Development and validation of a simultaneous analytical method for non-steroidal therapeutic compounds in cosmetics using liquid chromatography-tandem mass spectrometry.

Atopic dermatitis is a typical chronic inflammatory skin disease that affects all age groups and requires basic skin care for treatment. Anti-inflammatory and antiallergy steroids are the most frequently used treatments but they are limited due to their side effects caused by a weakening of the immune system. Many consumers focus on performance as a criterion for selecting cosmetics. However, steroids have been illegally used to improve the performance of cosmetics, and consumers have been adversely affected by the corresponding side effects. In this paper, we propose a simple and rapid method using liquid chromatography-tandem mass spectrometry to simultaneously analyze ten non-permitted atopic therapeutic compounds in cosmetic products: chlorpheniramine maleate, ketotifen fumarate, doxepin hydrochloride, azelastine hydrochloride, bufexamac, clotrimazole, tranilast, fusidic acid, tacrolimus, and pimecrolimus. Additionally, the major characteristic fragment ions for tacrolimus, pimecrolimus, and clotrimazole were identified by time-of-flight mass spectrometry. The specificity, linearity, limit of detection, limit of quantification, recovery, precision, accuracy, and stability of the proposed method were validated. The limit of detection and quantification were in the ranges of 5.05-203.30 pg/mL and 15.15-609.90 pg/mL, respectively. The proposed analysis method could help improve the safety management of cosmetics.

Combination of large volume sample stacking with polarity switching and cyclodextrin electrokinetic chromatography (LVSS-PS-CDEKC) for the determination of selected preservatives in pharmaceuticals.

In this study, a large volume sample stacking (LVSS) with polarity switching (PS) and cyclodextrin electrokinetic chromatography (CDEKC) method has been developed for the simultaneous separation and determination of 8 preservatives: methylparaben (MP), ethylparaben (EP), propylparaben (PP), butylparaben (BP), isobutylparaben (IBP), sorbic acid (SA), benzoic acid (BA), p-hydroxybenzoic acid (PHBA) in pharmaceuticals. The effects of some typical parameters such as sample volume, applied voltage, composition and pH of the running buffer and organic modifier concentration were examined and optimized. Moreover, the impact of type and concentration of cyclodextrin as electrolyte modifiers was also investigated. The detection limits of analytes for the elaborated LVSS-PS-CDEKC method were found to be in 0.8-5 ng mL-1 range, which were around 500 times lower than normal CDEKC without preconcentration technique. All analytes were completely resolved in less than 11 min in an uncoated fused-silica capillary of 75 µm internal diameter (I.D) x 50 cm length. The electrophoretic separation was performed in a 2 mM α-cyclodextrin and 25 mM tetraborate system (pH = 9.3) with an applied voltage of 25 kV. The established method was validated and confirmed to be applicable for the determination of the preservatives in a quality control of pharmaceuticals.

Simple chemiluminescence determination of ketotifen using tris(1,10 phenanthroline)ruthenium(II)- Ce(IV) system.

A new method using chemiluminescence (CL) detection has been developed for the simple determination of ketotifen fumarate (KF). The method is based on the catalytic effect of KF in the CL reaction of tris(1,10 phenanthroline)ruthenium(II), Ru(phen)3 (2+), with Ce(IV) in sulfuric acid medium. The CL response was detected using a lab-made chemiluminometer. Effects of chemical variables were investigated and under optimum conditions, the CL intensity was proportional to the concentration of the drug over the range 0.34-34.00 µg mL(-1) KF. The limit of detection (S/N=3) was 0.09 µg mL(-1). Effects of common ingredients were investigated and the method was applied successfully for determining KF in pharmaceutical formulations and human plasma. The percent of relative standard deviation (n=11) at level of 3.4 µg mL(-1) of KF was 4.6% and the minimum sampling rate was 70 samples per hour. The possible CL mechanism is proposed based on the kinetic characteristic of the CL reaction, CL spectrum, UV-Vis and phosphorescence spectra.

