APPLICATION OF HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC METHOD FOR THE DETERMINATION OF LEVODOPA, CARBIDOPA, AND ENTACAPONE IN TABLET DOSAGE FORMS

A voltammetric method coupled with chemometrics for determination of a ternary antiparkinson mixture in its dosage form: greenness assessment

An electroanalytical methodology was developed by direct differential pulse voltammetric (DPV) measurement of Levodopa (LD), Carbidopa (CD) and Entacapone (ENT) mixture using bare glassy carbon electrode (GCE) in Britton Robinson (BR) buffer (pH = 2.0). A multivariate calibration model was then applied to the exported preprocessed voltammetric data using partial least square (PLS) as a chemometric tool. Additionally, the model was cross-validated and the number of latent variables (LVs) were determined to produce a reliable model for simultaneous quantitation of the three drugs either in their synthetic mixtures or in their marketed pharmaceutical formulation with high accuracy and precision. Data preprocessing was used to tackle the problem of lacking bi-linearity which is commonly found in electrochemical data. The proposed chemometric model was able to provide fast and reliable technique for quantitative determination of antiparkinson drugs in their dosage forms. This was successfully achieved by utilizing sixteen mixtures as calibration set and nine mixtures as validation set. The percent recoveries for LD, CD and ENT were found to be 100.05% ± 1.28%, 100.04% ± 0.53% and 99.99% ± 1.25%, respectively. The obtained results of the proposed method were statistically compared to those of a previously reported High Performance Liquid Chromatography (HPLC) methodology. Finally, the presented analytical method strongly supports green analytical chemistry regarding the minimization of potentially dangerous chemicals and solvents, as well as reducing energy utilization and waste generation.

Fast Detection of Entacapone by a Lanthanide-Organic Framework with Rhombic Channels

Entacapone (ENT) is a powerful catechol-O-methyl transferase inhibitor that is used for the diagnosis and treatment of Parkinson's syndrome, but the amount used must be well controlled to avoid overtreatment and side effect. Fast and selective detection of ENT needs well-matched energy levels and well-designed sensor-ENT interaction which is highly challenging. In this work, a water stable europium-based metal-organic framework (Eu-TDA) was synthesized to detect ENT by luminescence with excellent reusability and selectivity in the presence of main coexisting and interference species of plasma with a limit of detection of 5.01 μM. The experimental results showed that the luminescence of Eu-TDA can be effectively quenched by ENT via well-designed photoinduced electron transfer mechanism and internal filtration effect mechanism in the system.

A rapid liquid chromatography/tandem mass spectrometry method for simultaneous determination of levodopa, carbidopa, entacapone and their six related compounds in film-coated tablets

RATIONALE

A liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed and validated to determine levodopa, carbidopa, entacapone, and corresponding six related substances - levodopa impurity B, levodopa impurity C, methyldopa, methylcarbidopa, entacapone impurity C, and entacapone impurity A - in film-coated tablets for the first time.

METHODS

Chromatographic separation was achieved with a gradient elution by using a C18 column, a mobile phase containing 0.5% formic acid in water and 0.5% formic acid in methanol. The mobile phase flow rate was 0.5 mL min^-1 . The UV detector was set at 280 nm and the triple quadrupole mass spectrometer was used in multiple reaction monitoring (MRM) mode.

RESULTS

The limit of detection (LOD) and limit of quantification (LOQ) results were 1.3 and 3.94 ng mL^-1 for levodopa impurity B; 5.26 and 15.9 ng mL^-1 for levodopa impurity C; 0.833 and 2.53 ng mL^-1 for methyldopa; 3.31 and 10.0 ng mL^-1 for methylcarbidopa; 1.67 and 5.06 ng mL^-1 for entacapone impurity C; and 0.61 and 1.86 ng mL^-1 for entacapone impurity A.

CONCLUSIONS

The method was rapid, linear, accurate, and reproducible. The LC/MS/MS method that was developed to determine the related substances and assay of levodopa, carbidopa, and entacapone can be used to evaluate the quality of regular samples in the pharmaceutical industry. It can be also used to test the stability of samples.

