Purpose
Tiapride is commonly used in Europe for the treatment of tics. The aim of this study was to examine the relationship between dose and serum concentrations of tiapride and potential ...influential pharmacokinetic factors in children and adolescents. In addition, a preliminary therapeutic reference range for children and adolescents with tics treated with tiapride was calculated.
Methods
Children and adolescents treated with tiapride at three university hospitals and two departments of child and adolescents psychiatry in Germany and Austria were included in the study. Patient characteristics, doses, serum concentrations, and therapeutic outcome were assessed during clinical routine care using standardised measures.
Results
In the 49 paediatric patients (83.7% male, mean age = 12.5 years), a positive correlation was found between tiapride dose (median 6.9 mg/kg, range 0.97–19.35) and serum concentration with marked inter-individual variability. The variation in dose explained 57% of the inter-patient variability in tiapride serum concentrations; age, gender, and concomitant medication did not contribute to the variability. The symptoms improved in 83.3% of the patients. 27.1% of the patients had mild or moderate ADRs. No patient suffered from severe ADRs.
Conclusions
This study shows that tiapride treatment was effective and safe in most patients with tics. Compared with the therapeutic concentration range established for adults with Chorea Huntington, our data hinted at a lower lower limit (560 ng/ml) and similar upper limit (2000 ng/ml).
The basal ganglia form a forebrain system that collects signals from a large part of the neocortex, redistributes these cortical inputs both with respect to one another and with respect to inputs ...from the limbic system, and then focuses the inputs of this redistributed, integrated signals into particular regions of the frontal lobes and brainstem involved in aspects of motor planning and motor memory. Movement disorders associated with basal ganglia dysfunction comprise a spectrum of abnormalities that range from the hypokinetic disorder (from which Parkinson's disease, PD, is the best-known-example) at one extreme to the hyperkinetic disorder (exemplified by Huntington's disease and hemiballism) at the other. In addition to disorders of movement, major mental disorders including schizophrenic-like states and attention deficit hyperactivity disorder (ADHD) have been linked to abnormalities in the basal ganglia and their allied nuclei. In this paper we discuss recent evidence indicating that a dopamine-induced dysbalance of basal ganglia neurocircuitries may be an important pathophysiological component in PD, schizophrenia and ADHD. According to our model, the deprivation of dopaminergic nigro-striatal input, as in PD, reduces the positive feedback via the direct system, and increases the negative feedback via the indirect system. The critical consequences are an overactivity of the basal ganglia output sites with the resulting inhibition of thalamo-cortical drive. In schizophrenia the serious cognitive deficits might be partly a result of a hyperactivity of the inhibitory dopamine D(2) transmission system. Through this dysinhibition, the thalamus exhibits hyperactivity that overstimulates the cortex resulting in dysfunctions of perception, attention, stimulus distinction, information processing and affective regulation (inducing hallucinations and delusions) and motor disabilities. Recent studies have strongly suggested that a disturbance of the dopaminergic system is also involved in the pathophysiology of ADHD. The most convincing evidence comes from the demonstration of the efficacy of psychostimulants such as the dopamine transporter (DAT) blocker methylphenidate in the symptomatic treatment of ADHD. Genetic studies have shown an association between ADHD and genes involved in dopaminergic neurotransmission (for example the dopamine receptor genes DRD4 and DRD5, and the DAT gene DAT1). DAT knockout mice display a phenotype with increased locomotor activity, which is normalized by psychostimulant treatment. Finally, imaging studies demonstrated an increased density of DAT in the striatum of ADHD patients. Which system is disturbed and whether this system is hyper- or hypoactive is not unambiguously known yet.