Single and mixed chemically modified carbon paste ion-selective electrodes for determination of ketotifen fumarate.

New modified carbon paste electrodes for determination of ketotifen fumarate in its pure and pharmaceutical preparations were constructed. The used modifiers are ketotifen phosphotungestate (Keto(3) PT), and ketotifen tetraphenylborate (Keto-TPB). Single and mixed ion-associate electrodes were prepared. Both Keto-TPB and mixed (Keto-TPB and Keto(3) PT) electrodes have a linearity range of 1.00 × 10(-5) -1.00 × 10(-2) mol L(-1) . The slopes were 58.30 and 54.20 mV/decade for Keto-TPB and mixed chemically modified carbon paste electrodes (CMCPE), respectively. The limits of detection were 1.42 × 10(-6) and 1.00 × 10(-5) mol L(-1) for Keto-TPB and mixed CMCPEs, respectively. The potential variation due to pH change is considered acceptable in the pH ranges 4.44-9.11 and 2.50-9.00 for Keto-TPB and mixed ion-exchanger CMCPE, respectively. The response time was ≤10 s for both electrodes. Selectivity coefficients values towards different inorganic cations, sugars, and amino acids reflect high selectivity of the prepared electrodes. Potentiometric titrations and standard addition methods were applied for the determination of ketotifen ion in its pure samples and pharmaceutical formulations (Zaditen tablet and syrup) using proposed electrodes. The electrodes were also tested in flow injection analysis (FIA). The results obtained from both methods were statistically treated by F- and t-tests. The carbon paste electrodes have the advantages of being more easily prepared and longer life span compared to the plastic membrane electrodes previously reported.

Identification and determination of ketotifen hydrogen fumarate, azelastine hydrochloride, dimetindene maleate and promethazine hydrochloride by densitometric method.

Conditions for determination of: ketotifen hydrogen fumarate, azelastine hydrochloride, dimetindene maleate and promethazine hydrochloride by densitometric method in substances and pharmaceuticals were provided. Maximum wavelenghts were: 228 nm for ketotifen hydrogen fumarate, 295 nm for azelastine hydrochloride, 265 nm for dimetindene maleate and 255 nm for promethazine hydrochloride. The limits of quantification were in the ranges of 0.2-5 microg/spot. The statistical data showed adequate accuracy and precision of developed methods.

In vitro study on the interaction of ketotifen fumarate with anhydrous theophylline

The purpose of the present study was to investigate the interaction between ketotifen fumarate and anhydrous theophylline in aqueous media of various pH (1.2 and 6.8). Using Job's continuous-variation analysis and Ardon's spectrophotomeric measurement methods, the values of the stability constants of theophylline with ketotifen were determined at a fixed temperature (37 ºC) at various pH. The stability constants, ranging between 5.66 and 9.92, were derived from Ardon's plot, indicating that comparatively stable complexes had formed as a result of an interaction between the drugs. However, following the interaction of theophylline with ketotifen, stability constants were <1 at gastric pH (1.2) and intestinal pH (6.8). Concurrent administration of ketotifen and theophylline could result in the formation of a stable complex and this is likely to reduce the therapeutic activities of both drugs.

O objetivo do presente estudo foi investigar a interação entre o fumarato de cetotifeno e a teofilina anidra em meios aquosos com vários pH (1,2 e 6,8). Utilizando a análise da variação contínua de Job e os métodos de medida espectrofotométrica de Ardon, os valores das constantes de estabilidade da teofilina com o cetotifeno foram determinados em temperatura fixa (37 oC) em vários pH. As constantes de estabilidade, variando entre 5,66 e 9,92 derivaram-se a partir do delineamento de Ardon, indicando, comparativamente, que complexos estáveis se formaram como resultado da interação entre os fármacos. Entretanto, seguindo a interação da teofilina com o cetotifeno, as constantes de estabilidade foram <1, em pH gástrico (1,2) e intestinal (8,8). A administração concomitante de cetotifeno e teofilina poderia resultar na formação de complexo estável, o que reduz a atividade terapêutica de ambos os fármacos.

