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

Apomorphine-induced operant deficits: a neuroleptic-sensitive but drug- and dose-dependent animal model of behavior

In order to further assess the alterations which might underly behavioral deficits associated with a reduced dopaminergic transmission, the effects of apomorphine at doses thought to stimulate dopaminergic autoreceptors were studied on rat operant behavior.

Low doses of apomorphine caused a reward deficit when animais were shifted from continuons reinforcement to fixed ratio schedules of food delivery (fig. 1). This effect could be accounted for by a decreased ability of secondary reinforcers to sustain responding and/or by a disruption of cognitive processes (Table 1). The apomorphine-induced reward deficit in the fixed ratio 4 schedule was reversed by “disinhibitory” neuroleptics including amisulpride, pimozide, pipotiazine and sulpiride, at low to moderate doses. Conversely, “conventional” neuroleptics such as chlorpromazine, fluphenazine, haloperidol, metoclopramide and thioridazine were found inactive in reversing the deficit caused by apomorphine (fig. 2). Results obtained after lesion of dopaminergic neurons by 6-hydroxydopamine suggested that the behavioral deficit induced by apomorphine was related not so much to a reduction in dopaminergic activity in given restricted areas such as the VTA (fig. 3), the nucleus accumbens (fig. 4) or the prefrontal cortex (fig. 5), as to a functional imbalance between mesolimbic and mesocortical dopaminergic systems.

Central D2receptor blockade and antipsychotic effects of neuroleptics. Preliminary study with positron emission tomography

The striatal D2receptor density/affinity index was assessed using positron emission tomography and76Br-Bromolisuride in 15 schizophrenics, first untreated, and afterwards receiving neuroleptics, and in 14 control subjects. The patients received low or conventional doses of neuroleptics. The schizophrenics receiving low doses (n= 6) had preponderant negative symptoms. Mean D2receptor occupancy was 24 ± 20%. Despite this weak central D2receptor blockade, a significant decrease in negative symptoms was observed, a result consistent with the hypothesis of a disinhibitory action of some neuroleptics administered in low doses. The patients treated with conventional doses (n= 9) had mixed positive and negative symptoms, and the mean D2receptor occupancy was 54 ± 13%. Significant decreases in positive symptoms, but also in negative symptoms, were obtained with this treatment. Before treatment, there was no significant difference in the striatal D2receptor density/affinity index between: 1) patients and controls, 2) negative and mixed schizophrenics, and 3) the subsequent responder and non-responder patients. In addition, the D2dopamine receptor occupancy by neuroleptics did not significantly differ in responder or nonresponder patients, suggesting that the central D2dopamine receptor blockade is a necessary, but insufficient condition to account for the antipsychotic effect of neuroleptics.

Determinants for clinical activity of neuroleptic drugs: chemical substances, doses, assessment tools

As emphasized by Lecrubier in 1980, the major finding of the last thirty years of classical neuroleptic use in schizophrenia is not that they are antischizophrenic or antipsychotic agents, but that they act on positive symptoms whatever the cause. There is now a widely accepted attribution of this kind of therapeutic property to the post-synaptic dopaminergic blockade induced by most of the neuroleptics when administered at high doses. On the other hand, during the last decade, various authors have reported clear evidence for a disinhibitory action of some neuroleptics when used at low doses. From a clinical point of view, the literature on the therapeutic action of low doses of neuroleptics seems quite controversial. In order to assess the exact determinants for clinical activity of neuroleptics (such as patient type, selected substances, administered doses) two series of independent controlled studies were conducted.

First series of studies: active drugs at low and high doses in schizophrenic patients

(Tables 1 to 6)

The first study was designed to assess the change of negative symptoms under low doses of neuroleptics. Sixty-two patients meeting the DSM III criteria of schizophrenia (subtypes: disorganized, catatonic or residual) were randomly assigned after a three-week washout period to six weeks’ treatment with either amisulpride (50 to 300 mg/day) or fluphenazine (2 to 12 mg/day), administered in keeping with a flexible dosage schedule. All patients had to meet the Andreasen criteria for negative symptoms (at least two of the following components had to be checked as present: anhedonia, alogia, affective flattening, avolition-apathy, attentional impairment). None of the patients presented one of the positive components to a marked degree: hallucinations, delusions, bizarre behavior, positive formal thought disorders. The evolution of symptomatology was assessed by means of the Brief Psychiatric Rating Scale (B.P.R.S.) and an ad hoc defective symptoms scale (D.S.A.S.), the sensitivity and reliability of which was previously tested in our department. The results show that the two groups (amisulpride versus fluphenazine) were initially highly comparable. Negative symptoms were severe, as evidenced by the D.S.A.S. scores, and by the presence of three items of the A6 criterion of the DSM III. The final global clinical assessment and the final D.S.A.S. scores both showed a significant improvement, with no statistically significant difference between the two treatments. Nevertheless, the scores of the “anergia” and “anxiety-depression” factors of the B.P.R.S. showed a significantly greater improvement in the amisulpride group.

