The AGNP-TDM expert group consensus guidelines: therapeutic drug monitoring in psychiatry

Therapeutic Drug Monitoring (TDM) is a valid tool to optimise pharmacotherapy. It enables the clinician to adjust the dosage of drugs according to the characteristics of the individual patient. In psychiatry, TDM is an established procedure for lithium, some antidepressants and antipsychotics. In spite of its obvious advantages, however, the use of TDM in everyday clinical practice is far from optimal. The interdisciplinary TDM group of the Arbeitsgemeinschaft fur Neuropsychopharmakologie und Pharmakopsychiatrie (AGNP) has therefore worked out consensus guidelines to assist psychiatrists and laboratories involved in psychotropic drug analysis to optimise the use of TDM of psychotropic drugs. Five research-based levels of recommendation were defined with regard to routine monitoring of plasma concentrations for dose titration of 65 psychoactive drugs: (1) strongly recommended, (2) recommended, (3) useful, (4) probably useful and (5) not recommended. A second approach defined indications to use TDM, e. g. control of compliance, lack of clinical response or adverse effects at recommended doses, drug interactions, pharmacovigilance programs, presence of a genetic particularity concerning the drug metabolism, children, adolescents and elderly patients. Indications for TDM are relevant for all drugs either with or without validated therapeutic ranges. When studies on therapeutic ranges are lacking, target ranges should be plasma concentrations that are normally observed at therapeutic doses of the drug. Therapeutic ranges of plasma concentrations that are considered to be optimal for treatment are proposed for those drugs, for which the evaluation of the literature demonstrated strong evidence. Moreover, situations are defined when pharmacogenetic (phenotyping or genotyping) tests are informative in addition to TDM. Finally, practical instructions are given how to use TDM. They consider preparation of TDM, analytical procedures, reporting and interpretation of results and the use of information for patient treatment. Using the consensus guideline will help to ensure optimal clinical benefit of TDM in psychiatry.

High dose vitamin E therapy in amyotrophic lateral sclerosis as add-on therapy to riluzole: results of a placebo-controlled double-blind study

Increasing evidence has suggested that oxidative stress may be involved in the pathogenesis of amyotrophic lateral sclerosis (ALS). The antioxidant vitamin E (alpha-tocopherol) has been shown to slow down the onset and progression of the paralysis in transgenic mice expressing a mutation in the superoxide dismutase gene found in certain forms of familial ALS. The current study, a double blind, placebo-controlled, randomised, stratified, parallel-group clinical trial, was designed to determine whether vitamin E (5000 mg per day) may be efficacious in slowing down disease progression when added to riluzole.

METHODS

160 patients in 6 German centres with either probable or definite ALS (according to the El Escorial Criteria) and a disease duration of less than 5 years, treated with riluzole, were included in this study and were randomly assigned to receive either alpha-tocopherol (5000 mg per day) or placebo for 18 months. The Primary outcome measure was survival, calculating time to death, tracheostomy or permanent assisted ventilation, according to the WFN-Criteria of clinical trials. Secondary outcome measures were the rate of deterioration of function assessed by the modified Norris limb and bulbar scales, manual muscle testing (BMRC), spasticity scale, ventilatory function and the Sickness Impact Profile (SIP ALS/19). Patients were assessed at entry and every 4 months thereafter during the study period until month 16 and at a final visit at month 18. Vitamin E samples were taken for compliance check and Quality Control of the trial. For Safety, a physical examination was performed at baseline and then every visit until the treatment discontinuation at month 18. Height and weight were recorded at baseline and weight alone at the follow-up visits. A neurological examination as well as vital signs (heart rate and blood pressure), an ECG and VEP's were recorded at each visit. Furthermore, spontaneously reported adverse experiences and serious adverse events were documented and standard laboratory tests including liver function tests performed. For Statistical Analysis, the population to be considered for the primary outcome measure was an "intent-to-treat" (ITT) population which included all randomised patients who had received at least one treatment dose (n = 160 patients). For the secondary outcome measures, a two way analysis of variance was performed on a patient population that included all randomised patients who had at least one assessment after inclusion.

RESULTS

Concerning the primary endpoint, no significant difference between placebo and treatment group could be detected either with the stratified Logrank or the Wilcoxon test. The functional assessments showed a marginal trend in favour of vitamin E, without reaching significance.

