title: Determination of ciprofloxacin in human plasma using high-performance liquid chromatography coupled with fluorescence detection: application to a population pharmacokinetics study in children with severe malnutrition.
abstract: Clinical pharmacokinetic studies of ciprofloxacin require accurate and precise measurement of plasma drug concentrations. We describe a rapid, selective and sensitive HPLC method coupled with fluorescence detection for determination of ciprofloxacin in human plasma. Internal standard (IS; sarafloxacin) was added to plasma aliquots (200 μL) prior to protein precipitation with acetonitrile. Ciprofloxacin and IS were eluted on a Synergi Max-RP analytical column (150 mm×4.6 mm i.d., 5 μm particle size) maintained at 40°C. The mobile phase comprised a mixture of aqueous orthophosphoric acid (0.025 M)/methanol/acetonitrile (75/13/12%, v/v/v); the pH was adjusted to 3.0 with triethylamine. A fluorescence detector (excitation/emission wavelength of 278/450 nm) was used. Retention times for ciprofloxacin and IS were approximately 3.6 and 7.0 min, respectively. Calibration curves of ciprofloxacin were linear over the concentration range of 0.02-4 μg/mL, with correlation coefficients (r(2))≥0.998. Intra- and inter-assay relative standard deviations (SD) were <8.0% and accuracy values ranged from 93% to 105% for quality control samples (0.2, 1.8 and 3.6 μg/mL). The mean (SD) extraction recoveries for ciprofloxacin from spiked plasma at 0.08, 1.8 and 3.6 μg/mL were 72.8±12.5% (n=5), 83.5±5.2% and 77.7±2.0%, respectively (n=8 in both cases). The recovery for IS was 94.5±7.9% (n=15). The limits of detection and quantification were 10 ng/mL and 20 ng/mL, respectively. Ciprofloxacin was stable in plasma for at least one month when stored at -15°C to -25°C and -70°C to -90°C. This method was successfully applied to measure plasma ciprofloxacin concentrations in a population pharmacokinetics study of ciprofloxacin in malnourished children.
authors.affiliation: Kenya Medical Research Institute (KEMRI)/Wellcome Trust Research Programme, Centre for Geographic Medicine Research (Coast), P.O. Box 230-80108, Kilifi, Kenya. sndirangu@kilifi.kemri-wellcome.org
authors.forename: Simon N
authors.initials: SN
authors.lastname: Muchohi
authors.forename: Nahashon
authors.initials: N
authors.lastname: Thuo
authors.forename: Japhet
authors.initials: J
authors.lastname: Karisa
authors.forename: Alex
authors.initials: A
authors.lastname: Muturi
authors.forename: Gilbert O
authors.initials: GO
authors.lastname: Kokwaro
authors.forename: Kathryn
authors.initials: K
authors.lastname: Maitland
mesh_terms: D002648:Child; D015362:Child Nutrition Disorders / Q000097:blood*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002939:Ciprofloxacin / Q000031:analogs & derivatives / Q000032:analysis / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics; D004355:Drug Stability; D006801:Humans; D016018:Least-Squares Analysis; D044342:Malnutrition / Q000097:blood*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence
chemical_list: D002939:Ciprofloxacin; C047224:sarafloxacin