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Old drug, new tricks: haloperidol inhibits secretion of proinflammatory cytokines.

OBJECTIVES: It was noted that treatment of a patient with acute mania by haloperidol was associated with marked improvement in activity of rheumatoid arthritis. The objective of this study was to examine the effects of haloperidol on inflammatory cytokine release in vitro, as a potential mechanism to explain the in vivo anti-inflammatory effects of haloperidol. METHODS: The effect of haloperidol on the production of inflammatory cytokines interleukin 1beta (IL1beta) and tumour necrosis factor alpha (TNFalpha) was measured in bacterial lipopolysaccharide stimulated whole blood cultures and on the promonocyte cell line THP-1, using commercial and in house enzyme linked immunosorbent assays to measure cytokine concentrations. RESULTS: Haloperidol inhibited lipopolysaccharide stimulated production of both IL1beta and TNFalpha in vitro in a dose dependent manner and over a prolonged time period. Marked inhibition was seen over a range of concentrations of haloperidol from 0.5 microgram/ml to 50 microgram/ml, including those predicted to occur in the patient's blood. CONCLUSIONS: Haloperidol treatment seemed to alleviate inflammation in rheumatoid arthritis. In vitro experiments would suggest that the mechanism is by direct inhibition of proinflammatory cytokine release. This phenomenon requires further investigation and may potentially lead to the development of novel treatment.

Adult↗

Haloperidol-mediated phosphoinositide hydrolysis via direct activation of alpha1-adrenoceptors in frontal cerebral rat cortex.

In addition to its effect on D2 dopamine receptor blockades, haloperidol is able to interact with multiple neurotransmitters (NTs). Its action on phosphoinositide (PI) turnover was studied on cerebral cortex preparations. It induces an increase in inositol phosphate (IP) accumulation, which was only blunted by the alpha1-adrenoceptor blocker prazosin. Haloperidol maximal effect (Emax) was less than the effect of the full agonist norepinephrine (NE), and dose-response curves for both NE in the presence of submaximal doses of haloperidol and haloperidol in the presence of Emax doses of NE showed that haloperidol behaves as a partial agonist of cerebral alpha1-adrenoceptors. Its effect on PI hydrolysis is mediated through phospholipase C activation, as 2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate (NCDC) and 1-[6-([(17beta)-3-methoxyestra- 1,3,5(10)-trien-17-yl]amino)hexyl]-1H-pyrrole-2,5-dione) (U-73122) were able to abrogate both haloperidol and NE actions. Further, the typical neuroleptic exerts a direct activation of alpha1-adrenoceptors as its actions were not modified by cocaine and persisted in spite of chemical rat cerebral denervation with 6-hydroxydopamine (6-OHDA). The possibility that this agonistic action on alpha1-adrenoceptors would be involved in haloperidol side effects is also discussed.

Animals↗

Plasma alpha-one acid glycoprotein and haloperidol concentrations in schizophrenic patients.

Thirty six schizophrenic patients were randomly assigned to placebo or haloperidol treatment for 6 weeks. Blood samples to measure plasma alpha-one acid glycoprotein (AAG), haloperidol and reduced haloperidol concentrations were obtained at baseline and weeks 2, 4, and 6. Blood samples were obtained 10-12 h after the evening dose and prior to the morning dose. Haloperidol and reduced haloperidol was assayed by HPLC with electrochemical detection. Plasma AAG levels were assayed by radial immunodiffusion. Patients were clinically assessed by the Brief Psychiatric Rating Scale (BPRS) and Abnormal Involuntary Movement Scale at baseline and weeks 2, 4, and 6. BPRS scores did not significantly decrease during placebo treatment, although a slight drop in plasma AAG levels was found. Haloperidol produced a significant decrease in BPRS scores and plasma AAG levels. Mean plasma haloperidol levels were 12.9 +/- 14.7 ng/ml at week 6. Significant correlations between decreasing BPRS scores and plasma AAG levels were not found with only a strong trend at week 2 (r = 0.445, p = 0.073). The role of AAG and psychotropic drug disposition in psychiatric patients requires further evaluation.

