Application of HILIC stationary phase to determination of dimethindene maleate in topical gel.

A novel high performance liquid chromatography method for the determination of dimethindene maleate in pharmaceutical gel using hydrophilic interaction liquid chromatography (HILIC) with UV detection was developed and validated. Following optimal conditions for the analysis of dimethindene maleate were used: analytical column SeQuant ZIC-HILIC (50mmx2.1mm, 5microm), and mobile phase consisted of a mixture of acetonitrile and aqueous solution of acetic acid (25mM) and ammonium acetate (2.5mM) (87.5:12.5, v:v). The analysis time was less than 3min at a flow rate of 0.3mlmin(-1). UV detection was performed at 258nm. The method was validated and system suitability parameters were evaluated. The method is suitable for application for routine determination of dimethindene maleate in topical pharmaceutical preparation.

HPLC determination of chlorhexidine gluconate and p-chloroaniline in topical ointment.

A novel fast isocratic reversed-phase HPLC method for simultaneous determination of chlorhexidine and its degradation product p-chloroaniline was developed. Zorbax SB Phenyl column (75 mm x 4.6 mm, 3.5 microm) was used for the separation. Mobile phase composed of acetonitrile and buffer solution of 0.08 M sodium phosphate monobasic containing 5 ml of triethylamine (0.5%) and adjust with 85% phosphoric acid to pH 3.0 in ratio 35:65 (v/v) pumped isocratically at flow rate 0.6 ml min(-1) was used. UV detection was performed at 239 nm, the total analysis time was about 10 min. The method is suitable for practical routine analysis of topical ointment in the quality control laboratory.

HPLC determination of calcium pantothenate and two preservatives in topical cream.

A RP-HPLC method for simultaneous determination of calcium pantothenate and two preservatives methylparaben and propylparaben present in topical cream was developed. Different analytical columns with various stationary phases were tested. During method development, Supelco Discovery C18 column (125 mmx4.0 mm, 5 microm) and Zorbax SB-CN column (150 mmx4.6 mm, 5 microm) were tested. Both were not convenient for analytical separation because of the co-elution of calcium pantothenate with dead volume, and problems with the peak-shape of all components. Good separation was achieved using Zorbax TSM (250 mmx4.6 mm, 5 microm) and Hypersil ODS column (250 mmx4.6 mm, 5 microm), the latter was finally used for the analysis. The analysis time was 12 min, at flow rate 0.7 ml min-1. Chromatography was performed using binary mobile phase composed of methanol and phosphoric acid, pH 2.5, 65:35 (v/v). UV detection was accomplished at 214 nm. The method was validated according to ICH guideline recommendations. The method is suitable for practical routine analysis of commercially produced topical pharmaceutical preparations.

Separation and determination of terbinafine and its four impurities of similar structure using simple RP-HPLC method.

A novel reversed-phase HPLC method for the simultaneous determination of active component terbinafine, its one impurity 1-methylaminomethylnaphtalene and three degradation products, beta-terbinafine, Z-terbinafine and 4-methyl-terbinafine occurring in pharmaceutical formulations after long-term stability tests, was developed and validated using propylparaben as an internal standard. The chromatographic separation was performed on a NUCLEOSIL 100-5-CN column, mobile phase for separation of all compounds consisted of a mixture of tetrahydrofurane, acetonitrile and citrate buffer pH 4.50 (10:20:70,v/v/v). The analysis time was less than 32 min at flow-rate of 0.8 ml min(-1). UV detection was performed at 226 nm. The method was validated and system suitability parameters were investigated. Method robustness and short-term standard solution stability were verified. Limits of detection for terbinafine degradation products/impurity were from 0.023 to 0.098 microg ml(-1), limits of quantitation were from 0.078 to 0.327 microg ml(-1). The method was applicable for routine determination of terbinafine and all its found impurities of similar structure with sufficient selectivity, precision and accuracy.