The second study, complementary to the first, aimed to check the efficacy of high doses of amisulpride on the productive symptoms of schizophrenia. In this case, only the B.P.R.S. was used due to the good correlation of this scale with the global severity of the positive symptomatology. After three weeks of treatment, consisting either of amisulpride at a high, flexible dosage (800 to 1200 mg/day) or of haloperidol (20 to 30 mg/day), each of the two groups of twenty patients showed a significant improvement. In particular, the “thought disorders” factor of the B.P.R.S. (which unfortunately does not correspond exactly to the “formal thought disorder” component of the Andreasen positive symptoms scale - S.A.P.S.) was greatly improved in both groups. Evolution of the other symptoms was however identical in the two groups.

Second series of studies: active drugs versus placebo in schizophrenia

(Figures 1 to 6)

As we know, dopaminergic blocking agents are able to induce negative symptomatology. Consequently, to separate the secondary syndrome from the true deficit, a longer washout period than that previously described has to be imposed. On the other hand, the longitudinal course of schizophrenia must be taken into account for correct interpretation of changes in symptomatology; for example, patients with negative symptoms may abruptly present productive episodes, in particular during the neuroleptic withdrawal period. For optimal control of these two variables (natural history of the disease, the blunting effect of neuroleptics), 90 patients presenting either or both subtypes of schizophrenia were selected and included in a two-step, double-blind, controlled study. Patients with negative symptoms underwent a six-week washout period, after which they were treated either with low doses of amisulpride (100 or 300 mg/day) or a placebo. Patients with initial positive symptoms received mandatory high doses of amisulpride. According to the protocol, negative patients presenting productive symptoms during the washout period were to be systematically assigned to the highdose group. First results concerning 38 patients with a predominant negative symptomatology are presented here. A very clear improvement can be shown both for the SANS global mean score and for the sum of global ratings in the groups treated with low doses of amisulpride compared to the placebo group. The scores of the alogia, blunted affect and attentional impairment subscales decrease dramatically as well with the active drug.

Classification of neuroleptic drugs - lack of relationship to effect on negative symptoms in schizophrenia

There is both pharmacological and clinical support for a classification of the schizophrenic syndrome into negative and positive subtypes. For neuroleptics that act upon both types of symptoms, it appears that lower doses are required for treatment of negative than for positive symptoms. Successful drug treatment of negative symptoms may therefore depend upon the choice of a correct dosage for the individual patient. Due to variation in pharamacokinetic parameters, similar doses of a neuroleptic drug may result in different plasma levels in individual patients, especially after oral medication. Pharmacokinetic variations, if not under proper control, may easily disguise a concentration-dependent relationship, such as the effects of a neuroleptic drug upon negative and positive symptoms. In drug treatment of negative symptoms it may therefore be an advantage to individualize the doses as a function of plasma drug level measurements, when available. No general relationship has been demonstrated between the chemical properties or pharmacodynamics of neuroleptic drugs and their potential to act upon negative symptoms. Also, the drugs which have been demonstrated to have an “energizing” effect have widely different pharmacokinetic properties. A chemical or pharmacological classification of neuroleptics therefore does not seem to give any information about their possible efficacy in treating negative symptoms in schizophrenia.

Multiple pharmacological mechanisms and clinical targets for neuroleptics: should a more operational classification be considered?

The disinhibitory effect has long been described as a therapeutic property of some neuroleptic drugs (NL) able to improve negative symptoms.

