Neuroendocrine responses to experimentally-induced psychological stress in healthy humans

Previous studies of hormonal and neurophysiological changes in response to psychological stress in humans have produced contrasting findings due to differing experimental procedures and consistent individual variability. Habituation effects, which influence physiological coping in response to exposure to repeated stress, need to be investigated more extensively. In the present study, twenty healthy male subjects were each exposed twice to the same psychosocial stressor (Stroop Color Word Interference task, public speaking and mental arithmetic in front of an audience) during a first session (day 1) and a second session (day 8). Plasma concentrations of norepinephrine (NE), epinephrine (EPI), adrenocorticotropic hormone (ACTH), cortisol (CORT) and prolactin (PRL) were measured immediately before the beginning of the tests and at their end, 30 min later, on both experimental days. For the total group, NE, EPI, ACTH, and CORT levels were significantly elevated, and PRL levels were significantly decreased, after stress exposure on day 1. ACTH and CORT levels showed less significant increases after stress on day 8. In contrast, NE and EPI responses to stress were not significantly blunted, and PRL response was unchanged on day 8. Cluster analysis revealed two groups of subjects who showed different habituation patterns for ACTH and CORT. The first group (n=12) of subjects showed a reduction of ACTH and CORT responses to stress on day 8. The subjects of the second group (n=8) displayed a significant increase of ACTH and cortisol in response to stress on day 8, without any habituation effect. These results increase the evidence concerning the involvement of the HPA axis and catecholamines in response to psychological stress, and suggest that possible individual differences in the neuroendocrine coping mechanisms may affect mood regulation and the state of health.

Determination of catecholamines in human plasma by high-performance liquid chromatography with electrochemical detection

In the present study, assays were improved for the determination of catecholamines in human plasma. High-performance liquid chromatography with electrochemical detection was employed for quantitative analysis. The influence of various parameters on chromatographic performance, such as the composition and the pH of the mobile phase, and the detection potential, was investigated. An accurate solid-phase extraction procedure, after catecholamine complexation with diphenylborate, was developed. The efficiency yield for all catecholamines was in the range 92-98%. Relative standard deviation values for repeatability and for intermediate precision were less than 2% and 3%, respectively, for all three analytes.

Vitamin C content and antioxidant activity of the fruit and of the Ayurvedic preparation of Emblica officinalis Gaertn

Emblica officinalis Gaertn. is one of the most important plants of Ayurved, the traditional Indian medicine. In this ancient medicine, the fruit of Emblica officinalis is processed according to a method named "Svaras Bhavana", whereby the therapeutic potential of the plant is enhanced by treating the main herb with its own juice. For many years, the activity of the fruits was attributed to the high content of ascorbic acid; however, this has recently been questioned. The aim of the paper is to clarify this matter. A reliable and feasible HPLC method with diode array detection has been developed for the determination of ascorbic acid in Emblica fruit and particularly in Emblica fruit processed according to the Ayurvedic method. The antioxidant effects have also been evaluated in comparison to the real levels of Vitamin C by different antioxidant tests. The data obtained show that the Emblica fruit contains ascorbic acid (0.4%, w/w), and that the Ayurvedic method of processing increases the healthy characteristics of the fruit thanks to a higher antioxidant activity and a higher content of ascorbic acid (1.28%, w/w). It has also been found that Vitamin C accounts for approximately 45-70% of the antioxidant activity.

Fluoxetine Metabolism and Pharmacological Interactions: The Role of Cytochrome P450

A review with 103 references. Fluoxetine is the parent drug of the SSRI (selective serotonin reuptake inhibitor) antidepressant class, and is still one of the most highly used drugs of this class world-wide. Fluoxetine now has largely (albeit not completely) substituted older and less safe drugs such as tricyclic antidepressants. Different cytochrome P450 isoforms are involved in the metabolism of fluoxetine, however, the main active metabolite, norfluoxetine, is produced by the CYP2D6 action in the human liver. In this paper, the main metabolic characteristics of fluoxetine will be reviewed, with particular attention paid to the role of cytochrome isozymes. The pharmacological interactions of the drug will be overviewed, especially those concerning other drugs used in psychiatric clinics, such as antipsychotics and antidepressants and the relationships between pharmacological interactions and cytochrome activity will be discussed. Recently, much attention has been drawn to the therapeutic drug monitoring (TDM) of fluoxetine, and in particular to the analysis of fluoxetine enantiomers for which enantiomeric separations and enantioselective metabolism will also briefly be mentioned.

