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BACKGROUND Guanfacine, a selective α2A-adrenoreceptor agonist, is a second-line medication for treating children and adolescents with attention-deficit/hyperkinetic disorder (ADHD). The dosage administered as milligram per body weight to balance the potential benefits and risks of treatment. Therapeutic drug monitoring (TDM) is useful for identifying a patient's therapeutic window to optimize individual drug dosing and reduce the risk of adverse drug reactions. However, in children and adolescents, intravenous sample collection is especially stressful and thus remains a primary challenge, restricting the use of TDM. Therefore, evaluating alternative specimens to facilitate TDM is a worthwhile task. The aim of this study was to assess the feasibility of using oral fluid for TDM of guanfacine in children and adolescents. METHODS Herein, nine patients (median age 8.1 years; 6 boys, 3 girls) undergoing treatment with guanfacine were included. Simultaneously collected oral fluid and serum samples were deproteinized using methanol containing a stable isotope-labeled internal standard prior to the determination of guanfacine by liquid chromatography-tandem mass spectrometry. Pearson's correlation and paired t-test were used for statistical analysis. RESULTS The mean serum guanfacine concentration was three times higher than that detected in oral fluid (7.47 ng/mL vs. 2.36 ng/mL; t (8) = 5.94; P < 0.001). A strong positive linear correlation (r = 0.758, P = 0.018) was identified between oral fluid and serum concentrations. A strong but non-significant negative correlation (r = -0.574, P = 0.106) was detected between the oral fluid pH and oral fluid-to-serum concentration ratio. CONCLUSIONS The strong correlation between oral fluid and serum concentration and the probable small effect of oral fluid pH on oral fluid-to-serum concentration ratio supports guanfacine as a suitable candidate for TDM in oral fluid.

PURPOSE Therapeutic drug monitoring is highly recommended for children and adolescents treated with neurotropic/psychotropic drugs. For interpretation of therapeutic drug monitoring results, drug concentrations (C/D) expected in a "normal" population are helpful to identify pharmacokinetic abnormalities or nonadherence. Using dose-related concentration (DRC) factors obtained from pharmacokinetic data, C/D ranges expected under steady state can be easily calculated by multiplication of DRC by the daily dose. DRC factors, however, are defined only for adults so far. Therefore, it was the aim of this study to estimate DRC factors for children and adolescents and compare them with those of adults. METHODS To obtain pharmacokinetic data (apparent total clearance of drugs from plasma after oral administration, elimination half-life, area under the curve, and minimum serum drug concentration) from children and adolescents treated with psychotropic drugs, a systematic review of published literature was performed, and the pharmaceutical companies that market these drugs were contacted. Available information was used for the calculation of DRC factors. RESULTS Fourteen of 26 drugs had similar DRC factors to those reported for adults; 8 and 4 had higher and lower factors, respectively. The antidepressants citalopram, clomipramine, fluvoxamine, and imipramine and the antipsychotics haloperidol and olanzapine showed higher DRC factors than those calculated for adults. The DRC factors of amphetamine and methylphenidate were higher in children (6-12 years) but not in adolescents (13-17 years). On the contrary, the antipsychotic quetiapine and the mood-stabilizing antiepileptics lamotrigine, oxcarbazepine, and topiramate showed lower DRC factors than those calculated for adults. CONCLUSIONS It was concluded that concentrations of neuroactive/psychoactive drugs to be expected in blood for a given dose may differ between adults and children or adolescents, most probably owing to age-dependent differences in the elimination of these drugs.

BACKGROUND The relationship between daily dose, serum concentrations, and clinical outcomes of olanzapine as well as the influencing factors thereof in children and adolescents treated for different psychiatric disorders were investigated in daily clinical practice. In addition, it was examined whether the current recommended therapeutic range (TR) for adult patients with psychotic disorders is valid for minors. METHODS The Competence Network for Therapeutic Drug Monitoring (www.tdm-kjp.com) routinely collects demographic and clinical outcome data as well as serum concentrations of children and adolescents treated with psychotropics. The therapeutic effect is documented using the Clinical Global Impression Scale subscale for Global Improvement. Adverse drug reactions (ADRs) are assessed using the Udvalg for Kliniske Undersogelser-Side Effect Rating Scale. RESULTS One hundred fifteen patients (mean age = 15.9 years; range = 10.4-18.8 years; 40.9% male) were included. The majority (72.1%) was cotreated with other psychotropic drugs. A positive medium linear relationship (r = 0.619; P < 0.001) between olanzapine dose (mean = 11.64 mg/d) and serum concentration (mean = 35.65 ng/mL) was found with a marked interindividual variability of serum concentrations. Neither relationship between olanzapine serum concentration and treatment response (clinical benefit documented in 80%) nor ADRs (documented in 53.3%, in 7.5% judged as severe) was detected. Most of the patients with psychotic and eating disorders (68.8% and 71.8%, respectively) had an olanzapine serum concentration within the TR suggested for adults. CONCLUSIONS There are several limitations of this study because of the naturalistic design, and our results should therefore be interpreted with caution. As most of the patients showed a clinical benefit under olanzapine concentrations within the TR for adults and only a minority had severe ADRs, it is reasonable to conclude a similar TR for children, adolescents, and adults.

