Simultaneous quantitation of Ofloxacin, Fexofenadine HCl and Diclofenac Potassium in affixed dose combinative formulation by HPLC-UV method

A high-pressure liquid chromatography (HPLC-UV) based simple and specific method for simultaneous quantitative determination of Ofloxacin, Fexofenadine HCl and Diclofenac Potassium has been developed and validated according to ICH guidelines. Chromatographic separation of the three drugs was carried out on 4.6 x 250 mm x 5 µ Licrospher RP Select B Column, using mobile phase constituted of methanol and phosphate buffer pH 3.5 (650: 350), pH adjusted to 3.5 ± 0.05 with dilute ortho-phosphoric acid and delivered at a flow rate of 1 ml/min. The eluents were detected at UV wavelength of 220 nm and the retention times for Ofloxacin, Fexofenadine HCl and Diclofenac Potassium were 2.5 minutes, 4 minutes and 11.5 minutes, respectively. This method is suitable and specific for the three drugs and was found to be linear (R² > 0.996), accurate, specific, reproducible and robust over a concentration range of 0.05 to 0.15 mg/ml for Ofloxacin, 0.015 to 0.045 mg/ml for Fexofenadine HCl and 0.0125 to 0.0375 mg/ml for Diclofenac Potassium. The proposed method is simple and convenient, hence easily utilized for the characterization and quantitation of the three drugs in a single formulation for combination therapy of rheumatoid arthritis, sepsis, infection with fever and flu.

Development and validation of a novel stability-indicating reversed-phase high-performance liquid chromatography method for assay of loratadine and determination of its related compounds

Loratadine is an important active pharmaceutical ingredient used in a wide variety of prescription and over-the-counter products for the treatment and relief of allergy symptoms. A novel stability-indicating gradient ion-pair RP-HPLC method for assay of loratadine and determination of both of its degradation compounds and process impurities has been developed. This method can separate loratadine from its eight structurally related compounds; it can also separate all of the related compounds from each other in less than 20 min. The stability-indicating capability of this method has been demonstrated by analyzing aged stability samples of loratadine. A 15 cm x 4.6 mm id YMC-Pack Pro C18 HPLC column was the primary column and a 15 cm x 4.6 mm id SunFire C18 column has been identified as an alternate (truly equivalent) column for this method. This gradient method uses mobile phases consisting of acetonitrile and an aqueous solution of 10 mM sodium acetate and 5 mM sodium dodecyl sulfate at pH 5.5. The new HPLC method was validated according to International Conference on Harmonization guidelines and proved to be suitable for routine QC use.

Structural characterization of in vitro rat liver microsomal metabolites of antihistamine desloratadine using LTQ-Orbitrap hybrid mass spectrometer in combination with online hydrogen/deuterium exchange HR-LC/MS

In vitro drug metabolism study is an integral part of drug discovery process. In this report, we have described the application of LTQ-Orbitrap hybrid mass spectrometer in conjunction with online hydrogen (H)/deuterium (D) exchange high resolution (HR)-LC/MS for structural characterization of in vitro rat liver microsomal metabolites of antihistamine desloratadine. Five metabolites M1--M5 have been identified, including three hydroxylated metabolites M1--M3, one N-oxide M4 and one uncommon aromatized N-oxide M5. Accurate mass data have been obtained in both full scan and MSn mode support assignments of metabolite structures with reported mass errors less than 3 ppm. Online H/D exchange HR-LC/MS experiments provide additional evidence in differentiating hydroxylated metabolites from N-oxides. This study demonstrates the effectiveness of this approach in structural characterization of drug metabolites.

Alternative and improved method for the simultaneous determination of fexofenadine and pseudoephedrine in their combined tablet formulation

An alternative method for the determination of fexofenadine (FEX) and pseudoephedrine (PSE) in their combined tablet formulation has been developed, employing the partial least squares (PLS) analysis of spectral data of the analytes in their pharmaceutical association. A full-factorially designed set of 16 synthetic samples was employed for calibration purposes. The calibration models were constructed with wavelengths selection, in the ultraviolet region, according to their predictive ability. These were validated internally by the leave-one-out procedure and externally, employing appropriate sets of validation samples. The described method was linear for both analytes, over the range 160.6-301.2 mg L(-1) for FEX (R(2)=0.9993) and between 325.6 and 610.5 mg L(-1) for PSE (R(2)=0.9992). It was accurate, exhibiting 99.8% and 99.9% drug recoveries for FEX and PSE, respectively (N=9), while in the intermediate precision experiment relative standard deviations were 1.4% for FEX and 1.2% for PSE. The contents of both analytes were assayed in commercial tablets employing this method and the results were compared with those furnished by HPLC, being in good statistical agreement. The method represents an improvement over the first derivative of spectral ratio (DSR) technique and allows high sample throughput with minimum reagent consumption and waste generation. The obtained results confirm that the method is highly suitable for its intended purpose.

