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Long-acting risperidone compared with oral olanzapine and haloperidol depot in schizophrenia: a Belgian cost-effectiveness analysis.

Patients with schizophrenia suffer numerous relapses and rehospitalizations that are associated with high direct and indirect medical expense. Suboptimal therapeutic efficacy and, in particular, problems with compliance are major factors leading to relapse. Atypical antipsychotic agents offer improved efficacy and a lower rate of extrapyramidal adverse effects compared with conventional antipsychotic drugs. Long-acting intramuscular risperidone combines these benefits with improvements in compliance associated with depot injections. To assist decision making regarding the place of long-acting risperidone in therapy, a cost-effectiveness analysis of strategies involving first-line treatment with long-acting risperidone, oral olanzapine or depot haloperidol was performed from the perspective of the Belgian healthcare system. A decision tree model was created to compare the cost effectiveness of three first-line treatment strategies in a sample of young schizophrenic patients who had been treated for 1 year and whose disease had not been diagnosed for longer than 5 years. The model used a time horizon of 2 years, with health state transition probabilities, resource use and cost estimates derived from clinical trials, expert opinion and published prices. The four health states in the model were derived from an analysis of the literature. The principal efficacy measure was the proportion of patients successfully treated, defined as those who responded to initial treatment and who had none to two episodes of clinical deterioration without needing a change of treatment over the 2-year period. Comprehensive sensitivity analysis was carried out to test the robustness of the model. A greater proportion of patients were successfully treated with long-acting risperidone (82.7%) for 2 years, compared with those treated with olanzapine (74.8%) or haloperidol (57.3%). Total mean costs per patient over 2 years were 16,406 Euro with long-acting risperidone, 17,074 Euro with olanzapine and 21,779 Euro with haloperidol (year of costing 2003). The mean cost-effectiveness ratios were 19,839 Euro, 22,826 Euro and 38,008 Euro per successfully treated patient for long-acting risperidone, olanzapine and haloperidol, respectively. Results of the sensitivity analysis confirmed that the results were robust to a wide variation of different input variables (effectiveness, dosing distribution, patient status according to healthcare system). Long-acting risperidone was the dominant strategy, being both more effective and less costly than either oral olanzapine or depot haloperidol. Long-acting risperidone appears to represent a favourable first-line strategy for patients with schizophrenia requiring long-term maintenance treatment.

Antipsychotic Agents↗

A double blind trial of lithium carbonate and haloperidol in Huntington's chorea.

Six patients with a family history of Huntington's chorea (HC) participated in a double blind crossover trial involving four treatments--lithium carbonate, haloperidol, lithium carbonate and haloperidol, and placebo. Each treatment was administered for three weeks and, at the end of each treatment period, assessments were made of chorea and a number of psychological variables. None of the treatments significantly affected chorea measurements. With regard to the psychological variables, the levels of irritability, the frequency of angry outbursts and depression did appear to be affected in some patients by the treatment. Three patients improved on a combination of lithium carbonate and haloperidol while the remaining three did not. Haloperidol alone significantly raised depression ratings above levels for other treatments including placebo. It is suggested that lithium carbonate and haloperidol together should be seriously considered in the treatment of HC when patients are excessively irritable and impulsive.

Anger↗

Mecamylamine effects on haloperidol-induced catalepsy and defecation.

Recent clinical experience with Tourette syndrome (TS) patients suggests that the nicotinic receptor antagonist, mecamylamine (Inversine), may be a useful adjunct to neuroleptic therapy for controlling tic symptom. This is consistent with previous preclinical findings demonstrating that mecamylamine can potentiate the cataleptic effects of neuroleptics in rats. However, these earlier preclinical studies employed high doses (1-2.5 mg/kg) of mecamylamine that may not be clinically relevant since human doses of mecamylamine used to treat TS have been much lower (0.03-0.1 mg/kg). In order to test the potential therapeutic properties of mecamylamine preclinically, we conducted catalepsy experiments in rats employing both a low and high dose of mecamylamine in combination with haloperidol. Sixty-four male Sprague Dawley rats were randomized into four treatment groups (n = 16/group). Each rat received an injection of either saline or mecamylamine (0.1 or 3.0 mg/kg s.c.) followed one hour later with a second injection of either saline or haloperidol (0.4 mg/kg s.c.). The bar test was used to measure duration of catalepsy at 3 hrs following the second injection. The results demonstrated that only the mecamylamine treated rats showed statistically significant haloperidol-induced catalepsy when measured at 3 hrs. In addition, haloperidol-induced defecation was not affected by the 0.1 mg/kg mecamylamine dose, but completely abolished by the 3.0 mg/kg dose. These findings suggest that a clinically relevant dose of mecamylamine (0.1 mg/kg) can affect the duration of haloperidol-induced catalepsy without having significant effects on gastrointestinal function.

