A Validated HPLC Method with Fluorescence Detection for the Determination of Droperidol in Pharmaceutical Tablets,Human Serum,and Human Milk

A sensitive and simple HPLC method with fluorimetric detection has been developed for determination of droperidol in pharmaceutical tablets, human serum, and human milk. Chromatography was performed on a 100 mm × 3 mm i.d. C₁₈ column with methanol–water, 30:70 (v/v), pH 3.5, as mobile phase at a flow-rate of 0.8 mL min⁻¹. The injection volume was 5 μL and detection was by monitoring emission at 324 nm after excitation at 283 nm. Droperidol and p-hydroxybenzoic acid (internal standard) eluted after 5.3 and 6.1 min, respectively. The method was validated over the concentration range 1.14 × 10⁻⁷ to 9.12 × 10⁻⁶ M. Selectivity was good and the limits of detection and quantitation of the method were approximately 3.54 × 10⁻⁸ and 1.07 × 10⁻⁷ M, respectively, corresponding to 13 and 40 ng mL⁻¹. The applicability of the method to determination of droperidol in pharmaceuticals, human serum, and human milk was demonstrated.

     

An LC Method for the Determination of Bupropion and Its Main Metabolite, Hydroxybupropion in Human Plasma

A new LC method has been developed and validated for the direct determination of bupropion and its main metabolite, hydroxybupropion in human plasma. Plasma samples were analyzed after a simple, one step protein precipitation with trichloroacetic acid using a C₈ column and mobile phase, consisting of methanol/acetonitrile/phosphate buffer (10 mM, pH 3.0) (40:10:50, v/v/v) and 20 mM 1-heptane sulfonic acid sodium salt with carbamazepine as the internal standard. UV detection was performed at 214 and 254 nm. The method was validated over the concentration range of 60–2,400 and 150–4,700 ng mL^?1 for bupropion and hydroxybupropion, respectively. The intra- and inter-day assay variability was less than 15% for the two analytes. Limit of detection values were 24.8 and 63.4 ng mL^?1 for bupropion and hydroxybupropion, respectively. The method developed was applied to quantification of bupropion and hydroxybupropion in human plasma.     

A Validated Thin-Layer Chromatographic Method for Analysis of Bupropion Hydrochloride in a Pharmaceutical Dosage Form

JPC – Journal of Planar Chromatography – Modern TLC - A simple and sensitive thin-layer chromatographic method has been established for analysis of bupropion hydrochloride in...     

An LC Method for the Determination of Bupropion and Its Main Metabolite,Hydroxybupropion in Human Plasma

A new LC method has been developed and validated for the direct determination of bupropion and its main metabolite, hydroxybupropion in human plasma. Plasma samples were analyzed after a simple, one step protein precipitation with trichloroacetic acid using a C₈ column and mobile phase, consisting of methanol/acetonitrile/phosphate buffer (10 mM, pH 3.0) (40:10:50, v/v/v) and 20 mM 1-heptane sulfonic acid sodium salt with carbamazepine as the internal standard. UV detection was performed at 214 and 254 nm. The method was validated over the concentration range of 60–2,400 and 150–4,700 ng mL⁻¹ for bupropion and hydroxybupropion, respectively. The intra- and inter-day assay variability was less than 15% for the two analytes. Limit of detection values were 24.8 and 63.4 ng mL⁻¹ for bupropion and hydroxybupropion, respectively. The method developed was applied to quantification of bupropion and hydroxybupropion in human plasma.

     

A simple and sensitive LC-ESI-MS (ion trap) method for the determination of bupropion and its major metabolite, hydroxybupropion in rat plasma and brain microdialysates

A specific and highly sensitive liquid chromatography-electrospray mass spectrometry (LC-ESI-MS) method for the direct determination of bupropion (BUP) and its main metabolite hydroxybupropion (HBUP) in rat plasma and brain microdialysate has been developed and validated. The analysis was performed on a Bonus RP C18 (100 mm × 2.1 mm i.d., 3.5 μm particles) column using gradient elution with the mobile phase consisting of acetonitrile and ammonium formate buffer (10 mM, pH 4). Plasma samples were analyzed after a simple, one-step protein precipitation clean-up with trichloroacetic acid (TCA), however clean-up for microdialysis samples was not necessary, enabling direct injection of the samples into the LC-ESI-MS system. Signals of the compounds were monitored under the multiple reaction monitoring (MRM) mode of the LC-ESI-MS (ion trap) for quantification. The precursor to product ion transitions of m/z 240-184 and m/z 256-238 were used to measure BUP and HBUP, respectively. The method was validated in both plasma and microdialysate samples, and the obtained lower limit of quantification (LLOQ) was 1.5 ng mL⁻¹ for BUP and HBUP in both matrices. The intra- and inter-day assay variability was less than 15% for both analytes. This LC-ESI-MS method provided simple sampling, rapid clean-up and short analysis time (<9 min), applicable to the routine therapeutic monitoring and pharmacokinetic studies of BUP and HBUP.     

CE Determination of Droperidol in Tablets and Human Serum

A capillary electrophoretic method was described for the determination of droperidol in pharmaceutical tablets and human serum. Droperidol and internal standard, lansoprazole, were separated on an uncoated fused-silica capillary using a run buffer containing borate (10 mM; pH 9.3) and aqueous methanol (20%, υ/υ). The signals were detected at 210 nm. The migration times for droperidol and internal standard were 2.1 and 2.9 min, respectively. The method has been validated in the range of 2.2 × 10^?5 ? 7.8 × 10^?5 M and applied to both tablets and human serum with good repeatability and no interference.     