In pharmacology behavioral models indicate a functional facilitation of dopaminergic transmission. Moreover, a group of negative symptoms very similar to those improved by disinhibitory NL may be induced as a side effect by other NL. Therefore the syndrome improved by these few NL could be linked to functional hypodopaminergic modifications. The improvement of negative symptoms by these few NL is linked in the Animal and in Man to the administration of low doses. We propose that these drugs be called “energizing neuroleptics”. Recent clinical studies have answered various important questions concerning this effect:

•

The energizing effect presents an original mecanism of action and a target “transnosological” syndrome. The corresponding group of NL should appear in the classifications alongside sedative and antihallucinatory (or antiflorid) NL.

Schizophrénie : La prescription des neuroleptiques antiproductifs et antidéficitaires en France

Le concept de neuroleptique déshinibiteur est utilisé par les psychiatres français depuis environ 20 ans. Cet effet suppose l’existence d’une efficacité thérapeutique portant sur la symptomatologie déficitaire des schizophrènes. Tous les neuroleptiques ne présentent pas cette propriété, de plus,en accord avec les travaux pharmacologiques, il semble que l’existence de cette propriété soit liée à l’emploi de faibles posologies. Lorsqu’on augmente les doses, leur profil devient identique à celui des neuroleptiques classiques. On a de plus montré en pharmacologie que ces neuroleptiques originaux facilitent à faible dose le fonctionnement de certains systèmes dopaminergiques.

Par ailleurs, l’observation clinique suggère que les syndromes productifs et déficitaires sont non seulement différents mais s’opposent sur de nombreux points. Les stimulants dopaminergiques (amphétamine) sont capables d’induire des syndromes productifs, ce type de pathologie est améliorée par les bloqueurs dopaminergiques (Neuroleptiques classiques). On oublie souvent que les bloqueurs dopaminergiques sont capables d’induire un syndrome de type déficitaire et que ce type de pathologie semble bénéficier d’une facilitation du fonctionnement dopaminergique (Neuroleptiques antidéficitaires faibles doses, Dopa) (tableau 1). Nous avons donc fonnulé l’hypothèse que deux types d’anomalies du fonctionnement dopaminergique en partie opposés étaient à l’origine des deux types de symptomatologies. La dopamine constituerait donc un élément modulant (sans l’expliquer) de la symptomatologie schizophrénique. Pour souligner cette dimension symptomatique nous avons proposé d’appeler les deux groupes de neuroleptiques antiproductifs et antidéficitaires plutôt qu’antipsychotiques et désinhibiteurs.

Un certain nombre d’études thérapeutiques semblent confirmer la réalité de l’effet antidéficitaire. La plupart de ces produits étant commercialisés depuis plus de dix ans en France, nous avons voulu vérifier si cette longue expérience retrouvait au niveau de la pratique les caractéristiques de l’effet antidéficitaire prenant en compte simultanément le type de malade, le choix d’une sous-classe de neuroleptiques et un type de posologie. Cent psychiatres ont décrit leur opinion sur l’utilité ou pas de huit neuroleptiques en fonction de l’indication. Les syndromes productifs (paranoïdes et mixtes aigus) sont traités par des substances sédatives (lévomépromazine, cyamémazine), antiproductives (chlorpromazine, halopéridol, fluphénazine) ou des doses élevées de neuroleptiques antidéficitaires (pipotiazine). Les syndromes déficitaires aigus ou chroniques sont traités par les produits antidéficitaires (pipotiazine, pimozide, sulpiride). L’utilité des substances antiproductives lorsqu’un syndrome déficitaire est présent est niée par la majorité des prescripteurs (tableau 2). Les posologies proposées sont classiques pour les syndromes productifs. Les posologies proposées dans le traitement des syndromes déficitaires par les substances antidéficitaires sont quatre à cinq fois plus faibles que celles proposées pour les mêmes substances comme traitement antiproductif (tableau 3). Les schizophrénies paranoïdes et mixtes stabilisées sont traitées selon deux stratégies dont les posologies se chevauchent très peu : soit posologie antiproductive la plus faible possible, soit posologie antidéficitaire environ deux fois plus faible (figure 1).

En pratique, ces résultats semblent montrer qu’en cas de syndrome déficitaire, aigu, chronique ou survenant chez des malades antérieurement paranoïdes ou mixtes, le choix d’une faible posologie de certains neuroleptiques est une habitude thérapeutique qui persiste à long terme en France.

