Central D2-dopamine receptor occupancy in schizophrenic patients treated with antipsychotic drugs

Using positron emission tomography and the carbon 11-labeled ligand raclopride, central D2-dopamine receptor occupancy in the putamen was determined in psychiatric patients treated with clinical doses of psychoactive drugs. Receptor occupancy in drug-treated patients was defined as the percent reduction of specific carbon 11-raclopride binding in relation to the expected binding in the absence of drug treatment. Clinical treatment of schizophrenic patients with 11 chemically distinct antipsychotic drugs (including both classic and atypical neuroleptics such as clozapine) resulted in a 65% to 85% occupancy of D2-dopamine receptors. In a depressed patient treated with the tricyclic antidepressant nortriptyline, no occupancy was found. The time course for receptor occupancy and drug levels was followed after withdrawal of sulpiride or haloperidol. D2-dopamine receptor occupancy remained above 65% for many hours despite a substantial reduction of serum drug concentrations. In a sulpiride-treated patient, the dosage was reduced in four steps over a nine-week period and a curvilinear relationship was demonstrated between central D2-dopamine receptor occupancy and serum drug concentrations. The results demonstrate that clinical doses of all the currently used classes of antipsychotic drugs cause a substantial blockade of central D2-dopamine receptors in humans. This effect appears to be selective for the antipsychotics, since it was not induced by the antidepressant nortriptyline.

Decreased tyrosine transport in fibroblasts from schizophrenic patients

Amino acid transport was studied in vitro in cultured fibroblasts from schizophrenic patients and controls. An isolated decrease in the transport capacity (Vmax) for tyrosine was observed in cells from the patients. The Km for tyrosine transport was unaffected. The kinetic parameters for phenylalanine, tryptophan, leucine and glycine transport did not differ between patients and controls. Competitive inhibition among the amino acids transported by the L-system and its exchange properties were normal in cells from the patients. No differences in intracellular levels of amino acids between patients and controls were observed. The decreased tyrosine transport in the cells from schizophrenic patients appears not to be related to any known amino acid transport system and may reflect a more general defect in plasma membrane function in schizophrenia.

Muscle biopsy findings, conduction velocity and refractory period of single motor nerve fibres in schizophrenia

Eight untreated and eight neuroleptic treated male schizophrenic patients were studied. Light and electron microscopical analysis of muscle biopsies from the anterior tibial muscle showed a spectrum of pathological changes without significant quantitative or qualitative differences between the two groups. The changes included atrophic fibres, central nuclei, "moth-eaten fibres", "ring fibres", fibre splitting and subsarcolemmal and intermyofibrillar glycogen droplets. Electrophysiological investigation of single motor unit properties showed impaired peripheral impulse propagation in both patient groups while the conduction velocity and the refractory period of single motor nerve fibres were within the same range as in healthy subjects. In conclusion there are neuromuscular abnormalities in schizophrenic patients which cannot be attributed to medication or drug abuse.

Regional brain glucose metabolism in drug free schizophrenic patients and clinical correlates

Regional brain glucose metabolism was investigated in healthy volunteers (n = 10) and in drug free schizophrenic patients (n = 20). The metabolism was determined by positron emission tomography (PET) with 11C-glucose as the tracer. Diagnosis of schizophrenia was made according to RDC and DSM III. Eight patients had their first psychotic episode, four patients had a subchronic course and eight patients had a chronic course with an exacerbation of their illness. Computed tomography (CT) of the brain were made in all the subjects. Regions of interest (n = 35) were drawn on displayed CT images and the marked regions were transferred to the corresponding slice of the PET examination. The PET investigation was made in a dimly lit, quiet room with the eyes of the subject covered. The time course of the 11C-glucose uptake was measured by a four ring PET scanner (PC-384-7B). Metabolic rates of glucose varied greatly among the schizophrenic patients investigated. The variance was significantly greater than that of the controls in most regions. Decreases in mean levels of metabolic rates were related to patients with subchronic or chronic courses. Changes in metabolism were not related to previous duration of neuroleptic treatment of the patients. Left-right asymmetries were found in the temporal lobe (area 22) and the basal frontal cortex (area 11), the metabolic rates of the patients being lower on the left side compared to the controls. Asymmetry of the metabolic rate of the amygdala in hebephrenic patients was the opposite of that found in paranoid patients and controls. Negative correlations between regional metabolic rates and autistic or negative symptoms were found. Thus, the lower the metabolic rate was, the more autistic the patient. Metabolic rates were not correlated to atrophic changes of the brain. No basis for a specific alteration in frontal cortical metabolism of schizophrenics was obtained. Changes in regional metabolic rates in schizophrenia are suggested to reflect disturbances in more general mechanisms which are of importance in neuronal function.

