title: Simultaneous assay of sildenafil and desmethylsildenafil in neonatal plasma by ultra-performance liquid chromatography-tandem mass spectrometry.
abstract: Sildenafil is used to treat pulmonary hypertension in neonatal and pediatric patients. Pharmacokinetic studies in these patients are complicated by the limited sample volume. We present the validation results of an assay method to quantitate sildenafil and desmethylsildenafil simultaneously in 50 microL of plasma. Deuterated sildenafil was used as an internal standard. After liquid-liquid extraction, analytes were separated on an ultra-performance liquid chromatography (UPLC)-column and quantified via tandem mass spectrometry. The calibration range was linear, with acceptable accuracy and a precision of <15% for both compounds. The lower limits of quantification were 1 ng/mL. Matrix effects were present, but inter-plasma batch variability was under 12%. The method was successfully applied to samples from a pharmacokinetic study into sildenafil pharmacokinetics in neonates, making maximum use of the limited number and amount of plasma samples available.
authors.affiliation: Department of Hospital Pharmacy (Clinical Pharmacology Unit), Erasmus University Medical Center, Rotterdam, The Netherlands.
authors.forename: Bregje C
authors.initials: BC
authors.lastname: Witjes
authors.forename: Maurice J
authors.initials: MJ
authors.lastname: Ahsman
authors.forename: Bart C
authors.initials: BC
authors.lastname: van der Nagel
authors.forename: Dick
authors.initials: D
authors.lastname: Tibboel
authors.forename: Ron A
authors.initials: RA
authors.lastname: Mathot
mesh_terms: D001499:Bayes Theorem; D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000097:blood / Q000188:drug therapy; D007202:Indicators and Reagents; D007231:Infant, Newborn; D010726:Phosphodiesterase Inhibitors / Q000097:blood* / Q000493:pharmacokinetics / Q000627:therapeutic use; D010879:Piperazines / Q000097:blood* / Q000493:pharmacokinetics / Q000627:therapeutic use; D010949:Plasma / Q000737:chemistry; D011687:Purines / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use; D012015:Reference Standards; D015203:Reproducibility of Results; D000068677:Sildenafil Citrate; D012997:Solvents; D013450:Sulfones / Q000097:blood* / Q000493:pharmacokinetics / Q000627:therapeutic use; D053719:Tandem Mass Spectrometry
chemical_list: D007202:Indicators and Reagents; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D012997:Solvents; D013450:Sulfones; D000068677:Sildenafil Citrate