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Repeated haloperidol increases both calmodulin and a calmodulin-binding protein in rat striatum.

Repeated treatment with the antipsychotic drug, haloperidol, leads to an increased behavioral sensitivity to dopamine agonists exhibited upon withdrawal from the drug. An increase in the particulate content of the endogenous Ca(2+)-binding protein, calmodulin, has been demonstrated after repeated treatment of rats with haloperidol. In this study, the anatomical specificity of the effect of repeated haloperidol treatment on the content and subcellular localization of calmodulin was investigated. Responsivity of calmodulin localization to dopaminergic input following drug treatment was assessed by determining the subcellular localization of calmodulin following an in vivo amphetamine challenge before sacrifice. Male, Sprague-Dawley rats were treated with 0.5 mg/kg haloperidol (s.c.) for 3 weeks and withdrawn from the drug for 4 days. Repeated haloperidol increased calmodulin content only in the striatum but altered the subcellular distribution of calmodulin in rat limbic forebrain and frontal cortex. In the latter areas, the soluble calmodulin was increased while the particulate calmodulin was decreased. There was no change in calmodulin in either hippocampus or cerebellum in response to drug treatment. Challenge with the dopamine mimetic, amphetamine, before sacrifice was effective in redistributing calmodulin only in striatum from rats that had been treated repeatedly with haloperidol, demonstrating an increased sensitivity of the translocation process. In order to determine whether a change in a calmodulin-binding protein would accompany the drug-induced increase in calmodulin, striatal calmodulin-binding proteins were examined using a biotinylated calmodulin overlay technique. Repeated haloperidol treatment enhanced calmodulin binding to a 150 kDa protein in striatal membranes. The 150 kDa protein exhibited the same gel mobility and subcellular distribution as myosin light chain kinase immunoreactivity. There was an increase in myosin light chain kinase immunoreactivity in striatal membranes after repeated haloperidol that was apparent in animals withdrawn either 4 or 10 days from haloperidol treatment. Therefore, repeated haloperidol could increase the rat striatal content of calmodulin and potentially that of the calmodulin-binding protein, myosin light chain kinase. Increases in striatal calmodulin and myosin light chain kinase may signal a greatly enhanced sensitivity of actin-myosin interactions after repeated haloperidol that could contribute to haloperidol-induced neurochemical or morphological changes involved in drug-induced synaptic plasticity.

Amphetamine↗

A comparison of the efficacy and safety of olanzapine versus haloperidol during transition from intramuscular to oral therapy.

BACKGROUND: Acutely agitated patients with schizophrenia who receive intramuscular (IM) medications typically are switched to oral (PO) antipsychotic maintenance therapy. OBJECTIVE: The goal of this study was to assess the efficacy and safety of olanzapine versus those of haloperidol during transition from IM to PO therapy. We used additional data from a previously reported trial to test the hypothesis that the reduction in agitation achieved by IM olanzapine 10 mg or IM haloperidol 7.5 mg would be maintained following transition to 4 days of PO olanzapine or PO haloperidol (5-20 mg/d for both). We also hypothesized that olanzapine would maintain its more favorable extrapyramidal symptom (EPS) safety profile. METHODS: This was a multinational (hospitals in 13 countries), double-blind, randomized, controlled trial. Acutely agitated inpatients with schizophrenia were treated with 1 to 3 IM injections to olanzapine 10 mg or haloperidol 7.5 mg over 24 hours and were entered into a 4-day PO treatment period with the same medication (5-20 mg/d for both). The primary efficacy measurement was reduction in agitation, as measured by the Positive and Negative Syndrome Scale-Excited Component (PANSS-EC) score. Adverse events and scores on EPS rating scales were assessed. RESULTS: A total of 311 patients (204 men, 107 women; mean [SD] age, 38.2 [11.6] years) were enrolled (131, 126, and 54 patients in the olanzapine, haloperidol, and placebo groups, respectively). In all, 93.1% (122/131) of olanzapine-treated patients and 92.1% (116/126) of haloperidol-treated patients completed the IM period and entered the PO period; 85.5% (112/131) of olanzapine-treated patients and 84.1% (106/126) of haloperidol-treated patients completed the PO period. IM olanzapine and IM haloperidol effectively reduced agitation over 24 hours (mean [SD] PANSS-EC change, -7.1 [4.81 vs -6.7 [4.3], respectively). Reductions in agitation were sustained throughout the PO period with both study drugs (mean [SD] change from PO period baseline, -0.6 [4.8] vs -1.3 [4.4], respectively). During PO treatment, haloperidol-treated patients spontaneously reported significantly more acute dystonia than olanzapine-treated patients (4.3%[5/116] vs 0% [0/122], respectively; P = 0.026) and akathisia (5.2% [6/116] vs 0% [0/122], respectively; P = 0.013). Significantly more haloperidol-treated patients than olanzapine-treated patients met categorical criteria for treatment-emergent akathisia (18.5% [17/92] vs 6.5% [7/107], respectively; P = 0.015). CONCLUSIONS: In the acutely agitated patients with schizophrenia in this study, both IM olanzapine 10 mg and IM haloperidol 7.5 mg effectively reduced agitation over 24 hours. This alleviation of agitation was sustained following transition from IM therapy to 4 days of PO treatment (5-20 mg/d for both). During the 4 days of PO treatment, olanzapine-treated patients did not spontaneously report any incidences of acute dystonia, and olanzapine had a superior EPS safety profile to that of haloperidol. The combination of IM and PO olanzapine may help improve the treatment of acutely agitated patients with schizophrenia.

