Search PubMed⌕ Search

Biomedical subjects

G Chouinard

Publications and source records attributed to G Chouinard.

At least 55 records · Page 3Linked to original sources
PubMed1994

Risperidone and clozapine in the treatment of drug-resistant schizophrenia and neuroleptic-induced supersensitivity psychosis.

1. Supersensitivity psychosis (SSP) has emerged as a potential side effect of long-term neuroleptic therapy similar to tardive dyskinesia (TD). 2. Six schizophrenic patients with SSP, considered to be drug-resistant, were treated with risperidone, while another 5 were treated with clozapine. 3. The 6 risperidone-treated patients (all women) were rated on the Clinical Global Impression Improvement Scale as at least very much improved. Among the 5 clozapine-treated patients, all 4 men were found to have a marked response to clozapine, while the female patient was judged to be minimally improved. 4. It is hypothesized that not only TD but also SSP arise from destruction of cholinergic interneurons in the striatum as a consequence of prolonged neuroleptic administration. Thus, the drug-induced parkinsonism, which was proposed as mediating the antipsychotic effect of dopamine D2 blocking drugs, depends on the integrity of these cholinergic neurons. If these neurons are destroyed, drugs such as haloperidol lose their therapeutic effect. 5. In contrast, atypical neuroleptics like clozapine and risperidone reduce dopamine release in the striatum independently of prior production of extrapyramidal symptoms and, in this way, may be effective in psychotic illnesses unresponsive to classical anti-D2 neuroleptics. 6. In the present sample of patients, it is worth noting that schizophrenic men were good responders to clozapine. In comparison, risperidone was found to be efficacious in schizophrenic women.

Adult↗
PubMed1994

A double-blind controlled study of intramuscular zuclopenthixol acetate and liquid oral haloperidol in the treatment of schizophrenic patients with acute exacerbation.

We carried out a 9-day double-blind clinical trial comparing intramuscular zuclopenthixol acetate with liquid oral haloperidol in the treatment of 40 newly admitted schizophrenic patients with acute exacerbation. A parallel-group design was used with stratification by sex. Zuclopenthixol acetate (50 to 150 mg) was given intramuscularly every 3 days, whereas liquid haloperidol (10 to 30 mg daily) was given orally three times a day, with supplementary doses of each medication given under double-blind conditions when needed for agitation. No other sedative drugs, including benzodiazepines, were administered. The mean daily dose was 18.9 mg for haloperidol as compared with a mean dose per 3 days of 117.6 mg for zuclopenthixol. The two treatments were found to be equally efficacious on the Brief Psychiatric Rating Scale and Clinical Global Impression Scale. Both drugs induced similar extrapyramidal side effects. However, more tremors were associated with zuclopenthixol as was a tendency for tardive dyskinesia to be unmasked at the end of the injection interval. Sedation was higher with zuclopenthixol acetate than with haloperidol. Serum creatinine phosphokinase levels were not significantly increased after zuclopenthixol injections. The results of this trial suggest that zuclopenthixol acetate given intramuscularly every second to third day offers an alternative to conventional liquid oral haloperidol in the management of acute schizophrenia.

Acute Disease↗
PubMed1994

Clonazepam in the treatment of panic disorder: a double-blind, placebo-controlled trial investigating the correlation between clonazepam concentrations in plasma and clinical response.

Thirty-two outpatients with a DSM-III diagnosis of panic disorder or agoraphobia with panic attacks were randomly assigned to 4 weeks of treatment with clonazepam or placebo, after a 1-week placebo washout period. Twenty-nine patients entered the double-blind phase of the study and were eligible for intent-to-treat analysis. Clonazepam-treated patients experienced significantly fewer panic attacks, and these were of lesser intensity and short duration than those in placebo-treated patients (p < 0.001). Clonazepam was also superior to placebo with respect to symptoms of anxiety and depression (p < 0.001). The mean dose of clonazepam at week 4 was 2.2 mg (standard deviation, 0.7 mg). There was significant (p < 0.05) correlation between drug concentration in plasma and decrease in the global measure of the severity of panic disorder (r = 0.68); similar trends were seen for the decreases in frequency (r = 0.60) and severity (r = 0.55) of panic attacks, but not between concentration in plasma and decline in generalized anxiety. The most common adverse event was drowsiness, which occurred in 9 of 13 clonazepam-treated patients.

Adult↗
PubMed1994

A comparison of venlafaxine, trazodone, and placebo in major depression.

