Plasma amisulpride levels in schizophrenia or schizoaffective disorder

Therapeutic Drug Monitoring in Psychiatry: Enhancing Treatment Precision and Patient Outcomes

Psychiatric disorders often require pharmacological interventions to alleviate symptoms and improve quality of life. However, achieving an optimal therapeutic outcome is challenging due to several factors, including variability in the individual response, inter-individual differences in drug metabolism, and drug interactions in polytherapy. Therapeutic drug monitoring (TDM), by measuring drug concentrations in biological samples, represents a valuable tool to address these challenges, by tailoring medication regimens to each individual. This review analyzes the current landscape of TDM in psychiatric practice, highlighting its significance in optimizing drug dosages, minimizing adverse effects, and improving therapeutic efficacy. The metabolism of psychiatric medications (i.e., mood stabilizers, antipsychotics, antidepressants) often exhibits significant inter-patient variability. TDM can help address this variability by enhancing treatment personalization, facilitating early suboptimal- or toxic-level detection, and allowing for timely interventions to prevent treatment failure or adverse effects. Furthermore, this review briefly discusses technological advancements and analytical methods supporting the implementation of TDM in psychiatric settings. These innovations enable quick and cost-effective drug concentration measurements, fostering the widespread adoption of TDM as a routine practice in psychiatric care. In conclusion, the integration of TDM in psychiatry can improve treatment outcomes by individualizing medication regimens within the so-called precision medicine.

Stereoselective Inhibition of High- and Low-Affinity Organic Cation Transporters

Many drugs have chiral centers and are therapeutically applied as racemates. Thus, the stereoselectivity in their interactions with membrane transporters needs to be addressed. Here, we studied stereoselectivity in inhibiting organic cation transporters (OCTs) 1, 2, and 3 and the high-affinity monoamine transporters (MATs) NET and SERT. Selectivity by the inhibition of 35 pairs of enantiomers significantly varied among the three closely related OCTs. OCT1 inhibition was nonselective in almost all cases, whereas OCT2 was stereoselectively inhibited by 45% of the analyzed drugs. However, the stereoselectivity of the OCT2 was only moderate with the highest selectivity observed for pramipexole. The (R)-enantiomer inhibited OCT2 4-fold more than the (S)-enantiomer. OCT3 showed the greatest stereoselectivity in its inhibition. (R)-Tolterodine and (S)-zolmitriptan inhibited OCT3 11-fold and 25-fold more than their respective counterparts. Interestingly, in most cases, the pharmacodynamically active enantiomer was also the stronger OCT inhibitor. In addition, stereoselectivity in the OCT inhibition appeared not to depend on the transported substrate. For high-affinity MATs, our data confirmed the stereoselective inhibition of NET and SERT by several antidepressants. However, the stereoselectivity measured here was generally lower than that reported in the literature. Unexpectedly, the high-affinity MATs were not significantly more stereoselectively inhibited than the polyspecific OCTs. Combining our in vitro OCT inhibition data with available stereoselective pharmacokinetic analyses revealed different risks of drug-drug interactions, especially at OCT2. For the tricyclic antidepressant doxepine, only the (E)-isomer showed an increased risk of drug-drug interactions according to guidelines from regulatory authorities for renal transporters. However, most chiral drugs show only minor stereoselectivity in the inhibition of OCTs in vitro, which is unlikely to translate into clinical consequences.

Age, Sex, and Comedication Effects on the Steady-State Plasma Concentrations of Amisulpride in Chinese Patients with Schizophrenia

BACKGROUND

Amisulpride, a second-generation atypical antipsychotic drug, was first marketed in Europe in the 1990s. This study aimed to provide a reference for the clinical application of amisulpride. The effects of age, sex, or specific comedications on amisulpride concentrations in Chinese patients with schizophrenia in the real world were investigated.

METHODS

A retrospective study was conducted of data on amisulpride based on the therapeutic drug monitoring service database at the Zigong Affiliated Hospital of Southwest Medical University.

RESULTS

Based on the inclusion criteria, 195 plasma samples from 173 patients (67.05% female and 32.95% male patients) were included for in-depth analysis. The median daily dose of amisulpride was 400 mg/d, median plasma concentration was 457.50 ng/mL, and median concentration/dose (C/D) ratio was 1.04 ng/mL/mg/d. The daily dose of amisulpride positively correlated with measured steady-state plasma concentrations. A significant difference was observed in the subgroup analysis of the combination with valproic acid, zopiclone, or aripiprazole on plasma concentrations. Combining amisulpride with these drugs increased the C/D ratios by 0.56-, 2.31-, and 0.77-fold, respectively. After adjusting for age, the median C/D ratio was found to be significantly different between female and male patients. However, no significant differences in daily dose, plasma concentration, and C/D ratio were noted with respect to sex and age of the patients.

CONCLUSIONS

Sex differences were inferred for the first time in this study, with differential effects on daily dose, steady-state plasma concentration, and C/D ratio associated with the population. In the included study samples, blood concentrations were distributed in the range of 223.25-823.55 ng/mL, which perhaps needs to be evaluated in line with the reference range of ammonia-sulfur ratios in the Chinese population.

Population pharmacokinetics of Amisulpride in Chinese patients with schizophrenia with external validation: the impact of renal function

Introduction: Amisulpride is primarily eliminated via the kidneys. Given the clear influence of renal clearance on plasma concentration, we aimed to explicitly examine the impact of renal function on amisulpride pharmacokinetics (PK) via population PK modelling and Monte Carlo simulations. Method: Plasma concentrations from 921 patients (776 in development and 145 in validation) were utilized. Results: Amisulpride PK could be described by a one-compartment model with linear elimination where estimated glomerular filtration rate, eGFR, had a significant influence on clearance. All PK parameters (estimate, RSE%) were precisely estimated: apparent volume of distribution (645 L, 18%), apparent clearance (60.5 L/h, 2%), absorption rate constant (0.106 h-1, 12%) and coefficient of renal function on clearance (0.817, 10%). No other significant covariate was found. The predictive performance of the model was externally validated. Covariate analysis showed an inverse relationship between eGFR and exposure, where subjects with eGFR= 30 mL/min/1.73 m2 had more than 2-fold increase in AUC, trough and peak concentration. Simulation results further illustrated that, given a dose of 800 mg, plasma concentrations of all patients with renal impairment would exceed 640 ng/mL. Discussion: Our work demonstrated the importance of renal function in amisulpride dose adjustment and provided a quantitative framework to guide individualized dosing for Chinese patients with schizophrenia.