Animals↗

Intravenous haloperidol for tranquilization in critical care patients: a review and critique.

The management of agitated, combative, fearful critically ill patients is a significant challenge for critical care nurses. Intravenously administered haloperidol can be effective in treating these patients. Because the U.S. Food and Drug Administration has not approved the use of haloperidol intravenously, there are no widely accepted guidelines for intravenous use of this drug. This chapter reviews the literature and provides information to critical care nurses in the use of intravenous haloperidol. Haloperidol's pharmacologic properties are described; several published case studies are reviewed; and potential adverse effects associated with haloperidol's use are presented.

Aged↗

Effectiveness of antipsychotic therapy in a naturalistic setting: a comparison between risperidone, perphenazine, and haloperidol.

BACKGROUND: Therapeutic ineffectiveness and noncompliance with antipsychotic agents are major contributors to rehospitalization in patients with psychotic disorders. It is unknown whether risperidone's favorable side effect profile compared with that of the conventional antipsychotics results in improved compliance and reduced hospitalizations in a naturalistic setting. The purpose of this study was to test the hypothesis that treatment with risperidone reduces readmission rates and associated costs when compared with treatment with perphenazine or haloperidol. METHOD: Inpatients prescribed either risperidone, perphenazine, or haloperidol between January 1, 1995, and December 31, 1995, as a single oral antipsychotic at discharge were retrospectively identified. Data were collected for that index hospitalization and for a 1-year follow-up period. Primary outcome measures included re-admission rates, changes in antipsychotic therapy, anticholinergic drug use, and costs. RESULTS: There were 202 evaluable patients (81 treated with risperidone, 78 with perphenazine, and 43 with haloperidol). Baseline demographics were similar between groups except that more patients in the risperidone group had a primary diagnosis of psychotic disorder or had been hospitalized in the year prior to study. The percentage of patients readmitted during the 1-year follow-up period was similar among drug groups (41% risperidone, 26% perphenazine, and 35% haloperidol) when controlled for baseline differences in diagnosis and hospitalization history (p = .32). Anticholinergic drug use was more common in the haloperidol group (p = .004). Mean yearly cost (drug + hospitalization) in the risperidone group was $20,317, nearly double that in the other treatment groups (p < .001). CONCLUSION: The results from this naturalistic study indicate that the high cost of risperidone is not offset by a reduction in readmission rates when compared with conventional antipsychotics.

Adolescent↗

Risperidone liquid concentrate and oral lorazepam versus intramuscular haloperidol and intramuscular lorazepam for treatment of psychotic agitation.

