title: Liquid chromatographic assay of nifedipine in human plasma and its application to pharmacokinetic studies.
abstract: A highly sensitive, selective and reproducible reversed-phase high-performance liquid chromatographic method has been developed for the determination of nifedipine in human plasma with minimum sample preparation. The method is sensitive to 3 ng/ml in plasma, with acceptable within- and between-day reproducibilities and linearity (r2 > 0.99) over a concentration range from 10-200 ng/ml. Acidified plasma samples were extracted using diethyether containing diazepam as internal standard and chromatographic separation was accomplished on C18 column using a mobile phase consisting of acetonitrile, methanol and water (35:17:48, v/v). The within-day precision ranged from 2.22 to 4.64% and accuracy ranged from 102.4-106.4%. The day-to-day precision ranged from 2.34-7.07% and accuracy from 95.1-100.1%. The relative recoveries of nifedipine from plasma ranged from 91.0-107.3% whereas extraction recoveries were 88.6-93.3%. Following eight 6-week freeze-thaw cycles, nifedipine in plasma samples proved to be stable with accuracy ranging from 0.64 to 3.0% and precision ranging from 3.6 to 4.15%. Nifedipine was also found to be photostable for at least 120 min in plasma, 30 min in blood and for 60 min in aqueous solutions after exposure to light. The method is sensitive and reliable for pharmacokinetic studies and therapeutic drug monitoring of nifedipine in humans after the oral administration of immediate-release capsules and sustained-release tablets to five healthy subjects.
authors.affiliation: Department of Clinical Pharmacy, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia. hisham@ksu.edu.sa
authors.forename: H S
authors.initials: HS
authors.lastname: Abou-Auda
authors.forename: T A
authors.initials: TA
authors.lastname: Najjar
authors.forename: K I
authors.initials: KI
authors.lastname: Al-Khamis
authors.forename: B M
authors.initials: BM
authors.lastname: Al-Hadiya
authors.forename: N M
authors.initials: NM
authors.lastname: Ghilzai
authors.forename: N F
authors.initials: NF
authors.lastname: Al-Fawzan
mesh_terms: D002121:Calcium Channel Blockers / Q000097:blood* / Q000493:pharmacokinetics; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D009543:Nifedipine / Q000097:blood* / Q000493:pharmacokinetics; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D002121:Calcium Channel Blockers; D009543:Nifedipine