Adult↗

Differential effects of haloperidol on the rat pituitary: decreased biosynthesis, processing and release of anterior lobe pro-opiomelanocortin.

The effects of chronic haloperidol treatment on pro-opiomelanocortin (POMC) synthesis, processing, and release in the anterior (AL) and intermediate (IL) lobes of the rat pituitary were studied. In the IL, 14 days of haloperidol administration promoted an increase in the level of POMC mRNA, and a corresponding elevation of levels of beta-endorphin (beta E), alpha-melanocyte-stimulating hormone (MSH), and gamma 3 MSH. In the AL, a reduction of POMC mRNA as well as immunoreactive beta E, adrenocorticotropin (ACTH), and gamma 3 MSH was observed. Column chromatography revealed that this treatment promoted an apparent alteration of POMC processing in AL: the conversion of larger, precursor-sized peptides to smaller, more-processed forms was relatively inhibited. Circulating levels of both N-acetyl-beta E and corticosterone were elevated following haloperidol challenge in drug-naive animals. Resting plasma levels of both, however, were not changed following chronic haloperidol treatment. Pituitary culture studies demonstrated that chronic haloperidol treatment increased the releasability of IL-derived products, while simultaneously decreasing the releasability of those products from the AL. These results suggest that pituitary POMC biosynthesis, processing and release are under at least partial dopaminergic control in both the IL and the AL of the pituitary, but by different mechanisms; chronic haloperidol treatment upregulates the POMC system in IL, but downregulates it in AL, despite similarities of the responses of both lobes to acute haloperidol challenge.

Animals↗

Effect of melanotropin release inhibiting factor on changes by haloperidol and centbutindole in cerebral cortical 5-hydroxytryptamine receptors.

The effect of melanotropin release inhibiting factor (Pro-Leu-Gly-NH2, MIF) was determined on changes induced by two neuroleptics, haloperidol and centbutindole, in cerebral cortical 5-hydroxytryptamine (5-HT) receptors. Male Sprague-Dawley rats were injected daily i.p. with vehicle, haloperidol (1.0 mg/kg) or centbutindole (0.5 mg/kg), respectively, for 21 days. On day 22, these 3 groups were further divided into 2 subgroups and injected with either vehicle or MIF (2.0 mg/kg, i.p.) daily for 3 days. 3H-5-HT was used to study 5-HT1 receptors, and 3H-spiroperidol to label 5-HT2 receptors in the cerebral cortex. Chronic administration of haloperidol significantly increased (39.7%) the maximal binding capacity (Bmax) of 3H-5-HT binding to 5-HT1 receptors. Dissociation constant (Kd) values did not change. Centbutindole had no effect on 5-HT1 receptors. MIF had no effect on 5-HT1 receptors, nor did it alter haloperidol-induced increases in the Bmax of 3H-5-HT binding to 5-HT1 receptors. Chronic administration of centbutindole significantly increased (61.1%) the Bmax of 3H-spiroperidol binding to 5-HT2 receptors. No change occurred in the Kd values. Chronic treatment with haloperidol had no effect on 5-HT2 receptor characteristics. MIF had no effect on 5-HT2 receptors or on the increase in 5-HT2 receptor density induced by centbutindole. The behavioral syndrome induced by 5-hydroxytryptophan (5-HTP) (50, 100 and 200 mg/kg, i.p.) was also measured in rats treated chronically with haloperidol or centbutindole. Haloperidol had no effect on the 5-HTP syndrome, whereas centbutindole stimulated by 24-45% the intensity of the syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Long-term application of haloperidol: effects on dopamine and acetylcholine receptors.

