HPLC-UV analytical method for determination of pizotifen after in vitro transdermal diffusion studies.

Pizotifen malate is an antihistamine and serotonin inhibitor used in the preventive treatment of migraine and eating disorders. A simple, rapid, accurate and precise high-performance liquid chromatography (HPLC) method involving ultraviolet detection was validated for the quantitative analysis of pizotifen malate in samples from in vitro transdermal diffusion studies. The method was validated for specificity, linearity, accuracy, precision, limit of detection, limit of quantification and robustness. Drug stability in the solution was also determined under different conditions. Separation was carried out using a 250 × 4.0 mm Kromasil(®) C(18) column at room temperature. The detector response, fitted at 254 nm, was found to be linear in a concentration range between 0.24 and 24.0 µg/mL. The limit of detection was 0.02 µg/mL and the limit of quantification was 0.07 µg/mL. Finally, in vitro transdermal diffusion of pizotifen malate was characterized using the validated HPLC method.

Validation and application of reversed phase high-performance liquid chromatographic method for quantification of pizotifen malate in pharmaceutical solid dosage formulations.

The aim of this study was to develop and validate an isocratic reversed phase high-performance liquid chromatographic method for quantification of pizotifen malate in pharmaceutical solid dosage formulations. Good chromatographic separation of pizotifen malate was achieved by using an analytical column, C(18) ODS column. The system was operated at 40°C oven temperature using a mobile phase consisting of acetonitrile and acetate buffer pH 7.0 (60:40) at a flow rate of 2 ml/min. The method showed high sensitivity with good linearity (r(2)= 0.99997) over the tested concentration range of 0.0020-0.0300 mg/ml for pizotifen malate. Detection was carried out at 231 nm and retention time was 2.838 min. Placebo and blank studies were performed and no peak was observed at the retention time of pizotifen malate. The intermediate precision and accuracy results (mean ± RSD, n=3) were (99.11±0.21) % and (99.19±0.55) % respectively with tailing factor (1.26±0.19). The proposed method was validated in terms of selectivity, linearity, accuracy, precision, range, detection and quantitation limit, system suitability and solution stability.This method can be successfully employed for simultaneous quantitative analysis of pizotifen malate in pharmaceutical solid dosage formulations.

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.