Altered relationships between metabolic rates of glucose in brain regions of schizophrenic patients

Regional brain glucose metabolism was studied with positron emission tomography (PET) in healthy volunteers (n = 9) and schizophrenic patients (n = 15). The patients were in an acute phase of the disease and drug free. Cerebral metabolic rate with 11C-glucose as the tracer (CMRgl) was determined in both cortical and subcortical structures. In the healthy volunteers significant correlations were found between metabolic rates of some regions, but no relationships were found between CMRgl of limbic cortical areas and that of neocortical or subcortical structures. In the patients, high and significant positive correlations were found between metabolic rates in the neocortical areas, the limbic cortical areas and the subcortical areas. The results indicate differences in the neuronal interplay between regions of healthy and schizophrenic subjects. It is proposed that neuronal systems guiding the specificity and diversity in neuronal functions between different brain regions, are abnormal in schizophrenic patients. Such a disturbance may be the basis for the diversity of psychiatric symptoms in schizophrenics.

The Bücherer-Strecker synthesis of D- and L-(1-11C)tyrosine and the in vivo study of L-(1-11C)tyrosine in human brain using positron emission tomography

The synthesis of D- and L-(1-11C)tyrosine, starting with 11C-cyanide, is reported. DL-(1-11C)Tyrosine was prepared by the Bücherer-Strecker reaction, from carrier added 11C-cyanide with an incorporation of 80% in 20 min. The isolation of the pure D- and L-amino acid isomers from the enantiomeric mixture was accomplished within 15 min by preparative HPLC using a chiral stationary phase and a phosphate buffer as the mobile phase. Typically, the total synthesis time was 50 min (including purification) from end of trapping of 11C-cyanide, with a radiochemical yield of D- and L-amino acid of 40%-60%. The D- and L-(1-11C)tyrosine were both obtained optically pure, with a carrier added specific activity of 0.3-0.5 Ci/mmol and a radiochemical purity better than 99%. The 11C labelled L-tyrosine was used in an in vivo study in the human brain using positron emission tomography (PET).

Zuclopenthixol acetate in Viscoleo--a new drug formulation. An open Nordic multicentre study of zuclopenthixol acetate in Viscoleo in patients with acute psychoses including mania and exacerbation of chronic psychoses

Eighty-three acutely disturbed, psychotic patients were included in an open multicentre study. The aim of the study was to evaluate the clinical effect of zuclopenthixol acetate in Viscoleo (CPT-A). Each patient received from one to four intramuscular injections of CPT-A during the 6-day study period. The duration of action after one injection was between 2 and 3 days and doses from 50 mg to 150 mg were sufficient for most patients. Treatment with CPT-A caused a pronounced and rapid reduction of the psychotic symptoms. At the end of the 6-day test period the mean total score on BPRS in acute non-manic and exacerbated chronic patients was reduced by more than 50 per cent. In acute manic patients the mean total score on BRMS was reduced by 57 per cent already 1 day after injection. Rapidly after the injection of CPT-A a useful short-acting sedation can be expected, but the risk for oversedation even after a second injection is low. The frequency of unwanted effects, including extrapyramidal reactions, was low and the severity of symptoms was most often mild. With a rapid onset of action, a duration of effect of 2 to 3 days, and few and mild side effects, CPT-A offers advantages over the neuroleptic preparations conventionally used in the initial treatment of acutely disturbed, psychotic patients.