Rats were injected daily with haloperidol, 0.5 mg/kg i.p., or pimozide, 2 mg/kg i.p., for a period of 8 or 16 days, respectively. 24 h after the last injection of haloperidol, these rats were challenged with gamma-butyrolactone (GBL) in doses of 200-750 mg/kg i.p. In haloperidol-treated rats, higher doses of GBL are needed in order to increase the rate of dopa accumulation. This finding demonstrates the development of supersensitivity of dopamine (DA) autoreceptors towards endogenously released DA. Pimozide had no effect on the increased rate of dopa accumulation induced by increasing doses of GBL. From this data it is concluded that pimozide in our model is mainly active on postsynaptic DA receptors and haloperidol is active on pre- and postsynaptic DA receptors. In rats treated chronically with daily injections of haloperidol, benztropine, in a dose of 50 mg/kg, induced a decrease in dopa accumulation which was more marked than the decrease seen with benztropine, 50 mg/kg in animals treated with a single injection of haloperidol only. The opiate antagonist, naloxone at a dose of 10 mg/kg, had no effect on these results. Benztropine, 50 mg/kg i.p., had no effect on the increased rate of dopa accumulation induced by GBL, 400 mg/kg. The data support the hypothesis that in parallel to the development of supersensitive postsynaptic DA receptors, there is a development of subsensitivity in cholinergic receptors within the nigro-neostriatal system. Further the results show that a new DA-acetylcholine equilibrium is reached during long-term haloperidol treatment. The implications of these findings in regard to extrapyramidal side effects during long-term neuroleptic treatment are briefly discussed.

4-Butyrolactone↗

D2 dopamine receptor occupancy during low-dose treatment with haloperidol decanoate.

OBJECTIVE: The aim of this study was to examine the relationships among clinical effects, central D2 dopamine receptor occupancy, and plasma concentrations of haloperidol in eight clinically stabilized schizophrenic outpatients who were responding to treatment with low doses of haloperidol decanoate. METHOD: During a 4-week interval of haloperidol decanoate dosage (dose range = 30-50 mg), the patients' D2 receptor occupancy was determined with positron emission tomography on two occasions. Plasma concentrations of haloperidol were determined with a sensitive high-performance liquid chromatography method. RESULTS: One week after injection of haloperidol decanoate, the mean D2 receptor occupancy was 73% (range = 60%-82%), and the mean plasma concentration of haloperidol was 4.6 nmol/liter (range = 2.9-9.7). After 4 weeks, the mean D2 receptor occupancy had decreased to 52% (range = 20%-74%), and the mean haloperidol concentration to 2.3 nmol/liter (range = 1.0-4.4). CONCLUSIONS: The D2 receptor occupancy 1 week after injection was high and comparable to that previously found in patients responding to acute treatment with classic neuroleptics. Prevention of relapse was maintained despite low D2 receptor occupancy during the latter part of the treatment interval. These observations indicate that continuously high D2 receptor occupancy may not be necessary to prevent schizophrenic relapses. The results emphasize the need for systematic clinical evaluation of intermittent low-dose treatment strategies.

Adult↗

Functional sites of neuroleptic drug action in the human brain: PET/FDG studies with and without haloperidol.

OBJECTIVE: The functional pathways through which antipsychotic drugs act in the brain to decrease psychosis remain unknown, despite our knowledge that their site of initial action is through blockade of dopamine D2 receptors. The authors sought to define the brain regions that are functionally altered by neuroleptic drugs. METHODS: Regional cerebral glucose metabolism was studied in 12 subjects with schizophrenia while they were receiving a fixed dose of haloperidol, again 5 days after withdrawal of the drug, and a third time 30 days after withdrawal. Positron emission tomography with an [18F]fluorodeoxyglucose tracer was used in a within-subject design. RESULTS: The analysis demonstrated a decrease in glucose metabolism in the caudate and putamen 30 days after withdrawal, indicating that haloperidol treatment enhanced glucose utilization in these areas. The thalamus, bilaterally but only in anterior areas, showed the same response to haloperidol. Only in the frontal cortex and in the anterior cingulate had metabolism increased 30 days after withdrawal, indicating that in those two cortical areas haloperidol depressed glucose metabolism. In the 5-day drug free scans, no regions differed significantly from those in the haloperidol condition, despite numerical changes. CONCLUSIONS: It appears that 5 days of neuroleptic withdrawal are inadequate to escape the effects of neuroleptic drugs on regional cerebral glucose metabolism. The pattern and localization of changes in metabolic activity between the haloperidol condition and the 30-day drug-free condition suggest that haloperidol exerts its primary antidopaminergic action in the basal ganglia. It is proposed that the additional changes in the thalamus and cortex are secondary to this primary site of drug action, mediated through classically described striato-thalamo-cortical pathways.