BACKGROUND: Although agitation associated with psychosis is a common presentation in the psychiatric emergency service, there is no consensus concerning the best treatment. Standard treatment often consists of intramuscular (i.m.) injection of high-potency neuroleptics, sometimes combined with benzodiazepines. The objective of this study was to determine the relative efficacy, safety, and tolerability of oral risperidone versus intramuscular haloperidol, both in combination with lorazepam, for the emergency treatment of psychotic agitation in patients who are able to accept oral medications. METHOD: A convenience sample of psychotic patients admitted to a large psychiatric emergency service who required emergency medication for the control of agitation and/or violence was offered risperidone (2 mg liquid concentrate) and oral lorazepam (2 mg) as an alternative to standard care at the institution, haloperidol (5 mg i.m.) and lorazepam (2 mg i.m.). Subjects who refused the oral medications were given the intramuscular treatment as a component of routine care. RESULTS: Thirty patients were enrolled in each treatment group. Although men were significantly more likely to choose oral medication (chi2 = 5.165, p < .023), other demographic characteristics did not differ significantly between the 2 treatment groups. Both groups showed similar improvement in agitation as measured by 5 agitation subscales of the Positive and Negative Syndrome Scale (PANSS), the Clinical Global Impressions (CGI) scale, and time to sedation. No patients receiving risperidone demonstrated any side effects or adverse events, while 1 patient receiving intramuscular treatment with haloperidol developed acute dystonia. One subject receiving risperidone required subsequent treatment with haloperidol for ongoing agitation. CONCLUSION: Oral treatment with risperidone and lorazepam appears to be a tolerable and comparable alternative to intramuscular haloperidol and lorazepam for short-term treatment of agitated psychosis in patients who accept oral medications.

Acute Disease↗

Transdermal nicotine and haloperidol in Tourette's disorder: a double-blind placebo-controlled study.

BACKGROUND: Preclinical animal and open-trial clinical trials using nicotine gum and the transdermal nicotine patch found that treatment with nicotine potentiates the effects of neuroleptics in reducing the dyskinetic symptoms of Tourette's disorder. We sought to verify and expand these findings in a prospective double-blind placebo-controlled trial. METHOD: Seventy patients with DSM-IV Tourette's disorder were treated with either transdermal nicotine (7 mg/24 hours) or placebo patches in a 33-day, randomized, double-blind study. Each patient received an individually based optimal dose of haloperidol for at least 2 weeks prior to random assignment to nicotine or placebo treatment. A new patch was worn each day for the first 5 days. On the sixth day, the dose of haloperidol was reduced by 50%. Daily patch applications were then continued for an additional 2 weeks (through day 19), at which time the patch was discontinued, but the 50% dose of haloperidol was continued for an additional 2 weeks (through day 33). Clinical and safety assessments were made at each visit. RESULTS: Patients who completed all 19 days of nicotine (N = 27) or placebo (N = 29) patch treatment were used in efficacy analyses. As documented by the Clinician- and Parent-rated Global Improvement scales, transdermal nicotine was superior to placebo in reducing the symptoms of Tourette's disorder. The Yale Global Tic Severity Scale was less sensitive in detecting a placebo/drug difference than were the global improvement scores, suggesting that some of the improvement may not have been related to treatment-related changes in tic severity, but to the emotional and behavioral symptoms. The side effects of nausea and vomiting were significantly more common in the nicotine group (71% [N = 25] and 40% [N = 14]) than in the placebo group (17% [N = 6] and 9% [N = 3]) (nausea, p = .0001; vomiting, p = .004). CONCLUSION: Transdermal nicotine was superior to placebo in reducing behavioral symptoms when patients were receiving an optimal dose of haloperidol, when the dose of haloperidol was reduced by 50%, and when the patch had been discontinued for 2 weeks. These findings confirm earlier open-label findings and suggest that combining nicotinic receptor modulation and neuroleptics could be a therapeutic option for the treatment of Tourette's disorder. While side effects limit chronic use of nicotine, it may be useful on a p.r.n. basis. Further clinical research is warranted to investigate the use of novel nicotinic receptor modulating agents with improved safety profiles over nicotine.

Administration, Cutaneous↗

A single-blind, randomized trial comparing quetiapine and haloperidol in the treatment of tardive dyskinesia.