The Determination of Parkinson's Drugs in Human Urine by Applying Chemometric Methods

The spectrophotometric-chemometric analysis of levodopa and carbidopa that are used for Parkinson's disease was analyzed without any prior reservation. Parkinson's drugs in the urine sample of a healthy person (never used drugs in his life) were analyzed at the same time spectrophotometrically. The chemometric methods used were partial least squares regression (PLS) and principal component regression (PCR). PLS and PCR were successfully applied as chemometric determination of levodopa and carbidopa in human urine samples. A concentration set including binary mixtures of levodopa and carbidopa in 15 different combinations was randomly prepared in acetate buffer (pH 3.5).). UV spectrophotometry is a relatively inexpensive, reliable, and less time-consuming method. Minitab program was used for absorbance and concentration values. The normalization values for each active substance were good (r2>0.9997). Additionally, experimental data were validated statistically. The results of the analyses of the results revealed high recoveries and low standard deviations. Hence, the results encouraged us to apply the method to drug analysis. The proposed methods are highly sensitive and precise, and therefore they were implemented for the determination of the active substances in the urine sample of a healthy person in triumph.

Micellar HPLC-UV method for the simultaneous determination of levodopa, carbidopa and entacapone in pharmaceuticals and human plasma

A method based on micellar liquid chromatography to quantify levodopa, carbidopa and entacapone in plasma is reported. The sample pretreatment was a simple dilution in a pure micellar solution then filtration and direct injection, without requiring extraction or purification steps. The three drugs were resolved from the matrix in 7 min, using an aqueous solution of 0.1 M sodium dodecyl sulphate-10% n-propanol-0.3 tiethylamine, adjusted at pH 2.8 with 0.02 M orthophosphoric acid as mobile phase, running under isocratic mode at 1.0 mL/ min through VP-ODS column. The detection was done by UV (ultraviolet) absorbance at 225 nm. The method was successfully validated by the International Conference Harmonization guidelines in terms of: selectivity, linearity (r² > 0.998) over the concentration ranges of 0.025-1.2, 0.05-1.0 and 0.3-2.0 μg mL^-1 with limits of detection of 0.01, 6.16 × 10^-3 and 0.02 μg mL^-1 and limits of quantification of 0.03, 0.02 and 0.07 μg mL^-1 for levodopa, carbidopa and entacapone, respectively. The proposed method was applied successfully for quantification of the studied drugs in their different dosage forms. Moreover, the method was further extensive to the quantification of the studied drugs in spiked human plasma and was successfully validated by the guidelines of the European Medicines Agency. The proposed procedures were successfully evaluated to determine the studied drugs in real human plasma. The procedure was found reliable, practical, cost-effective, available, short period, easy-to-handle, low-cost, environmental-friendly, secure, useful for the analysis of numerous samples per day. Lastly, the method was performed to the analysis of incurred, using quality control samples in the same analytical run, with adequate results. Therefore, it can be implementable for custom analysis in clinical laboratories.

Development and Validation of a RP-HPLC Method for Determination of Related Substances and Degradants in Entacapone

A new reverse phase-liquid chromatography (RP-HPLC) method has been developed for simultaneous determination of entacapone and its pharmacopoeia impurities, in-house impurities and degradation impurities (total 17 analytes). Chromatographic separation was achieved on a C18 column (size: 250 × 4.6 mm; 5 µm particle size) at a flow rate of 1.0 mL/min with 210 nm detection. The mobile phase (MP) consists of 1.361 g of potassium di-hydrogen phosphate and 1.742 g of di-potassium phosphate in 1.0 L water, pH adjusted to 2.5 with ortho phosphoric acid (MP-A) and acetonitrile (MP-B) through gradient elution. The product was subjected to stress conditions such as acid, base, peroxide, thermal and photolytic degradation. Two new impurities above 2% level were observed and isolated through preparative HPLC and well characterized. However, no interference observed due to degradation impurities and entacapone and its EP impurities, in-house impurities. As part of the method validation, specificity, limit of detection, limit of quantitation (LOQ), linearity, accuracy, precision, robustness and ruggedness were determined. LOQ values were achieved between 0.01 and 0.04%. Good linearity (r(2) > 0.99) was obtained ranging from LOQ to 150%. Recovery was verified for all impurities at concentrations ranging from LOQ to 150%. Hence, a newly developed RP-HPLC method was capable for well separation of all analytes with acceptable resolution and tailing factor.

A novel methionine/palladium nanoparticle modified carbon paste electrode for simultaneous determination of three antiparkinson drugs

A simple and novel method for the simultaneous determination of entacapone (EN), levodopa (LD) and carbidopa (CD) based on a methionine/palladium nanoparticle modified carbon paste electrode is described.