Alini Dall Cortivo Lange

Validation of UV Spectrophotometric Method for Quantitative Determination of Entacapone in Tablets Using Experimental Design of Plackett‐Burman for Robustness Evaluation and Comparison with HPLC

Abstract Validation of UV spectrophotometric method for quantitative determination of entacapone in tablets using acetonitrile as solvent. The validation of analytic method was realized through the study of the following analytic parameters: specify linearity, precision, accuracy, and robustness. The excipients of the formulation did not interfere at 305 nm, demonstrating the specificity of the method. The method was linear (r=0.99996) at concentrations ranging from 3.0 to 20.0 µg ml−1, precise (repeatability and intermediated precision), exact (method of standard addition), and robust. The results confirmed that the method is valid and useful to the routine quality control of entacapone in coated tablets. The method was compared to a high‐performance liquid chromatography (HPLC) method, which was previously developed and validated to the same drug. There was not a significant difference between the methods for entacapone quantitation.

Development and validation of a dissolution test for telithromycin in coated tablets

A dissolution test for telithromycin tablets was validated and developed. In order to choose the most discriminatory one, the conditions to carry out are 900 mL of sodium phosphate buffer at pH 7.5, paddles at 50 rpm stirring speed, time test set to 60 min and using USP apparatus 2 with paddles. The UV spectrophotometric method for determination of telithromycin released was developed and validated. The method presents linearity (r = 1) in the concentration range of 20–60 μg/mL. Precision and recoveries were good, 100.62 and 97.06%, respectively. The method was successfully used for the dissolution test of telithromycin tablets.

LC method for telithromycin in tablets: a stability-indicating assay.

A liquid chromatographic (LC) method for the quantitative determination of telithromycin, the first member of the ketolides, which is a new class of macrolides, was developed. Analytical parameters were studied according to International Conference on Harmonization (ICH) guidelines. An Ace RP-18 octadecyl silane column (250 mm x 4.6 mm, 5 microm) maintained at 50 degrees C was used as the stationary phase, and methanol and 0.067 M potassium monobasic phosphate buffer pH 4.0 (55:45, v/v) were used as the mobile phase with UV detection at 265 nm. In forced degradation studies, the effects of acid, base, oxidation, UV light and temperature were investigated showing no interference in the drug peak. The method was linear (r=0.9999) at concentration ranging from 10.0 to 40.0 microg/mL, precise (intra-day relative standard deviation [RSD] and inter-day RSD values<2.0%), accurate (mean recovery=100.76%), specific and robust. Detection and quantitation limits were 0.0027 and 0.0082 microg/mL, respectively. The results showed the proposed method is suitable for its intended use. The validated method may be used to quantify telithromycin tablets and to determine the stability of the drug. The method is able to separate telithromycin from its degradation products and tablet excipients for its sensitivity and reproducibility. These results are in accordance with a previous microbiological assay study, which used the same tested conditions showing that the methods can be interchangeable.

HPLC-DAD for the determination of three different classes of antifungals: method characterization, statistical approach, and application to a permeation study.

This study describes and characterizes methods for high-performance liquid chromatography diode array detection (HPLC-DAD) analysis of formulations containing molecules with antifungal activity of three different classes: terbinafine and butenafine (allylamines), miconazole and fluconazole (azoles), and geraniol, neral and geranial (monoterpenes). All methods used the same chromatographic column (RP18 ), enabling the analysis to be performed in a single batch. The specificity was extensively discussed through the establishment of purity peak methods. The analytical parameters (linearity, precision and accuracy) were calculated and discussed in detail using specific statistical approaches. All substances showed satisfactory results for chromatographic and analytical parameters. Limits of 1.3% to mean repeatability and 2.0% for intermediate precision are suggested as acceptance criteria in validation of methods by HPLC-DAD, in situations where there is no extensive pretreatment of the samples. The methods proved to be robust and significant factors were discussed regarding their influence on chromatographic parameters (retention time, resolution, tailing factor and column efficiency). Finally, the application of the developed methods was demonstrated by the results of a permeation study of the antifungal agents through bovine hoof membranes.

Photodegradation kinetics of lodenafil carbonate, structure elucidation of two major degradation products using UPLC-MS/MS and in vitro cytotoxicity

The photostability of lodenafil carbonate was studied and some degradation products were observed. A stability-indicating liquid chromatography method for the determination of lodenafil carbonate was used to determine the kinetics of photodegradation. The identification of two major photodegradation products was performed by an isocratic ultra performance liquid chromatography-tandem mass spectrometry method (UPLC-MS/MS). UPLC-MS/MS was carried out on a Waters® Acquity Ultra Performance LC system coupled to a Micromass® Quadrupole Time of Flight tandem mass spectrometer equipped with an electrospray ionization interface in positive ion mode. The column applied was Acquity UPLC® BEH C18; the mobile phase consisted of a mixture of methanol–formic acid 0.1% pH 4.0 (55 : 45, v/v) at a flow-rate of 0.4 mL min−1 and UV detection at 290 nm. The photodegradation of lodenafil carbonate followed first-order reaction kinetics and the kinetic parameters of degradation rate constant and t90% were calculated. Under photodegradation conditions, ion products were detected at m/z 393 (DP-1) and at m/z 377 (DP-2). The product DP-1 is 4-ethoxy-3-(1-methyl-7-oxo-3-propyl-6,7-dihydro-1H-pyrazolo [4,3-d]pyrimidin-5-yl)-benzenesulfonic acid and DP-2 probably is 4-ethoxy-3-(1-methyl-7-oxo-3-propyl-6,7-dihydro-1H-pyrazolo [4,3-d]pyrimidin-5-yl) benzenesulfinic acid. The degraded samples of lodenafil carbonate were also evaluated in order to determine the in vitro cytotoxicity against mononuclear cells.