BACKGROUND: While the atypical antipsychotics should ultimately reduce the prevalence of tardive dyskinesia, it is likely to remain a significant clinical problem for a long time to come. No strategy has clearly emerged as the treatment of choice for tardive dyskinesia. Atypical antipsychotics have reduced propensities for producing acute extrapyramidal symptoms (EPS) and possibly tardive dyskinesia and may be effective in treating patients with established tardive dyskinesia. METHOD: This 12-month, randomized, investigator-blinded study compared the efficacy of quetiapine (N = 22) and haloperidol (N = 23) in treating patients with DSM-IV schizophrenia or schizoaffective disorder and established tardive dyskinesia. Dyskinesia was assessed using the Extrapyramidal Symptom Rating Scale (ESRS) dyskinesia subscale scores and the Clinical Global Impression (CGI) dyskinesia scores. Other EPS, weight, serum prolactin level, and glycosylated hemoglobin level were also assessed. Subjects were enrolled in the study between April 2000 and March 2002. RESULTS: Mean endpoint doses were 400 mg/day of quetiapine and 8.5 mg/day of haloperidol. Compared with the haloperidol group, the quetiapine group showed significantly greater improvements in ESRS dyskinesia (6 and 9 months [p or= 50% symptom reduction) was greater with quetiapine than haloperidol (64% [9/14] and 37% [6/16] at 6 months; 55% [6/11] and 28% [4/14] at 12 months). Other EPS decreased significantly with quetiapine at 3 (p =.01), 6 (p =.01), and 9 (p =.002) months. Serum prolactin levels decreased with quetiapine but increased with haloperidol, differing significantly between the groups at endpoint (p =.005). No significant changes in weight or glucose metabolism were recorded in either group. CONCLUSION: Quetiapine effectively reduces the severity of tardive dyskinesia and is well tolerated in patients with established tardive dyskinesia.

Adult↗

Safety of haloperidol and penfluridol in pregnancy: a multicenter, prospective, controlled study.

OBJECTIVE: To assess the safety of the butyrophenone neuroleptics haloperidol and penfluridol in pregnancy. METHOD: The rate of major anomalies was compared between a cohort of pregnant women counseled for gestational exposure to haloperidol or penfluridol and a control group counseled for nonteratogen exposure. This multicenter, prospective, controlled study was conducted within the European Network of Teratology Information Services (ENTIS) and included women who contacted 1 of 4 teratology information services for counseling between January 1989 and December 2001. RESULTS: We followed up on the outcomes of 215 pregnancies exposed to haloperidol (N = 188) or penfluridol (N = 27)-78.2% (of 206) were in the first trimester-and compared to outcomes of 631 ENTIS controls. The rate of congenital anomalies did not differ between the haloperidol/penfluridol-exposed group and the control group (6/179 = 3.4% vs. 22/581 = 3.8%, p = .787). No difference was found by limiting the analysis to those exposed to butyrophenones during the first trimester. There were 2 cases of limb defects in the butyrophenone-exposed group (1 after haloperidol and 1 after penfluridol exposure) and none in the controls. A higher rate of elective terminations of pregnancy (8.8% vs. 3.8%, p = .004), a higher rate of preterm birth (13.9% vs. 6.9%, p = .006), a lower median birth weight (3155 g vs. 3370 g, p < .001), and a lower median birth weight of full-term infants (3250 g vs. 3415 g, p = .004) were found in the butyrophenone-exposed group compared to the controls. CONCLUSION: This study suggests that haloperidol and penfluridol do not represent a major teratogenic risk. Since a possible association between butyrophenone exposure and limb defects cannot be ruled out with this sample size, a level II ultrasound with emphasis on the limbs should be considered in pregnancies with first trimester exposure.

Abnormalities, Drug-Induced↗

Risperidone and haloperidol augmentation of serotonin reuptake inhibitors in refractory obsessive-compulsive disorder: a crossover study.