Selective serotonin reuptake inhibitors (SSRIs): therapeutic drug monitoring and pharmacological interactions

New-generation antidepressants are a heterogeneous class of drugs used in the treatment of depression and related disorders. This review deals with the first new-generation antidepressant class to enter the pharmaceutical market, i.e., selective serotonin reuptake inhibitors (SSRIs), which are still the most prescribed and widely used ones. Their common characteristics are the comparable clinical efficacy, good tolerability and relative safety in comparison to "first generation antidepressants", i.e. classic tricyclic antidepressants and monoamine oxidase inhibitors. This class of drugs includes fluoxetine, citalopram, paroxetine, sertraline, fluvoxamine and, since 2011, vilazodone. In this review, the main pharmacodynamic and pharmacokinetic properties of the six commercially available SSRIs are described, focusing on side and toxic effects, chemical-clinical correlations, interactions with other drugs, the role of therapeutic drug monitoring (TDM) and related bioanalytical methodologies.

Quantitation of olanzapine in tablets by HPLC, CZE, derivative spectrometry and linear voltammetry

Four analytical methods have been developed for the quality control of pharmaceutical formulations containing the novel antipsychotic drug, olanzapine: high performance liquid chromatography (HPLC), capillary zone electrophoresis (CZE), derivative spectrometry and linear voltammetry. All methods require only a simple extraction procedure of olanzapine from the tablets before analysis. HPLC with ultraviolet detection at 260 nm is carried out with a C8 column and a mobile phase constituted of acetonitrile and aqueous tetramethylammonium perchlorate. CZE is performed in an uncoated capillary with phosphate buffer, pH 3.0, as the background electrolyte, with UV detection at 214 nm. Spectrophotometry uses the derivative of the spectrum at 298 nm. In linear voltammetric method (LSV) the current intensity of the oxidation wave at +495 mV is measured. All methods gave similar results in terms of precision and accuracy. For HPLC and CZE, repeatability and intermediate precision, expressed by the RSD was better than 1.8%. The accuracy, resulting from recovery experiments, was between 99.9 and 101.1%. Spectrometry and voltammetry gave slightly higher RSD values (up to 2.9%) and a larger variation of the accuracy (the recovery was between 97.8 and 102.6%). However, the requirements for quantitative analysis are fulfilled for all methods.

Enantiomeric separation of fluoxetine and norfluoxetine in plasma and serum samples with high detection sensitivity capillary electrophoresis

A capillary electrophoresis method was optimized for the stereoselective analysis of the antidepressant drug fluoxetine and its main demethylated metabolite norfluoxetine using a cyclodextrin-modified sodium phosphate buffer at pH 2.5. The combination of a neutral and a negatively charged cyclodextrin, dimethylated-beta- and phosphated-gamma-respectively, provided the baseline enantiomeric separation of the two compounds. The very low concentrations of chiral selectors employed together with the use of a high sensitivity detection cell of special design (zeta-shaped) in a diode array UV detector allowed us to reach a limit of detection of 0.005 and 0.01 microg/mL for fluoxetine and norfluoxetine, respectively. Analysis of fluoxetine and norfluoxetine standard mixtures showed a reproducibility of migration times and peak area and linearity in the concentration range of 0.1-2.0 microg/mL. The optimized method was applied to the analysis of clinical serum and plasma samples of patients under depression therapy. In all the analyzed samples the enantiomeric forms of fluoxetine and norfluoxetine were easily identified. The fluoxetine and metabolite enantiomeric ratio confirmed the stereoselectivity of the metabolic process of the fluoxetine drug in accordance with the literature data.

Spectrophotometric determination of glutathione and of its oxidation product in pharmaceutical dosage forms

A simple and sensitive spectrophotometric method suitable for the stability control of pharmaceutical dosage forms containing glutathione (gamma-glutamyl-cysteinyl-glycine), GSH, is described. Besides GSH, the method quantitatively determines its oxidation product, GSSG. The colour reactions of GSH and GSSG with ammonium tetrachloropalladate have been investigated and the optimum reaction conditions, spectral characteristics and composition of the yellow water-soluble complexes have been established. The assay results of pharmaceutical formulations showed good accuracy and precision over the concentration range of 5 x 10(-5)-6 x 10(-4) M GSH.