Administration, Oral↗

Dextromethorphan phenotyping and haloperidol disposition in schizophrenic patients.

This study examined the relationship between the metabolic ratios of dextromethorphan/dextrorphan, haloperidol disposition, and the incidence of extrapyramidal side effects in schizophrenic patients. Eighteen schizophrenic patients were phenotyped with a test dose of dextromethorphan prior to the initiation of haloperidol treatment. The metabolic ratio of dextromethorphan/dextrorphan was determined in each patient. Patients were treated with oral haloperidol 10 mg/day for 2 weeks. Blood samples for haloperidol and reduced haloperidol were obtained at week 2 of haloperidol treatment. Haloperidol and reduced haloperidol plasma concentrations were assayed by HPLC with electrochemical detection. Significant correlations of dextromethorphan/dextrorphan metabolic ratios vs. plasma haloperidol concentrations, reduced haloperidol concentrations, and reduced haloperidol/haloperidol ratios were found (r = 0.726, P = 0.0007; r = 0.782, P = 0.0001; and r = 0.619, P = 0.006, respectively). Ten patients who experienced extrapyramidal side effects had higher reduced haloperidol concentrations and reduced haloperidol/haloperidol ratios than the other patients (2.49 +/- 1.42 [S.D.] ng/ml vs. 1.10 +/- 0.46 ng/ml, P = 0.014 and 0.287 +/- 0.102 vs. 0.192 +/- 0.065, P = 0.030). The former also had a trend to have higher haloperidol concentrations and dextromethorphan/dextrorphan ratios than the latter (8.04 +/- 2.91 ng/ml vs. 5.83 +/- 1.79 ng/ml, P = 0.066 and 0.023 +/- 0.017 vs. 0.011 +/- 0.010, P = 0.077). Phenotyping patients has the potential to assist clinicians in predicting plasma drug concentrations during the subsequent neuroleptic drug treatment. Further research with phenotyping and psychotropic drug metabolism in psychiatric patients is needed.

Adult↗

Withdrawal-associated changes in peripheral nitrogen oxides and striatal cyclic GMP after chronic haloperidol treatment.

The irreversible nature of haloperidol-induced tardive dyskinesia suggests a neurotoxic etiology, although the causes are unknown. Since nitric oxide demonstrates neurotoxic as well as neuroprotectant properties, and antipsychotics can inhibit nitric oxide (NO) synthase in vitro, this study investigates the NO-cGMP pathway as a pre-determining factor in chronic haloperidol-associated dyskinesia in rats. Sprague-Dawley rats were administered either water, oral haloperidol (0.25 mg/kg per day po), the guanylyl cyclase-nNOS inhibitor, methylene blue (MB; 5 mg/kg per day ip) or haloperidol plus MB for 3 weeks. In a second protocol, rats received water or haloperidol orally for 17 weeks, followed by 3 weeks withdrawal. Either saline (ip) or MB (ip) was administered for 3 weeks prior to haloperidol withdrawal. Vacous chewing movements (VCMs) were continuously monitored, followed by the determination of serum nitrogen oxides (NO(x)) and striatal cGMP at week 20. Chronic haloperidol engendered significant VCMs, with acute withdrawal resulting in significantly reduced plasma NO(x) and striatal cGMP. Furthermore, NO(x) and cGMP suppression was amplified by pre-withdrawal MB administration. Sub-acute haloperidol similarly induced incremental VCMs, but without effect on NO(x) or cGMP. However, haloperidol plus MB also induced significantly greater VCMs with decreased cGMP compared to haloperidol alone. Thus, NO(x)-cGMP inhibition persists pronounced after long-term haloperidol treatment and withdrawal. MB potentiation of these effects suggests that haloperidol inhibits a NO-dependent neuro-protective response to oxidative stress in the striatum that may pre-determine TD development.

