Amr M. Badawy

Utility of p-Chloranilic Acid For Spectrophotometric Determination of Some Antihistaminic Drugs

Abstract A simple, sensitive and accurate spectrophotometric procedure has been described for determination of three antihistaminic drugs, loratadine (I), dimethindene maleate (II), and clemastine hydrogen fumarate (III). The procedure is based on the interaction of each of these drugs with p-chloranilic acid (P-CA) in methylene chloride to give a stable highly coloured chromogen exhibiting maximum absorbance at 530 nm. Optimization of different experimental parameters as well as the stoichiometry of the reaction have been studied. Conformity to Beers Law enables determination of these drugs in concentration ranges of 40–320 μg. ml−1, 40–240 μg. ml 40–400 μg. ml−1 for drugs I,II and III respectively. The validity of the suggested procedure was checked by applying the standard addition technique using different pharmaceutical dosage forms. Results revealed high accuracy and good reproducibility, when compared with reference methods.

A Validated HPLC Method for Separation and Determination of Promethazine Enantiomers in Pharmaceutical Formulations

A simple, rapid, and validated method for separation and determination of promethazine enantiomers was developed. Promethazine was separated and quantitated on a Vancomycin Chirobiotic V column (250 × 4.6 mm), using a mixture of methanol, acetic acid, and triethylamine (100:0.1:0.1%, by volume) as a mobile phase at 20°C and at a flow rate of 1 mL/min. The UV-detector was set to 254 nm. Acetyl salicylic acid (Aspirin®) was used as an internal standard. The applied HPLC method allowed separation and quantification of promethazine enantiomers with good linearity (r > .999) in the studied range. The relative standard deviations (RSD) were 0.29 and 0.36 for the promethazine enantiomers with accuracy of 100.06 and 100.08. The limit of detection and limit of quantification of promethazine enantiomers were found to be 0.04 and 0.07 μg/mL, respectively. The method was validated through the parameters of linearity, accuracy, precision, and robustness. The HPLC method was applied for the quantitative determination of promethazine in pharmaceutical formulations.

Validated HPLC Method for Separation and Determination of Terbutaline Enantiomers

Abstract A simple, rapid, and validated method for separation and determination of terbutaline enantiomers was developed. Terbutaline was separated and determined on a Vancomycin Chirobiotic V column (250 × 4.6 mm), using a mixture of methanol, acetic acid, and triethylamine (100:0.1:0.1% v/v/v) as a mobile phase at 20°C and at a flow rate of 1 ml/min. The UV detector was set to 276 nm. Acetyl salicylic acid (aspirin) was used as an internal standard. The applied high-performance liquid chromatography (HPLC) method allowed separation and quantification of terbutaline enantiomers with good linearity (r > 0.999) in the studied range. The relative standard deviations (RSD) were 1.10 and 1.32% for the terbutaline enantiomers with accuracy of 99.80 and 99.55. The limit of detection and limit of quantification of terbutaline enantiomers were found to be 0.05 and 0.10 µg · ml−1, respectively. The method was validated through the parameters of linearity, accuracy, precision, and robustness. The HPLC method was applied for the quantitative determination of terbutaline in pharmaceutical formulations.

Stability-indicating chemometric methods for the determination of tazarotene

Two multivariate calibration methods-principal component regression (PCR) and partial least square (PLS)-have been used to determine tazarotene in the presence of its degradation products. Both methods are useful in spectral analysis because of the simultaneous inclusion of many spectral wavelengths instead of the single wavelength used in derivative spectrophotometry. A great improvement in the precision and predictive abilities of these multivariate calibrations was observed. A calibration set was constructed for the mixture and the best model was used to predict the concentration of the selected drug. The proposed methods were applied successfully in the determination of tazarotene in laboratory-prepared mixtures and in commercial preparations. Tazarotene was analyzed with mean accuracies of 100.006 ± 0.695 and 100.007 ± 0.690 using the PCR and PLS methods, respectively. The validity of the proposed methods was assessed using the standard addition technique. The proposed methods were found to be rapid, simple and required no preliminary separation. They can therefore be used for the routine analysis of tazarotene in quality-control laboratories.

Stability-indicating spectrophotometric methods for determination of tazarotene in the presence of its alkaline degradation product by derivative spectrophotometric techniques.

The stability of tazarotene (TZ) was investigated and two stability-indicating methods-namely, first derivative and a derivative ratio spectrophotometric method-were used to determine tazarotene in the presence of its alkaline degradation product (HD) using methanol as a solvent. A linear relationship was obtained in the range 1-10 µg ml⁻¹ for both methods. By applying the proposed methods, it was possible to determine tazarotene in its pure powdered from with accuracy 99.35 ± 1.410 (n = 10) for the first derivative method and 99.45 ± 1.053 (n = 10) for the derivative ratio method. First derivative and derivative ratio methods were used for the analysis of laboratory-prepared mixtures containing different ratios of tazarotene and its degradation product and they were valid in the presence of up to 70% and 80% degradation product, respectively. The proposed methods were validated and found to be suitable as stability-indicating assay methods for tazarotene in pharmaceutical formulations.

A VALIDATED HPLC METHOD FOR SEPARATION AND DETERMINATION OF EPINASTINE HYDROCHLORIDE ENANTIOMERS

A simple, rapid, and validated method for separation and determination of epinastine hydrochloride was developed. Epinastine hydrochloride enantiomers was separated and determined on a Chiralcel® OD-R column (250 × 4.6 mm i.d., 0.5 μm particle size), using a mixture of n-hexane: isopropanol: diethylamine: triflouroacetic acid (85: 15: 0.1: 0.1% v/v/v/v) as a mobile phase at 20°C and at a flow rate of 1 mL/min. The UV detector was set to 254 nm. Epinastine hydrochloride 1000 μg/mL was used as an external standard. The applied HPLC method allowed the separation and quantification of epinastine hydrochloride enantiomers with good linearity (r > 0.999) in the studied range. The relative standard deviations (RSD) were 1.076 and 0.769% for the epinastine hydrochloride enantiomers with accuracy of 99.65 and 99.77 for the enantiomeric pair separated. The limit of detection and limit of quantification of epinastine hydrochloride enantiomers were found to be 20 and 60 μg/mL, respectively. The method was validated through the parameters of linearity, accuracy, precision, and robustness. The HPLC method was applied for the quantitative determination of epinastine hydrochloride in pharmaceutical formulations.