Psychopharmacotherapy in children and adolescents is characterized by an increased susceptibility for adverse events and an increased risk of ineffective treatment due to specific age-dependent and ...developmental characteristics in comparison to adults. Dosing in paediatric psychiatric patients requires careful handling, since the dose recommendations for adults can not simply be extrapolated to minors because of pharmacokinetic and pharmacodynamic differences. In addition, psychopharmacotherapy in children and adolescents is hampered by lack of high quality evidence on efficacy and safety in many indications and subsequently a high degree of off-label use. Therapeutic Drug Monitoring (TDM) is an established and useful tool in psychiatry to individualize and optimize the outcomes (efficacy/safety balance) of psychopharmacological drug treatment in the individual patient by dose adjustments based upon measured serum concentrations. In children and adolescents the administration of psychotropic drugs is a general indication for performing TDM. However, TDM studies specific in these age groups are necessary to identify age and indication specific therapeutic ranges of serum concentrations. Systematic collection of data on drug exposure, serum concentrations and clinical characteristics as well as outcomes can generate such practice-based evidence. A German-Swiss-Austrian competence network for TDM in child and adolescent psychiatry using a multi-centre internet-based data infrastructure was founded to document and collect demographic, safety and efficacy data as well as blood concentrations of psychotropic drugs in children and adolescents (further information: www.tdm-kjp.com).
Atypical antipsychotics are nowadays the most widely used drugs to treat schizophrenia and other psychosis. Unfortunately, some of them can cause major metabolic adverse effects, such as weight gain, ...dyslipidemia and type 2 diabetes. The underlying lipogenic mechanisms of the antipsychotic drugs are not known, but several studies have focused on a central effect in the hypothalamic control of appetite regulation and energy expenditure. In a functional convergent genomic approach we recently used a cellular model and demonstrated that orexigenic antipsychotics that induce weight gain activate the expression of lipid biosynthesis genes controlled by the sterol regulatory element-binding protein (SREBP) transcription factors. We therefore hypothesized that the major genes involved in the SREBP activation of fatty acids and cholesterol production (SREBF1, SREBF2, SCAP, INSIG1 and INSIG2) would be strong candidate genes for interindividual variation in drug-induced weight gain. We genotyped a total of 44 HapMap-selected tagging single nucleotide polymorphisms in a sample of 160 German patients with schizophrenia that had been monitored with respect to changes in body mass index during antipsychotic drug treatment. We found a strong association (P=0.0003-0.00007) between three markers localized within or near the INSIG2 gene (rs17587100, rs10490624 and rs17047764) and antipsychotic-related weight gain. Our finding is supported by the recent involvement of the INSIG2 gene in obesity in the general population and implicates SREBP-controlled lipogenesis in drug-induced metabolic adverse effects.
Marked inter-individual variation has been observed with respect to the risk of weight gain and related metabolic disturbances during antipsychotic treatment, which in part could be explained by ...heritability. Such adverse effects have been proposed to occur through drug-induced mechanisms involving both the central nervous system and different peripheral tissues.
We genotyped tagSNPs in several genes ( ADIPOQ, PRKAA1, PRKAA2, PRKAB1, PRKAG1, PRKAG2, PRKAG3, FTO and FABP3) that regulate lipid and energy homeostasis for their possible association to antipsychotic-induced weight gain.
In a sample of 160 patients of German origin with schizophrenia who had been monitored with respect to body weight, we found marked association between antipsychotic-related changes in BMI and 6 markers in the adiponectin gene ( ADIPOQ).
These findings support previous observations (in patients' serum) that adiponectin is involved in antipsychotic-mediated metabolic adverse effects.
Information about therapeutic serum levels of fluoxetine (FLX) and its major metabolite norfluoxetine (NORFLX) in children and adolescents is scarce.
Therapeutic drug monitoring (TDM) of FLX was ...routinely performed in 71 subjects treated for a major depressive disorder (MDD) (10-60 mg/d FLX, median: 20 mg/d). Correlations between serum concentration and dosage, age, gender, smoking habits and adverse events were analysed.
Serum concentrations of the active moiety (FLX + NORFLX) ranged from 21 to 613 ng/mL (mean concentration of 213 ± 118 ng/mL, median: 185 ng/mL). High inter-individual variability in serum concentrations of the active moiety of FLX at each dosage level was observed and no relationship between serum concentration and clinical outcome was found. Apart from smoking, none of the factors tested had a significant eff ect on the serum concentration.