CONCLUSION

Neither the primary nor the secondary outcome measures could determine whether a megadose of vitamin E is efficacious in slowing disease progression in ALS as an add-on therapy to riluzol. Larger or longer studies might be needed. However, administration of this megadose does not seem to have any significant side effects in this patient population.

Neuromelanin inhibits enzymatic activity of 26S proteasome in human dopaminergic SH-SY5Y cells

Recently, impairment of the ubiquitin-proteasome system is suggested to be responsible for the neuronal death in ageing and Parkinson's disease. The specific degeneration of dopamine neurons containing neuromelanin (NM) suggests that NM itself may be involved in the cellular dysfunction and death, even though the direct link has never been reported. We examined the effects of NM isolated from the human substantia nigra on the proteasome activity in human dopaminergic SH-SY5Y cells. NM reduced the activities of 26S proteasome, as shown in situ using a green fluorescent protein homologue targeted to 26S proteasome and also in vitro using ubiquitinated lysozyme as a substrate. However, NM did not affect 20S proteasome activity in vitro. NM reduced the amount of PA700 regulatory subunit of 26S proteasome, but did not affect that of alpha- and beta-subunits of 20S proteasome. These results suggest that NM may inhibit the ubiquitin-26S proteasome system, and determine the selective vulnerability of dopamine neurons in ageing and related disorders.

Therapeutic monitoring of psychotropic drugs: an outline of the AGNP-TDM expert group consensus guideline

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.

Consequences of a single short lasting cerebral oligemia and the influence of iron injected into the substantia nigra or in the ventrolateral striatum of the rat. Trigger of Parkinson?s disease pathogenesis?

One BCCA-phase (bilateral clamping of carotid arteria) leads to an extensive release of striatal dopamine with a subsequent formation of free radicals (Heim et al., 200b). Early investigations did not show histological damage to cerebral structures after 24 and 60 min duration of a BCCA phase (Melzacka et al., 1994). The study here turned out that oligemic damage and an increase in iron (FeCl3) concentration in the ventral striatum was responsible for most of the defective performance of the animals investigated. Striatal damaged animals were unable to correct their deficient performance to the same extent as was possible for animals which had been damaged through BCCA and FeCl3 in the substantia nigra. Furthermore it turn out that with the use of a comprehensive behaviour profile which was able to gather 22 parameters simultaneously, 15 of these parameters did not correspond in the performance of the controls already after BCCA alone. Since during the ageing process, pathological effects may occur in vulnerable structures not only from disturbances to cerebral blood-perfusion but also from enrichment of iron in vulnerable structures (Connor, 1992) the question arose whether this situation did not reveal pathological mechanisms that might triggered the early symptoms of Parkinson's disease.

Transmission disequilibrium studies in children and adolescents with obsessive-compulsive disorders pertaining to polymorphisms of genes of the serotonergic pathway

Pharmacological and challenge study data showed an involvement of the serotonergic system in the development of obsessive-compulsive disorder (OCD). We studied transmission disequilibrium of polymorphisms in three candidate genes of the serotonergic pathway in 64 trios comprising patients with early onset OCD and both of their parents. Polymorphisms of the following genes were studied: tryptophan hydroxylase 1 (rs1800532), serotonin transporter (polymorphism in the promoter region; 5-HTTLPR) and the serotonin 1 B receptor (rs6296). This is, to our knowledge, one of the first family based association studies pertaining to children and adolescents with OCD. We did not detect transmission disequilibrium of the investigated polymorphisms in OCD. Hence, these polymorphisms do not play a major role in the genetic predisposition to early onset OCD.

Effects of secretin on extracellular amino acid concentrations in rat hippocampus

In 1998, Horvath et al. (1998) observed a marked improvement in speech, eye contact, and attention in autistic children five weeks after treatment with secretin, which ocurred in the course of an endoscopic investigation. Since autism is hypothesized to be a hypoglutamatergic disorder we investigated the in vivo effects of secretin on extracellular amino acids in the rat brain. Studies were carried out on freely moving rats with microdialysis probes in the hippocampus. Amino acids were examined using tandem mass spectroscopy and HPLC/fluorometric detection. Following secretin injection (8.7 microg/kg i.p.), considerable increases in microdialysate glutamate and gamma-aminobutyric acid (GABA) levels were observed; other amino acids were not affected. The observed increased microdialysate concentrations of glutamate and GABA following secretin application may explain the results of the Horvath study.

