Simple, rapid and highly sensitive HPLC method for measurement of Lamotrigine in human plasma and its clinical applications

Spikes in Lamotrigine concentrations levels and associated clinical toxicity may occur unpredictably. This study describes the development and validation of a simple, more rapid, highly sensitive and economical method for measuring Lamotrigine [LTG] concentration levels in human plasma using HPLC-UV and its clinical applications. Analyte from plasma was extracted with methanol [protein precipitation] and separated on the analytical column Diamonsil C[18] [150mmx4.6mm, 5 micro m] Waters-Milford, MA, United States. Mixture of 0.1% Trifluoroacetate and Methanol used as mobile phase in a 59:41 volume/volume mixture with an isocratic flow rate of 1.5 ml/min and wavelength was adjusted to 260nm. Standard curve of lamotrigine showed good linearity over the range of 1.0-50 micro g/mL [r[2]=0.9961] and LLOQ was 1.0 micro g/ml. The Specificity, Recovery, Accuracy, Stability, Robustness and RSDs for both intraday and interday precision were within acceptable limits. The highly sensitive HPLC assay for determination of LTG in human plasma was demonstrated, validated and applied in Therapeutic Drug Monitoring [TDM] of sixty seven epilepsy patients who were using LTG. The proposed method can be easily applied in routine Therapeutic monitoring of LTG, Besides TDM, stated method can be also very useful for Bioequivalence studies, Pharmacovigilance and Pharmacokinetics studies

Determinations of mifepristone and its metabolites and their pharmacokinetics in healthy female Chinese subjects / 药学学报

The aim of this study is to establish an HPLC method for simultaneous determinations of mifepristone and its metabolites, mono-demethylated mifepristone, di-demethylated mifepristone and C-hydroxylated mifepristone in plasma and to evaluate the pharmacokinetic characteristics of mifepristone tablet. Twenty healthy female Chinese subjects were recruited and a series of blood samples were collected before and after 0.25, 0.5, 1.0, 1.5, 2.0, 4.0, 8.0, 12.0, 24.0, 48.0, 72.0 and 96.0 hours administration by a single oral dose of 75 mg mifepristone tablet. Mifepristone and its three metabolites were extracted from plasma using ethyl acetate and determined by high performance liquid chromatography. The main pharmacokinetic parameters of mifepristone and its metabolites, including Cmax, tmax, MRT, t(1/2), V, CL, AUC(0-96 h) and AUC(0-infinity), were calculated by Drug and Statistical Software Version 2.0. The simple, accurate and stable method allows the sensitive determinations ofmifepristone and its metabolites in human plasma up to 4 days after oral administration of 75 mg mifepristone tablet and the clinical applications of their pharmacokinetic studies.

Determination of betamethasone in human plasma by liquid chromatography with tandem mass / 药学学报

A sensitive and selective liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and validated for the determination of betamethasone in human plasma. The analyte was isocratically eluted on a Venusil XBP C8 column (200 mm ×3.9 mm ID, 5 μm) with methanol-water with a triple quad LC-MS/MS using ESI with positive ionization. Ions monitored in the multiple reaction monitoring (MRM) mode were m/z 393.3→355.2 for betamethasone and m/z 361.3→343.2 for prednisolone (IS). Betamethasone was extracted from 0.5 mL human plasma with ethyl acetate. The validation study demonstrated excellent precision and accuracy across the calibration range of 0.5 - 80.0 injection in healthy Chinese volunteers.

Determination of loratadine in human plasma by LC-MS and its pharmacokinetic studies / 中国临床药理学与治疗学

AIM:To establish an LC-MS method for determining the concentrations of loratadine (LOR) in human plasma and to evaluate its pharmacokinetic characteristics. METHODS: A ZORBAX Eclipse XDB-C8 (5 μm, 150 mm×4.6 mm) column was used, atmospheric pressure electronic spray ionization (AP-ESI) and ion mass spectrum (m/z) of 388.2 (M+H)+ were selected to quantify LOR, and 275.1 (M+H)+ for ropivacaine (internal standard, IS). RESULTS: The linear range of LOR standard curve was 0.5-50 ng·ml-1, and the determination limit was 0.5 ng·ml-1. The pharmacokinetic parameters of LOR after a single dose of 20 mg tablet (T1), capsule (T2) and reference (R) were as follows, the half life (t1/2) 13.52±1.35, 13.14±0.98 and 14.00±1.25 h, the time to peak concentration (Tmax) 1.24±0.06, 1.18±0.12 and 1.17±0.12 h, the peak concentration (Cmax) 21.72±7.70, 21.49±8.34 and 20.50±8.65 ng·ml-1, the area under time-concentration curve (AUC0-48 and AUC0-∞) 137.24±47.84 and 146.61±51.03 ng·ml-1·h, 139.65±45.69 and 148.04±48.10 ng·ml-1·h, 134.19±49.03 and 143.70±52.08 ng·ml-1·h, the relative bioavailability of LOR tablet and capsule were (105.49±8.08)% and (102.90±10.02)%, respectively. CONCLUSION: The LC-MS method for determining the concentration of LOR in human plasma is sensitive and accurate and can be used for LOR bioavailability and pharmacokinetic studies. LOR tests and reference are bioequivalent.