Optimization of a LC method for the enantioseparation of a non-competitive glutamate receptor antagonist, by experimental design methodology

The aim of this work was to obtain the direct optical resolution of a new glutamate receptor antagonist ((p-chloro)1-aryl-6,7,-dimethoxy-1,2,3,4-tetrahydroisoquinoline, PS3), by liquid chromatography on Chiralcel OD column. A response surface methodology (RSM) was employed to optimize the enantiomeric separation of the racemate with the lowest number of experiments; in particular, a face-centred design (FCD) was applied to evaluate the influence of critical parameters on the experimental response. Furthermore, in order to find the best compromise between several responses, a multicriteria decision-making approach, the Derringer's desirability function, was successful to simultaneously optimize the responses resolution and migration times of the two enantiomers. The proposed LC method provided the baseline enantioseparation of the investigated drug. 9.3% (v/v) ethanol added to n-hexane as mobile phase, 1.0 mL min(-1) flow rate, and 18 degrees C column temperature were the optimum experimental conditions allowing to achieve the highest enantioresolution of PS3 in less than 17 min.

Optimization of the separation of some psychotropic drugs and their respective metabolites by liquid chromatography

A chemometric procedure is described to optimize the separation of some drugs used in the treatment of psychotic disorders: haloperidol, levomepromazine, risperidone, venlafaxine, carbamazepine and their main metabolites: reduced haloperidol, 9-hydroxy risperidone, desmethyl levomepromazine, desmethyl venlafaxine. The purpose of the procedure is the unambiguous identification and detection in biological fluids. Isocratic reversed-phase liquid chromatography with diode array detection was utilized. An experimental design methodology was carried out in which the experimental response is selectivity. In this way the designs for mixture compounds and for process variables (five variables) was performed which produced 36 experiments to carry out. The desirability function was used to select optimum separation conditions. The procedure provides a chromatogram of well separated solutes.

Study of the extraction procedure by experimental design and validation of a LC method for determination of flavonoids in Citrus bergamia juice

A reversed-phase high-performance liquid chromatographic (HPLC) separation with photo-diode array detection was developed for the simultaneous determination of flavonoids extracted from Citrus bergamia juice. It employs a C18 reversed-phase column and a linear gradient elution system with methanol/water with 5% acetic acid (v/v), as mobile phase. The method was validated in terms of detection limits (LOD), quantitation limits (LOQ), linearity, precision and accuracy. Limits of detection ranged from a low of 0.007 mg ml(-1) (narirutin) to a high of 0.018 mg ml(-1) (didymin). The limits of quantitation were between a low of 0.011 mg ml(-1) (7-OH flavanone) and a high of 0.024 mg ml(-1) (didymin). An excellent linear response was observed over the range specified for all analytes, as confirmed by the correlation coefficient with ranged from 0.9982 and 0.9999. The intra-day R.S.D.% ranged from 0.11 to 3.64%. The intermediate precision R.S.D.% were not higher than 7.62%. The accuracy of the method was confirmed with an average recovery ranging, except for neoeriocitrin, between 88.07% and 102.45%. Since the extraction conditions can affect analyte recovery, a suitable optimization strategy of the procedure was needed. The experimental parameters optimized were extraction time, temperature, and solvents. A multivariate approach was used to provide direct evaluation of the selected variables and related interactions. The D-optimal design was constructed by applying the exchange algorithm. All experimental results were computed by NEMROD-W software. This methodology led us to obtain the best recovery for all the flavonoids in the least number of experiments.