The N-methyl-D-aspartate antagonist memantine retards progression of Huntington’s disease

According to the excitotoxicity hypothesis, neurotoxicity due to glutamate is regarded as potential factor in the progredient neurodegeneration of Huntington's disease (HD). Memantine, as a glutamate receptor antagonist, should counteract this mechanism. Its effectiveness (up to 30 mg/day) with regard to retardation of progression was thus examined in 27 HD patients in a two year, open and multicentre trial. The results suggest that memantine treatment of HD may be useful in terms of retardation of the progression of the disorder.

Coenzyme Q10 serum levels in Huntington's disease

Mitochondrial dysfunction contributes to the neurodegenerative process in Huntington's disease (HD). Coenzyme Q10 (CoQ10) enhances mitochondrial complex I activity and may therefore provide a therapeutic benefit in HD. We compared serum CoQ10 levels of previously untreated-and treated HD patients with those of healthy controls. CoQ10 did not significantly (ANCOVA F(dF 2, dF 55) = 2.57; p=0.086) differ between all three groups. However, the post hoc analysis showed no significant (p = 0.4) difference between treated HD patients ([CoQ10]: 88.12 [mean]+/-24.44 [SD], [range] 48.75-146.32 [pg/million platelets]) and controls (93.71+/-20.72, 65.31-157.94), however previously untreated HD patients (70.10+/-21.12, 38.67-106.14) had marked (p = 0.051) lower CoQ10 results than treated HD patients and controls (p = 0.017). Our results support that CoQ10 supplementation in HD patients may reduce impaired mitochondrial function in HD.

Quantitation of 5HT3 receptors in forebrain of serotonin transporter deficient mice

Mice deficient in the serotonin transporter (5HTT) display highly elevated extracellular 5HT levels. 5HT exerts ist effects via at least fourteen different cloned 5HT receptors located pre- and postsynaptically. In contrast to the other 5HT receptors, the 5HT3 receptor is a ionotropic receptor with ligand-gated cation channel function. Since G-protein-coupled 5HT receptors show extensive adaptive changes in 5HTT-deficient mice, we investigated whether 5HT3 receptors are also altered in these mice. Using quantitative autoradiography, we found that 5HT3 receptors are upregulated in frontal cortex (+46%), parietal cortex (+42%), and in stratum oriens of the CA3 region of the hippocampus (+18%) of 5HTT knockout mice. Changes in 5HT3 receptor mRNA expression, as determined by quantitative in situ hybridisation, were less pronounced. The adaptive changes of 5HT3 receptor expression constitute a part of the complex regulatory pattern of 5HT receptors in 5HTT knockout mice.

Dopamine receptor agonists in the therapy of Parkinson?s disease

Forty years after its introduction by Birkmayer and Hornykiewicz (1961), L-DOPA-based therapy of Parkinson's disease remains the central pillar in the management of the disorder. Nevertheless, it is not unproblematic, and dopamine receptor agonists play increasingly important roles in antiparkinsonian therapy. Pharmacological and pharmacokinetic properties of these agents are briefly reviewed and followed by a detailed summary of available literature concerning controlled trials in Parkinson's disease. It is concluded that there is little unequivocal evidence to suggest that any of the major dopamine receptor agonists should be invariably preferred in the therapy of Parkinson's disease; their application must be based on the needs and responses of individual patients.

The dopamine receptor agonist lisuride attenuates iron-mediated dopaminergic neurodegeneration