BACKGROUND: Although serotonin reuptake inhibitors (SRIs) are the first-line treatment for obsessive-compulsive disorder (OCD), approximately half of patients with OCD do not respond adequately to SRI monotherapy. Patients with predominant obsessions are common in OCD and are often difficult to treat, necessitating adjunctive treatment. METHOD: This was a 9-week, double-blind, placebo-controlled, crossover study comparing the benefits of 2-week adjunctive treatments with risperidone, haloperidol, and placebo in patients with OCD (DSM-IV criteria) who continued to have severe symptoms despite taking a stable dose of an SRI. Eligible patients must have been receiving a therapeutic dose of an SRI for at least 12 weeks and at the screening visit had a score > or = 10 on items 1-5 (obsession) and a total score > or = 16 on the Yale-Brown Obsessive Compulsive Scale (YBOCS). Data were collected from January 1999 through April 2002. RESULTS: Sixteen patients were enrolled and 12 completed the study. On the YBOCS, both risperidone and haloperidol significantly reduced obsession (p < .05) when compared with placebo. There was a tendency that haloperidol, and to a lesser degree risperidone, also reduced the compulsion and the total YBOCS scores. These results were accompanied by a reduction in the Hopkins Symptom Checklist 90-revised (SCL-90R) anxiety scale score. According to the 17-item Hamilton Rating Scale for Depression, the SCL-90R depression scale, and the Profile of Mood States, risperidone, but not halo-peridol, also improved depressed mood. Neither risperidone nor haloperidol changed neurocogni-tive function during the 2-week treatment. All 12 patients completed the 2-week risperidone treatment, but 5 of the 12 terminated haloperidol treatment early owing to intolerable side effects. CONCLUSION: Adjunctive risperidone improved obsessions and depressed mood and was well tolerated in patients with SRI-refractory OCD.

Adult↗

Response and relapse in patients with schizophrenia treated with olanzapine, risperidone, quetiapine, or haloperidol: 12-month follow-up of the Intercontinental Schizophrenia Outpatient Health Outcomes (IC-SOHO) study.

OBJECTIVE: The primary aim of this study was to compare the effectiveness of 12 months' treatment with olanzapine, risperidone, quetiapine, or haloperidol in preventing relapse of schizophrenia. The study also examined other measures of clinical effectiveness and tolerability. METHOD: Outpatients with schizophrenia (ICD-10 or DSM-IV), who initiated or changed antipsychotic treatment, entered this 3-year, naturalistic, prospective, observational study between November 2000 and December 2001. At baseline, subsets of patients were prescribed monotherapy with olanzapine (N = 3222), risperidone (N = 1116), quetiapine (N = 189), or haloperidol (N = 256). Patients remaining on monotherapy were assessed using the Clinical Global Impression-Schizophrenia scale. Relapse rate was determined from the responder subset. Treatment patterns, patient perception of treatment compliance, substance and alcohol intake patterns, and treatment tolerability were recorded. Results are based on 12-month treatment data. RESULTS: Compared to haloperidol-treated patients, olanzapine- and risperidone-treated patients had approximately 3 to 4 times higher odds of response at 12 months (p <or= .001) and 6 times lower odds of relapse (p <or= .001 for olanzapine-treated patients). Among patients treated with atypical antipsychotics, olanzapine- and risperidone-treated patients had lower odds of relapse (although the difference was not significant at p <or= .001) and significantly higher odds of response (p <or= .001) compared to quetiapine-treated patients. The tolerability profile generally favored the atypical antipsychotics over haloperidol. CONCLUSION: These interim results support the findings of randomized controlled trials and verify that in this naturalistic study, patients treated with olanzapine or risperidone monotherapy were less likely to experience relapse than patients who received haloperidol. The clinical effectiveness and tolerability profile varied significantly between the atypical antipsychotics.

Adult↗

[The discovery of haloperidol].

Haloperidol was synthesized on the 11th of February 1958 by Bert Hermans at the Janssen Laboratories, Beerse, Belgium. Simple but ingenuous methods of animal pharmacology suggested to Paul Janssen and his collegues that this butyrophenone derivative, called R1625, then halop-peridol, would be of great interest: qualitatively, the pharmacological action of R1625 was similar to chlorpromazine, but R1625 was very more powerful since it produced effects with much smaller doses than chlorpromazine. Soon after the synthesis and animal studies, haloperidol was administered in humans by Divry, Bobon et Collard, psychiatrists at the Liege Hospital. The first clinical publication, on the 28th of October, 1958, described the effects of haloperidol in agitation states. The subsequent clinical studies, including those of the prestigious French school of Sainte-Anne hospital, confirmed that haloperidol belongs to the pharmacological family of neuroleptics, as it was defined by J. Delay and P. Deniker in 1955. These clinical studies demonstrated also that haloperidol was particularly active against delusions and hallucinations. Numbers of chronically inpatients were able to leave hospital and to live home thanks to this new drug, which remains one of the more prescribed neuroleptics 40 years after its discovery.