TDM of psychotropic drugs is widely used, but there is little consensus regarding its optimal use in the clinical context. This prompted a multidisciplinary group comprised of clinical biochemists, clinical pharmacologists, and psychiatrists of the AGNP (Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie) to provide a consensus guideline. This will allow clinical psychiatrists, practitioners, and laboratory directors involved in psychopharmacotherapy to optimize TDM of antidepressants, antipsychotics, and opioid substituents. Recommendations are also given on the combined use of TDM and pharmacogenetic tests.

The acetylenic selective monoamine oxidase (MAO) type B suicide inhibitor selegiline (previously called L-deprenyl) has proved to be a useful adjuvant to levodopa therapy and monotherapy of Parkinson's disease (PD). Selegiline is readily absorbed from the gastrointestinal tract and rapidly enters the brain and spinal cord following oral administration. The drug binds to brain regions with a high MAO-B content, such as the thalamus, the striatum, the cortex, and the brainstem. It is extensively metabolized in humans, mainly in the liver, to form desmethylselegiline and methamphetamine, which are further metabolized to amphetamine. Eighty-six percent of the 10-mg dose was recovered in the urine within 24 hours. These data suggest that accumulation of metabolites does not occur. Although not all features of its anti-PD action are known, studies using brain obtained at autopsy from patients who had been treated with 10 mg of selegiline showed that selective inhibition of MAO-B, with the concomitant increase of phenylethylamine and dopamine (DA) but not of serotonin or noradrenaline, in the basal ganglia may be regarded as its mode of action. The protective effects afforded by selegiline in PD, resulting in a delayed need for levodopa therapy, have been variously interpreted in terms of the involvement of an endogenous neurotoxin or an oxygen free radical mechanism (oxidative stress) in the development of PD. However, although many different hypotheses have been advanced and recent findings have emphasized the significance of oxidative stress in the pathogenesis of the disease, the cause of chronic nigral cell death and the underlying mechanisms remain, as yet, elusive. Therefore, there is no clear knowledge regarding an understanding of the reported effects of selegiline on the progression of PD. Nevertheless, selegiline might be expected to have some protective effects in reducing the production of potentially neurotoxic compounds resulting in the MAO-catalyzed oxidation of DA. In addition, some evidence suggests both an indirect (via induction of radical-scavenging enzymes) and a direct antioxidant function for selegiline. On the other hand, the reported protective effect of selegiline might also receive a contribution from the diminished potentiation of the N-methyl-D-aspartate receptor by the polyamine binding site. Finally, the effects of selegiline might also involve preventing, or perhaps to some extent reversing, the decline in resistance normally associated with cellular aging because of its neurotrophine-like action. However, even in the early clinical stage of PD, the sequence of events leading to nigral cell death may be too far advanced for selegiline to exhibit its maximum potential.

The distribution of nitric oxide synthase (NOS) within the brain of the common marmoset, a non-human primate species, was investigated using the [3H]L-citrulline formation assay and Western blot analysis. No hemispheric asymmetry of specific NOS activity was shown. The highest levels of NOS were found in the putamen and caudate nucleus--more than twice those in the cortex and the cerebellum, the brain regions with the lowest activities. The regional distribution pattern was similar to that in the ferret brain and contrasted to that in the mouse and bovine brain. Analysis of NOS catalytic activities in subcellular fractions revealed marked differences in the subcellular localization. Neuronal NOS accounted mainly for the measured catalytic activity in the brain. Differences in the regional distribution pattern of brain NOS activity among species may be indicative of diversities in the functional role of nitric oxide and NOS in mammals.