Many dopamine agonists used in the treatment of Parkinson's disease are suggested to be potentially neuroprotective. On the basis of its structure, the dopamine agonist lisuride may share this characteristic. In the current study discrete asymptomatic lesions were produced by the injection of iron-laden neuromelanin into the rat substantia nigra and the animals treated with lisuride to determine the protective potential of this substance. Two treatment regimes were utilised. In the neuroprotective protocol, animals were treated with 0.1 mg.kg(-1) lisuride twice daily 3 days prior to, and 7 days following, the iron lesion. In the neurorescue protocol, the animals received 0.1 mg.kg(-1) lisuride twice daily for 1 week beginning on the fourth day post surgery. Eight weeks post surgery, tyrosine hydroxylase-positive neurons surrounding the injection site (33% of total nigral volume) were counted. Dopamine neuron number in iron-lesioned animals was reduced to 50% of that in vehicle-injected animals. The absence of motoric disturbances or a striatal dopamine deficit in these animals suggests a subclinical dopaminergic lesion. Dopamine neuron number in the quantified area in sham-injected animals receiving lisuride or iron-lesioned animals receiving lisuride in both the neuroprotection and neurorescue groups were not significantly reduced. These results suggest that lisuride can protect neurons against iron-induced cell death and might thus be neuroprotective in Parkinson's disease.

The neuromelanin of human substantia nigra: structure, synthesis and molecular behaviour

The pigmented neurons of the substantia nigra (SN) are typically lost in Parkinson's disease: however the possible relationship between neuronal vulnerability and the presence of neuromelanin (NM) has not been elucidated. Early histological studies revealed the presence of increasing amounts of NM in the SN with aging in higher mammals, showed that NM granules are surrounded by membrane, and comparatively evaluated the pigmentation of SN in different animal species. Histochemical studies showed the association of NM with lipofuscins. However, systematic investigations of NM structure, synthesis and molecular interactions have been undertaken only during the last decade. In these latter studies, NM was identified as a genuine melanin with a strong chelating ability for iron and affinity for compounds such as lipids, pesticides, and MPP+. The affinity of NM for a variety of inorganic and organic toxins is consistent with a postulated protective function for NM. Moreover, the neuronal accumulation of NM during aging, and the link between its synthesis and high cytosolic concentration of catechols suggests a protective role. However, its putative neuroprotective effects could be quenched in conditions of toxin overload.

Arguments for the use of dopamine receptor agonists in clinical and preclinical Parkinson's disease

On the basis of experimental studies which have demonstrated deleterious effects of L-DOPA (L-3,4-dihydroxyphenylalanine) in vivo and in vitro, it has been suggested that L-DOPA itself may contribute to the progression of Parkinson's disease. This hypothesis is, for many clinicians, the rationale for postponing the employment of and reducing the applied dosage of L-DOPA and for beginning therapy with dopamine receptor agonists or the monoamine oxidase type B (MAO-B) inhibitor selegiline. Furthermore, clinical studies have demonstrated that early treatment with dopamine receptor agonists is associated with a lower incidence of motor fluctuations and dyskinesia. Dopamine receptor agonists exert their symptomatic effect by directly activating dopamine receptors, bypassing the presynaptic synthesis of dopamine and the degenerating nigro-striatal dopaminergic system. They can thus also be of benefit late in the therapy of the disorder. In addition, the pharmacological profile of dopamine receptor agonists suggests a possible neuroprotective effect. This paper reviews briefly the pharmacology of dopamine receptor agonists and basic knowledge concerning the dopamine receptor stimulation which underlies their therapeutic effect. Preclinical approaches for demonstrating neuroprotective effects and their clinical relevance are also discussed.

Dopamine receptor agonists in current clinical use: comparative dopamine receptor binding profiles defined in the human striatum

The aim of this study was to compare dopamine receptor binding affinities of all currently approved dopamine receptor agonist treatments for Parkinson's disease (PD) in human brain tissue. Alpha-dihydroergocryptine and lisuride displayed higher comparative affinities (Ki=35.4 and 56.7 nM, respectively) for D1 receptors, than the D1/D2 dopamine agonist pergolide (Ki=447 nM). The second generation non-ergot dopamine receptors agonists pramipexole and ropinirole demonstrated no affinity for D1 receptors at concentrations up to 10(-4) M. The ergoline dopamine agonists cabergoline and lisuride displayed the highest affinities for the D2 receptor (Ki=0.61 and 0.95 nM, respectively). Surprisingly, the second generation non-ergot dopamine receptors agonists pramipexole and ropinirole only weakly inhibited binding to D2 receptors (Ki=79.5 and 98.7 microM, respectively using [3H]spiperone). Interestingly we also found that the affinities of cabergoline (Ki=1.27 nM), lisuride (Ki=1.08 nM) and pergolide (Ki=0.86 nM) for the D3 receptor subtype were comparable to that of pramipexole (Ki=0.97 nM). The present results thus support the hypothesis that the antiparkinsonian effect of dopamine receptor agonists is mediated by a more complex interactions with dopamine receptor subtypes than currently believed.