Animals↗

Adrenergic receptors' responsiveness after acute and chronic treatment with haloperidol in the presence of calcium channel blockade.

The effects of acute and chronic (14 days) treatment with haloperidol (0.5 mg/kg ip) given alone or 15 min after nifedipine (5 mg/kg ip) on responsiveness of the alpha1- and beta-adrenergic receptors was investigated ex vivo by measuring of the second messenger responses. The accumulation of inositol phosphate (IP) or cyclic AMP were measured in brain cortical slices challenged with noradrenaline or isoproterenol. The facilitatory effect of a single dose of haloperidol on IP accumulation (an increase by approximately 50%) was abolished by nifedipine pretreatment. After chronic treatment with haloperidol alone its facilitatory effect disappeared, but a treatment with haloperidol after nifedipine caused a significant increase in IP accumulation. No treatment affected the responses from beta-adrenoceptors. These data show that the action of chronically administered haloperidol may be changed by the concomitant calcium channel blockade that prevents development of adaptation to persistent presence of the drug.

Adrenergic alpha-Agonists↗

Medication continuation and compliance: a comparison of patients treated with clozapine and haloperidol.

BACKGROUND: This study compares medication continuation and regimen compliance with the atypical antipsychotic medication clozapine versus the conventional antipsychotic haloperidol. METHOD: Data from a 15-site double-blind, randomized clinical trial (N = 423) were used to compare patients with DSM-III-R schizophrenia assigned to clozapine or haloperidol in terms of duration of participation while taking the randomly assigned study drug (continuation) and the proportion of prescribed pills that were taken (compliance). Multiple regression analysis was used to determine the relationship of baseline characteristics and measures of clinical change to continuation for the entire sample and for patients assigned to each medication. RESULTS: Patients assigned to clozapine continued taking the study drug for a mean of 35.5 weeks as compared with only 27.2 among patients assigned to haloperidol (F = 4.45, df = 1,422; p = .0001). No differences were found between the groups in the proportion of prescribed pills that were returned at any timepoint. Among patients assigned to haloperidol, poorer continuation was associated with being older and greater continuation with receiving public support. Among patients on clozapine treatment, continuation was poorer among African American patients and greater among patients who showed reduced clinical symptoms and akathisia. Continuation with clozapine was greater even after adjusting for these factors. CONCLUSION: Continuation with medication is greater with clozapine than haloperidol and is partly explained by greater symptom improvement and reduced side effects. No differences were found in regimen compliance.

Adult↗

A double blind comparison of zuclopenthixol acetate with haloperidol in the management of acutely disturbed schizophrenics.

The aim of this study was to evaluate the efficacy and side effects of zuclopenthixol acetate compared with haloperidol in the management of the acutely disturbed schizophrenic patient. Suitable subjects diagnosed as having schizophreniform disorder or acute exacerbation of schizophrenia admitted to the psychiatric wards Hospital Kuala Lumpur were randomised to receive either zuclopenthixol acetate or haloperidol. They were rated blind for three consecutive days using the Brief Psychiatric Rating Scale (BPRS), Clinical Global Impression (CGI) and UKU Side Effects Scale. Apart from repeat injections of the same medication, no other anti-psychotic was given for the duration of the study. 50 subjects entered the study of which 44 completed. 23 were given zuclopenthixol acetate and 21 haloperidol. Both groups significantly reduced BPRS and CGI scores on all 3 days compared to the initial rating (p < 0.001). There was however no difference between the zuclopenthixol acetate and haloperidol group scores on all days (p > 0.05). More subjects on haloperidol than zuclopenthixol required more than 1 injection during the study. Both groups had minimal side effects. Zuclopenthixol acetate was effective in the management of the acutely disturbed schizophrenic.

Adult↗

Neurotensin levels in specific brain regions and hypnotic sensitivity to ethanol and pentobarbital as a function of time after haloperidol administration in selectively bred rat lines.