Adult↗

Olanzapine versus haloperidol treatment in first-episode psychosis.

OBJECTIVE: It has been hypothesized that the morbidity and mortality associated with schizophrenia can be prevented by providing effective treatment during the first episode of psychosis. Hence, the authors examined patients with first-episode psychosis to determine the efficacy and safety of olanzapine and haloperidol treatment. METHOD: A subpopulation of first-episode patients (N=83) from a large prospective, multicenter, international, double-blind, 6-week acute treatment study was evaluated. These patients were selected from a pool of 1,996 patients who had a DSM-III-R diagnosis of schizophrenia, schizoaffective disorder, or schizophreniform disorder and who also met the following criteria: 1) the length of their current psychotic episode had to be 5 or fewer years, and 2) patients had to be 45 years of age or younger at onset of first psychotic symptoms. RESULTS: Compared to haloperidol, olanzapine showed a statistically significantly greater reduction in the Brief Psychiatric Rating Scale (BPRS) total and negative scores and in the Positive and Negative Syndrome Scale total and positive scores. Clinical response (defined as 40% or greater improvement in BPRS total score from baseline) was also statistically significantly higher in olanzapine-treated patients (67.2%) than in haloperidol-treated patients (29.2%). Olanzapine-treated patients further showed statistically significant improvements in the Simpson-Angus scale and Barnes Akathisia Scale scores, while haloperidol-treated patients showed a worsening on both measures. Compared to olanzapine-treated multiple-episode patients in the parent study, olanzapine-treated first-episode patients achieved an even statistically significantly higher response. Haloperidol-treated first-episode patients experienced statistically significantly more extrapyramidal symptoms than haloperidol-treated multiple-episode patients. CONCLUSIONS: In patients experiencing first-episode psychosis, olanzapine had a risk-benefit profile significantly superior to that of haloperidol. The study results suggest that novel antipsychotic agents such as olanzapine should be considered as a preferred option in first-episode psychosis, on the basis of both safety and efficacy advantages.

Age of Onset↗

Subjective experience and D2 receptor occupancy in patients with recent-onset schizophrenia treated with low-dose olanzapine or haloperidol: a randomized, double-blind study.

OBJECTIVE: The authors tested the hypothesis that a dopamine D(2) receptor occupancy level between 60% and 70% in patients with recent-onset schizophrenia would result in optimal subjective experience. In addition, they sought preliminary evidence on whether subjective experience is better with low-dose olanzapine than with low-dose haloperidol. METHOD: Subjects (N=24) who met DSM-IV criteria for schizophrenia were randomly assigned to 6 weeks of double-blind treatment with either olanzapine, 7.5 mg/day, or haloperidol, 2.5 mg/day. Subjective experience, psychopathology, and extrapyramidal symptoms were assessed at baseline and at endpoint. After 6 weeks, D(2) receptor occupancy was assessed with [(123)I]iodobenzamide single photon emission computed tomography. RESULTS: The two study groups were similar at baseline. After 6 weeks, patients receiving olanzapine had a significantly lower mean dopamine D(2) receptor occupancy (51.0%, range=36%-67%) than those given haloperidol (65.5%, range=45%-75%). Receptor occupancy between 60% and 70% was associated with optimal subjective experience, and subjective experience improved significantly in the haloperidol group. CONCLUSIONS: A level of D(2) receptor occupancy between 60% and 70% is optimal for subjective experience of patients with recent-onset schizophrenia. Substantial interindividual variation in D(2) receptor occupancy was seen at fixed low-dose levels of olanzapine and haloperidol. Olanzapine, 7.5 mg/day, showed no superior subjective response over haloperidol, 2.5 mg/day. Olanzapine may need to be dosed higher than 7.5 mg/day for most patients with recent-onset schizophrenia, and haloperidol needs to be individually titrated in the very low dose range to reach optimal occupancy.

