A double-blind comparative study of remoxipride and haloperidol in schizophrenic and schizophreniform disorders

Pharmacology of the atypical antipsychotic remoxipride, a dopamine D2 receptor antagonist

Remoxipride is a substituted benzamide that acts as a weak but very selective antagonist of dopamine D2 receptors. It was introduced by Astra (Roxiam) at the end of the eighties and was prescribed as an atypical antipsychotic. This article reviews its putative selective effects on mesolimbic versus nigrostriatal dopaminergic systems. In animals, remoxipride has minimal cataleptic effects at doses that block dopamine agonist-induced hyperactivity. These findings are predictive of antipsychotic activity with a low likelihood of extrapyramidal symptoms. Remoxipride also appears to be effective in more recent animal models of schizophrenia, such as latent inhibition or prepulse inhibition. In clinical studies, remoxipride shows a relatively low incidence of extrapyramidal side effects and its effects on prolactin release are short-lasting and generally mild. The clinical efficacy of remoxipride is similar to that of haloperidol or chlorpromazine. Although its clinical use was severely restricted in 1993, due to reports of aplastic anemia in some patients receiving remoxipride, this drug has been found to exhibit relatively high selectivity for dopamine D2 receptors making remoxipride an interesting tool for neurochemical and behavioral studies.

The Australian multicentre double-blind comparative study of remoxipride and thioridazine in schizophrenia

A double-blind, randomized study of parallel group design comparing remoxipride and thioridazine (dose range 150-600 mg/day of either drug) was undertaken at 11 Australian centres. A total of 144 patients (remoxipride = 73, thioridazine = 71) with DSM-III-R schizophrenia or schizophreniform disorder commenced the study, and 89 patients (remoxipride = 45, thioridazine = 44) completed the 6 weeks of the trial. The mean daily doses at last rating were 404 mg (remoxipride) and 378 mg (thioridazine). Initial Brief Psychiatric Rating Scale scores decreased by a mean 8.7 points in both remoxipride and thioridazine groups. Equivalent treatment responses were also confirmed by Clinical Global Impression. During the study, sedatives or hypnotics were needed by 68% of the remoxipride patients and 51% of the thioridazine patients. Thioridazine was associated with more postural hypotension, drowsiness, increased sleep, headache, dizziness on rising, dry mouth, sexual dysfunction and weight gain, while remoxipride patients reported more insomnia. There were no differences between remoxipride and thioridazine on dystonia, hypokinesia, dyskinesia, rigidity and akathisia. The results indicate that remoxipride has similar antipsychotic efficacy to thioridazine but causes fewer side effects.

A cognitive-neuroscience approach for elucidation of mechanisms underlying temporal information processing

Temporal processing of durations in the range of seconds or more is cognitively mediated, whereas processing of brief durations below 100 ms appears to be based on brain mechanisms beyond cognitive control. In a series of experiments, applying a single-behavior-multiple-brain-systems strategy, activity of various neurotransmitter systems was pharmacologically changed and effects on temporal information processing were studied. In addition, concomitant changes in different psychological functions, such as cortical arousal, speed of information processing, and memory were measured. This experimental strategy proved to be highly efficient for elucidating mechanisms underlying temporal information processing in humans. Temporal processing of durations in the range of seconds was markedly impaired by pharmacologic agents which induced deterioration of memory functions. On the other hand, temporal processing of brief durations below 100 ms was shown to be largely independent of pharmacologically induced impairment of cognitive functioning, but may rather depend on D2 receptor activity in the basal ganglia.

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.

Clinical profile of remoxipride--a combined analysis of a comparative double-blind multicentre trial programme

Nine double-blind studies comparing remoxipride to haloperidol in the treatment of acute schizophrenia formed the basis of this analysis. All studies followed a basic protocol with the main assessments performed regularly during the 4-6 week trial period according to the same methodology, thus allowing the data to be pooled. The results showed that remoxipride in a daily dose of 150-600 mg had a therapeutic effect comparable to that of haloperidol (5-45 mg/day), both on positive and negative symptoms. There was a clear advantage for remoxipride over haloperidol with regard to adverse events/symptoms, particularly extrapyramidal symptoms, but also drowsiness/somnolence and tiredness/fatigue. Anticholinergic drugs were used consistently less frequently as concomitant medication to alleviate extrapyramidal symptoms in the remoxipride group: the use of sedatives/hypnotics was approximately the same in both groups. Based on these and supportive clinical data, remoxipride seems to have a clinical profile characterized by antipsychotic efficacy in acute schizophrenia, apparently equal to that of haloperidol, and good tolerability in being non-sedative (in terms of drowsiness/somnolence) and with low incidences of extrapyramidal, autonomic, and endocrine symptoms.

Selective dopamine D2 antagonist and prolactin response in acute schizophrenia--results from remoxipride studies. The Canadian Remoxipride Study Group

1. In a double-blind dose finding study prolactin was assessed at baseline and end of treatment in three groups of acute schizophrenics receiving low, intermediate and high doses of remoxipride as compared to a controlled group that received haloperidol. 2. Remoxipride only in high doses (300-600 mg daily) has produced a modest increase in prolactin levels at endpoint as compared to the much higher increase in prolactin secretion that accompanied haloperidol treatment. 3. The weak effects on prolactin as well as the previously reported low incidence of extrapyramidal side effects confirm the profile of remoxipride as a selective dopamine D2 antagonist with preferential effects on the mesolimbic and mesocortical tracts. 4. Male responders to either remoxipride or haloperidol treatment had significantly higher baseline prolactin levels regardless of dose and drug used. In females, there was no difference in baseline prolactin between responders and nonresponders.