Characteristics, Properties and Analytical Methods for Determination of Dropropizine and Levodropropizine: A Review.

Dropropizine is a peripheral antitussive drug that acts by inhibiting cough reflex through its action on the peripheral receptors and their afferent conductors. It is marketed in a racemic form or its pure enantiomer called levodropropizine and both are available worldwide in various drug dosage formulations such as tablets, sirup and oral solution. Due to the widespread use of antitussives in the clinic it is necessary to develop efficient analytical methodologies for quality control and also for pharmacokinetic, bioavailability and bioequivalence studies. This review presents a survey of the characteristics, properties and analytical methods used for drug determination, being carried out through scientific articles as well as in official compendia. From the analyzed studies, the majority reports the use of HPLC/UV techniques for drug determination, but also spectrophotometric UV/Vis methods as well as gas chromatography, and voltammetric, potentiometric and conductometric titration methods. In addition, the methodologies addressed the determination of dropropizine or levodropropizine in different types of matrices such as raw material, pharmaceutical formulations, plasma and urine. Despite the extensive clinical use of dropropizine, data from this review evidenced a still limited number of studies dealing with analytical methods for its determination in different matrices, which may be of concern since the applicability of these methods is important for quality assurance, efficacy and safety of the medicine.

Delapril and Indapamide: Development and Validation of a Stability-Indicating Core-Shell LC Method and Its Application for Simultaneous Tablets Assay.

Background: The combination of delapril (DEL) and indapamide (IND) may be regarded as an optimal drug treatment for hypertensive patients. However, there is no published study concerning the suitable stability conditions and evaluation of drugs in the raw material and commercial product. Objective: The aim of the present study was to develop an innovative, high-throughput, and stability-indicating LC method for the simultaneous analysis of DEL and IND in combined dosage form. Methods: Analyses were performed using a core-shell C18 column (100 mm × 4.6 mm id, 2.6 µm) at 45°C using isocratic elution for the mobile phase composed of triethylamine solution (0.3%, pH 5.0)-acetonitrile-methanol (58 + 35 + 7, v/v/v). The separation was obtained within 3.5 min at a flow rate of 1.0 mL/min and UV detection set at 213 nm. Results: The specificity and stability-indicating capability of the method were proven through degradation studies, which also showed that there is no interference of the formulation excipients, showing that the peak is free from any co-eluting peak. Conclusions: The method showed adequate precision, with relative standard deviation values lower than 1.85%. Excellent values of accuracy were obtained, with a mean value of 98.64% for IND and 98.65% for DEL. Experimental design was used during validation to calculate and prove the method robustness. Highlights: The proposed LC method was successfully validated according to International Conference on Harmonisation requirements and applied for the simultaneous determination of DEL and IND in tablets, presenting suitability for stability studies and contributing to improve the QC of pharmaceuticals.

Chemometric-Assisted Spectrophotometric Method for the Simultaneous Quantitative Determination of Ezetimibe and Simvastatin in Their Combined Dosage Forms.

The multivariate method, partial least-squares (PLS), was used as a calibration procedure for the simultaneous UV spectrophotometric determination of ezetimibe and simvastatin in their pharmaceutical forms. The method was developed and satisfactorily validated according to International Conference on Harmonization guidelines with respect to specificity, linearity, precision, accuracy, and robustness. In this study, the PLS algorithms are based on the absorption spectra of 25 different mixtures of drugs obtained by a multilevel factorial design. The method was linear in the concentration range of 2-8 µg/mL for ezetimibe and 4-16 µg/mL for simvastatin (r2 > 0.99; n = 7) at wavelengths of 238 and 247 nm, respectively. The LOD and LOQ were 0.28 and 0.93 µg/mL for ezetimibe and 0.16 and 0.53 µg/mL for simvastatin, respectively. Precision and accuracy data, evaluated by RSD, were lower than 2%. The method, which proved to be robust, was performed with a 2n full-factorial design. The validated method is simple and low cost, has a low use of polluting reagents, and is environmental friendly. Therefore, the proposed method was successfully applied for the simultaneous quantitative analysis of ezetimibe and simvastatin in commercial formulations.

Pinaverium Bromide: Development and Validation of Spectrophotometric Methods for Assay and Dissolution Studies.