Adolescent↗

Treatment of cognitive impairment in early psychosis: a comparison of risperidone and haloperidol in a large long-term trial.

OBJECTIVE: Cognitive impairment is a major determinant of functional outcome in schizophrenia. Treatment of cognitive impairment at the time of the first episode may have the potential to change functional outcomes of the illness. This study examined changes associated with treatment with risperidone compared with haloperidol in aspects of cognitive functioning known to be associated with functional outcomes. The study was conducted in a large group of patients experiencing their first episode of schizophrenia. METHOD: Cognitive assessments were conducted in 533 patients experiencing their first episode of schizophrenia or a related psychosis who had been randomly assigned to receive low doses of risperidone or haloperidol. The cognitive assessments were repeated at several different follow-up intervals; 359 patients were reexamined at the 3-month follow-up. The assessments included examinations of verbal and visuospatial episodic memory, vigilance, executive functioning, processing speed, and verbal fluency. Patients' clinical symptoms were also rated with the Positive and Negative Syndrome Scale. RESULTS: Improvements from baseline were found in the risperidone-treated patients for episodic memory, verbal fluency, vigilance, executive functioning, and visuomotor speed. Haloperidol-treated patients also showed improvements from baseline in episodic memory, vigilance, and visuomotor speed but not in executive functioning or verbal fluency. Comparison of differential treatment effects on a composite measure of cognitive functioning found that risperidone was significantly more beneficial than haloperidol after 3 months of treatment. Changes in Positive and Negative Syndrome Scale scores were correlated overall with improvement in the haloperidol-treated patients but not in the risperidone-treated patients. CONCLUSIONS: Treatment with risperidone at the time of the first episode of schizophrenia is associated with wide-ranging improvements in cognitive functioning. Overall improvement is significantly greater with risperidone than with haloperidol. Further, cognitive improvement associated with treatment with risperidone was not influenced by changes in symptoms, but that relationship was significant in haloperidol-treated patients.

Adult↗

Risperidone and haloperidol in first-episode psychosis: a long-term randomized trial.

OBJECTIVE: The first episode of psychotic illness is a key intervention point. The initial experience with medication can affect willingness to accept treatment. Further, relapse prevention is a treatment cornerstone during the first years of illness because active psychotic illness may affect lifetime outcomes. Thus, initial treatment of active symptoms and subsequent relapse prevention are central goals of pharmacotherapy. This study compared long-term effectiveness of risperidone versus haloperidol in first-episode psychosis patients. METHOD: First-episode psychosis patients (N=555, mean age=25.4 years) participated in a double-blind, randomized, controlled flexible-dose trial that compared risperidone (mean modal dose=3.3 mg) and haloperidol (mean modal dose=2.9 mg). The median treatment length was 206 days (maximum=1,514). RESULTS: Positive and Negative Syndrome Scale scores and Clinical Global Impression ratings improved significantly relative to baseline, with no significant differences between groups. Three-quarters of the patients achieved initial clinical improvement, defined as >20% reduction in total Positive and Negative Syndrome Scale score. However, among those who achieved clinical improvement, 42% of the risperidone group experienced a relapse compared with 55% of the haloperidol group. The median time to relapse was 466 days for risperidone-treated subjects and 205 days for those given haloperidol. These differences were statistically significant based on Kaplan-Meier survival analysis. Adverse effects distinguished the treatments: there were significantly more extrapyramidal signs and symptoms and adjunctive medication use in the haloperidol group and greater prolactin elevation in the risperidone group. There was less weight gain with haloperidol initially but no significant differences between groups at endpoint. CONCLUSIONS: Relatively low doses of antipsychotic drugs lead to significant symptom amelioration in the majority of first-episode psychosis patients. In the long term, risperidone prevents relapse in more patients and for a longer time and also induces less abnormal movements than haloperidol.

Adult↗

Effects of d-amphetamine and haloperidol on latent inhibition in healthy male volunteers.