It was shown that serum concentrations of the active moiety of FLX in children and adolescents seem to be similar to those in adults, with a high level of inter-individual variation. The proportion of patients who showed benefits from treatment with a dose of 20 mg/d FLX was high.
The study was aimed at the evaluation of weight gain associated with atypical antipsychotics and its clinical risk factors in children and adolescents. Weight and body mass index (BMI) of initially ...hospitalised patients treated with clozapine (n = 15), olanzapine (n = 15), and risperidone (n = 15) were prospectively monitored on a weekly basis for the first 6 weeks. Different clinical risk factors were tested for their association with weight gain in the three groups. All three groups experienced significant weight gain between baseline and endpoint (p < 0.0001). For all weight measures, planned comparisons were all significant between olanzapine vs. clozapine and risperidone, respectively. Average weight gain was significantly higher for the olanzapine group (mean = 4.6 kg, SD = 1.9) than for the risperidone (mean = 2.8 kg, SD = 1.3) and clozapine (mean = 2.5 kg, SD = 2.9) groups. Olanzapine and risperidone, but not clozapine, caused a disproportionately higher weight gain in children and adolescents in comparison to adults.
There are developmental and age-dependent differences in the pharmacokinetics and the pharmacodynamics of drugs in children and adolescents. Therefore, there is a need to carry out standardised ...studies to find out therapeutic ranges of plasma/serum concentrations in psychopharmacotherapy of children and adolescents. The aim of this prospective study was to examine the relationship between quetiapine serum concentration, treatment response, and side effects in a clinical setting to elucidate the age-specific therapeutic range of quetiapine in adolescents.
Over a period of two years, therapeutic drug monitoring (TDM) was routinely performed in 21 adolescents (mean age was 15.9+/-1.5 years, 57% male) with psychotic disorders according to the guidelines of the AGNP TDM expert group. The psychopathology was assessed by using the Clinical Global Impression Scale (CGI) and the Brief Psychiatric Rating Scale (BPRS). Side effects were assessed by using the Dose Record and Treatment Emergent Symptom Scale (DOTES). Trough quetiapine concentrations were determined under steady state conditions after multiple-dose regimes (median 600 mg/day; range 100-800 mg/day).
There was a marked variability of the serum concentrations, ranging from 19-877 ng/ml. 40.8% of the determined values were below and 24.5% above the therapeutic range (70-170 ng/ml) recommended for adults. None of the patients had severe side effects. We found a weak correlation between dose and serum concentration of quetiapine and no relationship between serum concentration and treatment response.
There are several limitations of this study, and our results should therefore be interpreted with caution. Notwithstanding, differences in the ontogenesis of pharmacokinetics and pharmacodynamics may be the reason for the difference in the relationship between blood concentrations and therapeutic response to psychopharmaca in children, adolescents and adults. Further studies using larger samples, baseline assessment of psychopathology, definition of the treatment interval and investigation of clinically relevant interactions with various co-medications are warranted to improve the limitations of this pilot study.
The aim of this prospective naturalistic study was to examine for the first time the relationship between dosage, serum concentration and clinical outcome in children and adolescents with ...impulsive-aggressive symptoms during risperidone therapy.
Steady state trough serum concentrations of risperidone and 9-hydroxyrisperidone (the active moiety) were measured in 103 subjects. The therapeutic effect was assessed by the clinical global impression improvement subscale and side effects by the Udvalg for Kliniske Undersogelser-side effect rating scale.
We found a linear relationship between the risperidone dose and the serum concentration of the active moiety (Spearman rho=0.53) and no correlation between the serum concentration and either the therapeutic effect or side effects. There was no effect of gender and co-medication.
This study has the typical limitations of naturalistic studies, therefore our results should be interpreted with caution. Based on the serum concentrations at the therapeutically effective dose range (0.25-1.5 mg/day) we obtained first information on a possibly appropriate therapeutic serum range for the risperidone treatment of children and adolescents with impulsive-aggressive symptoms. Further studies with greater sample sizes are needed to validate our results and to examine the influence of genetic polymorphisms on the serum concentration of risperidone.
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