Animals↗

Early suppression of striatal cyclic GMP may predetermine the induction and severity of chronic haloperidol-induced vacous chewing movements.

Haloperidol persists in brain tissue long after discontinuation while haloperidol-induced tardive dyskinesia often worsens after withdrawal of the drug. The mechanism of haloperidol-associated tardive dyskinesia is unknown, although neurotoxic pathways are suspected. Nitric oxide (NO) synthase (NOS) inhibitors exacerbate haloperidol-induced catalepsy, while haloperidol itself is a potent neuronal NOS inhibitor in vitro. Since NO and cGMP are involved in striatal neural plasticity, this study investigates a possible relation between cGMP and extrapyramidal symptoms as early predictors of haloperidol-associated tardive dyskinesia. Sprague-Dawley rats were administered either water or oral haloperidol (0.25 mg/kg/d p.o.) for 17 weeks, followed by 3 weeks withdrawal. Saline (i.p.) or the nNOS/guanylate cyclase inhibitor, methylene blue (5 mg/kg/d i.p.), were co-administered with haloperidol for the first three weeks of treatment. Vacous chewing movements (VCM's) were continuously monitored, followed by the determination of striatal cGMP and peripheral serum nitrogen oxide (NOx) levels. Chronic haloperidol engendered significant VCM's, with acute withdrawal associated with significantly reduced striatal cGMP levels as well as reduced serum NOx. Furthermore, suppressed cGMP levels were maintained and VCM's were significantly worse after early administration of methylene blue to the chronic haloperidol group. However, serum NOx was unchanged from control. We conclude that the central effects of chronic haloperidol on striatal NO-cGMP function persist for up to 3 weeks post-withdrawal. Moreover, suppression of striatal cGMP constitutes an early neuronal insult that determines the presence and intensity of haloperidol-associated motor dysfunction.

Animals↗

Relationship between haloperidol plasma concentration, debrisoquine metabolic ratio, CYP2D6 and CYP2C9 genotypes in psychiatric patients.

BACKGROUND: Around seven percent of Caucasians are poor metabolizers of cytochrome P450, CYP2D6 due to genetically impaired activity of the enzyme. Haloperidol in vitro and in vivo inhibits the activity of CYP2D6 and also the involvement of the enzyme in haloperidol metabolism has been reported. The present study was aimed to evaluate the possible inhibition of CYP2D6 during haloperidol treatment, and to determine the effect of CYP2D6 and CYP2C9 genotypes on the plasma concentration of haloperidol. METHODS: Thirty Caucasian psychiatric patients under haloperidol monotherapy were studied. CYP2D6 activity was evaluated by the debrisoquine metabolic ratio (MR), subjects with MR > 12.6 were named as poor metabolizers. Haloperidol plasma concentration was determined by high performance liquid chromatography. RESULTS: The number of patients with debrisoquine MR > 12.6 was higher than the expected comparing to healthy volunteers (13 % vs. 6.6 %, respectively). Debrisoquine MR was correlated with the dose of haloperidol (r = 0.40, p < 0.05), and also with the plasma concentration (r = 0.58, p < 0.001). Additionally, three patients comedicated with inhibitors of CYP2D6 were studied, all of them had a debrisoquine MR > 12.6, however only one was genetically poor metabolizer of CYP2D6. CYP2D6 and CYP2C9 genotypes were not related to the dose or plasma concentration of haloperidol. CONCLUSIONS: The present data support the dose-dependent inhibitory effect of haloperidol on CYP2D6, and the influence of this enzyme activity on haloperidol plasma concentration under steady-state conditions. The inhibitory effect of haloperidol on CYP2D6 enzyme activity may result in drug interactions and unexpected high plasma concentrations when drugs metabolized by the same enzyme are given concomitantly with haloperidol.