Latent inhibition (LI) refers to a retardation of learning about the consequences of a stimulus when that stimulus has been passively presented a number of times without reinforcement. Acute positive-symptom schizophrenics, normal volunteers who score high on questionnaire measures of schizotypy and non-patients or animals treated with dopamine agonists show reduced LI. Neuroleptic drugs, such as haloperidol, administered at low doses, potentiate LI and effectively reverse disruption of LI induced by dopamine agonists in animals. However, a high dose of haloperidol, administered on its own, has been found to reduce LI. We examined the effects on LI of acute oral administration of an indirect dopamine-agonist, d-amphetamine (5 mg), and a nonselective dopamine receptor antagonist, haloperidol (5 mg), in normal male volunteers, using an associative learning task. Replicating previous reports, we found that d-amphetamine reduced LI; haloperidol also reduced LI, but only in subjects who scored low on the Psychoticism scale of the Eysenck Personality Questionnaire. In a subsequent study, no effect was found of 2 mg oral haloperidol administration on LI. The effect of 5 mg haloperidol on LI is interpreted as similar to that observed with a high dose of haloperidol in rats.

Adrenergic Agents↗

Use of haloperidol infusions to control delirium in critically ill adults.

OBJECTIVE: To describe and discuss the use of continuous intravenous infusions of haloperidol to treat severe delirium and agitation in 3 intensive care unit (ICU) patients. CASE SUMMARIES: Three severely agitated patients in ICU did not respond to conventional therapy with opiates, benzodiazepines, and intermittent intravenous doses of haloperidol. In each case, control was achieved rapidly after initiation and titration of a continuous haloperidol infusion. Two patients had a history of schizophrenia. No adverse effects attributable to therapy were identified. DISCUSSION: Haloperidol is often used in the ICU for control of severe agitation, even in patients without a psychiatric history. It usually is given by bolus intravenous injection, sometimes in high doses (> 5 mg), even though that is not approved by the Food and Drug Administration. Intravenous haloperidol is generally well tolerated, but multiform ventricular tachycardia has been reported. Experience with continuous haloperidol infusions is growing, and it appears to be an effective method for control of severe agitation or delirium. In our experience and in other limited published data, adverse effects are rare, but prolongation of the QT interval has occurred and multiform ventricular tachycardia is likely a risk. CONCLUSIONS: In selected patients, a continuous infusion of haloperidol may be a useful alternative for control of agitation and delirium. Close monitoring for QT prolongation or rhythm disturbances is mandatory.

Adult↗

Haloperidol decanoate v. fluphenazine decanoate as maintenance therapy in chronic schizophrenic in-patients.

In a double-blind study of 38 chronic schizophrenic in-patients, haloperidol decanoate was compared with fluphenazine decanoate as maintenance therapy over 60 weeks. Both drugs were given by injection at 4-week intervals. Haloperidol and fluphenazine were assumed to be equipotent; the mean starting dose of the former was 127 mg and of the latter 106 mg. The number of withdrawals over 60 weeks was similar in both groups but relapses, strictly defined, were significantly more frequent in the haloperidol group. When patients were switched to haloperidol, Parkinsonism diminished more quickly than in the fluphenazine group, but after 60 weeks there was no difference in severity in the two drug groups. The higher relapse rate and the quicker reduction in Parkinsonism in the haloperidol group might be due to a misjudgement in equivalent doses of the two drugs. Plasma haloperidol steady state levels were reached in most patients by 8-12 weeks. Plasma neuroleptic and prolactin levels, week-by-week systemic drug availability and Parkinsonism showed less variation between injections with haloperidol than with fluphenazine.

Adult↗

Single-dose haloperidol for the prophylaxis of postoperative nausea and vomiting after intrathecal morphine.