Effects of prolonged ingestion of graded doses of licorice by healthy volunteers

Licorice can induce a hypermineralocorticoid syndrome. Current literature usually refers to the effects of sweets containing glycyrrhizin, but little is known about the consequences of a prolonged intake of "pure licorice". We administered graded daily doses of dried, aqueous extract of licorice root, containing 108, 217, 380 and 814 mg of glycyrrhizin, to 4 groups of 6 healthy volunteers of both sexes for 4 weeks. No significant effects occurred in groups 1 and 2. After 2 weeks, side effects leading to withdrawal from the protocol occurred in a female in group 3 (headache), a male with a family history of hypertension in group 4 (arterial hypertension), and a female also taking oral contraceptives in group 4 (hypertension, hypokalaemia and peripheral edema). In group 4, transient reduction in kalaemia and increase in body weight were found after 1 and 2 weeks, respectively. A depression of plasma renin activity occurred in groups 3 and 4. In healthy subjects, only the highest doses of licorice led to untoward effects. These were favoured by subclinical disease or oral contraceptives, and were less common and pronounced than what has been reported after the intake of glycyrrhizin taken as such or as a flavouring agent in confectionery products.

Childhood neglect and parental care perception in cocaine addicts: relation with psychiatric symptoms and biological correlates

Childhood neglect and poor child-parent relationships have been reported to increase substance use disorders susceptibility. Stressful environmental factors, including emotional neglect, could affect individual personality traits and mental health, possibly inducing stable changes in hypothalamic-pituitary-adrenal (HPA) axis and brain mono-amine function, in turn involved in addictive behavior vulnerability. Therefore, we decided to investigate homovanillic (HVA) and prolactin (PRL) plasma levels, as expression of possible changes in dopamine function, ACTH and cortisol plasma levels, as measures of HPA axis function, and concomitant psychiatric symptoms profile in abstinent cocaine addicts, in relationship to their childhood history of neglect and poor parental care perception.

METHODS

Fifty abstinent cocaine dependent patients, and 44 normal controls, matched for age and sex, were submitted to a detailed psychiatric assessment (DSM IV criteria). All patients and controls completed the Symptoms Check List-90 (SCL-90) and the Buss Durkee Hostility Inventory (BDHI), to evaluate psychiatric symptoms frequency and aggressiveness levels. The Childhood Experience of Care and Abuse-Questionnaire (CECA-Q) and Parental Bonding Instrument (PBI) have been used to retrospectively investigate parent-child relationships. Blood samples were collected to determine HVA, PRL, ACTH and cortisol basal plasma levels.

RESULTS

Cocaine addicted individuals in general showed significantly lower HVA, and higher PRL, ACTH and cortisol basal levels respect to controls. In particular, neuroendocrine changes characterized cocaine addicts with childhood history of neglect and low perception of parental care. Obsessive-compulsive, depression and aggressiveness symptoms have been found related to poor parenting, inversely associated to HVA levels and directly associated to PRL, ACTH and cortisol levels.

CONCLUSIONS

These findings suggest the possibility that childhood experience of neglect and poor parent-child attachment may partially contribute to a complex neurobiological derangement including HPA axis and dopamine system dysfunctions, playing a crucial role in addictive and affective disorders susceptibility.

Experimentally induced aggressive behavior in subjects with 3,4-methylenedioxy-methamphetamine ("Ecstasy") use history: psychobiological correlates

PURPOSE

Objective measures of experimentally induced aggressiveness were evaluated in 12 male 3,4-methylenedioxy-methamphetamine (MDMA, "Ecstasy") users, in comparison with 20 healthy male subjects.

METHODS

All the subjects were preliminarily submitted to DSM-IV interviews and Buss-Durkee Hostility Inventory (BDHI). During a laboratory task, the Point Subtraction Aggression Paradigm (PSAP), subjects earned monetary reinforcers with repeated button presses, and were provoked by the subtraction of money that was attributed to a fictitious other participant. Subjects could respond by ostensibly subtracting money from the fictitious subject (the aggressive response). Escape responses were also possible protecting the counter from monetary subtractions.