Adult↗

Haloperidol in the acute treatment of migraine: a randomized, double-blind, placebo-controlled study.

OBJECTIVE: To assess the efficacy and safety of i.v. haloperidol in treatment of acute migraine headache in a double-blind, randomized, placebo-controlled study design. BACKGROUND: Neuroleptics are mainly used as antiemetics in acute migraine. In a previous open trial haloperidol was effective in relieving migraine pain. DESIGN: Patients were randomized into 2 groups receiving intravenously either 5 mg haloperidol in 500 mL of normal saline or 500 mL of normal saline alone. Pain was assessed by visual analogue scale (VAS) before and 1 to 3 hours after the infusion. If the patient felt no relief in pain intensity 1 to 3 hours after the infusion and had received placebo, he/she then received haloperidol infusion as an open trial. The open trial also included 7 patients who refused from the placebo-controlled trial. About 1 month after the infusion the patients were contacted by telephone and interviewed about the side effects of the treatment. RESULTS: Forty patients were enrolled into the double-blind, placebo-controlled study. Before the infusion the VAS values were 7.7 in the haloperidol and 7.2 in the placebo group. After the infusion the VAS values were 2.2 in the haloperidol and 6.3 in the placebo group (P < .0001). Significant pain relief was achieved in 80% of the patients treated with haloperidol, whereas only 3 patients (15%) responded to placebo (P < .0001). Seventeen patients treated with placebo without response together with 7 patients who refused from the placebo-controlled study participated in the open trial. In this group VAS declined from 6.7 to 2.4 and 79% of these patients felt significant pain relief. The most common side effects caused by haloperidol were sedation and akathisia, the latter being more troublesome. These effects were very common in patients participating in the double-blind (80%) and open (88%) trials. Sixteen percent of the patients considered the side effects intolerable and would not like the migraine attacks to be treated with haloperidol in the future. Three patients (7%) returned to the emergency ward because of a relapse. CONCLUSIONS: This study shows that i.v. haloperidol is very effective in relieving migraine-associated pain. Because the majority of the patients had taken other medication without response, haloperidol appears to be an effective rescue medication even when other types of treatment have failed. Relapses are rare, but side effects are common, limiting the use of haloperidol in some patients.

Acute Disease↗

Block of delayed-rectifier potassium channels by reduced haloperidol and related compounds in mouse cortical neurons.

Haloperidol is known as an antagonist of dopamine D2 receptors. However, it also blocks a variety of ion channels at concentrations above the therapeutic range. Reduced haloperidol (R-haloperidol), one of the main metabolites of haloperidol, has been reported to accumulate in certain tissues, particularly in brain cortex, and it may produce the pharmacological effects associated with haloperidol treatment. In this study, we assessed the effect of R-haloperidol and other related compounds on native delayed-rectifier potassium channels (K(DR)) in mouse cortical neurons by using the whole-cell patch-clamp technique. Although R-haloperidol has much lower affinity to D2 receptors than haloperidol, the IC50 of R-haloperidol to block K(DR) currents was 4.4 microM, similar to its parent compound. The binding site of R-haloperidol is on the cytoplasmic side of the channel because its quaternary derivative preferentially inhibited the currents from intracellular side. 4-Chlorophenyl-4-hydroxypiperidine (4C4HP) is the active fragment of haloperidol because other compounds containing this moiety, including L-741,626 (3-[4-(4-chlorophenyl)-4-hydroxypiperidin-L-yl]-methyl-1H-indole) and loperamide, also blocked K(DR) channels. The potency of the 4C4HP fragment positively correlated with the hydrophobicity index (clogP) of the compounds tested. We conclude that R-haloperidol is a K(DR) channel blocker, although it does not interfere with the normal channel function at a clinically relevant concentration.

Animals↗

Haloperidol decanoate. A preliminary review of its pharmacodynamic and pharmacokinetic properties and therapeutic use in psychosis.