Neuropsychological test performance, brain morphological measures and CSF monoamine metabolites in schizophrenic patients

Twenty-three drug-free patients with an acute schizophrenic psychosis were studied by clinical rating scales, neuropsychological tests, computed tomography (CT) of the brain and analysis of monoamine metabolites in the cerebrospinal fluid (CSF). The psychological tests used were the Swedish version of the Wechsler-Bellevue Intelligence scale (WBI) and the Block Design test. The patients' performance in the Block Design test was negatively correlated to the width of the third and lateral ventricles. Test profiles indicative of schizophrenic cognitive impairment and left hemisphere dysfunction correlated significantly with a wide third ventricle, but not with the size of the lateral ventricles. Patients with a test profile indicative of left hemisphere dysfunction also had wider Sylvian fissures than the remaining patients. Neuropsychological test scores did not correlate with the CSF levels of the monoamine metabolites HVA, MHPG and 5-HIAA. Positive psychotic and autistic symptoms did not correlate with psychological test results, monoamine metabolites or with CT measures. The association between neuropsychological impairment and enlargement of the brain ventricles is in line with previous findings indicating that a subgroup of schizophrenic patients may be identified by neuropsychological and morphological methods.

Dexamethasone suppression test in schizophrenic patients before and during neuroleptic treatment

The dexamethasone suppression test (DST) was performed in 21 drug-free schizophrenic patients. The patients satisfied DSM-III and Research Diagnostic Criteria for schizophrenia and were in an acute phase of the disease. In 15 of the patients the DST was repeated after about 5 weeks of treatment with neuroleptics. DST compliance was checked by analysis of dexamethasone concentrations in plasma. In the acute phase 71% (at 04 p.m.) of the patients were nonsuppressors. After neuroleptic treatment the frequency of abnormal responders had decreased to 20%. The decrease in nonsuppressors was not due to alteration of the dexamethasone concentration between the two test occasions. Prolactin levels were markedly increased at the second test occasion compared with the first. There were no significant relationships between cortisol levels, cortisol suppression and prolactin levels. The high frequency of nonsuppressors among schizophrenic patients in the acute phase of the disease indicates that acute stress may be a confounding factor in the outcome of DST.

Effect of sulpiride on vigilance in healthy subjects

The effects of the antipsychotic drug sulpiride on vigilance, as measured by choice reaction time and critical flicker fusion, and on heart-rate and skin conductance, were studied in healthy volunteers (n = 6). The measurements were carried out 4 and 28 h after oral and i.v. administration of 100 mg sulpiride and during placebo condition. None of the tests or measurements showed statistically significant differences between the placebo and the active drug condition. The results were related to corresponding serum concentrations of sulpiride, the half-life elimination and the total amount of sulpiride found in the blood. No consistent trends in effects were observed. The results were interpreted as indicating minimal or no effects of sulpiride on the above measures of vigilance and autonomic activation.

Plasma amino acids in relation to cerebrospinal fluid monoamine metabolites in schizophrenic patients and healthy controls

Compared to healthy controls, unmedicated schizophrenic patients had significantly higher plasma concentrations of taurine, methionine, valine, isoleucine, leucine, phenylalanine, and lysine. Except for taurine, these amino acids share the L-transport system for neutral amino acids. In the patients, homovanillic (HVA) acid levels in CSF were decreased and the plasma levels of the amino acids competing with tyrosine and tryptophan for transport into the brain, were all negatively correlated to the CSF concentrations of HVA and 5-HIAA. These findings could be explained by a change in the affinity of the L-system or by a decrease in its overall capacity in schizophrenia. Raised plasma levels of the competing amino acids may limit the brain uptake of tyrosine, leading to a diminished dopamine turnover, and resulting in a compensatory development of supersensitive dopamine receptors.