A double-blind, placebo-controlled trial was undertaken to compare the safety and efficacy of venlafaxine and trazodone in patients with major depression. Two hundred twenty-five patients entered an initial 6-week treatment phase, and 149 completed it. Ninety-six patients who were responders continued in a 1-year, double-blind, long-term phase during which they received the same medication and doses they had during the short-term phase. Both active treatments were significantly more effective than placebo on some measures during the short-term study, but venlafaxine produced more improvement in the cognitive disturbance and retardation factors on the Hamilton Rating Scale for Depression. Trazodone was more effective against the sleep disturbance factor. Patients on venlafaxine were most likely to enter the long-term phase and to remain in the trial longest. The side effect profiles of the three treatment groups were compared. Venlafaxine was most likely to cause nausea, whereas trazodone was associated with the most dizziness and somnolence.

Adult↗
PubMed1993

Loss of striatal cholinergic neurons as a basis for tardive and L-dopa-induced dyskinesias, neuroleptic-induced supersensitivity psychosis and refractory schizophrenia.

In the first section of this paper several aspects of tardive dyskinesia (TD) (clinical, epidemiological, pharmacological) are reviewed. We propose that this syndrome is not the consequence of dopamine receptor proliferation, but results from damage or degeneration of striatal cholinergic interneurons. We suggest that this cellular damage is caused by prolonged overactivation of these neurons, which occurs when they are released from dopaminergic inhibition following neuroleptic administration. Overactivity of central cholinergic systems during akinetic and motor retarded depression could be a contributory cause. The predisposition to L-DOPA-induced peak-dose dyskinesia in Parkinson's disease may depend on the same type of striatal neuronal loss. In the second part of the paper, the subject of supersensitivity psychosis and drug-resistant schizophrenia is reviewed. These two syndromes, are commonly associated with TD, have similar predisposing factors and pharmacology to TD, and are potentially persistent. We suggest that these conditions also result from degeneration of cholinergic striatal interneurons following chronic neuroleptic administration. The efficacy of clozapine for such treatment-refractory psychoses is explained in terms of its blockade of D-1 dopamine receptors. Other drugs effective against refractory psychoses (e.g. risperidone) are predicted to reduce activation at D-1 receptors.

Antipsychotic Agents↗
PubMed1993

Clinical review of risperidone.

Phase II clinical trials with risperidone have proven it to have a potent antipsychotic effect, improving both positive and negative symptoms of schizophrenia. It was found to have a low potential for inducing extrapyramidal symptoms and has been shown to have a possible antidyskinetic effect without increasing parkinsonism. Risperidone has a rapid onset of action and a favourable side-effect profile. One-year data on risperidone suggest that its therapeutic action in patients with chronic schizophrenia can be maintained without the significant neurological side-effects associated with the use of standard neuroleptics.

Antipsychotic Agents↗
PubMed1993

A Canadian multicenter placebo-controlled study of fixed doses of risperidone and haloperidol in the treatment of chronic schizophrenic patients.

In a double-blind study, 135 inpatients with a diagnosis of chronic schizophrenia were randomly assigned to 8 weeks of treatment with one of six parallel treatments: risperidone (a new central 5-hydroxytryptamine2 and dopamine D2 antagonist), 2, 6, 10, 16 mg/day; haloperidol, 20 mg/day; or placebo, after a single-blind placebo washout period. Doses were increased in fixed increments up to a fixed maintenance dose reached after 1 week. On the Clinical Global Impression-Severity of Illness and Improvement, all active medications were superior to placebo except for risperidone (2 mg) on the Clinical Global Impression-Improvement. On the total Positive and Negative Syndrome Scale (PANSS) score and positive subscale, superiority to placebo was observed for all treatment groups except for haloperidol and risperidone (2 mg), which tended to be superior to placebo on total PANSS and the positive subscale, respectively. On the PANSS negative subscale, only risperidone (6 mg/day) was significantly better than placebo. Risperidone (6 mg) was superior to haloperidol on the total PANSS, General Psychopathology, and Brief Psychiatric Rating Scale subscales. Although there was a linear increase in parkinsonism with increasing risperidone dosage, there were no statistically significant differences between risperidone (2, 6, and 16 mg/day) and placebo. At doses of 6 to 16 mg, risperidone displayed a marked antidyskinetic effect compared with placebo. This effect was more pronounced in patients with severe dyskinesia. By contrast, haloperidol produced significantly more parkinsonism than placebo and risperidone (2, 6 and 16 mg), with no effect on tardive dyskinesia. These data suggest that risperidone, at the optimal therapeutic dose of 6 mg/day, produced significant improvement in both positive and negative symptoms without an increase in drug-induced parkinsonian symptoms and with a significant beneficial effect on tardive dyskinesia.