Evidence indicates that sensitivity to ethanol is a good predictor of the development of alcoholism. Thus, identification of neuronal processes that regulate ethanol sensitivity has been the subject of much recent research. The present studies were designed to further test the hypothesis that neurotensinergic processes mediate, in part, hypnotic sensitivity to ethanol. Single doses of haloperidol were administered to lines of rats [selectively bred for high and low sensitivity (HAS and LAS, respectively) to hypnotic effects of ethanol] to produce increases in neurotensin (NT) levels in brain regions. At 20 h after administration, haloperidol produced dose-dependent increases in NT immunoreactivity levels in nucleus accumbens (NA) and caudate putamen (CP) in both HAS and LAS lines. Levels of NT in NA and CP returned to control values at 48 h after 4 mg/kg haloperidol. These studies used two measures of hypnotic sensitivity to ethanol: duration of loss of righting reflex (sleep time) and blood ethanol concentration at regain of righting reflex (BECRR). At 20 h, but not 48 h, after haloperidol treatment, both HAS and LAS rats displayed increases in ethanol-induced sleep time with concomitant decreases in BECRR. Pentobarbital-induced sleep time was not increased 20 h after administration of 4 mg/kg haloperidol; however, hypnotic sensitivity to both pentobarbital and ethanol was increased by acute (30-min) pretreatment with 1 mg/kg. These results suggest that NT levels in NA, acting via NT receptors, enhance hypnotic sensitivity to ethanol, but not pentobarbital.

Alcoholic Intoxication↗

Distinct roles for nigral GABA and glutamate receptors in the regulation of dendritic dopamine release under normal conditions and in response to systemic haloperidol.

The regulation of dendritic dopamine release in the substantia nigra (SN) likely involves multiple mechanisms. GABA and glutamate inputs to nigrostriatal dopamine neurons exert powerful influences on dopamine neuron physiology; therefore, it is probable that GABA and glutamate likewise influence dendritic dopamine release, at least under some conditions. The present studies used in vivo microdialysis to determine the potential roles of nigral GABA and glutamate receptors in the regulation of dendritic dopamine release under normal conditions and when dopamine signaling in the basal ganglia is compromised after systemic haloperidol administration. Nigral application of the GABA(A) receptor antagonist bicuculline by reverse dialysis significantly increased spontaneous dopamine efflux in the SN. However, spontaneous dopamine efflux in the SN was not significantly affected by local application of the glutamate receptor antagonists 6-cyano-7-nitroquinoxaline-2,3-dione or (+/-)-3-[2-carboxypiperazine-4-yl]-propyl-1-phosphonic acid. Systemic haloperidol administration significantly increased the extracellular dopamine measured in the SN. Blockade of nigral GABA(A) receptors by local bicuculline application did not alter this effect of systemic haloperidol, despite the bicuculline-induced increase in spontaneous dendritic dopamine efflux. In contrast, nigral application of either glutamate receptor antagonist significantly attenuated the increases in dendritic dopamine efflux elicited by systemic haloperidol. These data suggest that under normal conditions, activity of GABA afferents to SN dopamine neurons is an important determinant of the spontaneous level of dendritic dopamine release. Circuit-level changes in the basal ganglia involving an increased glutamatergic drive to the SN appear to underlie the increase in dendritic dopamine release that occurs in response to systemic haloperidol administration.

Animals↗

[Sudden death following a single oral administration of haloperidol].

A 39-year-old man was admitted with myasthenia, alcoholic hepatitis and electrolyte abnormalities due to an inadequate nutritional state. On admission the ECG showed a prolonged QTc interval (0.46 s). The patient was treated with intravenous fluid and supplementary vitamins and minerals. On the third day of admission the patient developed a delirium, partly due to alcohol withdrawal, and was therefore treated with oxazepam 50 mg 3 times daily and a single dose of haloperidol 5 mg. One hour after ingesting haloperidol, the patient suddenly succumbed and resuscitation was not successful. The autopsy revealed a cardiomyopathy but no explanation for the sudden death. Due to the temporal relationship between the ingestion of haloperidol and this sudden death, we assume that haloperidol induced a fatal arrhythmia in the presence of a preexisting prolonged repolarisation time. To the best of our knowledge, sudden death after a single oral therapeutic dose of haloperidol has not previously been described.

Administration, Oral↗