An experimental design methodology applied to the enantioseparation of a non-steroidal anti-inflammatory drug candidate

An experimental design methodology has been applied to the enantioseparation of a new synthesized aryl propionic acid of pharmaceutical interest, namely 2-[(4'-benzoyloxy-2'-hydroxy)phenyl-propionic acid] (DF-1770y) by chiral capillary zone electrophoresis (CCZE). The chiral separation of the studied compound has been achieved employing vancomycin as the chiral selector. The partial filling-counter current method has been used in order to avoid the presence of the absorbing chiral selector in the path length of the detector and to increase the method sensitivity. A central composite design has been employed to optimize the experimental conditions for a fast separation of the enantiomers of the new synthesized aryl propionic acid. Critical parameters such as chiral selector concentration, pH and temperature have been studied to evaluate how they affected responses such as resolution and migration times. The desirability function approach has been employed in order to find the best compromise between the different experimental responses. The proposed CCZE method provided the baseline enantioseparation of the investigated drug. A Britton-Robinson buffer at pH 6.4 supplemented with 7 mM of vancomycin at 22 degrees C and -20 kV were the optimum experimental conditions allowing to achieve the highest enantioresolution of DF-1770y in less than 8.5 min.

Validation of a LC method for the analysis of oxaliplatin in a pharmaceutical formulation using an experimental design

A rapid and sensitive RP-HPLC method with UV detection for routine control of oxaliplatin in a pharmaceutical formulation (Eloxatin) was developed. Quantitation was accomplished with the internal standard method. The procedure was validated by linearity (correlation coefficient=0.999948), accuracy, robustness and intermediate precision. Experimental design was used during validation to calculate method robustness and intermediate precision. For robustness test three factors were considered: percentage v/v of acetonitrile, flow rate and temperature; an increase in the flow rate results in a decrease of the drug found concentration, while the percentage of organic modifier and temperature have no important effect on the response. For intermediate precision measure the considered variables were: analyst, equipment and days. The RSD value (2.27%, n=24) indicated a good precision of the analytical method.

Spontaneous reporting of adverse drug reactions in elderly patients in Sicily (Italy)

The aim of this study was to investigate the spontaneous reports of suspected adverse drug reactions, observed in elderly patients (over 65 years of age) in Sicily (Italy) during the period from 1 January 1995 to 31 December 1997. Of 1307 reports, the geriatric ADRs were 284 (21.7%); 92 (32.4%) of these were serious. There was a correlation between the reporting rates of ADRs and the increase of age. Similar trends are seen in the number of serious ADR reports. Old-older patients result most frequently affected by serious ADRs. The antimicrobial and musculo-skeletal drugs were responsible for 48. 3% of the whole suspected geriatric ADRs. The commonest ADRs reported for the elderly, affected skin and the gastrointestinal system. There was probably a correlation between multi-drug consumption, comorbidity and seriousness of ADRs. A higher percentage of serious ADRs originated from university hospitals (57. 1%).

[Infectious diseases in general practice and antibiotic prescription. Observational study in Sicily]

Drug utilisation studies have shown wide differences, among different countries, in the prescribing behaviour in general practice. In Italy, for instance, the choice of antibiotic prescription seems to show a wider use of parental antibiotic. Aim of this study was to describe antibiotic prescribing pattern and therapeutic doses used by Sicilian general practitioners (GPs) and evaluate their prescribing attitudes regarding the use of parental ones. Each practitioner had to fill a questionnaire for each therapeutic intervention ended with an antibiotic prescription during a period of 6 months. Diagnosis and drugs were classified according to the International Classification of Diseases (ICD-10) and to Anatomical Therapeutic Chemical Classification (ATC), respectively. On 9395 prescriptions performed by 76 doctors of 25 Sicilian towns, the analysis indicated that acute respiratory symptoms represent the commonest indication (31.7%) for a medical consultation, and that Macrolides [such as azithromycin (8.8%) and clarithromycin (8.3%)], Penicillin [such as amoxycillin (7.1%%) and co-amoxiclav (8.4%)], III generation of Cephalosporins [such as cefixime (5.5%) and ceftriaxone (5.1%)] represent the most common used therapeutic groups. The choice of the route of administration was influenced by age of the patients and, more significantly, by symptoms and signs of the disease, rather than by bacteria suspected to cause the disease. In conclusion, our data clearly indicate lack of knowledge of antibacterial therapy guidelines among GPs in Sicily, as well as the need of an independent educational training in order to improve knowledge of antibiotics and to decrease the cost of the health care.