Haloperidol decanoate is a depot preparation of haloperidol, a commonly used butyrophenone derivative with antipsychotic activity. Haloperidol decanoate has no intrinsic activity: its pharmacodynamic actions are those of haloperidol--primarily that of central antidopamine activity. The monthly administered depot formulation has several clinical and practical advantages over oral haloperidol: better compliance and more predictable absorption; more controlled plasma concentrations; fewer extrapyramidal side effects; less frequent reminders of condition; and reduced medical workload. In open and controlled studies, haloperidol decanoate has produced adequate maintenance or improvement of the condition of patients with psychoses (mainly schizophrenia) when an abrupt change from orally administered haloperidol or other antipsychotic drugs has been instituted. Limited comparative studies indicate that the depot and oral forms of haloperidol are equally effective, and that haloperidol decanoate is at least as effective as depot forms of fluphenazine, pipothiazine, flupenthixol and perphenazine in controlling the symptoms of psychosis. Extrapyramidal side effects and the need for concomitant anti-Parkinsonian drugs may be a problem, but may be less frequent than with oral haloperidol or other depot antipsychotics. Thus, haloperidol decanoate offers a useful alternative in the treatment of psychoses to orally administered haloperidol or to other depot antipsychotic drugs.

Haloperidol↗

[Effect of haloperidol decanoate on the dopaminergic system in the rat brain].

The effect of haloperidol decanoate and haloperidol on the dopaminergic system in the rat brain was studied. Each rat was treated with either once daily ip injection of haloperidol (5 mg/kg) for 4 weeks or a single sc injection of haloperidol decanoate followed by once daily ip injection of saline for 4 weeks. Three weeks after cessations of injections, the levels of dopamine (DA) and its metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), were determined in the striatum, limbic area and frontal cortex 4 hours after a single ip injection of haloperidol (1 mg/kg). The haloperidol decanoate-treated rats showed lower levels of DOPAC and/or HVA than the rats of the other two groups. The DA level was higher only in the limbic area of the rats treated with haloperidol decanoate than that of the rats treated with saline. There was no difference of the levels of DA and its metabolites between the saline and haloperidol-treated rats. These results indicate that the haloperidol decanoate-treated rats developed a tolerance to an acute effect of haloperidol on stimulation of DA turnover in the three areas examined, while the haloperidol-treated rats developed no tolerance under these experimental conditions. A single sc injection of haloperidol decanoate to rat is expected to produce a long lasting blocking of the central DAergic system for at least 7 weeks. Such a property of this drug appears favourable for the maintenance therapy of schizophrenia.

Animals↗

A 12-week, double-blind comparison of olanzapine vs haloperidol in the treatment of acute mania.

BACKGROUND: This randomized controlled trial compares the efficacy and safety of olanzapine vs haloperidol, as well as the quality of life of patients taking these drugs, in patients with bipolar mania. METHODS: The design consisted of 2 successive, 6-week, double-blind periods and compared flexible dosing of olanzapine (5-20 mg/d, n = 234) with haloperidol (3-15 mg/d, n = 219). RESULTS: Rates of remission (Young-Mania Rating Scale score of < or =12 and 21-item Hamilton Rating Scale for Depression score of < or =8 at week 6) were similar for olanzapine- and haloperidol-treated patients (52.1% vs 46.1%, respectively; P =.15). For the subgroup of patients whose index episode did not include psychotic features, rates of remission were significantly greater for the olanzapine group compared with the haloperidol group (56.7% vs 41.6%, P =.04). Relapse into an affective episode (mania and/or depression) occurred in 13.1% and 14.8% of olanzapine- and haloperidol-treated patients, respectively (P =.56). Switch to depression occurred significantly more rapidly with haloperidol than with olanzapine when using survival analysis techniques (P =.04), and significantly more haloperidol-treated patients experienced worsening of extrapyramidal symptoms, as indicated by several measures. Weight gain was significantly greater in the olanzapine group compared with the haloperidol group (2.82 vs 0.02 kg, P<.001). The olanzapine group had significant improvement in quality of life on several dimensions compared with the haloperidol group. CONCLUSIONS: These data suggest that olanzapine does not differ from haloperidol in achieving overall remission of bipolar mania. However, haloperidol carries a higher rate of extrapyramidal symptoms, whereas olanzapine is associated with weight gain.

Acute Disease↗

Biochemical and molecular effects of chronic haloperidol administration on brain and muscle mitochondria of rats.