Adult↗
PubMed1993

A double-blind randomized clinical trial of rapid tranquilization with I.M. clonazepam and I.M. haloperidol in agitated psychotic patients with manic symptoms.

This double-blind clinical trial studied 16 acutely agitated psychotic patients with manic or manic-like symptoms who needed rapid tranquilization and were therefore on maintenance treatment. They were randomized to receive intramuscular preparations of clonazepam (1 to 2 mg) or haloperidol (5 to 10 mg) at 0, 0.5, and 1.0 hours. Both medications produced significant reduction of manic symptoms within two hours of initial treatment; however, haloperidol produced beneficial results more rapidly than clonazepam. All patients completed the study, with the exception of one haloperidol-treated patient who developed severe parkinsonism. It was concluded that I.M. clonazepam is an effective, safe, but slower-acting alternative to I.M. haloperidol in the treatment of agitated psychiatric patients in need of rapid tranquilization.

Adolescent↗
PubMed1993

Brofaromine in depression: a Canadian multicenter placebo trial and a review of standard drug comparative studies.

Brofaromine is a new, reversible, and selective type-A monoamine oxidase inhibitor (MAOI) that also has serotonin reuptake inhibitory properties. Its dual pharmacologic effects offer promise in the treatment of a wide spectrum of depressed patients while producing less severe anticholinergic side effects in comparison with standard drugs. A multicenter, double-blind, placebo-controlled study including 220 patients was undertaken to evaluate the efficacy and safety of brofaromine in major depression. This study of a fixed-dose design and 6 weeks' duration found that brofaromine was significantly better than placebo on the Overall Evaluation of Efficacy, Beck self-rating scale, HAM-D Bech subscale, HAM-D total 14 items (minus the three sleep items), HAM-D depressed mood item and retardation factor, and worse than placebo on the insomnia items of HAM-D. Significantly more patients on placebo than on brofaromine did not complete the trial due to lack of efficacy. In comparative controlled studies (n = 899), brofaromine was found to be at least as efficacious as tricyclic antidepressants (imipramine) and standard MAOIs (tranylcypromine and phenelzine). Reductions of at least 50% in the HAM-D total score were seen in 58-66% of patients treated with either brofaromine or imipramine (n = 609). Brofaromine also was found to be of comparable efficacy to tranylcypromine in two clinical trials (n = 132), one of which included patients considered to have a treatment-resistant depression (n = 39). In another double-blind study that compared brofaromine (150 mg/day) to phenelzine (45 mg/day) (n = 158), there was no difference between brofaromine and phenelzine.

Adolescent↗
PubMed1992

Sertraline in the treatment of obsessive compulsive disorder: two double-blind, placebo-controlled studies.

Sertraline is a non-tricyclic, potent and selective serotonin reuptake inhibitor (SSRI) which is currently approved for the treatment of depression in several countries, including the UK and the USA. The role of serotonin in the aetiology of obsessive compulsive disorder (OCD) has been established through considerable indirect evidence. The strongest evidence comes from the fact that drugs known to be SSRIs have been found to be useful in the pharmacotherapy of OCD. Two double-blind, placebo-controlled studies, including a total of 412 patients, were undertaken to evaluate the efficacy and safety of sertraline in OCD. The first of these studies of a flexible dosing design showed that sertraline, given for eight weeks in daily dosages of 50-200 mg, was a safe and effective treatment for OCD, and superior to placebo. The second study of a fixed dose design and 12 weeks duration confirmed the efficacy and safety of sertraline in OCD at fixed dosages of 50, 100, or 200 mg/day and demonstrated that further improvement in OCD symptoms can be achieved through continued treatment with sertraline. A comparison between the results of these two studies and similar studies with clomipramine shows that, while both drugs have significant therapeutic efficacy, their side-effect profiles may be markedly distinct.

1-Naphthylamine↗
PubMed1991

Pertussis toxin selectively interferes with the responses of the HL-60 human promyelocytic cell line to dimethylsulfoxide.