RESULTS

Money-earning responses were not different in Ecstasy users and controls; aggressive responses were significantly higher in Ecstasy users in comparison with control subjects (F=20.74, P<.001). Baseline adrenocorticotropic hormone (ACTH) and cortisol (CORT) levels were higher in Ecstasy users than in controls. No difference was found in norepinephrine (NE) and epinephrine (EPI) basal levels of the two groups. During the experimentally induced aggressiveness, plasma ACTH concentrations increased significantly less and NE and EPI levels, together with heart rate (HR), increased significantly more in Ecstasy users than in healthy subjects. Despite ACTH-blunted responses, CORT did not increase differently from controls in Ecstasy users. PSAP aggressive responses positively correlated with catecholamines and CORT changes, BDHI Direct Aggression and Irritability scores, both in Ecstasy users and controls. A significant correlation was found between Ecstasy exposure extent and aggressive responses (r=.78, P<.001).

IMPLICATIONS

Our findings suggest that Ecstasy users have higher outward-directed aggressiveness than healthy subjects. Aggressiveness in MDMA subjects seems to be associated more with MDMA pharmacological effects than with personality traits: Nevertheless, a premorbid psychobiological proneness to aggressive behavior cannot be excluded. Increased catecholamines reactivity, basal hypothalamus-pituitary-adrenal (HPA) axis hyperactivity, and blunted ACTH responses could be due to MDMA action on monoaminergic pathways and adrenal function.

Interaction of licorice on glycyrrhizin pharmacokinetics

The effects of components of aqueous licorice root extract (LE) on the pharmacokinetics of glycyrrhizin (G) and glycyrrhetic acid (GA) were investigated in rats and humans. The aim of this work was to define the role of pharmacokinetics in G toxicity. In the procedure, G and GA were detected in biological fluids by means of recently improved HPLC methods. Significantly lower G and GA plasma levels were found in rats and humans treated with LE compared to the levels obtained with those in which G alone was administered. The pharmacokinetic curves showed significant differences in the areas under the plasma-time curve (AUC), Cmax, and Tmax parameters. The data obtained from urine samples are in agreement with the above results and confirm a reduced bioavailability of G present in LE compared to pure G. This should be attributed to the interaction during intestinal absorption between the G constituent and the several components in LE. The modified bioavailability could explain the various clinical adverse effects resulting from the chronic oral administration of G alone as opposed to LE.

Neuroendocrine responses to experimentally-induced emotions among abstinent opioid-dependent subjects

The present study investigated neuroendocrine and cardiovascular changes during experimentally-induced affective states in abstinent heroin-dependent subjects and healthy controls. The procedure for eliciting emotions in all subjects used pleasant and unpleasant stimuli that did not differ in subjective arousal properties. We investigated whether the valence of the stimuli differentially affected neuroendocrine responses by comparing neutral, pleasant and unpleasant pictures on heart rate (HR), systolic (SBP) and diastolic blood pressure (DBP), methyl-OH-phenyl-glycol (MHPG), norepinephrine (NE), epinephrine (EPI), adrenocorticotrophic hormone (ACTH) and cortisol (CORT) plasma levels. Twelve abstinent heroin-dependent subjects, in comparison with 12 control subjects, were submitted to three experimental sessions, each on one of three experimental days a week apart, in counterbalanced order: day 1=unpleasant pictures, day 2=pleasant pictures, day 3=neutral pictures. In the rating of subjective arousal pleasant and unpleasant stimuli received the same high score in comparison with neutral stimuli; a different cardiovascular and neuroendocrine pattern was obtained in healthy subjects: unpleasant stimuli elicited increases in HR, SBP, MHPG, NE, ACTH, CORT, whereas neutral and pleasant stimuli did not induce any significant response in hormonal levels. In contrast, in heroin addicts, despite increased perceptions of unpleasantness, HR, SBP, MHPG and NE levels did not increase after disliked stimuli; these subjects also reported increased arousal during exposure to neutral stimuli. In comparison with controls, addicted individuals showed higher CORT and ACTH basal levels, and a consequent lack of response to unpleasant stimuli. The results indicate that neuroendocrine and cardiovascular systems respond selectively to affective, motivationally relevant stimuli, and that substance use disorders may be associated with dysregulation of emotion-processing mechanisms.