The objectives of the current study were to evaluate (1) the respiratory rates and enzyme activities of brain and muscle mitochondria from rats chronically treated with haloperidol, (2) the protective role of dopamine (DA) D-1 (SKF38393) and D-2 (quinpirole) receptor agonists, and (3) the effect of haloperidol on the mitochondrial DNA (mtDNA) and protein synthesis. Thirty male Sprague-Dawley rats were subdivided into the following five groups: controls, haloperidol, haloperidol plus SKF38393, haloperidol plus quinpirole, and haloperidol plus SKF38393 and quinpirole. We compared the respiratory rates and enzymatic activities of brain and muscle mitochondria from controls with other groups. We finally analyzed the mitochondrial protein synthesis and mtDNA alterations (deletions, point mutations, and depletion) in two rats from each group. In brain but not in muscle from haloperidol-treated rats, we found a decrease of oxygen consumption rates using glutamate plus malate (-68 +/- 35%, P < 0.05) and succinate (-78 +/- 20%, P < 0.05) as substrates as well as low complex I, II, and V activities (-35 +/- 15%, P < 0.05; -54 +/- 13%, P < 0.05; and -60 +/- 33%, P < 0.01; respectively). The administration of SKF38393 alone or together with quinpirole prevented most of haloperidol-induced effects, whereas the protective effects of quinpirole alone were lower. Brain mitochondrial protein synthesis was decreased in haloperidol-treated rats and was not prevented by SKF38393, quinpirole, or both. We did not find mtDNA abnormalities in brain or muscle mitochondria from haloperidol-treated rats. Chronic administration of haloperidol in rats is associated with a nonspecific deleterious effect in the activity of electron transport chain of brain, and this effect is only partially prevented by DA D-1 agonists. These results suggest that other mechanisms different from DA receptors pathway can contribute to the expression of behavioral supersensitivity.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

Haloperidol alone or in combination for acute mania.

BACKGROUND: The main objectives in treating mania are to control dangerous behaviour, reduce suicide, produce appropriate acute sedation and shorten the episode of mood disturbance. Among different drugs, haloperidol has for many years been used in treating psychotic patients, but it has a troublesome side effect profile. OBJECTIVES: To assess the effects of haloperidol for the treatment of mania in comparison with placebo or other active drugs, either as monotherapy or add-on treatment. SEARCH STRATEGY: We searched the Cochrane Collaboration Depression, Anxiety and Neurosis Controlled Trials Register (11 October 2005), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 3, 2005), MEDLINE (1966-2003), EMBASE (1980-2003), CINAHL (1982-2003), PsycINFO (1872-2003) and reference lists. We also contacted experts, triallists and pharmaceutical companies in the field. SELECTION CRITERIA: Randomised trials comparing haloperidol with placebo or other active treatment in the treatment of acute manic or mixed episodes in patients with bipolar disorder or schizoaffective disorder. DATA COLLECTION AND ANALYSIS: Two authors independently assessed trial quality and extracted data. We contacted study authors for additional information. We collected adverse effects information from the trials. MAIN RESULTS: Fifteen trials involving 2022 people were included. Compared to placebo, haloperidol was more effective at reducing manic symptoms, both as monotherapy (Weighted Mean Difference (WMD) -5.85, 95% Confidence Interval (CI) -7.69 to -4.00) and as adjunctive treatment to lithium or valproate (WMD -5.20, 95% CI -9.26 to -1.14). There was a statistically significant difference, with haloperidol being less effective than aripiprazole (Relative Risk (RR) 1.45, 95% CI 1.22 to 1.73). No significant differences between haloperidol and risperidone, olanzapine, carbamazepine or valproate were found. Compared with placebo, a statistically significant difference in favour of haloperidol in failure to complete treatment (RR 0.74, 95% Cl 0.57 to 0.96) was reported. Haloperidol was associated with less weight gain than olanzapine (RR: 0.28, 95% CI 0.12 to 0.67), but with a higher incidence of tremor (RR: 3.01, 95% CI 1.55 to 5.84) and other movement disorders. AUTHORS' CONCLUSIONS: There is some evidence that haloperidol is an effective treatment for acute mania. From the limited data available, there was no difference in overall efficacy of treatment between haloperidol and olanzapine or risperidone. Some evidence suggests that haloperidol could be less effective than aripiprazole. Referring to tolerability, when considering the poor evidence comparing drugs, clinicians and patients should consider different side effect profiles as an important issue to inform their choice.

Amisulpride↗

Reduced haloperidol plasma concentration and clinical response in acute exacerbations of schizophrenia.

