Simultaneous separation and quantitation of four antiepileptic drugs—a study with potential for use in patient drug level monitoring

An LC-ESI-MS/MS assay for the therapeutic drug monitoring of 15 anti-seizure medications in plasma of children with epilepsy

Oral anti-seizure medications (ASMs) is the preferred option for the clinical treatment of epilepsy. Therapeutic Drug Monitoring (TDM) has become an important means of individualized treatment of epilepsy. A sensitive, accurate and rapid LC-ESI-MS/MS method was developed and validated for the simultaneous determination of 15 ASMs in human plasma (carbamazepine, gabapentin, prebaglin, phenytoin, zonisamide, oxcarbazepine, tiagabine, lamotrigine, topiramate, phenobarbital, lacosamide, primidone, 10,11-dihydro-10-hydroxycarbamazepine, ethosuximide, and levetiracetam). The sample preparation procedure was an one-step protein precipitation with methanol (MeOH). The mass detection was performed in ionization polarity switching mode (positive-negative-positive) using multiple reaction monitoring mode. A "boot-shaped" gradient elution program was applied to separate and concentrate those target analytes resulting in symmetrical peak shapes within 10 min, without endogenous interference. The method showed great linearity over their concentration ranges with acceptable correlation coefficients (0.9966~0.9996). The precision and accuracy values for intra- and inter-assays were within ±15%. Consequently, the method was successfully implemented on pediatric patients undergoing mono- or polytherapy for epilepsy and provided timely concentration results to ordering clinicians.

A Rapid LC-MS-MS Method for the Quantitation of Antiepileptic Drugs in Urine

Epilepsy is a common neurologic disease that requires treatment with one or more medications. Due to the polypharmaceutical treatments, potential side effects, and drug-drug interactions associated with these medications, therapeutic drug monitoring is important. Therapeutic drug monitoring is typically performed in blood due to established clinical ranges. While blood provides the benefit of determining clinical ranges, urine requires a less invasive collection method, which is attractive for medication monitoring. As urine does not typically have established clinical ranges, it has not become a preferred specimen for monitoring medication adherence. Thus, large urine clinical data sets are rarely published, making method development that addresses reasonable concentration ranges difficult. An initial method developed and validated in-house utilized a universal analytical range of 50-5,000 ng/mL for all antiepileptic drugs and metabolites of interest in this work, namely carbamazepine, carbamazepine-10,11-epoxide, eslicarbazepine, lamotrigine, levetiracetam, oxcarbazepine, phenytoin, 4-hydroxyphenytoin, and topiramate. This upper limit of the analytical range was too low leading to a repeat rate of 11.59% due to concentrations >5,000 ng/mL. Therefore, a new, fast liquid chromatography-tandem mass spectrometry (LC-MS-MS) method with a run time under 4 minutes was developed and validated for the simultaneous quantification of the previously mentioned nine antiepileptic drugs and their metabolites. Urine samples were prepared by solid-phase extraction and analyzed using a Phenomenex Phenyl-Hexyl column with an Agilent 6460 LC-MS-MS instrument system. During method development and validation, the analytical range was optimized for each drug to reduce repeat analysis due to concentrations above the linear range and for carryover. This reduced the average daily repeat rate for antiepileptic testing from 11.59% to 4.82%. After validation, this method was used to test and analyze patient specimens over the course of approximately one year. The resulting concentration data were curated to eliminate specimens that could indicate an individual was noncompliant with their therapy (i.e., positive for illicit drugs) and yielded between 20 and 1,700 concentration points from the patient specimens, depending on the analyte. The resulting raw quantitative urine data set is presented as preliminary reference ranges to assist with interpreting urine drug concentrations for the nine aforementioned antiepileptic medications and metabolites.

Development and Validation of RP-LC Method for the Determination of Cinnarizine/Piracetam and Cinnarizine/Heptaminol Acefyllinate in Presence of Cinnarizine Reported Degradation Products

Specific stability indicating reverse-phase liquid chromatography (RP-LC) assay method (SIAM) was developed for the determination of cinnarizine (Cinn)/piracetam (Pira) and cinnarizine (Cinn)/heptaminol acefyllinate (Hept) in the presence of the reported degradation products of Cinn. A C₁₈ column and gradient mobile phase was applied for good resolution of all peaks. The detection was achieved at 210 nm and 254 nm for Cinn/Pira and Cinn/Hept, respectively. The responses were linear over concentration ranges of 20–200, 20–1000 and 25–1000 μgmL⁻¹ for Cinn, Pira, and Hept respectively. The proposed method was validated for linearity, accuracy, repeatability, intermediate precision, and robustness via statistical analysis of the data. The method was shown to be precise, accurate, reproducible, sensitive, and selective for the analysis of Cinn/Pira and Cinn/Hept in laboratory prepared mixtures and in pharmaceutical formulations.

Development and Validation of HPTLC Method for Estimation of Carbamazepine in Formulations and Its In Vitro Release Study

A new, simple, and rapid high-performance thin-layer chromatographic method was developed and validated for quantitative determination of Carbamazepine. Carbamazepine was chromatographed on silica gel 60 F254 TLC plate using ethyl acetate-toluene-methanol (5.0 + 4.0 + 1.0 v/v/v) as mobile phase. Carbamazepine was quantified by densitometric analysis at 285 nm. The method was found to give compact spots for the drug (Rf=0.47 ± 0.01). The linear regression analysis data for the calibration plots showed good linear relationship with r2=.9995 in the concentration range 100–600 ng/spot. The method was validated for precision, recovery, repeatability, and robustness as per the International Conference on Harmonization guidelines. The minimum detectable amount was found to be 16.7 ng/spot, whereas the limit of quantitation was found to be 50.44 ng/spot. Statistical analysis of the data showed that the method is precise, accurate, reproducible, and selective for the analysis of Carbamazepine. The method was successfully employed for the estimation of equilibrium solubility, quantification of Carbamazepine as a bulk drug, in commercially available preparation, and in-house developed mucoadhesive microemulsion formulations and solution.

