title: Validated liquid chromatographic-ultraviolet method for the quantitation of tadalafil in human plasma using liquid-liquid extraction.
abstract: A highly selective, sensitive and rapid HPLC method has been developed and validated to quantify tadalafil in human plasma. The tadalafil and internal standard (loratadine, I.S.) were extracted by liquid-liquid extraction technique followed by an aqueous back-extraction allowing injection of an aqueous solvent in the HPLC system. The chromatographic separation was performed on a reverse phase BDS Hypersil C-18 column (250 mm x 4.6 mm, 5 microm, Thermo Separation Co., USA) with a mobile phase of acetonitrile and aqueous solution containing 0.012 M triethylamine+0.020 M orthophosphoric acid (50/50, v/v). The analytes were detected at 225 nm. The assay exhibited a linear range of 5-600 ng/mL for tadalafil in human plasma. The lower limit of quantitation (LLOQ) was 5 ng/mL. The within- and between batch precision (expressed as coefficient of variation, C.V.) did not exceed 10.3% and the accuracy was within -7.6% deviation of the nominal concentration. The recovery of tadalafil from plasma was greater than 66.1%. Stability of tadalafil in plasma was excellent with no evidence of degradation during sample processing (auto-sampler) and 30 days storage in a freezer. This validated method is applied for the clinical study of the tadalafil in human volunteers.
authors.affiliation: Department of Medicinal and Pharmaceutical Chemistry, Faculty of Pharmacy and Medical Sciences, Amman University, P.O. Box 263, Amman 19328, Jordan. ashoksharya@hotmail.com
authors.forename: Ashok K
authors.initials: AK
authors.lastname: Shakya
authors.forename: Ahmed N A
authors.initials: AN
authors.lastname: Abu-awwad
authors.forename: Tawfiq A
authors.initials: TA
authors.lastname: Arafat
authors.forename: Munther
authors.initials: M
authors.lastname: Melhim
mesh_terms: D002243:Carbolines / Q000097:blood*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D010726:Phosphodiesterase Inhibitors / Q000097:blood*; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*; D000068581:Tadalafil
chemical_list: D002243:Carbolines; D010726:Phosphodiesterase Inhibitors; D000068581:Tadalafil