Effects of sulpiride and chlorpromazine on autistic and positive psychotic symptoms in schizophrenic patients--relationship to drug concentrations

Schizophrenic patients were treated with fixed doses of sulpiride (800 mg/day) or chlorpromazine (CPZ) (400 mg/day) during a period of 8 weeks using a double-blind design. There were 25 patients in each group and all of them fulfilled the Research Diagnostic Criteria (RDC) for schizophrenia. Autistic and psychotic symptoms were rated with subscales developed from the Comprehensive Psychopathological Rating Scale (CPRS). Autistic symptoms were also rated with a subscale of the Nurse's Observation Scale for Inpatient Evaluation (NOSIE). Sulpiride was superior to CPZ in reducing the autistic symptoms. Patients with low concentrations of sulpiride in serum had a better recovery rate from autistic symptoms than those with high concentrations. Both drugs reduced positive psychotic symptoms to the same degree.

Scale construction of the Swedish CPRS version

A sample of 161 schizophrenic and depressive patients were interviewed in a Stockholm hospital to find out whether the Comprehensive Psychopathological Rating Scale construction carried out by Maurer et al. [Int. Pharmacopsychiat. 17: 338-353, 1982] and valid for German-speaking areas could be reproduced with a Swedish-speaking sample. Only the superimposed 2-factor solution resembled, in its factor-structure, that of Maurer et al. (depressive and schizophrenic syndrome). The fact that a 'depressive' syndrome was found instead of a 'manic-depressive' syndrome, is to be attributed to the different sample compositions.

Clinical and biochemical effects of citalopram, a selective 5-HT reuptake inhibitor--a dose-response study in depressed patients

Citalopram is a bicyclic phtalane derivative. In animal experiments, citalopram has been demonstrated to possess a potent and highly selective inhibitory effect on serotonin reuptake. Several studies in man have indicated that citalopram given in daily doses of 40-60 mg has antidepressant properties and few side effects. The present double-blind study investigated the effects of three doses of citalopram (5 mg, 25 mg, and 50 mg) on depressive symptoms and various biochemical variables in 26 depressive patients. A significant reduction of the clinical ratings of depressive symptoms occurred at all dose levels. In endogenously depressed patients, a dose of 25 or 50 mg daily seemed to have the most pronounced antidepressive effect. The side effects were few and not related to dose level. A highly significant decrease in 5-HIAA in the CSF was found. MO-PEG in the CSF was also significantly decreased, while HVA in the CSF was increased. In addition, a significant decrease in the plasma concentrations of valine, leucine, tyrosine, and histidine was found. None of the biochemical effects was dose-dependent. The complex pattern of biochemical effects indicate that the amelioration of depressive symptoms might be related to effects of citalopram on central monoaminergic mechanisms and peripheral amino acid concentrations.

Pharmacokinetics of oral moclobemide in healthy human subjects and effects on MAO-activity in platelets and excretion of urine monoamine metabolites

The plasma concentrations of the MAO-inhibitor moclobemide (Ro 11-1163) were determined in six healthy male subjects after oral (tablets) administration. Effects on MAO activity in platelets and excretion of monoamine metabolites in urine were investigated. The design of the study was a double-blind cross-over study with single oral doses of placebo, 50, 100 and 200 mg of moclobemide. The elimination profile of the drug showed that the half life of the unchanged drug ranged between 1 and 2 h except in one subject with a half-life of about 4 h. The mean bioavailability calculated using flow model concepts was F = 0.43 after 50 mg, F = 0.47 after 100 mg and F = 0.59 after 200 mg. The outlier with a t 1/2 of 4 h was found to have a bioavailability of more than 0.80 after all 3 doses. The slightly increasing bioavailability with higher doses was interpreted as evidence of saturable hepatic first-pass elimination of the drug. MAO activity in platelets was measured before and 2, 6 and 24 h after drug administration. No inhibition of platelet MAO was obtained at any point in time or dose level, as to be expected since moclobemide preferentially inhibits MAO A. Urine excretion of the monoamine metabolites homovanillic acid (HVA), dihydroxyphenylacetic acid (DOP-AC), 3-methoxy-4-hydroxy-phenylglycol (MOPEG) and 5-hydroxyindoleacetic acid (5-HIAA) was followed during 48 h after placebo, 50 and 200 mg of moclobemide. Time but not dose contributed significantly to the variability in excretion of the monoamine metabolites.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino acids in plasma and CSF and monoamine metabolites in CSF: interrelationship in healthy subjects