5-HT2A promoter polymorphism -1438G/A in children and adolescents with obsessive-compulsive disorders

Positive association between obsessive compulsive disorder (OCD) and the A-allele of the 5-HT(2A)-receptor promoter polymorphism -1438G/A has recently been reported in adults. We performed an association analysis of this polymorphism in 55 children and adolescents with OCD and in 223 controls consisting of unrelated students. We detected statistically significant differences in genotype (P < 0.05) and allele frequencies (P < 0.05) between individuals with OCD and controls. In this, to our knowledge, first association study based on children and adolescents with OCD, we confirm an association of the A-allele of the 5-HT2A receptor gene with OCD.

[Current preclinical findings on substances against Parkinson's disease]

Striatal dopamine loss provides the premise for dopamine substitution in palliative therapy for Parkinson's disease (PD). This includes firstly L-dopa (L-3,4-dihydroxyphenylalanine, levodopa) and dopamine receptor agonists. Although this therapy has been demonstrated to induce marked clinical improvement in the early stages of PD, its use is limited in the long term by a loss of efficacy. In addition, most patients develop the "long-term L-dopa syndrome," which is characterized by a decrease in the control of Parkinsonian symptoms (decrease in the drug's effect) and the appearance of certain motor disturbances including episodes of akinetic freezing, debilitating dyskinesias, and on-off periods. The aim in developing new drugs is to achieve better therapeutic approaches. In the case of PD, the main strategies are to develop (1) alternatives to L-dopa therapy for alleviating the striatal dopamine deficit while avoiding or retarding the long-term L-dopa syndrome, (2) antidyskinetic approaches, and (3) neuroprotective drugs aimed at causal treatment of PD which is able to preserve the remaining dopaminergic neurones and to halt or at least retard the disease process. This article reviews new approaches for the treatment of PD and presents findings from our studies using a new experimental in vivo model of PD.

Relationships between various behavioural abnormalities and nigrostriatal dopamine depletion in the unilateral 6-OHDA-lesioned rat

While rotational asymmetry is used as a characteristic behavioural sign of striatal dopamine (DA) loss in unilateral animal models of Parkinson's disease (PD), there is relatively little analysis of how other common behavioural deficits relate to nigrostriatal DA depletion. We analysed the relationships between several deficits induced by unilateral 6-OHDA lesions and striatal neurochemistry, as well as neuronal loss in the dopaminergic substantia nigra (SN). Behaviour was evaluated from before until 6 weeks after surgery and abnormalities appeared in body axis, head position and sensorimotor performance as well as apomorphine-induced rotation. As expected, rotational behaviour correlated with striatal DA loss and not with other striatal neurotransmitters measured. Similar observations were found for sensorimotor deficits ('disengage task'). Both deficits were observed in rats with >70% loss of TH+ nigral neurons and >80% loss of striatal DA. Additional postural abnormalities appeared with mean losses of 87% of nigral DA neurons and 97% striatal DA, consistent with observations in patients with advanced PD. The data show that the repertoire of behavioural abnormalities manifested by hemiparkinsonian rats relate directly to the degree of nigrostriatal DA loss and, therefore, mimic features of PD. Analysis of such behaviours are relevant for chronic therapeutic studies targeting PD.

The relevance of preclinical studies for the treatment of Parkinson's disease

An essential element of pharmaceutical development, defined as the period between the discovery of a new agent and its market release, is provided by the "preclinical studies". They consist of the in vitro and in vivo studies performed before examination of the agent in human subjects. Regulatory authorities prescribe specific requirements regarding the nature and number of preclinical studies. In the present paper, we discuss the relevance of these studies for the treatment of Parkinson's disease (PD) on the basis of three examples: the L-DOPA ( L-3,4-dihydroxyphenylalanine, levodopa) story; the development of selegiline as a palliative and neuroprotective drug; and the safety concerns regarding tolcapone, an inhibitor of central and peripheral catechol-O-methyltransferase (COMT).