A 5-year retrospective study of amisulpride steady-state plasma concentration in patients with schizophrenia in real-life settings based on therapeutic drug monitoring data

OBJECTIVE

Here, we present a retrospective analysis of the last 5 years' data collected in real-life settings as direct evidence to evaluate the optimal therapeutic window of amisulpride (AMI) for psychiatric patients.

METHODS

Retrospective analysis of the therapeutic drug monitoring (TDM) results of AMI in outpatients and inpatients were obtained from the Xi'an Mental Health Center from 2017 to 2021.

RESULTS

The interquartile (P25-P75) AMI concentrations ranged 212.20-574.25 ng/mL. The results showed that the proportion of outpatients who received TDM once was significantly higher than that of inpatients who received TDM once (P < 0.001), whereas the reverse was true for those who experienced TDM more than twice (P < 0.001). Higher estimated plasma concentrations were identified in inpatients, female patients, and patients over 59 years of age. Nearly 57.21% of the samples had high concentrations (>320 ng/mL).

CONCLUSIONS

The optimal therapeutic reference range for AMI may require reconstruction to guide the use of AMI for the treatment of schizophrenia.

Amisulpride steady-state plasma concentration and adverse reactions in patients with schizophrenia: a study based on therapeutic drug monitoring data

The aim of the study was to evaluate the reference range of amisulpride for Chinese patients with schizophrenia and to assess its possible influencing factors based on therapeutic drug monitoring information. The relative adverse reactions of patients induced by amisulpride were also systematically investigated. A total of 425 patients with schizophrenia were assessed, including Positive and Negative Syndrome Scales, Treatment Emergent Symptom Scale, blood routine examination, hepatorenal function, lipids, hormones, as well as myocardial enzymes at baseline, and following treatment with amisulpride for 8 weeks. The steady-state plasma concentration of amisulpride was assayed using two-dimensional liquid chromatography. At the same dose, the amisulpride plasma concentration of patients combined with clozapine was higher than that without clozapine. The therapeutic reference range of amisulpride can be defined as 230.3-527.1 ng/ml for Chinese patients with schizophrenia. The potential side effects appear to be associated with significantly increased levels of LDH, CK, creatine kinase isoenzyme (CK-MB), TC and decreased level of E 2 , relative to the amisulpride plasma concentration. These findings could provide individualized medication and reduce the adverse effects of amisulpride for Chinese patients with schizophrenia.

Modeling and Simulation for Individualized Therapy of Amisulpride in Chinese Patients with Schizophrenia: Focus on Interindividual Variability, Therapeutic Reference Range and the Laboratory Alert Level

Purpose

To explain the high inter-individual variability (IIV) and the frequency of exceeding the therapeutic reference range and the laboratory alert level of amisulpride, a population pharmacokinetic (PPK) model in Chinese patients with schizophrenia was built based on therapeutic drug monitoring (TDM) data to guide individualized therapy.

Patients and Methods

Plasma concentration data (330 measurements from 121 patients) were analyzed using a nonlinear mixed-effects modeling (NONMEM) approach with first-order conditional estimation with interaction (FOCE I). The concentrations of amisulpride were detected by HPLC-MS/MS. Age, weight, sex, combination medication history and renal function status were evaluated as main covariates. The model was internally validated using goodness-of-fit, bootstrap and normalized prediction distribution error (NPDE). Recommended dosage regimens for patients with key covariates were estimated on the basis of Monte Carlo simulations and the established model.

Results

A one-compartment model with first-order absorption and elimination was found to adequately characterize amisulpride concentration in Chinese patients with schizophrenia. The population estimates of the apparent volume of distribution (V/F) and apparent clearance (CL/F) were 12.7 L and 1.12 L/h, respectively. Age significantly affected the clearance of amisulpride and the final model was as follows: CL/F=1.04×(AGE/32)^−0.624 (L/h). To avoid exceeding the laboratory alert level (640 ng/mL), the model-based simulation results showed that the recommended dose of amisulpride was no more than 600 mg/d for patients aged 60 years, 800 mg/d for those aged 40 years and 1200 mg/d for those aged 20 years, respectively.

Conclusion

Dosage optimization of amisulpride can be carried out according to age to reduce the risk of adverse reactions. The model can be used as a suitable tool for designing individualized therapy for Chinese patients with schizophrenia.

Transitory restless arms syndrome in a patient with antipsychotics and antidepressants: a case report

BACKGROUND

Restless arms syndrome (RAS) is characterized by uncomfortable aching or burning sensations in the arms. RAS is regarded as an upper limb variant of restless legs syndrome (RLS). The lack of specific diagnostic criteria makes it difficult to recognize the RAS. Therefore, RAS is usually neglected in clinical practice. Moreover, when a patient was diagnosed with RAS, the adjustment of medications was the first choice for doctors, which may make the patient's condition unstable.

CASE PRESENTATION

A 33-year-old woman was diagnosed with schizophrenia and major depressive disorder. Starting with 0.6 g/d amisulpride, 0.1 g/d quetiapine, 75 mg/d venlafaxine sustained-release tablets, the patient reported symptoms of RAS (itching arms) on the fourth day since the latest hospitalization. After ruling out other factors, her RAS was suspected to be induced by antidepressants or antipsychotics. Without medication adjustment, RAS spontaneously remitted.

CONCLUSIONS

This case suggests that psychiatrists should pay attention to RAS when using antipsychotics and/or antidepressants. Moreover, RAS may be transitory. When a patient manifests RAS, observation may be one choice instead of an immediate medication adjustment.