Enantiomeric separation of citalopram and its metabolites by capillary electrophoresis

A simple and fast capillary electrophoretic method has been developed for the enantioselective separation of citalopram and its main metabolites, namely N-desmethylcitalopram and N,N-didesmethylcitalopram, using beta-cyclodextrin (beta-CD) sulfate as the chiral selector. For method optimisation several parameters were investigated, such as CD and buffer concentration, buffer pH, and capillary temperature. Baseline enantioseparation of the racemic compounds was achieved in less than 6 min using a fused-silica capillary, filled with a background electrolyte consisting of a 35 mM phosphate buffer at pH 2.5 supplemented with 1% w/v beta-CD sulfate and 0.05% w/v beta-CD at 25 degrees C and applying a voltage of -20 kV. A fast separation method for citalopram was also optimized and applied to the analysis of pharmaceutical formulations. Racemic citalopram was resolved in its enantiomers in less than 1.5 min using short-end injection (8.5 cm, effective length) running the experiments in a background electrolyte composed of a 25 mM citrate buffer at pH 5.5 and 0.04% w/v beta-CD sulfate at a temperature of 10 degrees C.

Liquid chromatographic determination of oxcarbazepine and its metabolites in plasma of epileptic patients after solid-phase extraction

A method based on high-performance liquid chromatography with UV detection in combination with solid-phase extraction for sample pretreatment has been developed for the simultaneous analysis of the antiepileptic drug oxcarbazepine and its main metabolites in human plasma. The extraction of the analytes from plasma samples was carried out by means of a selective solid-phase extraction procedure using hydrophilic-lipophilic balance cartridges. The separation was obtained on a reversed-phase column (C(18), 150x4.6 mm I.D., 5 micrometer) using a phosphate buffer-acetonitrile-methanol-triethylamine mixture (final apparent pH* 3.5) as the mobile phase. Under these chromatographic conditions, oxcarbazepine and its metabolites 10,11-dihydro-10-hydroxycarbamazepine, 10,11-dihydro-10,11-dihydroxycarbamazepine and the internal standard are baseline separated in less than 9 min. The extraction yield values were >94% for all analytes and the precision, expressed by the RSD%, was in the low percentage range. For the entire method, including sample pre-treatment and HPLC determination, the linearity of the calibration lines, expressed by the linear correlation coefficient, was better than 0.995; the limit of quantitation was 15 ng ml(-1). The method was applied to plasma samples from patients undergoing chronic treatment with oxcarbazepine, both in monotherapy and in polytherapy. Based on the analytical parameters precision, accuracy, limit of quantitation and analysis time the method is suitable for routine application in therapeutic drug monitoring.

A sensitive high-performance liquid chromatographic method using electrochemical detection for the analysis of olanzapine and desmethylolanzapine in plasma of schizophrenic patients using a new solid-phase extraction procedure

A high-performance liquid chromatographic method with amperometric detection for the analysis of the novel antipsychotic drug olanzapine and its metabolite desmethylolanzapine in human plasma has been developed. The analysis was carried out on a reversed-phase column (C8, 150 x 4.6 mm I.D., 5 microm) using acetonitrile-phosphate buffer, pH 3.8, as the mobile phase. The detection voltage was + 800 mV and the cell and column temperature was 30 degrees C. The flow-rate was 1.2 ml min(-1). Linear responses were obtained between 5 and 150 ng ml(-1), with repeatability <3.3%. A careful pretreatment of the biological samples was implemented by means of solid-phase extraction (SPE) on C8 cartridges. The method requires 500 microl of plasma for one complete analysis. Absolute recovery exceeded 97% for both olanzapine and desmethylolanzapine, and the detection limit was 1 ng ml(-1) for both analytes. Repeatability, intermediate precision and accuracy were satisfactory. This sensitive and selective method has been successfully applied to therapeutic drug monitoring in schizophrenic patients treated with Zyprexa tablets.