Plasma and cerebrospinal fluid (CSF) concentrations of amino acids were measured in 65 healthy volunteers (50 men and 15 women). The CSF levels of the monoamine metabolites homovanillic acid (HVA), 3-methoxy-4-hydroxyphenylethylene glycol (MOPEG), and 5-hydroxyindoleacetic acid (5-HIAA) were also determined. Sex differences were observed in both plasma and CSF amino acid levels as well as in the relationship between these concentrations. No significant correlations were observed between the CSF levels of HVA and 5-HIAA, and the concentrations of their precursor amino acids in either plasma or CSF. The MOPEG level in CSF correlated positively with the plasma concentrations of several amino acids.

Relationships between drug concentrations in serum and CSF, clinical effects and monoaminergic variables in schizophrenic patients treated with sulpiride or chlorpromazine

Schizophrenic patients were treated with fixed doses of sulpiride (800 mg) or chlorpromazine (400 mg) during eight weeks using a double-blind design. In order to examine relationships between pharmacokinetic, clinical and biochemical parameters in relation to treatment the following variables were recorded before and 1, 2, 4 and 8 weeks after treatment. Concentrations of sulpiride, CPZ, 7-OH-CPZ, nor1-CPZ were determined in serum and CSF using liquid chromatography and mass fragmentography. Clinical variables were psychotic morbidity and side effects as evaluated by CPRS, NOSIE and side effect ratings. Monoaminergic variables were concentrations of the major cerebral monoamine metabolites, HVA, 5-HIAA and MOPEG in the cerebrospinal fluid as measured by mass fragmentography. Prolactin levels in serum and CSF were measured by radioimmunoassay. During steady state, concentrations of sulpiride in serum varied fourfold between patients and CPZ twentyfold. Drug concentrations in serum and CSF were highly correlated in CPZ-but not in sulpiride-treated patients. Although sulpiride passed into the CSF, transport between serum and CSF was restricted. In the sulpiride group, improvement of psychotic morbidity and HVA elevation in CSF tended to be negatively related to the drug concentrations in serum. Sulpiride-treated patients with extrapyramidal side effects had significantly higher drug concentrations in serum. In CPZ-treated patients, improvement of psychotic morbidity, HVA elevation and prolactin elevation all tended to be positively correlated to drug concentrations in serum and CSF. CPZ-treated patients with extrapyramidal side effects also had significantly higher CPZ concentrations in serum. In both treatment groups, the MOPEG reduction in CSF tended to be correlated to improvement of psychotic morbidity. The study supplied clinical evidence for the view that antipsychotic drugs belonging to the phenothiazine and benzamide series induce antipsychotic effects in schizophrenic patients in a graded fashion which is proportional to the degree of interaction with the central dopaminergic mechanisms. The results also support the view that sulpiride has a more selective effect on central dopaminergic mechanisms than chlorpromazine. In the schizophrenic patients studied and with the doses used, sulpiride concentrations tended to be maximal with regard to clinical and biochemical effects. For CPZ on the other hand, drug concentrations in some patients seemed to be too low to induce optimal effects.