Chemometrically assisted optimization and validation of a new HPLC method for the determination of paliperidone in pharmaceuticals

Paliperidone is an antipsychotic drug, which is used for the acute and maintenance treatment of schizophrenia. In this study, a new method was developed for the determination of Paliperidone in its extended-release tablets. Face-centered central composite design was applied for optimization of the method. Factors were decided as acetonitrile content, pH of the mobile phase and buffer concentration through preliminary studies. Optimal flow rate (1?mL/min), column temperature (35°C) and internal standard (Bupropion) were also determined during preliminary studies. Retention factors and tailing factors of Paliperidone and Bupropion were selected as responses. Derringer’s desirability function was applied for simultaneously optimization of these four responses. Optimal conditions were predicted as phosphate buffer (pH:3, 23?mM): acetonitrile (76:24, v:v). Developed method was validated in terms of linearity, detection and quantification limits, accuracy, precision, specificity and robustness. Method was found linear in the concentration range of 0.125-100?µg/mL. Mean equation of the calibration curve was y?=?0.0807 x - 0.0102 (R²?=?0.9999). Accuracy and precision of the method was evaluated with recovery values (98-102%) and relative standard deviation values (<2%), respectively. All other parameters were found acceptable. The method was successfully applied for the determination of Paliperidone in its extended-release tablets.     

Determination of Carbamazepine and its Main Metabolite Carbamazepine-10,11-Epoxide in Rat Brain Microdialysate and Blood Using ESI–LC–MS (Ion Trap)

A new analytical method has been developed and validated for determination of the anti-epileptic drug carbamazepine (CBZ) and its main metabolite carbamazepine-10,11-epoxide (CBZ-E) using ESI–LC–MS (ion trap). The compounds were separated on a C18 (150 × 2.1 mm I.D., 3 μm particles) column and were isocratically eluted in the mobile phase consisting of water–acetonitrile–acetic acid (74.5:25:0.5, v/v) using the flow rate of 0.4 mL min⁻¹. The other anti-epileptic drug oxcarbamazepine (OXC) was used as an internal standard. The retention times for CBZ-E, OXC and CBZ were 5.6, 6.8, 12.8 min. Signals of the compounds were monitored under multi-reaction monitoring mode (MRM) of ESI–LC–MS (ion trap) for the quantification. Selected ions of CBZ-E, OXC and CBZ in MRM were m/z 253→210, m/z 253→180 and m/z 237→194. The method was validated over the concentration range of 5.0–500.0 ng mL⁻¹ and was applied to rat brain microdialysate and blood samples for the determination of CBZ and main metabolite. The brain microdialysate and the blood sample were collected simultaneously after intra-peritoneal injection of CBZ (12 mg kg⁻¹) during a period of 10 h. No interference from endogenous substances and matrix effect were found on the separation of microdialysates and blood samples. The consequent signals of the compounds were resolved and integrated clearly. The LC–MS method was presented as an alternative to investigate pharmacokinetic parameters of CBZ and CBZ-E in blood and brain studies.

     

Development of a CD‐MEKC method for investigating the metabolism of tamoxifen by flavin‐containing monooxygenases and the inhibitory effects of methimazole,nicotine and DMXAA

A selective and low‐cost CD‐MEKC method under acidic conditions was developed for investigating the N‐oxygenation of tamoxifen (TAM) by flavin‐containing monooxygenases (FMOs). The inhibitory effects of methimazole (MMI), nicotine and 5,6‐dimethylxanthenone‐4‐acetic acid (DMXAA) on the given FMO reaction were also evaluated; 100 mM phosphate buffer (pH 8.6) was used for performing the enzymatic reaction and the separation of TAM and its metabolite tamoxifen N‐oxide (TNO) was obtained with a BGE consisting of 100 mM phosphoric acid solution adjusted to pH 2.5 with triethanolamine containing 50 mM sodium taurodeoxycholate, 20 mM carboxymethyl β‐CD and 20% ACN. The proposed method was applied for the kinetics study of FMO1 using TAM as a substrate probe. A Michaelis–Menten constant (K_m) of 164.1 μM was estimated from the corrected peak area of the product, TNO. The calculated value of the maximum reaction velocity (V_max) was 3.61 μmol/min/μmol FMO1; 50% inhibitory concentration and inhibition constant (K_i) of MMI, the most common alternate substrate FMO inhibitor, were evaluated and the inhibitory effects of two other important FMO substrates, nicotine and DMXAA, a novel anti‐tumour agent, were investigated.     

Development and validation of a simple and efficient HPLC method for the determination of zonisamide in pharmaceuticals and human plasma

A simple and efficient liquid chromatographic method has been developed and validated for the determination of zonisamide in pharmaceuticals and human plasma. Plasma samples are analyzed after one step protein precipitation with methanol, and chromatographic separation of zonisamide and chloramphenicol (internal standard) is carried out using a C₁₈ column and the optimum mobile phase of acetonitrile/methanol/distilled water (20: 10: 70, v/v/v). The method is validated in both mobile phase and human plasma, and the obtained limits of quantification values are 0.099 and 0.12 μg/mL in mobile phase and human plasma, respectively. Fully validated method is reproducible and selective for the determination of zonisamide in pharmaceuticals and human plasma.