This study presents the development and validation of UV spectrophotometric methods for the determination of pinaverium bromide (PB) in tablet assay and dissolution studies. The methods were satisfactorily validated according to International Conference on Harmonization guidelines. The response was linear (r2 > 0.99) in the concentration ranges of 2-14 µg/mL at 213 nm and 10-70 µg/mL at 243 nm. The LOD and LOQ were 0.39 and 1.31 µg/mL, respectively, at 213 nm. For the 243 nm method, the LOD and LOQ were 2.93 and 9.77 µg/mL, respectively. Precision was evaluated by RSD, and the obtained results were lower than 2%. Adequate accuracy was also obtained. The methods proved to be robust using a full factorial design evaluation. For PB dissolution studies, the best conditions were achieved using a United States Pharmacopeia Dissolution Apparatus 2 (paddle) at 50 rpm and with 900 mL 0.1 M hydrochloric acid as the dissolution medium, presenting satisfactory results during the validation tests. In addition, the kinetic parameters of drug release were investigated using model-dependent methods, and the dissolution profiles were best described by the first-order model. Therefore, the proposed methods were successfully applied for the assay and dissolution analysis of PB in commercial tablets.

Dissolution method for delapril and manidipine combination tablets based on an absorption profile of manidipine.

The present study describes the development and validation of a dissolution method for delapril (DEL) and manidipine (MAN) combination tablets, using a simulated absorption profile based on in vivo data for MAN. The suitable in vitro dissolution profile for this formulation was obtained using 900 mL of citrate buffer pH 3.2 at 37 °C±0.5 °C as dissolution medium and USP apparatus 2 (paddle) at 75 rpm. All samples were analyzed by a liquid chromatography (LC) method. Under these conditions, a significant linear relationship between the absorbed (calculated by deconvolution approach) and dissolved fractions of MAN was obtained (R=0.997) and an in vivo-in vitro (IVIV) correlation for this particular formulation containing MAN can be established. Validation parameters for dissolution methodology such as the specificity, linearity, accuracy and precision were also evaluated according to the international guidelines, giving results within the acceptable range. Therefore, the proposed dissolution conditions can be applied for the simultaneous release analysis of DEL and MAN from the solid dosage form, contributing to the improvement of the quality control of pharmaceutics and minimizing the number of bioavailability studies.

Monolithic LC method applied to fesoterodine fumarate low dose extended-release tablets: Dissolution and release kinetics.

A dissolution test for fesoterodine low dose extended-release tablets using liquid chromatographic (LC) method equipped with a C18 monolithic column was developed and validated. LC system was operated isocratically at controlled temperature (40 °C) using a mobile phase of acetonitrile:methanol:0.03 M ammonium acetate (pH 3.8) (30:15:55, v/v/v), run at a flow rate of 1.5 mL/min and detected at 208 nm. The best dissolution conditions for this formulation were achieved using a USP apparatus 2 (paddle) at 100 rpm and 900 mL of phosphate buffer at pH 6.8 as the dissolution medium. Validation parameters such as the specificity, linearity, accuracy, precision, and robustness were evaluated according to international guidelines, giving results within the acceptable range. The kinetic parameters of drug release were also investigated using model-dependent methods and the dissolution profiles were best described by the Higuchi model. The validated dissolution test can be applied for quality control of this formulation.

Monolithic LC method applied to fesoterodine fumarate low dose extended-release tablets:Dissolution and release kinetics / 药物分析学报

A dissolution test for fesoterodine low dose extended-release tablets using liquid chromato-graphic (LC) method equipped with a C18 monolithic column was developed and validated. LC system was operated isocratically at controlled temperature (40 1C) using a mobile phase of acetonitrile:methanol:0.03 M ammonium acetate (pH 3.8) (30:15:55, v/v/v), run at a flow rate of 1.5 mL/min and detected at 208 nm. The best dissolution conditions for this formulation were achieved using a USP apparatus 2 (paddle) at 100 rpm and 900 mL of phosphate buffer at pH 6.8 as the dissolution medium. Validation parameters such as the specificity, linearity, accuracy, precision, and robustness were evaluated according to international guidelines, giving results within the acceptable range. The kinetic parameters of drug release were also investigated using model-dependent methods and the dissolution profiles were best described by the Higuchi model. The validated dissolution test can be applied for quality control of this formulation.

Stability-indicating micellar electrokinetic chromatography technique for simultaneous measurement of delapril and manidipine from a combination drug formulation.

A stability-indicating micellar electrokinetic chromatography (MEKC) method was developed and validated for simultaneous analysis of delapril (DEL) and manidipine (MAN) using salicylic acid as an internal standard. The MEKC method was performed using a fused-silica capillary (effective length of 72 cm) with 50 mM of borate buffer and 5 mM of anionic surfactant sodium dodecylsulfate at pH 9.0 as the background electrolyte. The separation was achieved at 25 kV applied voltage and 35 degrees C. The injection was performed at 50 mbar for 5 s, with detection at 208 nm. The method was linear in the range of 15-150 microg/mL (r2 = 0.9966) for DEL and 5-50 microg/mL (r2 = 0.9985) for MAN with adequate results for the precision (< or = 1.87%) and accuracy (98.94% for DEL and 100.65% for MAN). The specificity of the method and its stability-indicating capability was demonstrated through forced degradation studies, which showed that there was no interference from the excipients. The Plackett-Burman experimental design was used for robustness evaluation, giving results within the acceptable range. The method was successfully applied for analysis of the drugs, and the results were compared to an LC method, resulting in nonsignificant differences (P = 0.78 and 0.84 for DEL and MAN, respectively).