Sex differences in antipsychotic efficacy and side effects in schizophrenia spectrum disorder: results from the BeSt InTro study

Current guidelines for patients with schizophrenia spectrum disease do not take sex differences into account, which may result in inappropriate sex-specific treatment. In the BeSt InTro study, a total of 144 patients (93 men and 51 women) with a schizophrenia spectrum diagnosis and ongoing psychosis were included and randomized to amisulpride, aripiprazole, or olanzapine in flexible dose. This trial is registered with ClinicalTrials.gov (NCT01446328). Primary outcomes were sex differences in dose, dose-corrected serum levels, efficacy, and tolerability. Dosing was higher for men than for women in the aripiprazole group (p = 0.025) and, at trend level, in the olanzapine group (p = 0.056). Dose-corrected serum levels were 71.9% higher in women than in men for amisulpride (p = 0.019) and 55.8% higher in women than in men for aripiprazole (p = 0.049). In the amisulpride group, men had a faster decrease in psychotic symptoms than women (p = 0.003). Moreover, amisulpride was more effective than the other medications in men but not in women. Prolactin levels were higher in women than in men, especially for amisulpride (p < 0.001). Also, women had higher BMI increase on amisulpride compared to the two other antipsychotics (p < 0.001). We conclude that clinicians should be aware of the risks of overdosing in women, especially for amisulpride and aripiprazole. Amisulpride is highly effective in men, but in women, amisulpride showed more severe side effects and may thus not be the drug of first choice. Our study shows that sex differences should be taken into account in future studies on antipsychotics. Future research is warranted to evaluate these preliminary results.

Study on the relationship among dose, concentration and clinical response in Chinese schizophrenic patients treated with Amisulpride

OBJECTIVE

To provide therapeutic window of amisulpride dose and serum concentration.

METHODS

194 schizophrenics were assessed with PANSS. The concentration of Amisulpride in blood was tested. And relationship with concentration was analyzed.

RESULTS

The dose of amisulpride was 100mg∼1200 mg/d(555+/-218), plasma concentration was 20∼1280 ng/mL(349+/-223) and C/D ratio was 0.07∼1.65 (0.63+/-0.34). The correlation of dose and concentration was significantly correlated (r = 0.55; P < 0.05).It was found that concentration(P < 0.001), C/D ratio(r = 0.383, P < 0.001), rather than dose (-0.042,p > 0.05) related to age significantly.It was found no differences in dose(p > 0.05), concentration (p > 0.05) and C/D ratio(p > 0.05) between male and female patients. The change ratio of positive symptom was 10 %∼90 %, negative symptom was 5∼80 %, general symptoms was 5∼90 %, PANSS was 5∼90 %.The correlation between change ratio of positive symptom, general symptom and PANSS and dose, concentration were significant(P < 0.01), but not related with the change ratio of negative symptom(p>0.05).The both dose and concentration of amisulpride were higher significantly in effective group than that in ineffective group according to change ratio of positive symptom, negative symptom, general symptom and PANSS(P < 0.01).

CONCLUSION

The correlation of dose and concentration of amisulpride was significantly correlated. The recommended range 457∼637 ng/mL was suggested as average therapeutic window.

Augmentation of Antipsychotic Medications with Low-Dose Clozapine in Treatment-Resistant Schizophrenia-Case Reports and Discussion

Treatment resistance in schizophrenia is often encountered in clinical practice, with clozapine usually recommended as the appropriate therapy. However, where clozapine proves ineffective or cannot be tolerated due to side effects, treatment options are limited. In patients within forensic mental health services, residual symptomatology often presents a barrier to discharge and can have lasting effects on prospects for rehabilitation as well as risk to self and others. This paper presents a review of the relevant literature and three cases of a novel approach, utilising clozapine in doses usually considered subtherapeutic, in combination with the primary antipsychotic treatment. In all three patients, it improved clinical efficacy as well as tolerability, resulting in improvement that allowed discharge from the forensic hospital.

A systematic review and combined meta-analysis of concentration of oral amisulpride

AIMS

Amisulpride, a first-line schizophrenia treatment, has shown large interindividual variability in plasma/serum levels, often outside the reference range (100-320 ng/mL). This study aims to clarify the impact of dose, sex, age and related factors for the interpatient variability in amisulpride plasma/serum concentration.

METHODS

Both English and Chinese databases were searched from their inception to May 16, 2019, using the terms: amisulpride and (plasma OR serum OR blood OR "drug monitoring" OR concentration). Studies reporting concentrations and either a dose, associated factor, clinical outcome or side effect were included.

RESULTS

Fourteen studies with 1628 participants were eventually included. Eligible articles yielded data on drug concentration and dose, averaging 333.9 (95% confidence interval [CI]: 294.5-373.3) ng/mL and 636.2 (95% CI: 549.7-722.6) mg/d, respectively. The calculated mean concentration-to-dose (C/D) ratio was 0.60 (95% CI: 0.52-0.67) (ng/mL)/mg. Subgroup analysis suggested that female patients on combined lithium-amisulpride have higher concentration levels and C/D ratios. Age was slight positive associated with C/D ratio while not for plasma level. Smoker patients have high concentration level than nonsmoking patients but not for C/D. Responsive and nonresponsive groups did not differ in concentration and C/D.

CONCLUSION

Pooled concentration levels of amisulpride were higher than recommended with wide individual variation, especially in older patients, female patients and patients taking amisulpride combined with lithium. The specific therapeutic reference range for amisulpride may require reconstruction, which should consider the influence of age, sex, kidney function, drug-drug interactions, different dose regimens and sampling times in future study.

Amisulpride: Real-World Evidence of Dose Adaptation and Effect on Prolactin Concentrations and Body Weight Gain by Pharmacokinetic/Pharmacodynamic Analyses

BACKGROUND

Amisulpride is an antipsychotic used in a wide range of doses. One of the major adverse events of amisulpride is hyperprolactinemia, and the drug might also induce body weight gain.

OBJECTIVE

The aims of this work were to characterize the pharmacokinetics of amisulpride in order to suggest optimal dosage regimens to achieve the reference range of trough concentrations at steady-state (C_min,ss) and to describe the relationship between drug pharmacokinetics and prolactin and body weight data.

METHODS

The influence of clinical and genetic characteristics on amisulpride pharmacokinetics was quantified using a population approach. The final model was used to simulate C_min,ss under several dosage regimens, and was combined with a direct E_max model to describe the prolactin data. The effect of model-based average amisulpride concentrations over 24 h (C_av) on weight was estimated using a linear model.