Time course for effects of sulpiride and chlorpromazine on monoamine metabolite and prolactin levels in cerebrospinal fluid from schizophrenic patients

Schizophrenic patients were treated with the dopamine (DA)-2 receptor blocking drug sulpiride (800 mg daily) or the non-selective DA receptor blocking compound chlorpromazine (400 mg daily). Samples of lumbar cerebrospinal fluid (CSF) and blood were drawn before and after 1, 2, 4 and 8 weeks of treatment. Concentrations of the monoamine metabolites HVA, MOPEG and 5-HIAA in CSF and of prolactin (PRL) in CSF and serum were determined. In both treatment groups there were significant and similar elevations of HVA concentrations. HVA levels reached peaks after 1 to 2 weeks treatment and subsequently declined almost to the pretreatment level after 8 weeks. CSF and serum levels of PRL reached maximal levels within 2 weeks and remained stable at that level in both treatment groups. There were significantly higher PRL levels in sulpiride- than in chlorpromazine-treated patients. Women had higher PRL elevations in CSF in both treatment groups. The HVA/PRL ratio in CSF was significantly reduced in the sulpiride but not in the chlorpromazine group. After 1 week there was a significantly elevated 5-HIAA level in the chlorpromazine but not in the sulpiride group. In both groups, the MOPEG concentrations were significantly reduced in relation to pretreatment levels. The reduction was significantly more pronounced in the chlorpromazine group. The results indicate that sulpiride affects central DA metabolism in a similar way as chlorpromazine when administered in doses that induce antipsychotic effects. After both drugs evidence was obtained for the development of tolerance to the effect on the receptors that regulate HVA levels in the CSF but not to receptors regulating PRL release. The different effects of the drugs on PRL, 5-HIAA and MOPEG levels indicate that sulpiride has a more specific effect than chlorpromazine on dopaminergic mechanisms.

Clinical evaluation of sulpiride in schizophrenic patients--a double-blind comparison with chlorpromazine

To evaluate the clinical potential of sulpiride for the treatment of schizophrenic patients, a double-blind study was performed comparing fixed doses of sulpiride (800 mg daily) and chlorpromazine (400 mg daily). Twenty-five schizophrenic (RDC) patients participated in each treatment group. Antipsychotic effects were evaluated by CPRS and NOSIE ratings before and after 1, 2, 4 and 8 weeks of treatment. Interrater reliabilities for CPRS items and subscales were satisfactory. Treatment with sulpiride or chlorpromazine resulted in a significant reduction of psychotic morbidity as estimated by CPRS and global ratings. CPRS scores reflecting autism were significantly reduced in all ratings of sulpiride-treated patients, but only after four weeks in the chlorpromazine group. Total NOSIE scores indicated improvement in both treatment groups. A significant difference in favour of sulpiride was obtained for the NOSIE subscale "retardation". Extrapyramidal side effects occurred at a similar frequency in both treatment groups. Autonomic side effects occurred to a greater extent in chlorpromazine-treated patients. Lactation was reported only in four sulpiride-treated patients. Liver transaminase enzymes in serum were markedly elevated only in chlorpromazine-treated patients. The results indicate that sulpiride has a marked antipsychotic effect which is at least not inferior to that of chlorpromazine. A better effect on autistic components of behaviour was demonstrated for sulpiride. The results indicate a higher risk of lactation but a lower risk of anticholinergic side effects and liver toxicity for treatment with sulpiride than with chlorpromazine.

Effects of sulpiride and chlorpromazine on depressive symptoms in schizophrenic patients--relationship to drug concentrations

Schizophrenic patients were treated with fixed doses of sulpiride (800 mg/day) or chlorpromazine (CPZ) (400 mg/day) over a period of 8 weeks using a double-blind design. There were 25 patients in each group and all the patients were in an acute phase of their disease. They all fulfilled the Research Diagnostic Criteria (RDC) for schizophrenia. Depressive symptoms as rated according to the Comprehensive Psychopathological Rating Scale (CPRS) were present in the patients before treatment was started. The depressive and psychotic symptoms in both groups decreased in parallel during the whole period of treatment. Patients in the sulpiride group recovered more quickly from depressive symptoms than patients in the CPZ group. It was also found that patients with low concentrations of sulpiride or CPZ in serum recovered more completely from depressive symptoms and had fewer extrapyramidal side effects than patients with high drug concentrations.