Determination of ketotifen fumarate by capillary electrophoresis with tris(2,2'-bipyridyl) ruthenium(II) electrochemiluminescence detection.

On the basis of an europium (III)-doped Prussian blue analog film modifying platinum electrode as the working electrode, a Ru(bpy)3²âº-based electrochemiluminescence (ECL) assay coupled with capillary electrophoresis has been first established for the determination of ketotifen fumarate (KTF). Analytes were injected onto a separation capillary of 50 cm length (50 µm i.d., 360 µm o.d.) by electrokinetic injection for 10 s at 10 kV. Parameters related to the separation and detection were discussed and optimized. It was proved that 15 mM phosphate buffer at pH 8.0 could achieve the most favorable resolution, and the highest sensitivity of detection was obtained using the detection potential at 1.25 V and 5 mM Ru(bpy)3²âº in 100 mM phosphate buffer at pH 8.0 in the detection reservoir. Under the optimized conditions, the ECL intensity was in proportion to KTF concentration over the range from 3.0 × 10⁻8 to 5.0 × 10⁻6 g mL⁻¹ with a detection limit of 2.1 × 10⁻8 g mL⁻¹ (3σ). The relative standard deviations of the ECL intensity and the migration time were 0.95 and 0.26%, respectively. The developed method was successfully applied to determine KTF contents in pharmaceuticals and human urine with recoveries between 99.5 and 107.0%.

Flow injection determination of ketotifen fumarate using PVC membrane selective electrodes.

In this study a PVC membrane electrode for determination of ketotifen fumarate is reported, where ketotifen tetraphenylborate (Keto-TPB) was used as ion exchanger. The electrode has linear range of 5.6x10(-6)-1.0x10(-2) and 1.0x10(-5)-1.0x10(-2) mol/L, with detection limits 2.37x10(-6)and 4.60x10(-6) mol/L in batch and flow injection analysis (FIA), respectively. The electrodes show a Nernstian slope value (58.40 and 61.50 mV/decade in batch and FIA, respectively), and the response time is very short (

Application of a continuous square-wave potential program for sub nano molar determination of ketotifen.

An electroanalytical method has been developed for the determination of the ketotifen by continuous square wave adsorptive stripping voltammetry on a ultra-gold microelectrode (Au UME) in aqueous solution with phosphate buffer as supporting electrolyte. The best adsorption conditions were found to be pH 2.3, an accumulation potential of 300 mV (Au vs. Ag: AgCl-KCl 3 M) and an accumulation time of 400 ms. Variation of admittance in the detection process is created by inhibition of oxidation reaction of the electrode surface, by adsorption of ketotifen. Furthermore, signal-to-noise ratio was significantly increased by application of discrete fast Fourier transform (FFT) method, background subtraction and two-dimensional integration of the electrode response over a selected potential range and time window. Also in this work some parameters such as square-wave frequency, eluent pH, and accumulation time were optimized. Effects of square-wave frequency, step potential and pulse amplitude were examined for the optimization of instrumental conditions. The calibration curve is linear in the range 2.0x10(-7)---5.0x10(-12) M with a detection limit of 2.0x10(-12) M (ca. 0.7 pg/ml). The method maybe applied direct determination of the drug in pharmaceutical and biological samples. For a concentration of 5.0x10(-8) M a recovery value of 99.89% is obtained.

Determination of ketotifen by using calcein as chemiluminescence reagent.