RESULTS

A one-compartment model with first-order absorption and elimination best fitted the 513 concentrations provided by 242 patients. Amisulpride clearance significantly decreased with age and increased with lean body weight (LBW). C_min,ss was higher than the reference range in 65% of the patients aged 60 years receiving 400 mg twice daily, and in 82% of the patients aged > 75 years with a LBW of 30 kg receiving 200 mg twice daily. The pharmacokinetic/pharmacodynamic model included 101 prolactin measurements from 68 patients. The E_max parameter was 53% lower in males compared with females. Model-predicted prolactin levels were above the normal values for C_min,ss within the reference range. Weight gain did not depend on C_av.

CONCLUSIONS

Amisulpride treatment might be optimized when considering age and body weight. Hyperprolactinemia and weight gain do not depend on amisulpride concentrations. Modification of the amisulpride dosage regimen is not appropriate to reduce prolactin concentrations and alternative treatment should be considered.

Thorough QT study of the effect of intravenous amisulpride on QTc interval in Caucasian and Japanese healthy subjects

AIM

The D₂ /D₃ antagonist amisulpride has shown promising efficacy against postoperative nausea and vomiting (PONV) at low doses. We investigated whether intravenous amisulpride has an effect on the QTc interval in a formal Thorough QT study (TQT).

METHODS

This was a randomized, double-blind, placebo and positive-controlled, four-way crossover study. Forty healthy Caucasian and Japanese subjects were included to receive a single administration of 5 mg and 40 mg of i.v. amisulpride or a single oral dose of moxifloxacin or placebo per period.

RESULTS

The therapeutic dose of 5 mg amisulpride was associated with a slight, transient increase in mean ΔΔQTcF, from 2.0 ms prior to dosing to a peak of 5 ms (90% CI: 2.8, 7.1 ms) at 8 min, decreasing to 2.1 ms at 30 min after dosing. The supra-therapeutic dose of 40 mg given at twice the infusion rate was associated with prolongation in ΔΔQTcF peaking at 23.4 ms (90% CI: 21.3, 25.5 ms) at the end of infusion (8 min), returning below 10 ms within 1.5 h. Assay sensitivity was confirmed; ΔΔQTcF had increased by 12.3 ms (90% CI 10.1, 14.6 ms) at 4 h post-dose. The PK-PD relationship revealed no differences between Caucasian and Japanese subjects (p-value > 0.5).

CONCLUSIONS

Amisulpride has a plasma concentration-dependent effect on the QTc interval. The proposed therapeutic dose for management of PONV does not lead to a prolongation of QTcF above the threshold of regulatory concern, while such effect could not be excluded for the supratherapeutic dose.

A population approach to characterise amisulpride pharmacokinetics in older people and Alzheimer's disease

INTRODUCTION

Current prescribing guidelines for the antipsychotic amisulpride are based largely on pharmacokinetic (PK) studies in young adults, and there is a relative absence of data on older patients, who are at greatest risk of developing adverse events.

METHODS

This study aimed to develop a population PK model for amisulpride specifically in older people, by combining data from a richly sampled phase 1, single (50 mg) dose study in healthy older people (n = 20, 65-79 years), with a clinical dataset obtained during off label, low-dose (25-75 mg daily) amisulpride prescribing in older people with Alzheimer's disease (AD) (n = 25, 69-92 years), as part of an observational study.

RESULTS

After introducing a scaling factor based on body weight, age accounted for 20 % of the inter-individual variability in drug clearance (CL), resulting in a 54 % difference in CL between those aged 65 and those aged 85 years, and higher blood concentrations in older patients.

DISCUSSION

These findings argue for the consideration of age and weight-based dose stratification to optimise amisulpride prescribing in older people, particularly in those aged 85 years and above.

Prandial effect on the systemic exposure of amisulpride

A substituted benzamide, amisulpride is an atypical antipsychotic and a specific antagonist for dopamine D2 and D3 receptors. The prandial effect on amisulpride absorption remains unclear, therefore, this study was designed to investigate the effect of food on the systemic exposure to amisulpride in healthy volunteers. The study was a randomized, two-way crossed trial in which a single oral dose of amisulpride was administered on two occasions, with 7-days washout period between each drug administration. The volunteers were randomly divided into two groups and received amisulpride (50 mg) with Korean traditional food or under fasting state. Blood was serially taken, and the plasma amisulpride concentrations were measured by LC/MS/MS. At fasting state, amisulpride reached the first peak (37.1 ± 13.3 ng/ml) at ~2.3 h, and decreased down to 19.4 ± 4.3 ng/ml until 3.5 h, and then again went up to the second peak (25.3 ± 5.8 ng/ml) at 5 h followed by a slow decay with 10.6 h of half-life. In contrast, no double peaks were shown when the drug was given with meal. The maximum concentration of amisulpride (56.0 ± 12.7 ng/ml) was increased by a 1.5-fold compared with that under fasting (p > 0.05), and the time to peak shortened a little (1.7 ± 0.6 h).

A validated GC/MS method for the determination of amisulpride in whole blood

A sensitive GC/MS method for the determination of amisulpride in whole blood was developed, optimized and validated. Sample preparation included solid-phase extraction using HF Bond Elut C18 cartridges and further derivatization with heptafluorobutyric anhydride (HFBA). The limits of detection and quantification were 3.00 and 10.0 μg/L, respectively. The calibration curves were linear up to 1000 μg/L (R(2)≥0.991). Absolute recovery ranged from 94.2 to 101%. Accuracy was found to be between -8.7 and 1.9% and imprecision was less than 10.0%. The developed method covers the generally accepted therapeutic range but it can also cover levels above them. This makes our method suitable for the determination of amisulpride not only for clinical purposes on psychiatric patients, but also during the investigation of forensic cases where amisulpride is involved.

