Chiral Separation of Apremilast by Capillary Electrophoresis Using Succinyl-ß-Cyclodextrin-Reversal of Enantiomer Elution Order by Cationic Capillary Coating.

A stereospecific capillary electrophoresis method was developed for the separation of the novel, antipsoriatic agent, apremilast (APR). Six anionic cyclodextrin (CD) derivatives were screened for their ability to discriminate between the uncharged enantiomers. Only succinyl-ß-CD (Succ-ß-CD) presented chiral interactions; however, the enantiomer migration order (EMO) was unfavorable, and the eutomer, S-APR, migrated faster. Despite the optimization of all possible parameters (pH, cyclodextrin concentration, temperature, and degree of substitution of CD), the method was unsuccessful for purity control due to the low resolution and the unfavorable enantiomer migration order. Changing the direction of electroosmotic flow (EOF) by the dynamic coating of the inner surface of the capillary with poly(diallyldimethylammonium) chloride or polybrene resulted in EMO reversal, and the developed method could be applied for the determination of R-APR as the enantiomeric purity. Thus, the application of the dynamic capillary coating offers a general opportunity for enantiomeric migration order reversal in particular cases when the chiral selector is a weak acid.

Simultaneous Determination of Escitalopram Impurities including the R-enantiomer on a Cellulose tris(3,5-Dimethylphenylcarbamate)-Based Chiral Column in Reversed-Phase Mode.

A high-performance liquid chromatographic method was developed for the simultaneous determination of the related substances-three potential synthesis-related chemical impurities and the distomer-of escitalopram. The separation capacity of seven different polysaccharide-type chiral columns, including three amylose-based (Lux Amylose-1, Lux i-Amylose-1, Lux Amylose-2) and four cellulose-based columns (Lux Cellulose-1, Lux Cellulose-2, Lux Cellulose-3, and Lux Cellulose-4) were screened in the polar organic and reversed-phase modes. Lux Cellulose-1, based on cellulose tris(3,5-dimethylphenylcarbamate) as the chiral selector with an acetonitrile-water mixture containing 0.1% diethylamine was identified as the most promising separation system. Using the "one factor at a time" optimization approach, the effect of column temperature, flow rate, and mobile phase constituents on separation performance was evaluated, and the critical resolution values were determined. A U-shaped retention pattern was obtained when plotting the retention factors of the citalopram enantiomers versus the water content of the binary mobile phases on the Lux Cellulose-1 column. A thermodynamic analysis revealed enthalpy-driven enantioseparation in both the polar organic and reversed-phase modes. For further method optimizations, an L9 orthogonal array table was employed. Using the optimized parameters (Lux Cellulose-1 column with 0.1% (v/v) diethylamine in water/acetonitrile 55/45 (v/v); 0.8 mL/min flow rate at 25 °C), baseline separations were achieved between all compounds. Our newly developed HPLC method was validated according to the ICH guidelines and its application was tested with a commercially available pharmaceutical formulation. The method proved to be suitable for routine quality control of related substances and the enantiomeric purity of escitalopram.

Liquid chromatographic method for the simultaneous determination of achiral and chiral impurities of dapoxetine in approved and counterfeit products.

A reversed-phase high performance liquid chromatographic method was developed and validated for the simultaneous determination of the related substances of S-dapoxetine, including R-dapoxetine, (3S)-3-(dimethylamino-3-phenyl-1-propanol), S-3-amino-3-phenyl-1-propanol, 1-naphtol, 4-phenyl-2H,3H,4H-naphtho[1,2-b]pyran and 1-(2E)-Cinnamyloxynaphthalene. During the screening experiments seven different polysaccharide-type chiral stationary phases (amylose-based Lux-Amylose-1, Lux-i-Amylose-1 and Lux-Amylose-2, as well as cellulose-based Lux-Cellulose-1, Lux-Cellulose-2, Lux-Cellulose-3 and Lux-Cellulose-4) were tested in polar organic mode using a mobile phase consisting of 0.1% diethylamine in methanol, ethanol, 2-propanol and acetonitrile with 0.5 mL min-1 flow rate at 20 °C. Best results were obtained on Lux Cellulose-3 column with the ethanol-based mobile phase. To increase the retention factor of two, early-eluting impurities, water was added to the mobile phase. In order to counterbalance the increased total analysis time, higher column temperature (40 °C) and gradient elution, combined with flow-programming` was applied. Using the optimized conditions baseline separations were achieved for all compounds within 30 min. The method was validated according to the International Council on Harmonization guideline Q2(R1) and applied to the analysis of an approved, tablet formulation and dapoxetine-containing products sold on the internet. As expected, in the case of the pharmacy-acquired product, all of the monitored impurities were below 0.1%. However, interesting results were obtained when internet-acquired samples were analyzed. These tablets contained racemic dapoxetine and/or high concentration of R-dapoxetine impurity. Based on this work polysaccharide-based chiral stationary phases can be successfully applied for the simultaneous determination of achiral and chiral impurities in reversed-phase mode applying gradient elution and flow-rate programs. The study further underlines the importance of not only achiral, but also enantiomeric quality control, whenever counterfeiting of a single enantiomeric agent is suspected.