First-order derivative UV spectrophotometric method for simultaneous measurement of delapril and manidipine in tablets.

A first-order derivative spectrophotometric (1D-UV) method was developed and validated for simultaneous determination of delapril (DEL) and manidipine (MAN) in tablets. The 1D-UV spectra were obtained using change lambda = 4.0 nm and wavelength set at 228 nm for DEL and 246 nm for MAN. The method was validated in accordance with the ICH requirements, involving the specificity, linearity, precision, accuracy, robustness and limits of detection and quantitation. The method showed high specificity in the presence of two drugs and formulation excipients and was linear over the concentration range of 18-54 microg mL(-1) (r2 = 0.9994) for DEL and 6-18 microg mL(-1) (r2 = 0.9981) for MAN with adequate results for the precision (< or = 1.47%) and accuracy (98.98% for DEL and 100.50% for MAN). Moreover, the method proved to be robust by a Plackett-Burman experimental design evaluation. The proposed 'D-UV method was successfully applied for simultaneous analysis of DEL and MAN in tablets and can be used as alternative green method to separation techniques. The results were compared with the validated liquid chromatography, capillary electrophoresis and liquid chromatography-tandem mass spectrometry methods, showing non-significant difference.

Determination of fesoterodine in a pharmaceutical preparation by a stability-indicating capillary zone electrophoresis method.

A simple, stability-indicating capillary zone electrophoresis (CZE) method was developed and validated for the analysis of fesoterodine (FESO) in tablets. Optimal conditions for the separation of FESO and its degradation products were investigated. The method used 10 mM sodium phosphate buffer at pH 6.5 as the background electrolyte with an applied voltage of 30 kV (positive polarity).The capillary length was 80.5 cm (72 cm to the detector), and the detection wavelength was 208 nm. The method was validated in accordance with the International Conference on Harmonization requirements, which involved specificity, linearity, precision, accuracy, robustness, LOD, and LOQ. The stability-indicating capability of the method was established by stress degradation studies combined with peak purity assessment using photodiode array detection. The method was linear over the concentration range of 2-100 microg/mL (r2 = 0.9998) of FESO. Intraday and interday precision and accuracy evaluated by RSD, respectively, were all lower than 2%. The LOD and LOQ were 0.57 and 1.90 microg/mL, respectively. The method proved to be robust by a fractional factorial design evaluation. The proposed CZE method was successfully applied for the quantitative analysis of FESO in extended-release tablets to support its QC.

Second-Order Derivative UV Spectrophotometric Method for the Determination of Fesoterodine and Comparison with LC, CE and LC-MS/MS in Commercial Extended-Release Tablets.

The present work describes a second-order derivative UV spectrophotometric method for determination of a potent antimuscarinic drug, fesoterodine, in extended-release tablets. The method was developed and satisfactory validated according to ICH guideline with respect to specificity, linearity, precision, accuracy, and robustness. The response was linear in the concentration range of 2-24 µg mL-1 (r2 = 0.9999, n = 7) at wavelength 228 nm, which was the zero crossing point of excipient solutions. The detection and quantitation limits were 0.38 and 1.27 µg mL-1, respectively. Precision and accuracy data evaluated by relative standard deviation were lower than 2%. The method proved to be robust by a Plackett-Burman design evaluation. It is simple, it has low cost, and it has low use of polluting reagents. Therefore, the proposed method was successfully applied for the quantitative analysis of fesoterodine in commercial tablets, and the results were compared to validated methods by liquid chromatography, capillary electrophoresis and liquid chromatography-tandem mass spectrometry showing non-significant difference (P > 0.05).

Delapril and manidipine measurements by liquid chromatography-tandem mass spectrometry in a pharmaceutical formulation.

A simple, specific, fast and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous analysis of delapril (DEL) and manidipine (MAN) from their combination formulation was developed and validated using fesoterodine as the internal standard (IS). The LC-MS/MS method was carried out on a Luna C8 column (50 × 3.0 mm i.d., 3 µm) with a mobile phase consisting of methanol and 10 mmol L(-1) ammonium acetate (90 : 0, v/v), run at a flow rate of 0.25 mL min(-1). The mass spectrometry method was performed employing positive electrospray ionization operating in multiple reaction monitoring mode, monitoring the transitions of m/z 453.1 → 234.1 for DEL, m/z 611.1 → 167.0 for MAN and m/z 412.2 → 223.0 for IS. The total analysis time was 3 min and the method was linear in the concentration range of 6-1080 ng mL(-1) and 2-360 ng mL(-1) for DEL and MAN, respectively. Parameters investigated for the method validation, such as the specificity, linearity, precision, accuracy and robustness, gave results within the acceptable range. Moreover, the proposed method was successfully applied for the simultaneous determination of DEL and MAN and the results were compared to validated liquid chromatography and capillary electrophoresis methods showing non-significant differences (P = 0.9).