Cigarette smoking modulates medication-associated deficits in a monetary reward task in patients with schizophrenia

Imaging studies of reward processing have demonstrated a mesolimbic-mesocortical dopaminergic dysfunction in schizophrenia. Such studies on reward processing in patients and also in healthy controls showed that differential activations of dopaminergic brain areas are associated with adaptive changes in response speed related to different reward values. Given this relationship, we investigated reward processing on the behavioural level in a larger sample of 49 medicated patients with a diagnosis of schizophrenia (ICD-10 F20) and 49 healthy controls. Subjects were instructed to react by button press upon two different stimuli in order to retain a 60 % chance winning a previously announced high (1$) or low (20¢) amount of money paid to participants after the experiment. Concordant with previous reports on deficits in reward processing, acceleration of reaction times in patients upon low rewards differed significantly (p < 0.05) from healthy controls in our present behavioural study. This effect was pronounced in the non-smoking subgroup of patients (n = 24). In this subgroup, we also observed a significant (p < 0.05) positive correlation with medication type (relatively high vs. low D2 receptor affinity) and with the PANSS score, the latter with a trend to significance (p = 0.08). Our study demonstrates that reaction time measures in a monetary reward task might constitute a feasible behavioural proxy for dopaminergic dysfunction and its different dimensions regarding psychopathology but also medication in patients with schizophrenia. In line with clinical observations, our findings support the notion that smoking modulates medication-associated side effects on reward processing in patients with schizophrenia.

Poisoning: fact or fiction?

Analytical toxicology is a complex discipline. Simply detecting a poison in a biological sample does not necessarily mean that the individual from whom the sample was obtained had been poisoned. An analysis can prove exposure and perhaps give an indication of the magnitude of exposure, but the results have to be placed in proper context. Even if sampling was ante-mortem an analysis does not necessarily prove the effects that the drug or poison had on the victim immediately before or at the time of sampling. Tolerance is one big issue, the mechanism of exposure (how the drug got into the body) is another, and of course with post-mortem work there are always additional considerations such as site of sample collection and the possibility of post-mortem change in analyte concentration. There are also questions of quality and reliability, and whether a particular analysis and the interpretation placed upon the result are appropriate in a particular case.

Clinical pharmacology of dopamine-modulating agents in Tourette's syndrome

Forty years of research and clinical practice have proved dopamine (DA) receptor antagonists to be effective agents in the treatment of Tourette's syndrome (TS), allowing a significant tic reduction of about 70%. Their main effect seems to be mediated by the blockade of the striatal DA-D2 receptors. Various typical and atypical agents are available and there is still discord between experts about which of them should be considered as first choice. In addition, there are suggestions to use DA receptor agonists such as pergolide or non-DA-modulating agents. The present chapter is focusing on the clinical pharmacology of DA-modulating agents in the treatment of TS. The introduction outlines their clinical relevance and touches on the hypotheses of the role of DA in the pathophysiology of TS. Subsequently, general information about the mechanisms of action and adverse effects are provided. The central part of the chapter forms a systematic review of all DA-modulating agents used in the treatment of TS, including an overview of studies on their effectiveness, and a critical discussion of their specific adverse effects. The present chapter closes with a summary of the body of evidence and a description of the resulting recommendations for the pharmacological treatment of TS.

Therapeutic drug monitoring of common antipsychotics

The aim of this review is to provide information for interpreting outcome results from monitoring of antipsychotics in biological samples. A brief overview of the working mechanisms, pharmacological effects, drug interactions, and analytical methods of classical and atypical antipsychotics is given. Nineteen antipsychotics were selected based on their importance in the worldwide market as follows: amisulpride, aripiprazole, asenapine, bromperidol, clozapine, flupenthixol, haloperidol, iloperidone, lurasidone, olanzapine, paliperidone, perphenazine, pimozide, pipamperone, quetiapine, risperidone, sertindole, sulpiride, and zuclopenthixol. A straightforward relationship between administered dose, plasma or serum concentration, clinical outcome, or adverse effects is often lacking. Nowadays, focus lies on therapeutic drug monitoring and individualized therapy to find adequate treatment, to explain treatment failure or nonresponse, and to check patient compliance. However, extensive research in this field is still mandatory.

Plasma amisulpride in relation to prescribed dose, clozapine augmentation, and other factors: data from a therapeutic drug monitoring service, 2002-2010

OBJECTIVE

This study aimed to investigate the effect of dose and other factors on plasma amisulpride concentrations in clinical practice.

METHOD

Amisulpride therapeutic drug monitoring data 2002-2010 have been studied.

RESULTS

There were 296 samples (196 adult patients). Amisulpride was not detected in 10% of samples. In the remainder, the mean plasma amisulpride in relation to the prescribed dose (mg/day) was as follows: 100-200 (111 µg/L), 201-400 (254 µg/L), 400-800 (421 µg/L), and 800-1200 (494 µg/L). For prescribed doses up to 800 mg/day, only 51% of results were within 100-319 µg/L. There were no significant sex differences in mean plasma amisulpride or mean dose. The mean plasma amisulpride, but not the dose, was significantly higher in smokers. Linear regression analysis showed that dose explained only 42% of the variation in plasma amisulpride after log(10) transformation of both variables. There was no significant difference in the mean dose or mean plasma amisulpride in patients co-prescribed clozapine as compared with the remaining samples.

CONCLUSION

In practice, dose is a poor predictor of plasma amisulpride concentration. Therapeutic drug monitoring may not only help assess adherence, but also guide dosage.

Amisulpride versus moclobemide in treatment of clozapine-induced hypersalivation

OBJECTIVES

Previous publications demonstrated substitute benzamides as effective agents in treatment of clozapine-induced sialorrhea (CIS). The aim of this study was to compare efficacy of amisulpride and moclobemide (both from the substitute benzamide group) in controlling, or at least minimizing, CIS.

METHODS

The study was designed as a 6-week, two-center, fixed-dose, comparison study of 400 mg/day of amisulpride versus 300 mg/day of moclobemide as an adjunctive treatment in 53 schizophrenia and schizoaffective disorder patients (diagnosed according to DSM-IV) suffering from CIS. The patients were treated with each medication during 2 weeks, followed by a washout period of 2 weeks. Primary outcome measures included the reduction in the five-point Nocturnal Hypersalivation Rating Scale (NHRS). Secondary outcomes included the Positive and Negative Syndrome Scale (PANSS), Manic State Assessment Scale, and Extrapyramidal Symptom Rating Scale (ESRS).