HPLC analysis of the novel antipsychotic drug quetiapine in human plasma

A precise and feasible high-performance liquid chromatographic (HPLC) method for the analysis of the novel antipsychotic drug quetiapine in plasma has been developed. The analysis was carried out on a C8 (150x4.6 mm i.d., 5 micrometer) reversed-phase column, using a mixture of acetonitrile, methanol and pH 1.9 phosphate buffer as the mobile phase; triprolidine was used as the internal standard. Careful pretreatment of the biological samples was implemented by means of solid-phase extraction (SPE). A good linearity was found in the 4-400 ng ml(-1) quetiapine plasma concentration range. The application to some plasma samples of patients treated with Seroquel(R) tablets gave satisfactory results. The accuracy was good (quetiapine mean recovery=92%), as well as the precision (mean RSD=3.3%). The method seems to be suitable for the clinical monitoring of patients treated with quetiapine.

Therapeutic drug monitoring: chemical-clinical correlations of atypical antipsychotic drugs

In the last few years, new drugs for the treatment of schizophrenia have been introduced in therapy which have noticeably improved the quality of life of many schizophrenic patients. These new "atypical" drugs have chemical, pharmacological and clinical properties which are different from those of the classical neuroleptics. The most used drugs among the "atypical" antipsychotics are clozapine, olanzapine, quetiapine and risperidone. Despite several differences in their pharmacokinetic and pharmacodynamic profiles, they show some common properties: e.g. they don't cause extrapyramidal side effects, and they are active against the negative as well as positive symptoms of schizophrenia. The need for clinical monitoring of patients undergoing therapy is still evident because the onset of side effects is often related to high plasma concentrations of the drug. The clinical monitoring of patients can significantly improve the knowledge of pharmacological interactions among different CNS drugs, as well as enhance the compliance of the patients, thus leading to higher treatment efficacy. In order to carry out efficient clinical monitoring, reliable analytical methods are needed to determine the analytes even at very low concentrations and in the presence of other drugs. For this purpose, analytical techniques such as gas or liquid chromatography are often used coupled with sensitive and selective means of detection, such as fluorimetric, electrochemical or mass spectrometry detectors. The most recent studies on the determination of atypical antipsychotics will be reviewed in addition to the issue of sample pretreatment which is a critical step when the analysis of biological fluids is concerned.

Aggressive responding of male heroin addicts under methadone treatment: psychometric and neuroendocrine correlates

Objective measures of experimentally-induced aggressiveness were evaluated in 20 methadone-treated heroin addicts, in comparison to 20 normal healthy male subjects. All the subjects were submitted to preliminary DSM IV interviews, Buss Durkee Hostility Inventory (BDHI) and Minnesota Multiphasic Personality Inventory (MMPI II). During a laboratory task, the point subtraction aggression paradigm (PSAP), subjects earned monetary reinforcers with repeated button presses, and were provoked by the subtraction of money, which was attributed to a fictitious other participants. Subjects could respond by ostensibly subtracting money from the fictitious subject (the aggressive response), or protecting their counter (escape response). Money-earning responses were significantly lower (t=4.38, P<0.001) and aggressive responses significantly higher (t=5.45; P<0.001) in methadone patients in comparison to controls. During the experimentally-induced aggressiveness, plasma adrenocorticotropic hormone (ACTH), cortisol (CORT) and growth hormone (GH) concentrations increased significantly less and norepinephrine (NE) and epinephrine (EPI) levels, together with heart rate (HR), significantly more in methadone subjects than in healthy subjects. PSAP aggressive responses positively correlated with catecholamines changes, BDHI 'direct' and 'irritability' scores, MMPI 'psychopathic deviate' scores both in methadone subjects and controls, and with CORT responses only in healthy subjects. No correlation was found between methadone doses, or exposure extent, and aggressiveness levels. Our findings suggest that heroin dependent patients have higher outward-directed aggressiveness than healthy subjects, in relationship with monoamines hyper-reactivity, also under methadone medication. Aggressiveness in methadone patients seems to be related more to the personality traits than to drug effects. Hypothalamus-pituitary-adrenal (HPA) axis responses, unexpectedly dissociated from catecholamines rise among methadone patients, could be due to a long-lasting inhibitory action exerted by opiates on pro-opio-melanocortin (POMC), or to a premorbid psychobiological condition that exhausted hormonal reactivity.