Development and validation of HPLC method for determination of indomethacin and its two degradation products in topical gel.

Indomethacin forms by decomposition two degradation products: 4-chlorobenzoic acid and 5-methoxy-2-methylindoleacetic acid. They have to be monitored together with an active substance both during manufacturing process and storage of pharmaceuticals. European Pharmacopoeia (Ph. Eur. 4) describes titration method for determination of indomethacin, which is not very convenient in this case for practical use. Therefore, high performance liquid chromatography is the method-of-choice enabling determination of active substance and its degradation products during one-step procedure simultaneously and automatically. We have developed a fast, simple and fully automated analytical method for determination of indomethacin and its two impurities in pharmaceutical preparation using HPLC with UV detection. Various stationary phases were tested, especially new types of Zorbax columns made by Agilent. While the conventional C18 stationary phases were not convenient enough to achieve quick and reliable separation, Zorbax-Phenyl analytical column (75 mm x 4.6 mm, 3.5 microm) enables separation of indomethacin and its two degradation products during 7.5 min. Chromatography was performed using isocratic elution with binary mobile phase composed of acetonitrile and 0.2% phosphoric acid (50:50, v/v) at flow rate 0.6 ml/min. Even faster separation of standards was obtained with analytical column Zorbax SB-CN (150 mm x 4.6 mm, 5 microm). The separation was effected with mobile phase of the same composition, only the flow rate was increased to 1.2 ml/min. The analytical run was shortened to 5 min. Both methods use detection wavelength 237 nm and both can use either ketoprofen or flurbiprofen as internal standard for quantitation. The first method was finally chosen for validation because of the occurrence of placebo interferences in the case of using Zorbax SB-CN. System suitability parameters and validation parameters including method precision, accuracy, linearity, selectivity and robustness were set up. Afterwards, the method was successfully applied for the practical determination of indomethacin and its degradation products in a topical gel and for compound degradation control during stability studies.

Simultaneous HPLC determination of ketoprofen and its degradation products in the presence of preservatives in pharmaceuticals.

A novel and quick high-performance liquid chromatography (HPLC) method with UV spectrophotometric detection was developed and validated for the determination of five compounds in topical gel. The described method is suitable for simultaneous determination of active component ketoprofen, two preservatives methylparaben and propylparaben and two degradation products of ketoprofen--3-acetylbenzophenone and 2-(3-carboxyphenyl) propionic acid--in a topical cream after long-term stability tests using ethylparaben as an internal standard. The chromatographic separation was performed on a 5microm Supelco Discovery C18 column (125mm x 4mm i.d., Sigma-Aldrich); the optimal mobile phase for separation of ketoprofen, methylparaben, propylparaben, degradation products 3-acetylbenzophenone and 2-(3-carboxyphenyl) propionic acid and ethylparaben as internal standard consists of a mixture of acetonitril, water and phosphate buffer pH 3.5 (40:58:2, v/v/v). At a flow rate of 1.0ml min(-1) and detection at 233nm, the total time of analysis was less than 10min. The method was applied for routine analysis (batch analysis and stability tests) of these compounds in topical pharmaceutical product.

Determination of methylparaben, propylparaben, triamcinolone acetonide and its degradation product in a topical cream by RP-HPLC.

A novel reversed-phase high-performance liquid chromatographic (RP-HPLC) method was developed and validated for the determination of active component triamcinolone acetonide, its degradation product triamcinolone (occurring in formulation after long-term stability tests) and two preservatives presented in the cream-methylparaben and propylparaben, using hydrocortisone as an internal standard. The chromatographic separation was performed on a Supelco Discovery C18 column; the mobile phase for separation of all compounds consists of a mixture of acetonitrile and water (40:60 v/v). The analysis time was less than 9 min, at a flow rate of 0.6 mL min(-1) and detection at 240 nm. The method was found to be applicable for routine analysis (stability tests, homogeneity) in the pharmaceutical product topical cream Triamcinolon cream 0.1%.