Dopamine, schizophrenia, mania, and depression: Toward a unified hypothesis of cortico-striatopallido-thalamic function

Considerable evidence from preclinical and clinical investigations implicates disturbances of brain dopamine (DA) function in the pathophysiology of several psychiatric and neurologic disorders. We describe a neural model that may help organize theseindependent experimental observations. Cortical regions classically associated with the limbic system interact with infracortical structures, including the nucleus accumbens, ventral pallidum, and dorsomedial nucleus of the thalamus. In our model, overactivity in forebrain DA systems results in the loss of lateral inhibitory interactions in the nucleus accumbens, causing disinhibition of pallidothalamic efferents; this in turn causes rapid changes and a loss of focused corticothalamic activity in cortical regions controlling cognitive and emotional processes. These effects might be manifested clinically by some symptoms of psychoses. Underactivity of forebrain DA results in excess lateral inhibition in the nucleus accumbens, causing tonic inhibition of pallidothalamic efferents; this perpetuates tonic corticothalamic activity and prevents the initiation of new activity in other critical cortical regions. These effects might be manifested clinically by some symptoms of depression. This model parallels existing explanations for the etiology of several movement disorders, and may lead to testable inferences regarding the neural substrates of specific psychopathologies.

Antidepressant-like activity of amisulpride in two animal models of depression

Clinical reports suggest that amisulpride, in addition to its antipsychotic efficacy, may also have antidepressant properties. The present study was designed to evaluate potential antidepressant-like activity of amisulpride in two behavioural procedures: the forced swim test (FST) and the chronic mild stress (CMS) model. The duration of immobility time in FST was reduced by subchronic (three injections over a 24 h period) administration of imipramine (10 mg/kg) and amisulpride (1 and 3 mg/kg), although the effect of imipramine was more potent. The 5 mg/kg dose of amisulpride was marginally effective and higher doses of 10 and 30 mg/kg were inactive. In CMS, the stress-induced decrease in the consumption of 1% sucrose solution was gradually reversed by chronic treatment with imipramine (10 mg/kg) and amisulpride (5 and 10 mg/kg). Lower (1 or 3 mg/kg) or higher (30 mg/kg) doses of amisulpride were inactive. The magnitude of the effect of active doses of amisulpride in the CMS model was comparable to that of imipramine but its onset of action was faster; at the most active dose of 10 mg/kg, amisulpride significantly increased the sucrose intake in stressed animals within 2 weeks of treatment while imipramine required 4 weeks before first effects on the stress-induced deficit in sucrose consumption could be observed. These results provide further support for clinical observations that amisulpride may possess potent and rapid antidepressant activity.

Sulpiride for schizophrenia

BACKGROUND

The antipsychotic drug sulpiride was formulated over 20 years ago and was marked as having a low incidence of adverse effects and an effect on the negative symptoms of schizophrenia. This relatively inexpensive antipsychotic drug has a similar neuropharmacological profile to several novel atypical drugs.

OBJECTIVES

To estimate the clinical efficacy and tolerability of sulpiride.

SEARCH STRATEGY

Electronic searches of Biological Abstracts (1982-1997), CINAHL (1982-1998), Cochrane Schizophrenia Group's Register (March 1998), Cochrane Library (Issue 1, 1998), EMBASE (1980-1998), MEDLINE (1966-1998), PsycLIT (1974-1997), SIGLE (1994-1998), and Sociofile (1974-1997) were supplemented by reference searching, contacting authors and the manufacturers of sulpiride.

SELECTION CRITERIA

All randomised or quasi-randomised clinical trials focusing on the use of different doses of sulpiride or comparing sulpiride to (i) placebo; (ii) typical antipsychotic drugs; or (iii) atypical antipsychotic drugs, for those with schizophrenia or serious mental illness were selected.

DATA COLLECTION AND ANALYSIS

Trials were reliably selected and quality rated. Data were independently extracted, by two reviewers (BGOS, MF), and analysed on an intention-to-treat basis. It was assumed that people who did not complete the follow up had no improvement. Authors of trials were contacted for additional and missing data. Relative risk (RR) and 95% confidence intervals (CI) of dichotomous data were calculated with the random effects model and weighted mean difference (WMD) was calculated for continuous data.

MAIN RESULTS

The review currently includes 18 studies (30 citations). Studies are generally small and of poor quality. Limited evidence suggests that there is little difference between sulpiride and other drugs although the incidence of side effects may be less for sulpiride. There are no clear findings relating to negative symptoms.