UNLABELLED: Postoperative nausea and vomiting (PONV) occurs frequently with the use of intrathecal morphine. We studied the ability of a single, small dose of the inexpensive, long-acting, dopamine receptor-blocking drug, haloperidol, to prevent PONV after spinal anesthesia using local anesthetic with morphine 0.3 mg. One-hundred-eight adult patients undergoing elective lower limb orthopedic or endoscopic urologic procedures under spinal anesthesia were randomized to receive IM haloperidol 1 mg (H1), haloperidol 2 mg (H2), or placebo (P) after an intrathecal injection. Patients were assessed for 24 h after surgery, with treatment failure being defined as nausea >1 on a 10-cm visual analog scale or any vomiting or request for rescue antiemetic. Most treatment failures occurred during the first 12 h (60% overall), and haloperidol led to a dose-dependent decrease in PONV (first 12 h: 76% P, 56% H1, and 50% H2; P = 0.012). A history of PONV was strongly associated with PONV in the current study, regardless of treatment group. There were no dystonic reactions noted to either dose of haloperidol. We conclude that haloperidol reduces the incidence of PONV after intrathecal morphine, although this incidence remains a significant problem even with treatment. IMPLICATIONS: In this randomized, double-blinded, placebo-controlled trial, a single, small IM dose of haloperidol 1 mg or 2 mg reduced the incidence of postoperative nausea and vomiting after spinal anesthesia with local anesthetic and intrathecal morphine.

Adolescent↗

Haloperidol-induced torsade de pointes.

OBJECTIVE: To report a case of torsade de pointes related to the administration of high-dose intravenous haloperidol for the treatment of severe agitation. CASE SUMMARY: Reports in the literature of intravenous haloperidol-induced torsade de pointes are rare. We describe the case of a 41-year-old white woman with no predisposing factors who developed torsade de pointes 55 minutes after a dose of intravenous haloperidol 80 mg (total dosage 915 mg over 7 d). The results of the electrocardiogram were consistent with torsade de pointes and showed a prolonged QTc interval of 610 milliseconds. Intravenous magnesium sulfate 2 g/100 mL NaCl 0.9% was administered, which controlled the arrhythmia. The patient received one additional 80-mg haloperidol dose six hours after the arrhythmia-triggering dose, without reoccurrence of torsade de pointes. Haloperidol was then discontinued, and the patient had no further arrhythmias. CONCLUSIONS: Our case report and others from the literature suggest that intravenous haloperidol administration may prolong QT intervals in some patients, precipitating the potentially life-threatening arrhythmia torsade de pointes. Clinicians should be aware of haloperidol's potential to induce torsade de pointes, since it is used regularly for agitation and delirium in the critical care arena.

Adult↗

Risk of extrapyramidal syndromes with haloperidol, risperidone, or olanzapine.

OBJECTIVE: To compare the risk of extrapyramidal syndrome (EPS) between risperidone, olanzapine, and haloperidol, taking into account patients' past antipsychotic drug use and past EPS. METHODS: Data were obtained from the PHARMO-database, containing filled prescriptions of 450,000 community-dwelling people in the Netherlands from 1986 through 1999. We defined cohorts of first-time users of haloperidol, risperidone, or olanzapine aged 15 to 54 years. In the first 90 days of treatment, we assessed the occurrence of EPS, defined as first use of any antiparkinsonian agent. We estimated relative risks of EPS for risperidone and olanzapine versus haloperidol using a Cox proportional hazards model. Patients were subdivided according to prior use of antipsychotic and antiparkinsonian drugs. RESULTS: We identified 424 patients starting treatment with haloperidol, 243 with risperidone, and 181 with olanzapine. Prior use of antipsychotic plus antiparkinsonian medication was significantly more frequent among users of risperidone and olanzapine than in those using haloperidol (36.2%, 40.3%, and 4.5%, respectively; p < 0.001). Within most subgroups of comparable treatment history, patients using risperidone and olanzapine showed reduced risks of EPS compared with haloperidol, although some of these findings did not reach statistical significance (RR 0.03-0.22). However, this was not observed for patients using risperidone who had experienced EPS in the past (RR 1.30; 95% CI 0.24 to 7.18). CONCLUSIONS: In general, we observed reduced risks of EPS for risperidone and olanzapine compared with haloperidol within subgroups of patients with a similar treatment history. However, the added value of risperidone in patients who have experienced EPS in the past needs further study.

Adolescent↗