinely used in the clinical laboratory setting using liquid extraction and high-performance liquid chromatography (HPLC). In addition, a case of potential interaction of grapefruit juice with sildenafil citrate is presented. The peaks of sildenafil (measured as sildenafil salt) and internal standard were identified with an ultraviolet detector at 230 nm and detection limit at 10 ng/mL. In a single elderly male patient, grapefruit juice increased the Cmax of sildenafil by 42% (1067.7 ng/mL to 1517.0 ng/mL) although AUC was not significantly altered (4082.9 ng x h/mL to 4171.9 ng x h/mL) by grapefruit juice. Sildenafil could be determined in a simple and reliable method using HPLC with liquid extraction. This case indicated that grapefruit juice might increase the Cmax of sildenafil without significant change in AUC. A further study with an appropriate number of subjects is needed before determining the degree of interaction between grapefruit juice and sildenafil.
authors.affiliation: Division of Clinical and Administrative Pharmacy, College of Pharmacy, The University of lowa, Iowa City 52242, USA.
authors.forename: M
authors.initials: M
authors.lastname: Lee
authors.forename: D I
authors.initials: DI
authors.lastname: Min
mesh_terms: D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors*; D000368:Aged; D019540:Area Under Curve; D001628:Beverages; D002851:Chromatography, High Pressure Liquid; D002957:Citrus / Q000737:chemistry*; D018565:Food-Drug Interactions; D006207:Half-Life; D006801:Humans; D008297:Male; D010726:Phosphodiesterase Inhibitors / Q000097:blood*; D010879:Piperazines / Q000097:blood*; D011687:Purines; D015203:Reproducibility of Results; D000068677:Sildenafil Citrate; D013056:Spectrophotometry, Ultraviolet; D013450:Sulfones
chemical_list: D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068677:Sildenafil Citrate; D015106:3',5'-Cyclic-GMP Phosphodiesterases