REVIEWER'S CONCLUSIONS

Sulpiride may be an effective antipsychotic drug but evidence is limited and data relating to claims for its value against negative symptoms is not trial-based.

A risk-benefit assessment of sulpiride in the treatment of schizophrenia

Sulpiride is a substituted benzamide with a selective action on receptors of the dopamine D2-like family, and clinical and pharmacological data suggest that it could be considered to be an atypical antipsychotic. Sulpiride penetrates the blood-brain barrier poorly because of its low lipid solubility. It is mainly excreted unchanged in the urine, and accumulation of the drug could occur in patients with renal dysfunction and possibly in elderly patients with declining glomerular filtration rate. At low dosages (50 to 150 mg/day), sulpiride produces a disinhibiting and antidepressant effect, which is probably related to its action on D2 presynaptic autoreceptors, thus facilitating dopaminergic neurotransmission. Data have confirmed the efficacy of sulpiride in patients with acute or chronic schizophrenia during both short and long term treatment, but long term, placebo-controlled trials are still lacking. It is still doubtful whether sulpiride is more effective than typical antipsychotics for the treatment of negative symptoms. Data from clinical studies are controversial; the majority of authors indicate that sulpiride produces a better recovery rate from negative than from positive symptoms at low doses, but it shows a similar efficacy either on negative and positive symptoms at higher doses. The safety profile of sulpiride is similar to that of typical antipsychotics, although the frequency of adverse effects seems to be globally lower. Extrapyramidal reactions appear generally to be mild. Autonomic effects occur less frequently with sulpiride than with typical antipsychotics, showing no clinically relevant influence on cardiovascular parameters and, on the whole, good tolerability in elderly patients. Sulpiride is known to induce prolactin elevation in both serum and CSF, which may be associated with impotence in men and diminished gonadal function in women; these effects appear to be dosage-dependent. Sulpiride can be considered to be an atypical antipsychotic, considering its action on negative, defective symptoms, its partial activity against positive symptoms, and its low incidence of extrapyramidal adverse effects. Sulpiride could find its specific therapeutic role in elderly patients with schizophrenia, as it shows a good margin of safety between therapeutic dosages and toxic concentrations.

Levosulpiride: a review of its clinical use in psychiatry

Levosulpiride is the (-)-enantiomer of sulpiride. It has shown greater central antidopaminergic activity, antiemetic and antidyspeptic effects and lower acute toxicity than both the racemic and dextro forms. Several clinical studies indicate that levosulpiride has therapeutic efficacy in depressive and somatoform disorders, as well as in schizophrenic patients with predominant negative features. All controlled studies report a low frequency of extrapyramidal and autonomic side-effects. The increase of plasma prolactin concentration is the major drawback of the use of the drug, but its frequency may be reduced by low dosage.

Sulpiride: an antipsychotic with selective dopaminergic antagonist properties

OBJECTIVE

To review the pharmacology, pharmacokinetics, clinical investigations, and adverse effects of sulpiride as a treatment for schizophrenia.

DATA SOURCES

Information was selected from a MEDLINE search of English-language medical literature using "sulpiride" as the search term. Manual searches of pertinent journal article bibliographies also were performed.

STUDY SELECTION

Clinical investigations with a blind, controlled, randomized design and treatment durations of at least 6 weeks were preferred. Formal assessment of a patient's schizophrenia was required. One clinical investigation using a 4-week treatment duration and 1 open investigation were included for purposes of adverse reaction assessment.

DATA EXTRACTION

Clinical investigations were evaluated for design, sample size, diagnosis, duration, and outcome. Data from all investigations were selected by 1 author and reviewed by both authors.

DATA SYNTHESIS

Sulpiride is a substituted benzamide with selective dopaminergic blocking activity. Early pharmacology reports hypothesized that sulpiride was selective for dopamine (D)2 receptors only, but sulpiride also blocks D3 and D4 receptors. Sulpiride does not block D1, adrenergic, cholinergic, gamma-aminobutyric acid-ergic, histaminergic, or serotonergic receptors to an appreciable extent. The oral bioavailability of sulpiride is poor, with estimates approximating 35%. Sulpiride does not appear to have an extensive first-pass metabolism, nor is it extensively protein-bound. There have been no identified active metabolites, and elimination appears to depend primarily on the kidneys. Clinical studies support sulpiride as being equally effective as active controls in the acute treatment of patients with schizophrenia. Daily doses permitted in these clinical investigations ranged from 100 to 3200 mg. Further investigation is required to determine the usefulness of sulpiride as a chronic treatment of schizophrenia and its effectiveness in treating the negative symptoms of schizophrenia. Sulpiride may cause extrapyramidal effects, autonomic effects, tardive dyskinesia, and the neuroleptic malignant syndrome. The incidence of these adverse reactions has not been established.