Simultaneous determination of loratadine and desloratadine in pharmaceutical preparations using liquid chromatography with a microemulsion as eluent

A rapid HPLC procedure for analytical quality control of pharmaceutical preparations containing the antihistaminic drug substance loratadine and/or its analog desloratadine (which is also an active metabolite of loratadine) was developed using a microemulsion as the eluent. The separation was performed on a column packed with cyanopropyl bonded stationary phase adopting UV detection at 247 nm using a flow rate of 1 ml/min. The optimized microemulsion mobile phase consisted of 0.1M sodium dodecyl sulphate, 1% octanol, 10% n-propanol and 0.3% triethylamine in 0.02 M phosphoric acid, pH 3.0. The developed method was validated in terms of specificity, linearity, lower limit of quantification, lower limit of detection, precision and accuracy. With the proposed method satisfactory resolution between loratadine and desloratadine (resolution factor=3.85). The method requires a minimum of sample handling and is rapid (10 min), and reproducible (R.S.D.<2.0%). The mean recoveries of the analytes in pharmaceutical preparations were in agreement with those obtained from a reference method, as revealed by statistical analysis of the obtained results using the Student's t-test and the variance ratio F-test. Pseudoephedrine, the co-formulated drug substance, did not interference with the assay and was successfully separated using the developed HPLC method.

Development of a CZE method for the determination of mizolastine and its impurities in pharmaceutical preparations using response surface methodology

A fast and selective CZE method for the determination of mizolastine and related impurities is described. Response surface methodology was applied to study the influence of phosphate/triethanolamine (TEA) buffer concentration, heptakis(2,3,6-tri-O-methyl)-beta-CD (TMbetaCD) concentration, voltage and temperature. The optimum conditions were: 105 mM phosphate/TEA buffer (pH 3.0) containing 10 mM TMbetaCD, temperature 19 degrees C and voltage 30 kV. Validation of the method was performed in drug substance and drug product. Robustness was evaluated using a Plackett-Burman design, including pH among the considered factors. Applying the optimal conditions, the nine peaks were baseline separated in about 10 min. The method was applied to the quality control of mizolastine in controlled-release tablets.

Chiral separation of cetirizine by capillary electrophoresis

Chiral separation of cetirizine, a second-generation H(1)-antagonist, was studied by CD-mediated CE. Several parameters, including pH, CD type, buffer concentration, type of co-ion, applied voltage and temperature, were investigated. The best conditions for chiral separation were obtained using a 75 mM triethanolamine-phosphate buffer (pH 2.5) containing 0.4 mg/mL heptakis(2,3-diacetyl-6-sulfato)-beta-CD and 10% ACN. Online UV detection was performed at 214 nm, a voltage of 20 kV was applied and the capillary was temperature controlled at 25 degrees C by liquid cooling. Hydrodynamic injection was performed for 1 s. The method was validated for the quantification of levocetirizine in tablets and for enantiomeric purity testing of the drug substance. Selectivity, linearity, LOD and LOQ, precision and accuracy were evaluated for both methods. The amount of levocetirizine dihydrochloride in the commercially available tablets was quantified and was found to be within the specification limits of the claimed amount (5 mg). The amount of distomer in levocetirizine drug substance was found to be 0.87 +/- 0.09% w/w, which is in agreement with the certificate of analysis supplied by the company.

[Analysis of tablets containing the antihistamine loratadine: a contribution to the identification of impurities]

Thin-layer chromatography on silica gel (Merck) was employed to examine potential impurities present in loratadine-containing tablets. A method usable for testing of impurities was elaborated, which suitably supplements the determination of loratadine content using the spectrophotometric method in the UV region. The method was validated for selected pharmaceuticals.

Impurity profile study of loratadine

Three unknown impurities in loratadine bulk drug at levels below 0.1% (ranging from 0.05 to 0.1%) were detected by a simple isocratic reversed-phase high performance liquid chromatography (HPLC). These impurities were isolated from mother liquor sample of loratadine using reversed-phase preparative HPLC. Based on the spectral data (IR, NMR and MS) the structures of these impurities were characterized as 11-(N-carboethoxy-4-piperidylidene)-6,11-dihydro-5H-benzo(5,6) cyclopenta(1,2-b)-pyridine (I), 8-bromo-11-(N-carboethoxy-4-piperidylidene)-6,11-dihydro-5H-benzo(5,6) cyclopenta (1,2-b)-pyridine (II) and 8-chloro-11-(N-carboethoxy-4-piperidylidene)-5H-benzo(5,6) cyclopenta (1,2-b)-pyridine (III). The synthesis of these impurities was discussed.

Simultaneous determination of montelukast and loratadine by HPLC and derivative spectrophotometric methods

In this study, high performance liquid chromatography (HPLC) and second derivative spectrophotometry have been used and described for the simultaneous determination of montelukast and loratadine in pharmaceutical formulations. HPLC separation was achieved with a Symmetry C18 column and sodium phosphate buffer (pH adjusted to 3.7): acetonitrile (20:80, v/v) as eluent, at a flow rate of 1.0 ml/min. UV detection was performed at 225 nm. The LC method is simple, rapid, selective and stability indicating for the determination of montelukast. 5-Methyl 2-nitrophenol was used as internal standard for the purpose of quantification of both the drugs in HPLC. In the second-order derivative spectrophotometry, for the determination of loratadine the zero-crossing technique was applied at 276.1 nm, but for montelukast peak amplitude at 359.7 nm (tangent method) was used. Both methods were fully validated and a comparison was made for assay determination of selected drugs in formulations. The results confirm that the methods are highly suitable for its intended purpose.