The effects of pertussis toxin (PT) on the growth and dimethylsulfoxide (Me2SO4)-induced differentiation of the HL-60 human promyelocytic leukemia cell line were tested. Cell growth was quantified by direct cell counts. Cell differentiation was estimated by measuring the expression of myeloid-specific cell-surface antigens (Mo-1 and fMet-Leu-Phe [fMLP] receptors), the ability of the cells to produce superoxide anions on stimulation with fMLP, the calcium ionophore A23187 and phorbol 12-myristate 13-acetate (PMA), and by monitoring the level of expression of messenger RNA (mRNA) for tumor necrosis factor alpha (TNF alpha). By itself, PT did not affect the proliferation of HL-60 cells in serum-containing medium. In contrast, PT (but not its B-oligomer) dose-dependently inhibited the Me2SO4-induced expression of Mo-1, fMLP receptors, and the oxidative responses to the chemotactic factor and to A23187, but not to PMA. The addition of Me2SO4 induced a significant increase in the steady-state levels of TNF alpha mRNA, and this effect was strongly inhibited by PT. Finally, the bacterial toxin did not reverse the block of cell division that follows the addition of Me2SO4. These results provide evidence for the involvement of a PT substrate (presumably a guanine nucleotide-binding protein) in the regulation of the maturation of the excitation-response coupling sequence in human myeloid cell precursors and show that the regulation of cell division and maturation of HL-60 cells are under distinct sets of control mechanisms.

Cell Differentiation↗
PubMed1991

A guide to benzodiazepine selection. Part II: Clinical aspects.

To suit the specific needs of various clinical situations, selection of an appropriate benzodiazepine derivative should be based on consideration of their different pharmacokinetic and pharmacodynamic properties. Benzodiazepine derivatives that are rapidly eliminated produce the most pronounced rebound and withdrawal syndromes. Benzodiazepines that are slowly absorbed and slowly eliminated are most appropriate for the anxious patient, since these derivatives produce a gradual and sustained anxiolytic effect. Rapidly absorbed and slowly eliminated benzodiazepines are usually more appropriate for patients with sleep disturbances, since the rapid absorption induces sleep and the slower elimination rate may induce less tolerance to the sedative effect. Rational selection of a benzodiazepine for the elderly and for the suspected drug abuser is more problematic. The relevant pharmacokinetic and clinical considerations for these users are discussed. Certain derivatives may possess pharmacodynamic properties not shared by the entire benzodiazepine class; empirical studies have suggested the existence of anti-panic properties for alprazolam and clonazepam, antidepressant properties for alprazolam, and anti-manic properties for clonazepam and possibly lorazepam.

Aged↗
PubMed1991

Response to steroid suppression in major depression resistant to antidepressant therapy.

Because of the similarities in the psychiatric symptoms of Cushing's syndrome and those of major depression, and because the former generally remits when the hyperadrenalism is alleviated, an open clinical trial of the effect of steroid suppression in major depression was undertaken. Ten patients satisfying the DSM-III-R criteria for major depression, and classified as treatment-resistant, were included. Eight patients completed the study, which consisted of discontinuation of other psychotropic drugs and 2 months' treatment with one or more steroid suppressive agent (aminoglutethimide, ketoconazole and/or metyrapone). Six were classified as responders, and two as partial responders. In six, the improvement has been sustained for longer than 5 months after withdrawing the drugs. Side effects were mild to moderate. These results provide some evidence that steroids are involved in the maintenance of major depression, and that their suppression may lead to a readjustment of the hypothalamic-pituitary-adrenal axis with remission of the depression.

Adult↗
PubMed1990

Antiepileptic drugs in the treatment of neuroleptic-induced supersensitivity psychosis.

1. Supersensitivity psychosis (SSP) has emerged as a potential side-effect of long term neuroleptic therapy similar to tardive dyskinesia. 2. Five schizophrenic patients with SSP and considered to be drug-resistant were treated with antiepileptic drugs. All 5 improved initially, and in three the improvement was maintained at follow-up. 3. The proposed mechanism of action of the antiepileptic drugs is through correcting a pharmacological kindling effect in the limbic system which results from chronic neuroleptic therapy.

Adult↗
PubMed1990

A pilot study of magnesium aspartate hydrochloride (Magnesiocard) as a mood stabilizer for rapid cycling bipolar affective disorder patients.

1. Nine severe rapid cycling manic-depressive patients were treated with a magnesium preparation, Magnesiocard 40 mEq/day in an open label study for a period up to 32 weeks. 2. Magnesiocard was found to have clinical results at least equivalent to those of lithium in about 50% of these patients. These results were obtained in an exploratory study and should be interpreted with caution. 3. The possibility that Magnesiocard could replace or improve the efficacy of lithium as a preventive treatment of manic-depressive illness merits further clinical investigation.

Aspartic Acid↗