Compliance as a stable function in the treatment course of bipolar disorder in patients stabilized on olanzapine: results from a 24-month observational study.

Compliance is a key factor in the maintenance treatment of bipolar disorder. This noninterventional study was conducted to explore factors associated with higher levels of compliance in bipolar patients, all treated in routine clinical settings. Bipolar outpatients (Clinical Global Impression of Severity score ≤3) who had been stabilized with olanzapine mono- or combination therapy for ≥4 weeks were enrolled in the study. Compliance to medication was assessed at baseline and after 3, 6, 9, 12, 18, and 24 months by a physician-rated, 4-point categorical scale using the following classification: noncompliant (patients being compliant to treatment schedule less than 20% of the time) and low (20% to 59% of the time), moderate (60% to 79% of the time), and high (≥80% of the time) levels of compliance. Both baseline and post-baseline factors were used in a generalized estimating equations (GEE) model to predict the likelihood of high compliance. Of 891 eligible patients, 657 patients completed the 24-month observation period. High levels of compliance (≥80%) were observed in 67% of patients at baseline, increasing to 80% in study completers. High compliance at baseline was identified as a strong predictor of compliance during study participation (odds ratio (OR) = 6.9, 95% confidence interval (CI) = 5.0 to 9.5, p < 0.001). Factors associated with high compliance during the study (GEE model) included greater life satisfaction (p = 0.002), better insight into illness (p < 0.001), less work impairment (p = 0.007), and fewer days of inpatient care (p = 0.002). Compliance ratings varied by country (p < 0.001) and duration of post-baseline treatment (p = 0.014). In conclusion, a number of clinical, functional, and social factors were identified as predictors of compliance in patients with bipolar disorder. As compliance is crucial for the long-term management of these patients, more attention should be directed towards compliance itself and factors associated with compliance levels in everyday treatment settings.

General and domain-specific neurocognitive impairments in deficit and non-deficit schizophrenia.

Earlier studies suggested more severe overall cognitive impairments in deficit versus non-deficit schizophrenia; however, the specific contribution of different cognitive domains to this overall cognitive impairment remains unclear. The purpose of this study was to compare the two subtypes in general cognitive functioning as well as in individual cognitive domains using the composite score approach. One hundred and forty-three patients fulfilling the criteria for the deficit syndrome were compared with 123 patients diagnosed with non-deficit schizophrenia. Neurocognitive functioning was assessed by a neuropsychological test battery measuring the domains of sustained vigilance/attention, working memory, short-term memory, verbal memory, cognitive flexibility, and ideation fluency. Using the raw neuropsychological measures, we calculated a global index of cognitive impairment and domain-specific composite z-scores. Association between these composite scores and the deficit syndrome was examined by logistic regression analysis. After adjusting for relevant covariates including sex, age, education, smoking, and antipsychotic dose, results indicated a significant increase in the likelihood of deficit syndrome as a function of global (OR = 5.40; 95% CI 3.02-9.65) as well as domain-specific impairments (OR > 2 for all individual domains except for short-term memory). Cognitive flexibility was an independent predictor (OR = 2.92; 95% CI 1.47-5.80), whereas other cognitive domains demonstrated no unique contribution to the general cognitive impairment. Patients with deficit schizophrenia suffer from a more severe degree of neurocognitive impairment, which is qualitatively similar to the dysfunction seen in non-deficit schizophrenia. However, our results indicate that cognitive flexibility is specifically impaired in deficit versus non-deficit patients and may therefore represent a core feature of this subtype.

When doors of perception open: visual contrast sensitivity in never-medicated, first-episode schizophrenia.

Schizophrenia is characterized by impaired visual contrast sensitivity and anomalous perceptual experiences. The aim of this study was to investigate these phenomena in unmedicated patients with first-episode schizophrenia. Visual contrast sensitivity was measured with pulsed-pedestal and steady-pedestal tests, which bias information processing toward the parvocellular and magnocellular pathways, respectively. Anomalous perceptual experiences were investigated with the Structured Interview for Assessing Perceptual Anomalies (SIAPA). Results revealed that patients with schizophrenia (n = 20) exhibited increased contrast sensitivity values on the magnocellular test relative to the control participants (n = 20). In the parvocellular condition, there was no significant difference between the two groups. The higher magnocellular contrast sensitivity values were associated with increased visual SIAPA scores, especially at the two lowest spatial frequencies (0.25 and 0.5 cycles/degree). These results indicate the heightened sensitivity of magnocellular pathways in unmedicated first-episode schizophrenia, which may contribute to anomalous perceptual experiences and sensory overloading.