CONCLUSIONS

Sulpiride is a safe and effective pharmacotherapeutic treatment for the acute management of schizophrenia. A unique pharmacology does not appear to provide sulpiride with a greater effectiveness than the standard antipsychotics, but may provide it with minor safety advantages.

Treatment of negative symptoms in schizophrenia with amisulpride

BACKGROUND

The efficacy of low doses of certain neuroleptics in improving negative symptoms is still controversial. This study assessed the efficacy of amisulpride, a benzamide which increases dopaminergic transmission at low doses via presynaptic dopamine receptor blockade, on negative symptoms of schizophrenia.

METHOD

The study was designed as a parallel-group, double-blind, placebo-controlled trial. Patients had to fulfil DSM-III criteria for schizophrenia, Andreasen's criteria for negative schizophrenia, and to have a total score of at least 75 on the SANS; those treated with neuroleptics or antidepressants underwent a six-week placebo wash-out. One hundred and four in-patients were randomly assigned to amisulpride 100 mg/d, amisulpride 300 mg/d, or placebo for six weeks; 85 patients completed the study.

RESULTS

Both amisulpride doses were significantly more effective than placebo on the primary evaluation criterion (SANS total score, MANOVA P < 0.02). No significant changes were found in positive symptoms or in extrapyramidal symptoms.

CONCLUSIONS

Negative symptoms can be improved by low doses of amisulpride, favouring the hypothesis of dopaminergic hypofunction as one of the causes of negative symptoms.

An open clinical and biochemical study of ritanserin in acute patients with schizophrenia

The effect of the selective serotonin-2 antagonist ritanserin was investigated in an open study of patients with schizophrenia. The patients were in an acute psychotic state considered to require neuroleptic medication. No neuroleptic drug was allowed during the study or during the last month preceeding the study. Oxazepam or nitrazepam were allowed for sedation or sleep inducement. Safety, tolerability, potential antipsychotic effect, and drug effects on monoamine metabolites in serum and CSF and prolactin in serum were evaluated. Central D2-dopamine receptor occupancy was determined by positron emission tomography. Ten male patients (mean age 32.4) fulfilling DSM-III-R criteria for schizophrenia were included in the study. Nine of these patients completed 4 weeks' treatment with ritanserin 10 mg b.i.d. The clinical effect was evaluated by means of CPRS and SANS and significant improvement was seen after 4 weeks' treatment both in positive and negative symptoms. Ritanserin was well tolerated and no extrapyramidal symptoms or akathisia were seen. Concentrations of monoamine metabolites and prolactin did not change during treatment. Ritanserin did not occupy D2-dopamine receptors. Thus, no indications of any D2-dopamine-antagonistic activity were obtained. All patients had expected ritanserin levels in plasma during the whole study. This first study of a selective serotonin-2 antagonist in the treatment of acute schizophrenic patients demonstrated significant clinical effects. However, the open design of the study does not allow us to conclude with any certainty that the patients' improvement was due to a specific blockade of serotonin-2 receptors or unspecific factors, although a direct D2-dopamine blockade could be ruled out.

Catecholamines in autistic disorder: effects of amisulpride and bromocriptine in a controlled crossover study

