High-performance liquid chromatographic assay for minocycline in human plasma and parotid saliva

A sensitive and specific high-performance liquid chromatographic (HPLC) met hod with UV detection was developed for the determination of minocycline in human plasma and parotid saliva samples. Samples were extracted using an O asis(TM) HLB cartridge and were injected into a C-8 Nucleosil column. The H PLC eluent contained acetonitrile-methanol-distilled water-0.1% trifluoroac etic acid (25:2:72.9:0.1, v/v). Demeclocycline was used as internal standar d. The assay showed linearity in the tested range of 0.1-25 mu g/ml. The li mit of quantitation was 100 ng/ml. Recovery from plasma or parotid saliva a veraged 95%. Precision expressed as %CV was in the range 0.2-17% (limit of quantitation). Accuracy ranged from 93 to 111%. In the two matrices studied at 20 and 4 degrees C, rapid degradation of the drug occurred. Frozen at - 30 degrees C, this drug was stable for at least 2 months, the percent recov ery averaged 90%. The method's ability to quantify minocycline with precisi on, accuracy and sensitivity makes it useful in pharmacokinetic studies. (C ) 2000 Elsevier Science B.V. All rights reserved.