Rapid methods for determination of fluoxetine in pharmaceutical formulations

Two different analytical methods for the quality control of fluoxetine in commercial formulations have been developed and compared: a spectrofluorimetric method and a capillary zone electrophoretic (CZE) method. The fluorescence emission values were measured at lambda=293 nm when exciting at lambda=230 nm. The CZE method used an uncoated fused-silica capillary and pH 2.5 phosphate buffer as the background electrolyte. The extraction of fluoxetine from the capsules consisted of a simple one-step dissolution with methanol/water, filtration and dilution. Both methods gave satisfactory results in terms of precision; the best results were obtained for the electrophoretic method, with RSD% values always lower than 2.0%. The accuracy was assessed by means of recovery studies, which gave very good results, between 97.5 and 102.6%. Furthermore, both methods also have the advantage of being very rapid.

Colorimetric determination of acetylcysteine, penicillamine, and mercaptopropionylglycine in pharmaceutical dosage forms

A colorimetric determination of acetylcysteine, penicillamine, and mercaptopropionylglycine is described. The method is based on the oxidation of mercapto-compounds with iron(III) in the presence of 1,10-phenanthroline. The iron(II) formed was quantitatively and rapidly converted to the stable tris(1,10-phenanthroline)iron(II) complex measured spectrophotometrically at 515 nm. The results obtained from various commercial formulations indicate that the method proposed allows a simple, sensitive determination of these mercapto-drugs with good accuracy (99.5-101% recovery) and remarkable precision (RSD +/- 0.6-1.6%).

Determination of fluoxetine and norfluoxetine in human plasma by high-pressure liquid chromatography with fluorescence detection

Fluoxetine is an atypical antidepressant drug, which selectively inhibits the neuronal reuptake of serotonin, and is widely used in the treatment of depressive disorders. The aim of this research is the development of an HPLC method with fluorescence detection for the monitoring of fluoxetine plasma levels. The determination requires no more than 250 microl of plasma, which undergo solid phase extraction (SPE), then are injected in the HPLC. For the analytical separation a reversed phase C8 column (150 x 4.6 mm I.D.) was used, while the mobile phase was a mixture of acetonitrile and water containing perchloric acid and tetramethylammonium perchlorate (flow rate: 1 ml min(-1)). The very low levels of analytes in plasma required the employment of a fluorescence detector (lambda(exc) = 230 nm, lambda(em)=290 nm), which also granted a good selectivity. Fluoxetine is revealed as a single peak at a retention time of 9.7 min, while norfluoxetine, the main metabolite of fluoxetine, is revealed at a retention time of 8.1 min. Linearity was obtained over the concentration range 8-200 ng ml(-1) for both substances. The method seems suitable, in accuracy and precision, for the determination of fluoxetine plasma levels of patients; furthermore, it is rapid and sensitive.

Advances in the enantioseparation of second-generation antidepressant drugs by electrodriven methods

Stereochemistry is steadily increasing in importance in the development of new drugs, and the availability of pure enantiomer drugs can make therapy safer and more efficacious. In particular, almost all second-generation antidepressant drugs possess one or more chiral centres; however, only some of them are administered as single enantiomers. A fundamental part of the quality control of pharmaceutical formulations is the determination of enantiomeric excess and enantiomeric purity; this is also important for the therapeutic drug monitoring of depressed patients. For this purpose, efficient and reliable analytical methods are needed and electrodriven techniques (most of all CE, CEC and MEKC) are very efficient and inexpensive candidates for the role. In this review, the enantioselective electrodriven methods available for the analysis of second-generation antidepressant are presented and discussed. In particular, the following pharmacological classes of antidepressants will be considered: selective serotonin reuptake inhibitors (fluoxetine, citalopram, paroxetine, sertraline); norepinephrine reuptake inhibitors (reboxetine); serotonin and norepinephrine reuptake inhibitors (venlafaxine, milnacipran, duloxetine); and noradrenergic and specific serotonergic antidepressants (mirtazapine).

Separation of eleven central nervous system drugs by capillary zone electrophoresis

Several strategies to improve the separation of 11 central nervous system drugs (antipsychotics and antidepressants) with capillary zone electrophoresis were applied: the variation of the pH of the buffering background electrolyte, its ionic strength, addition of inclusion-complex forming beta-cyclodextrin or polyvinylpyrrolidone (PVP), respectively, as a replaceable, soluble, polymeric pseudo-stationary phase. Best separation was achieved at pH 2.5 and 35 mmol/l ionic strength (phosphate buffer), with 0.5% (w/v) PVP.