ABSTRACT The biochemical effects on catecholaminergic systems of the dopamine antagonist amisulpride and the dopamine agonist bromocriptine were evaluated in a double-blind, randomized, crossover study in children with autistic disorder. Plasma levels of dopamine, norepinephrine, and epinephrine; urinary concentrations of homovanillic acid (HVA), vanillyImandelic acid (VMA) and 3-methoxy-4-hydroxyphenylethylene glycol (MHPG); and plasma prolactin were measured. At doses of amisulpride and bromocriptine that had the expected opposing effects on plasma prolactin, the drugs' effects on the catecholaminergic systems were similar. Both agents unexpectedly lowered urinary HVA (total, free, and sulfated) although only amisulpride decreased the HVA levels significantly. This paradoxical decrease in HVA levels suggests that both dopamine agonists and antagonists could act on autoreceptors or presynaptic dopaminergic receptors in the central nervous system. There was no significant action of either drug on plasma epinephrine, urinary VMA, or urinary MHPG, suggesting that neither drug altered norepinephrine or epinephrine systems; however, a weak increase of plasma norepinephrine occurred after amisulpride treatment, consistent with effects observed with other neuroleptics. Neither agent altered plasma dopamine, suggesting that peripheral dopamine metabolism was unchanged. The clinical effects of amisulpride and bromocriptine have been reported to be unexpectedly complementary. The complementary clinical effects of a dopamine agonist and dopamine antagonist might speculatively be related to their similar action on dopamine autoreceptors, leading to a correction of the dopaminergic hyperactivity that has been postulated in autistic children.

Treatment of schizophrenia: a clinical and preclinical evaluation of neuroleptic drugs

Forty years after the first clinical report on the effectiveness of chlorpromazine in psychiatric patients, neuroleptic drugs are still the most widely used drugs in the treatment of schizophrenia. Indeed, there are no other drugs which have proven to be as effective in the treatment of this severe psychiatric disorder. Yet, there are still many unresolved problems relating to neuroleptic drugs. The present review gives a comprehensive overview of our knowledge (and our lack of knowledge) with respect to the clinical and preclinical effects of neuroleptic drugs and tries to integrate this knowledge in order to identify the neuronal mechanisms underlying the therapeutic and side effects of neuroleptic drugs.

Neuroleptics: preclinical and clinical differences

Neuroleptics: preclinical and clinical differences In this review we propose that the clinical and preclinical effects of neuroleptic drugs justify a distinction between classical and atypical neuroleptic drugs. Binding, biochemical, electrophysiological and behavioural studies have revealed clearcut differences between classical neuroleptics (like haloperidol and fluphenazine) and atypical neuroleptics (such as clozapine, thioridazine and remoxipride). These large differences are likely due to differences in the workingmechanisms. In view of the clinical relevance of these findings it is therefore both justified and essential to subdivide the neuroleptics in two distinct groups: the classical neuroleptics and the atypical neuroleptics.

Optically active benzamides as predictive tools for mapping the dopamine D2 receptor

Substituent variations on the pyrrolidinyl nitrogen of sulpiride, a selective D2 dopamine antagonist, showed that in vitro and in vivo activities are concentrated in the (S) optical series for N-alkyl analogs and in the (R) series for N-benzyl analogs. To account for these unusual structure-activity relationships, a pharmacophoric model was built from the crystallographic structure of (-)piquindone and extended to 14 other D2 antagonists. This model considers the lone pair orientation of the basic nitrogen rather than its spatial location. Two distinct active conformations for benzamides were defined, corresponding to the (S) and (R) series. An extended pharmacophore is then proposed involving four main anchoring areas: (i) an aromatic site Ar1, (ii) a tertiary nitrogen with its lone pair orthogonal to the Ar1 plane, (iii) a dipole delta 1 coplanar to the Ar1 ring and (iv) three sites for the N-substituent, including a small hydrophobic pocket and two different aromatic binding sites Ar2 and Ar3. To probe the predictive value of this model, structures were designed and several compounds were synthesized and tested as inhibitors of [125I]iodo-sulpiride binding to rat striatal membranes and as antagonists of apomorphine-induced stereotyped behavior in mice.

Factors associated with increased noradrenaline levels in schizophrenic patients

1. CSF NA levels were determined in a sample of DSM III-diagnosed schizophrenics and in a non-psychiatric control group. Schizophrenics with NA levels above and below the median were compared with respect to several clinical, historical, neuropsychological and biological variables. 2. Mean CSF NA levels were significantly higher in schizophrenics than in controls. 3. Schizophrenics with high CSF NA levels, as compared to those with low levels, had significantly higher scores on the CPRS subscale for positive symptoms. Moreover, in the former subgroup, C-EEG alpha relative activity was significantly lower and C-EEG beta relative activity was significantly higher in frontal and central leads. Two of the three patients who had been never treated with neuroleptics, and three of the six patients who had been neuroleptic-free for more than four weeks had high CSF NA levels. 4. These data support the relationship between increased CSF NA levels and the condition of overarousal of the schizophrenic patients, and suggest that prior neuroleptic treatment is not a major determinant of high CSF NA concentration in schizophrenics.

