A simple and rapid HPLC method was developed and validated for simultaneous determination of two antipsychotic drugs, olanzapine and aripiprazole, in spiked human plasma. Optimization studies were performed using experimental design approach. The most important analysis parameters were selected using fractional factorial design and optimum levels of these parameters were determined with Box-Behnken design. Separation was achieved on a monolithic column (Rp-18, 100-4.6 mm) set at 35°C with a flow rate of 0.8 ml/min. Gradient elution was performed with a mobile phase consisting of phosphate buffer (pH 3.14, 20 mM) and acetonitrile. Retention times of olanzapine and aripiprazole were 2.34 and 6.90 minutes, respectively. The method was linear in the range of 0.125-50.0 µg/ml for olanzapine and 0.500-50.0 µg/ml for aripiprazole. The quantification limits for olanzapine and aripiprazole were found 0.069 and 0.498 µg/ml, respectively. The method was found accurate and precise based on recovery values, which were between 99-102% and relative standard deviations, which were lower than 2%. Robustness of the method and the stability of analytes were also investigated.

In this study, a new, simple and specific stability indicating ion-pair LC method was developed and fully validated for the determination of asenapine in tablets. The analysis was performed on an Agilent Eclipse XDB-C8 column (4.6 x 150 mm, 3.5 µm particles) at 30˚C. A mixture of phosphate buffer (pH 3, 20 mM) containing 10 mM 1-heptane sulfonic acid and acetonitrile, (60:40, v/v) at a flow rate of 1 mL min-1 was used as mobile phase. Detection was performed by a diode array detector at 220 nm. The developed method was validated according to related ICH guideline and US Pharmacopeia and it was suitable in terms of accuracy, precision, specificity, robustness and stability. The method was linear in the concentration range of 0.5-100 µg mL-1. Limit of detection and limit of quantification values were calculated as 0.0836 µg mL-1 and 0.2788 µg mL-1 , respectively. This ion-pair LC method was applied successfully for the determination of asenapine in its sublingual tablets.

Background: Motilin is a peptide-structured gastrointestinal system hormone. In this study, a sensitive HPLC-fluorescence detection method was developed and validated for the quantification of motilin in human plasma. Materials & methods: Optimization processes were carried out with the experimental design methodology. Analyses were performed on a C8 column (4.6 × 150 mm, 3.5 μm particles) using water and acetonitrile containing trifluoroacetic acid as the mobile phase. Results & conclusion: The method was linear from 2 to 200 ng/ml of motilin. The assay variability was less than 5%. The limit of quantification was found to be 1.84 ng/ml. The applicability of the developed method was successfully demonstrated by quantifying the levels of motilin in human plasma samples.