Chemiluminescence (CL) was observed when potassium hexacyanoferrate(III) reacted with the mixture of calcein and ketotifen. Interestingly, the CL intensity would be enhanced by trace amounts of Mg2+ and the CL intensity was strongly dependent on ketotifen concentration. Based on this phenomenon, a flow injection CL method was established for the determination of ketotifen. The possible CL mechanism is proposed based on the kinetic characteristic of the CL reaction, CL spectrum, ultraviolet (UV) spectra and fluorescent spectra. The CL intensity was correlated linearly with concentration of ketotifen over the range of 6.0x10(-9) to 2.0x10(-7) g mL(-1) and the detection limit was 3x10(-9) g mL(-1). The relative standard deviation was 1.8% for 2.0x10(-8) g mL(-1) ketotifen (n=11). This method was applied to the determination of ketotifen in the tablets successfully.

Development and validation of a rapid HPLC method for the determination of ketotifen in pharmaceuticals.

In the present study, a simple, sensitive, rapid, and stability-indicating high performance liquid chromatographic (HPLC) method with ultraviolet detection for the analysis of ketotifen was developed and validated. The method was applied to the determination of ketotifen in pharmaceutical formulations (tablets and syrups). The HPLC method utilized isocratic elution technique with a reversed phase C8 column, detection at 297 nm and a mixture of methanol, triethylamine phosphate buffer (pH 2.8; 0.04 M), and tetrahydrofuran (43: 55: 2, v/v/v) as mobile phase at a flow rate of 1.2 mL/min. Total analysis time was about 7 min with typical retention time of ketotifen of about 5 min. The method was validated for selectivity, linearity, accuracy, and precision following International Conference of Harmonization, 1996 (ICH) recommendations. Due to its simplicity and accuracy, the method can be used for routine quality control analysis.

Coulometric titration of ketotifen in tablets.

A method for the determination of ketotifen involving its reaction with iodine in an alkaline medium is presented. In coulometric titration using biamperometric end-point detection 0.25-2 micromol (77-618 microg) of ketotifen was successfully determined. The elaborated method was applied to the determination of ketotifen in drugs.

Determination of some antihistaminic drugs by atomic absorption spectrometry and colorimetric methods.

Atomic absorption spectrometry (AAS) and colourimetric methods have been developed for the determination of pizotifen (I), ketotifen (II) and loratadine (III). The first method depends on the reaction of the three drugs (I); (II) and (III) with cobalt thiocyanate reagent at pH 2 to give ternary complexes. These complexes are readily extracted with organic solvent and estimated by indirect atomic absorption method via the determination of the cobalt content in the formed complex after extraction in 0.1 M hydrochloric acid. It was found that the three drugs can be determined in the concentration ranges from 10 to 74, 12 to 95 and 10 to 93 microg ml(-1) with mean percentage recovery of 99.71+/-0.87, 99.70+/-0.79 and 99.62+/-0.75%, respectively. The second method is based on the formation of orange red ion pairs as a result of the reaction between (I); (II) and (III) and molybdenum thiocyanate with maximum absorption at 469.5 nm in dichloromethane. Appropriate conditions were established for the colour reaction. Under the proposed conditions linearity was obeyed in the concentration ranges 3.5-25, 5-37.5 and 2.5-22.5 microg ml(-1) with mean percentage recovery of 99.60+/-0.41, 100.11+/-0.43 and 99.31+/-0.47% for (I): (II) and (III), respectively. The third method depends on the formation of radical ion using 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ). The colour formed was measured at 588 nm for the three drugs (I); (II) and (III), respectively. The method is valid in concentration range 10-80 microg ml(-1) with mean percentage recovery 99.75+/-0.44, 99.94+/-0.72 and 99.17+/-0.36% for (I); (II) and (III), respectively. The proposed methods were applied to the analysis of pharmaceutical preparations. The results obtained were statistically analysed and compared with those obtained by applying the official and reference methods.

Spectrophotometric determination of ketotifen in pharmaceutical preparations after isolation on ion-exchanger.

Spectrophotometric method have been proposed for the determination of ketotifen in complex "Position" (Polfa-Poznan) samples after preliminary separation of excipients. For the determinations of the ketotifen in Pozitan a relative standard deviation of +/-2.0% was found.