Effects of sulpiride and chlorpromazine on regional cerebral glucose metabolism in schizophrenic patients as determined by positron emission tomography

Positron emission tomography (PET) was used to determine regional brain glucose metabolism in schizophrenic patients (n = 17) before and during neuroleptic treatment. The patients had not been treated with neuroleptics for at least 3 weeks before the first study. All suffered from acute psychotic symptoms and were hospitalized to obtain neuroleptic treatment. After determination of regional brain metabolism without neuroleptic treatment, 11 patients were treated with sulpiride (800 mg/day) and 6 patients were treated with chlorpromazine (400 mg/day) over 5-6 weeks before the second PET investigation. The control group consisted of seven healthy male volunteers, also investigated twice 5 weeks apart. The PET investigation was made with the subject in a resting state. The tracer was uniformly labelled 11C-glucose. The metabolism was determined bilaterally in 15 brain regions cortical, as well as central regions. Metabolic rates differed among the groups. The sulpiride group had lower metabolic rates than the controls and the schizophrenic patients later treated with chlorpromazine. The sulpiride group, in which absolute metabolic rates were determined, were clinically more autistic and chronic than the chlorpromazine group. It was proposed that these facts could explain the lower metabolic rates in the sulpiride group. A significant change in metabolism in relation to drug treatment was only found in one brain region. The selective D2-receptor antagonist sulpiride increased the metabolic rate in the right lentiform nucleus in comparison with the patients treated with chlorpromazine and the controls. Likewise, relative metabolic rates were increased only in the right lentiform nucleus. Negative correlations between intensity of clinical symptoms and metabolism indicated that emotional tone and drive were related to brain metabolism. No correlations were found between drug concentrations and metabolism or clinical symptoms.

A fixed dose study of the plasma concentration and clinical effects of thioridazine and its major metabolites

Fifty-three patients in an acute episode or exacerbation of psychosis were given thioridazine 200 or 400 mg daily for 2 weeks. Thioridazine and its active metabolites, mesoridazine and sulforidazine, were estimated in plasma by high performance liquid chromatography (HPLC) and radioreceptor assay (RRA). One week after institution of treatment, plasma concentrations of drug were stable in the morning 12h after dosing. Drug levels varied widely between patients, but in all patients the relative level of thioridazine to mesoridazine was about one half and thioridazine to sulforidazine was about two fold. Estimates of neuroleptic activity by RRA and the weighted sum of thioridazine, mesoridazine and sulforidazine by HPLC were very similar. Plasma concentration of parent compound, metabolites, or the sum of active substances as estimated by HPLC or RRA, showed only modest correlations (rs = 0.10-0.22, all NS) to the degree of improvement as measured by change on the Brief Psychiatric Rating Scale. Significant correlations were observed between plasma concentrations of drug and side effects, including dry mouth, blurred vision, or total rating on the Somatic Symptoms Scale. Even patients receiving the lowest dose and achieving the lowest plasma concentrations of drug showed considerable improvement. There was suggestive evidence that the patients achieving the highest plasma levels of drug did not have the best clinical outcome. These and similar observations from other studies suggest that currently used doses of neuroleptics may be excessive. Optimal drug effects as well as stronger relationships between dose, drug concentration, and clinical therapeutic effects might best be sought at doses below those in common use.

Pharmacokinetics of neuroleptic drugs and the utility of plasma level monitoring

Variability in response to antipsychotic drug treatment may be caused by variable patient compliance, interactions with other drugs, pharmacokinetic variations and variations in concentration-response relationships at the receptor level. Pharmacokinetic variations may in some cases be compensated by individual dosage adjustments based on plasma drug level measurements. The interpatient variability in response to a certain time-course of drug concentrations at the receptor site could hitherto only be assessed by clinical judgement. New methods for in vivo assessment of receptor occupancy hold promise for possible measurement of parameters accounting for at least part of the interindividual variation in drug response at the receptor level. Monitoring of fluphenazine, perphenazine, thiothixene and sulpiride plasma levels by specific chemical assay methods seems to offer some guidance to individualization of drug doses. Definite therapeutic plasma level ranges have not been established for chlorpromazine and haloperidol. However, monitoring plasma levels of chlorpromazine or haloperidol might be of value when drug-induced toxicity is suspected, and as a means of controlling patient compliance.

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.