RESULTS

Both amisulpride and moclobemide were very effective in reducing CIS. Almost 74% of patients treated with amisulpride and 83% of patients treated with moclobemide showed some level of improvement on NHRS. Only in one patient treated with amisulpride, CIS worsened.

CONCLUSIONS

Both medications were safe and effective as treatment of CIS. Although moclobemide exceeded amisulpride in antisalivation activity, treatment of CIS with amisulpride leads to improvement in psychotic symptoms.

Beta-glucan from Saccharomyces cerevisiae reduces plasma lipid peroxidation induced by haloperidol

Since oxidative stress observed in schizophrenia may be caused partially by the treatment of patients with various antipsychotics, the aim of the study was to establish the effects of beta-d-glucan, polysaccharide derived from the yeast cell walls of species such as Saccharomyces cerevisiae, and the antipsychotics (the first generation antipsychotic (FGA) - haloperidol and the second generation antipsychotic (SGA) - amisulpride) action on plasma lipid peroxidation in vitro. Lipid peroxidation in human plasma was measured by the level of thiobarbituric acid reactive species (TBARS). The samples of plasma from healthy subjects were incubated with haloperidol or amisulpride in the presence of beta-glucan (4 μg/ml). The action of beta-d-glucan was also compared with the properties of a well characterized commercial monomeric polyphenol - resveratrol (3,4',5-trihydroxystilbene, the final concentration - 4 μg/ml). The two-way analysis variance showed that the differences in TBARS levels were depended on the type of tested drugs (p=7.9 × 10(-6)). We observed a statistically increase of the level of biomarker of lipid peroxidation such as TBARS after 1 and 24h incubation of plasma with haloperidol compared to the control samples (p<0.01, p<0.02, respectively). Amisulpride, contrary to haloperidol (after 1 and 24h) did not cause plasma lipid peroxidation (p>0.05). We showed that in the presence of beta-glucan, lipid peroxidation in plasma samples treated with haloperidol was significantly decreased. Moreover, we did not observe the synergistic action of beta-glucan and amisulpride on the inhibition of plasma lipid peroxidation. However, the beta-d-glucan was found to be more effective antioxidant, than the solution of pure resveratrol. The presented results indicate that beta-glucan seems to have distinctly protective effects against the impairment of plasma lipid molecules induced by haloperidol.

Amisulpride - dose, plasma concentration, occupancy and response: implications for therapeutic drug monitoring

OBJECTIVE

To evaluate the relationships between dose, plasma concentration, pharmacological activity and clinical outcome to evaluate the appropriateness of therapeutic drug monitoring (TDM) in patients receiving amisulpride.

METHOD

Literature search of Embase, Medline and PubMed databases.

RESULTS

Amisulpride plasma concentration is closely correlated with dose (r(2) = 0.96, P < 0.0001), dopamine occupancy, response and with extra-pyramidal symptoms (EPS). Dose is correlated with response, dopamine occupancy and EPS. Optimal clinical response was found at doses of 400-800 mg/day, corresponding to plasma levels of approximately 200-500 ng/ml. EPS appears to be more reliably predicted by a plasma level above 320 ng/ml than by a particular dose.

CONCLUSION

The effects and safety of amisulpride in the treatment of schizophrenia and schizoaffective disorder are predicted by daily dose. The plasma concentration threshold for response appears to be approximately 200 ng/ml. EPS are more reliably predicted by plasma level than by dose. TDM for patients prescribed amisulpride is thus of some clinical value.

Amisulpride doses and plasma levels in different age groups of patients with schizophrenia or schizoaffective disorder

Because of a unique pharmacodynamic profile, amisulpride seems appropriate for treatment of elderly patients with schizophrenia. In a large-scale naturalistic therapeutic drug monitoring study, daily amisulpride dose, trough and dose-corrected amisulpride plasma levels, co-medication, clinical effectiveness (CGI) and side effects (UKU) were compared between age groups in 395 patients with schizophrenia or schizoaffective disorder (46% women; mean age 39.1 +/- 14.2 years, range 18-83 years) under amisulpride therapy. Mean amisulpride doses (574 +/- 269 mg/day), plasma levels (304 +/- 274 ng/mL), dose-corrected amisulpride plasma levels (C/D ratios, 0.52 +/- 0.41 ng/mL:mg), clinical response (at least moderate improvement, 71.6%), and side effects (any side effect, 32.2%; extrapyramidal symptoms, 14.9%) were comparable between age groups (P > 0.25). At higher age, significantly more benzodiazepines (P = 0.04), non-benzodiazepine hypnotics (P = 0.004) and non-psychotropic medications (P < 0.0001) were prescribed. The naturalistic study showed higher C/D ratios in women (P = 0.019) and a slight increase of C/D ratios with age (P = 0.026), but no substantial age-dependent effects on amisulpride doses or plasma levels. In patients above 60 years, clinical response was associated with lower amisulpride plasma levels (P = 0.016) at comparable doses. Neither the age-dependent decrease of amisulpride clearance nor the significantly higher prevalence of co-morbidity and co-medication seem to be the reasons for definite clinical concerns against amisulpride treatment of elderly if contraindications are seriously taken.

Therapeutic drug monitoring for optimizing amisulpride therapy in patients with schizophrenia