Fesoterodine stress degradation behavior by liquid chromatography coupled to ultraviolet detection and electrospray ionization mass spectrometry.

In the present study, a rapid validated stability-indicating LC method was established and comprehensive stress testing of fesoterodine was carried out according to ICH guidelines. Fesoterodine was subjected to stress conditions of acid and basic hydrolysis, oxidation, photolysis and thermal decomposition. The degradation products formed under stress conditions were investigated by LC-UV and LC-ESI-MS. Successful separation of the drug from its degradation products was achieved on a monolithic C(18) column (100 mm × 4.6mm i.d.) maintained at 45°C using acetonitrile-methanol-0.03 mol L(-1) ammonium acetate (pH 3.8) (30:15:55, v/v/v) as the mobile phase. The flow rate was 2.4 mL min(-1) and the detection wavelength was 208 nm. Validation parameters such as specificity, linearity, precision, accuracy, and robustness were evaluated. Chromatographic separation was obtained within 2.5 min and it was suitable for high-throughput analysis. Fragmentation patterns of degradation products formed under different stress conditions were studied and characterized through LC-ESI-MS fragmentation. Based on the results, a drug degradation pathway was proposed, and the validated LC method was successfully applied to the quantitative analysis of fesoterodine in tablet dosage forms, helping to improve quality control and to assure therapeutic efficacy.

Determination of rupatadine in pharmaceutical formulations by a validated stability-indicating MEKC method.

A stability-indicating MEKC was developed and validated for the analysis of rupatadine in tablet dosage forms, using nimesulide as internal standard. The MEKC method was performed on a fused-silica capillary (50 microm id; effective length, 40 cm). The BGE consisted of 15 mM borate buffer and 25 mM anionic detergent SDS solution at pH 10. The capillary temperature was maintained at 35 degrees C and the applied voltage was 25 kV. The injection was performed using the hydrodynamic mode at 50 mbar for 5 s, with detection by photodiode array detector set at 205 nm. The method was linear in the range of 0.5-150 microg/mL (r2=0.9996). The specificity and stability-indicating capability of the method were proven through degradation studies inclusive by MS, and showing also that there was no interference of the excipients and no increase of the cytotoxicity. The accuracy was 99.98% with bias lower than 1.06%. The LOD and LOQ were 0.1 and 0.5 microg/mL, respectively. The proposed method was successfully applied for the quantitative analysis of rupatadine in pharmaceutical formulations, and the results were compared to a validated RP-LC method, showing non-significant difference (p>0.05).

Development and validation of a stability-indicating micellar electrokinetic chromatography method for the determination of ezetimibe in pharmaceutical formulations.

A micellar electrokinetic chromatography (MEKC) method was validated for the analysis of ezetimibe. The method was carried out on a fused-silica capillary (50 microm i.d.; effective length, 40 cm). The background electrolyte consisted of a 25 mM borate buffer and 25 mM anionic detergent SDS (pH 9.75)/methanol (90:10, v/v). The capillary temperature was maintained at 35 degrees C, the applied voltage was 30 kV; the injection was performed using a pressure mode at 50 mbar for 5 s, with detection at 232 nm. The method was linear in the range of 2-150 microg/mL (R2=0.9999). The specificity and the stability-indicating capability were proven through degradation studies, which also showed that there was no interference of the excipients. The limits of quantitation and detection were 2 and 0.41 microg/mL, respectively. The method was applied for the analysis of ezetimibe pharmaceutical formulations, and the results were compared to those of the liquid-chromatography method.

Simultaneous liquid chromatographic determination of ezetimibe and simvastatin in pharmaceutical products.

A reversed-phase liquid chromatographic (LC) method was developed and validated for the simultaneous determination of ezetimibe and simvastatin in pharmaceutical dosage forms. The LC method was carried out on a Synergi fusion C18 column (150 mm x 4.6 mm id) maintained at 45 degrees C. The mobile phase consisted of phosphate buffer 0.03 M, pH 4.5-acetonitrile (35 + 65, v/v) run at a flow rate of 0.6 mL/min, and detection was made using a photodiode array detector at 234 nm. The chromatographic separation was obtained within 15.0 min, and calibration graphs were linear in the concentration range of 0.5-200 microg/mL. Validation parameters such as specificity, linearity, precision, accuracy, and robustness were evaluated, giving results within the acceptable range for both compounds. Moreover, the proposed method was successfully applied for the routine quality control analysis of pharmaceutical products.