An HPLC with evaporative light scattering detection method for the quantification of PEGs and Gantrez in PEGylated nanoparticles

A rapid and precise HPLC method with evaporative light scattering detection (ELSD) for the separation and quantification of polyethyleneglycol 2000 (PEG 2000), polyethyleneglycol 6000 (PEG 6000) and poly(methyl vinyl ether-co-maleic anhydride) (Gantrez) in a nanosized pharmaceutical formulation has been developed. Separation was carried out on a PL aquagel-OH 30,8 microm column (300 mm x 7.5 mm), in a gradient elution with methanol-water as mobile phase at a flow rate of 1 ml/min. Quantification was determined in supernatants of PEGylated nanoparticles and the quantification limits were found to be 0.075 mg/ml for polyethyleneglycols and 0.25 mg/ml for Gantrez. The precision did not exceed 8% and accuracy range for PEGs (-11.50 and 10.61%) and Gantrez (-12.18 and 14.81%) were always within the acceptable limits. The amount of polyethyleneglycol associated to nanoparticles was also calculated by a Nuclear Magnetic Resonance Method ((1)H NMR). Likely, for both PEGs, a good relationship between both techniques was found. In summary, the developed HPLC technique provides an alternative for the routine and rapid analysis of PEGs and Gantrez in nanoparticle formulations.

Comparative study on major bioactive components in natural, artificial and in-vitro cultured Calculus Bovis

Major bioactive components in various Calculus Bovis, including natural, artificial and in-vitro cultured Calculus Bovis, were comparatively studied. An approach of high-performance liquid chromatography coupled with ultraviolet and evaporative light scattering detections (HPLC/UV/ELSD) was established to simultaneously determinate six bioactive components thereof, including five bile acids (cholic acid, deoxycholic acid, ursodeoxycholic, chenodeoxycholic acid, hyodeoxycholic acid) and bilirubin. ELSD and UV detector were applied to detect bile acids and bilirubin respectively. The assay was performed on a C(18) column with water-acetonitrile gradient elution and the investigated constituents were authenticated by comparing retention times and mass spectra with those of reference compounds. The proposed method was applied to analyze twenty-one Calculus Bovis extraction samples, and produced data with acceptable linearity, precision, repeatability and accuracy. The result indicated the variations among Calculus Bovis samples under different developmental conditions. Artificial and in-vitro cultured Calculus Bovis, especially in-vitro cultured ones, which contain total bioactive constituents no less than natural products and have the best batch-to-batch uniformity, suffice to be used as substitutes of natural Calculus Bovis.

Quality evaluation of Radix Astragali through a simultaneous determination of six major active isoflavonoids and four main saponins by high-performance liquid chromatography coupled with diode array and evaporative light scattering detectors

A method, high-performance liquid chromatography coupled with diode array and evaporative light scattering detectors (HPLC-DAD-ELSD), was developed to evaluate the quality of Radix Astragali through a simultaneous determination of six major active isoflavonoids and four main saponins. The wavelength at 280 nm was chosen to determine six isoflavonoids: calycosin-7-O-beta-D-glucoside (1), ononin (2), (6alphaR, 11alphaR)-9,10-dimethoxypterocarpan-3-O-beta-D-glucoside (3), (3R)-2'-hydroxy-3',4'-dimethoxyisoflavan-7-O-beta-D-glucoside (4), calycosin (5), and formononetin (6); and ELSD connected after DAD was employed to determine four saponins: astragaloside IV (7), astragaloside II (8), astragaloside I (9), and acetylastragaloside I (10). This assay was fully validated with respect to precision, repeatability and accuracy. The proposed method was successfully applied to quantify the ten components in eleven samples from different localities in China; significant variations were demonstrated in the content of these compounds in the samples from different areas. This simple, rapid, low-cost and reliable HPLC-DAD-ELSD method is suitable for routine quantitative analysis and quality control of traditional Chinese medicines (TCMs) consisting of bioactive multi-components with different structures such as Radix Astragali.

Simultaneous determination of nine components in Qingkailing injection by HPLC/ELSD/DAD and its application to the quality control

High-performance liquid chromatography coupled with photo diode array detection and evaporative light scattering detection (HPLC/DAD/ELSD) was established to simultaneously determine nine ingredients in Qingkailing injection. Four wavelengths at 240, 254, 280 and 330 nm, respectively, were chosen as the monitoring wavelength to determine two nucleosides (uridine and adenosine), geniposide, baicalin and two organic acids (chlorogenic acid and caffeic acid), and an evaporative light scattering detector combined was employed to determine three steroids (cholic acid, ursodeoxycholic acid and hyodeoxycholic acid). This assay was fully validated in respect to precision, repeatability and accuracy. The proposed method was successfully applied to quantify the nine ingredients in 19 different Qingkailing injection samples and by principal component analysis (PCA) and hierarchical clustering analysis (HCA), it demonstrated significant variations in the content of these compounds in the samples from different manufacturers and preparation procedures. This method could be readily utilized as a quality control method for traditional Chinese medicine (TCM).