Amisulpride is a clinically effective antipsychotic drug in a broad dose range with low propensity for extrapyramidal symptoms (EPS). Daily doses and plasma levels of amisulpride were analyzed within a large-scale therapeutic drug monitoring (TDM) survey to find plasma level ranges for optimized treatment under naturalistic conditions. Data of 378 schizophrenic patients treated with amisulpride (100-1550 mg) were included (40% female). Amisulpride plasma levels were analyzed at steady state; assessment comprised improvement (CGI-I) and side-effects, particularly EPS. For detection of cut-off values regarding non-response or EPS, receiver operating characteristics (ROC) curves were applied and the area under the ROC curve (AUC) was calculated. Amisulpride daily doses (594+/-262 mg) and plasma levels (315+/-277 ng/ml) were significantly correlated (r=0.53; P<0.0001). Patients with non-response to amisulpride (8.9%) had significantly (P<0.05) lower plasma levels (248+/-291 ng/ml) than patients with at least moderate improvement (316+/-253 ng/ml) despite comparable amisulpride doses (628+/-253 vs. 590+/-263 mg). Patients with EPS (14.6%) had significantly (P<0.05) higher amisulpride plasma levels (377+/-290 ng/ml) than patients without EPS (305+/-274 ng/ml) despite similar doses in both groups (595+/-266 vs. 594+/-246 mg). ROC analyses revealed significant predictive properties of amisulpride plasma levels (P<0.05) for non-response (AUC=0.65+/-0.05) and EPS (AUC=0.62+/-0.05), respectively. Daily amisulpride doses did not significantly predict non-response or EPS. Optimal amisulpride plasma level values to avoid non-response and EPS were 100 or 320 ng/ml, respectively. Analysis of clinical utility revealed that blood levels must be analyzed in 7 patients until one patient benefits from the TDM procedure by avoiding non-response or EPS. Although our results were mainly explorative, TDM of amisulpride seems very useful for clinical decision making.

Clozapine-resistant psychosis, smoking, and caffeine: managing the neglected effects of substances that our patients consume every day

More than 30% of patients with psychotic disorders who are refractory to antipsychotic treatment also fail to respond to clozapine. Despite the high prevalence of smoking and caffeine use in the psychiatric population, these habits are usually overlooked as factors contributing to antipsychotic treatment failure. We describe 2 male patients with severe treatment-resistant psychosis, one with schizophrenia and the other with bipolar affective disorder-both of whom smoked heavily, and the latter also consumed enormous amounts of caffeine-whose symptoms were refractory to clozapine. Both patients experienced a major, sustained amelioration of their psychotic symptoms when clozapine treatment was recommenced under supervision in the inpatient setting and the pharmacological interactions between clozapine, smoking, and caffeine were considered. Therapeutic strategies included gradual increases in daily doses of clozapine, monitoring clozapine plasma levels, using single daily doses of clozapine at night, and augmenting clozapine treatment with low doses of amisulpride, a selective antagonist at the dopamine D2 and D3 receptors. Smoking and excessive caffeine use are associated with poor therapeutic responses to clozapine and should be considered in the pharmacological management of treatment-refractory psychosis, regardless of the primary diagnosis.

Comparative validation of amisulpride determination in pharmaceuticals by several chromatographic, electrophoretic and spectrophotometric methods

Nine accurate methods for determination of amisulpride in tablets: reversed phase high pressure liquid chromatography (RP-HPLC), aqueous capillary electrophoresis (CE), non-aqueous CE, normal phase (NP) and reversed-phase (RP) high performance thin layer chromatography (HPTLC) with densitometry and videodensitometry, and direct and derivative UV spectrophotometry were developed and validated. The HPLC was carried out using Nova-Pak C8 column and mobile phase consisted of acetonitrile-methanol-phosphate buffer pH 4.50 (15:5:80, v/v/v) with flow rate 1 mL min(-1) and UV detection at 225 nm. The moclobemide was used as the internal standard. CE was performed using 75 microm x 82 cm fused silica capillary (65 cm effective), the internal standard was quetiapine. Detection was carried out at 225 nm. For aqueous analysis, the 30 mM phosphate buffer pH 6.00, 30 kV voltage and 30 degrees C temperature were chosen, non-aqueous determination was performed with ammonia acetate 1 mM in acetonitrile-methanol (1:1, v/v), 30 kV voltage and 25 degrees C temperature. NP-HPTLC was carried out using HPTLC silica F254 plates, developed with hexane-ethanol-propylamine (5:5:0.1, v/v/v) through 9 cm distance. RP-HPTLC was developed with HPTLC RP8F254 plates, with mobile phase of tetrahydrofuran-phosphate buffer pH 3.50 (4:6, v/v), distance 4.5 cm. Both analyses were performed in horizontal chambers and scanned with densitometer at 275 nm or videodensitometer at 254 nm. UV spectrophotometry was carried out in methanol, using 224 nm for direct assay and 258 nm (D1) for derivative assay. The precision and accuracy of all the methods were complexively compared. The highest accuracy was observed in RP-HPTLC, the highest precision was achieved in non-aqueous CE method. The differences were not significant, so all the elaborated methods can be used in routine analysis.

Possible levomepromazine-clozapine interaction: two case reports

OBJECTIVE

To report and comment upon two cases of suspected pharmacological interaction between the "classical" neuroleptic levomepromazine (LMP) and the "atypical" antipsychotic clozapine (CLZ).

CASE SUMMARY

The patients who simultaneously took the two drugs had unusually low plasma levels of CLZ and its metabolites, even though they took high doses of CLZ. The patients were considered "non-responders" to the treatment by the psychiatrist. When LMP was withdrawn from the therapy, plasma concentrations of CLZ returned to therapeutic levels and one of the two patients experienced the anticipated therapeutic response.

DISCUSSION

No information can be found in the literature regarding possible interactions between LMP and CLZ. However, the results of the two cases reported herein point out to a possible lack of therapeutic efficacy of CLZ therapy during this kind of polypharmacy.

CONCLUSION

While two cases are too few to draw any conclusion, it would be prudent on the part of psychiatrists to consider a possible drug interaction in patients receiving both CLZ and LMP who fail to respond to the therapy.

Clinical Pharmacokinetics of Atypical Antipsychotics

In the past, the information about the dose-clinical effectiveness of typical antipsychotics was not complete and this led to the risk of extrapyramidal adverse effects. This, together with the intention of improving patients' quality of life and therapeutic compliance, resulted in the development of atypical or second-generation antipsychotics (SGAs). This review will concentrate on the pharmacokinetics and metabolism of clozapine, risperidone, olanzapine, quetiapine, amisulpride, ziprasidone, aripiprazole and sertindole, and will discuss the main aspects of their pharmacodynamics. In psychopharmacology, therapeutic drug monitoring studies have generally concentrated on controlling compliance and avoiding adverse effects by keeping long-term exposure to the minimal effective blood concentration. The rationale for using therapeutic drug monitoring in relation to SGAs is still a matter of debate, but there is growing evidence that it can improve efficacy, especially when patients do not respond to therapeutic doses or when they develop adverse effects. Here, we review the literature concerning the relationships between plasma concentrations of SGAs and clinical responses by dividing the studies on the basis of the length of their observation periods. Studies with clozapine evidenced a positive relationship between plasma concentrations and clinical response, with a threshold of 350-420 ng/mL associated with good clinical response. The usefulness of therapeutic drug monitoring is well established because high plasma concentrations of clozapine can increase the risk of epileptic seizures. Plasma clozapine concentrations seem to be influenced by many factors such as altered cytochrome P450 1A4 activity, age, sex and smoking. The pharmacological effects of risperidone depend on the sum of the plasma concentrations of risperidone and its 9-hydroxyrisperidone metabolite, so monitoring the plasma concentrations of the parent compound alone can lead to erroneous interpretations. Despite a large variability in plasma drug concentrations, the lack of studies using fixed dosages, and discrepancies in the results, it seems that monitoring the plasma concentrations of the active moiety may be useful. However, no therapeutic plasma concentration range for risperidone has yet been clearly established. A plasma threshold concentration for parkinsonian side effects has been found to be 74 ng/mL. Moreover, therapeutic drug monitoring may be particularly useful in the switch between the oral and the long-acting injectable form. The reviewed studies on olanzapine strongly indicate a relationship between clinical outcomes and plasma concentrations. Olanzapine therapeutic drug monitoring can be considered very useful in assessing therapeutic efficacy and controlling adverse events. A therapeutic range of 20-50 ng/mL has been found. There is little evidence in favour of the existence of a relationship between plasma quetiapine concentrations and clinical responses, and an optimal therapeutic range has not been identified. Positron emission tomography studies of receptor blockade indicated a discrepancy between the time course of receptor occupancy and plasma quetiapine concentrations. The value of quetiapine plasma concentration monitoring in clinical practice is still controversial. Preliminary data suggested that a therapeutic plasma amisulpride concentration of 367 ng/mL was associated with clinical improvement. A therapeutic range of 100-400 ng/mL is proposed from non-systematic clinical experience. There is no direct evidence concerning optimal plasma concentration ranges of ziprasidone, aripiprazole or sertindole.

Combination of Clozapine and Ziprasidone in Treatment-Resistant Schizophrenia

OBJECTIVES

Therapeutic options for patients with treatment-resistant schizophrenia are limited. In such patients, combined application of atypical antipsychotic drugs is an often-used strategy. The authors tested the hypothesis that the combination of ziprasidone and clozapine would lead to an improvement in this patient group.

METHODS

Nine patients with treatment-resistant schizophrenia participated in this open clinical trial and received a combination regimen of ziprasidone and clozapine. Patients had to have remained on a stable dose of clozapine for at least 6 months to ensure a reasonable opportunity to respond to clozapine monotherapy. Clinical status was evaluated at baseline, and at 3 and 6 months' follow-up using the Brief Psychiatric Rating Scale (BPRS).

RESULTS

All patients completed the 6-month combination treatment. The mental state of 7 patients (77.8%) was improved and there was a significant reduction in the mean BPRS score over the 6 months treatment. The coadministration of ziprasidone in clozapine-treated patients did not result in a corresponding increase in side effects. The combination allowed a 18% reduction of the daily clozapine dose.

CONCLUSION

The combined application of clozapine and ziprasidone follows a neurobiologic rationale and appears to be safe and well tolerated without increasing the risk of side effects.

Clozapin-Augmentation mit atypischen Antipsychotika

Typical antipsychotic medications have considerably improved clinical outcome of patients suffering from schizophrenic psychoses, but up to 40% of the cases show treatment resistant symptoms. Even therapy with atypical antipsychotic drugs such as risperidone, quetiapine, olanzapine, sulpiride, amisulpride, and ziprasidone often fails to reach complete remission due to resistant, positive or negative symptoms or dose-limiting side effects. As this also holds true in the case of monotherapy with clozapine, a substance known to be effective against treatment-resistant schizophrenia, increasing numbers of patients receive atypical antipsychotic drugs in addition to clozapine. This review systematically evaluates case reports and clinical investigations on the use of clozapine combined with risperidone, olanzapine, quetiapine, sulpiride, amisulpride, or ziprasidone. Details on indication, methodology, and effects of the investigations are summarized. Only one double blind, placebo-controlled trial on the combination with sulpiride exists within a number of altogether 31 publications about 1182 treatments. Favorable effects on positive and/or negative symptoms or improvements of clozapine-induced side effects were described for every combination approach. In some cases pharmacokinetic interactions or serious unfavorable effects occurred. In conclusion it might be accepted that most of the combination therapies follow a neurobiological rational. There a major differences in the level of evidence that they are safe, tolerable and effective. We discuss criteria for the indication for augmenting clozapine therapy and the differential indication for existing alternatives. Additional randomized prospective trials are needed in order to evaluate these strategies systematically.

Augmentation With Amisulpride for Schizophrenic Patients Nonresponsive to Antipsychotic Monotherapy

Despite the effectiveness of antipsychotic medications in treatment of schizophrenia, about 30% of patients who receive an adequate treatment have significant persisting symptoms. The problem of treatment-resistant psychosis is an important and difficult one. The aim of this study was to retrospectively evaluate the efficacy and safety of amisulpride augmentation in treatment-resistant schizophrenic patients. To the best of our knowledge, this is the first report about resistant schizophrenic and schizoaffective patients treated with the combinations of risperidone and amisulpride and ziprasidone and amisulpride. Data were collected from patient records. A total of 15 resistant schizophrenic patients (7 men, 8 women, 54.0 +/- 16.9 years old) were included in the study. Before addition of amisulpride, the patients were treated with monotherapy by atypical neuroleptics (clozapine, olanzapine, risperidone, or ziprasidone). The mean amisulpride dose was 693.3 +/- 279.6 mg/d. The mental state of 12 (80%) patients treated with combination was improved. Three (20%) patients showed no change in their mental state. Only 2 patients treated with a combination of risperidone and amisulpride had mild side effects. The results are preliminary and require confirmation in a randomized controlled trial. The authors suggest that amisulpride may be a promising option as an augmentation strategy in treatment-resistant schizophrenic patients.