Twenty-nine hospitalized patients suffering acute exacerbations of schizophrenia were treated for 2 weeks with fixed daily oral doses of haloperidol prospectively calculated to achieve a haloperidol plasma concentration of either 8-18 ng/ml or 25-35 ng/ml. Reduced haloperidol as well as haloperidol concentrations were assayed to determine if the former enhanced the predictability of response. Wee 2 haloperidol plasma concentrations were negatively correlated to clinical response as measured by the percentage change in the BPRS score from baseline (r = -0.43, P less than 0.05). In contrast, week 2 plasma concentrations of reduced haloperidol, total haloperidol (haloperidol + reduced haloperidol), and reduced haloperidol/haloperidol ratio did not correlate with the change in the BPRS score. Chi-square analysis concluded that patients with ratios greater than one were no less likely to be treatment responders (less than 25% improvement in BPRS from baseline and week 2 BPRS less than 55) than those with ratios less than one. Although these data lend additional support to reports of a curvilinear relationship between haloperidol plasma concentration and clinical response, they also suggest that reduced haloperidol plasma concentrations are of no value in predicting treatment response.

Acute Disease↗

Neuroendocrine responsivities of the pituitary dopamine system in male schizophrenic patients during treatment with clozapine, olanzapine, risperidone, sulpiride, or haloperidol.

BACKGROUND: Atypical antipsychotic drugs, in clinical doses, occupy 5-HT2 receptors near saturation, while D2 dopamine receptors, assessed usually in striatum by SPECT or PET methods, are occupied to different degrees.We hypothesized that these differences in D2 receptor occupancies may also be evaluated by a neuroendocrine approach, namely by measuring the plasma prolactin responses to i. m. administered haloperidol, since the expected elevations depend mainly on the free remaining D2 receptors in the tuberoinfundibular tract. METHODS: We measured the plasma prolactin levels at 0,30, 60, 90, and 120 minutes after administration of 5 mg haloperidol i. m. in six groups of male patients with schizophrenia: a). 33 patients in a drug-free state,b). 15 patients on treatment with clozapine (range 200-600 mg/day), c). 15 patients on olanzapine (10-30mg/day), d). 14 patients on risperidone (8-16mg/day), e). 23 patients on haloperidol (10-40mg/day), f) 14 patients on sulpiride (600-1600mg/day). Data were also obtained from a group of 14 healthy male control subjects. The differences in baseline prolactin levels and in the responses to acute haloperidol of the seven groups were compared. RESULTS: The baseline prolactin levels did not differ significantly in the groups of controls (8.3+/-.8 ng/ml), drug-free patients (8.0+/-.6) and patients treated with clozapine (7.7+/-.8), they were moderately elevated in patients treated with olanzapine (16.8+/-.9), elevated in patients on haloperidol (34.4+/-7.3),and theyw ere even higher in the groups of patients treated with risperidone (54.9+/-2.4) or sulpiride (58.8+/-7.0). All groups of patients gave attenuated prolactin responses to i. m. haloperidol compared to healthy controls. During treatment with haloperidol, risperidone, or sulpiride, no significant prolactin increases after i. m. haloperidol were observed. The group treated with olanzapine gave significant prolactin increases, which were lower than those obtained in the group of patients treated with clozapine, who gave responses similar to that of the drug-free patients. CONCLUSIONS: lasma prolactin levels and responses to i. m. haloperidol of patients on treatment with antipsychotic drugs, reflect the prolactin release potencies of the drugs, which are related, but not restricted, to their affinities to D2 dopamine receptors. According to the prolactin baseline levels and responses to i. m. haloperidol, the drugs of this study can be categorized for their potency to the pituitary dopamine system that controls prolactin release, as follows: sulpiride > risperidone > haloperidol > olanzapine > clozapine. This categorization is similar to that obtained by binding studies in striatal D2 dopamine receptors using brain imaging techniques.

Adult↗

Nicotine potentiates haloperidol-induced catalepsy and locomotor hypoactivity.

Nicotine was found to potentiate the catalepsy and reduced locomotion following the administration of haloperidol. The ability of various doses of nicotine (0.1, 0.2, or 0.3 mg/kg) to potentiate the catalepsy produced by haloperidol (0.1, 0.2 or 0.4 mg/kg) was investigated. Nicotine potentiated the cataleptic effects of both the 0.2 and 0.4 mg/kg doses of haloperidol, but had no effect following the lowest (0.1 mg/kg) dose of haloperidol. The nicotine potentiation of catalepsy produced by the highest dose of haloperidol was independent of the dose of nicotine used. Nicotine alone did not produce catalepsy. A second experiment evaluated the ability of nicotine to potentiate the decreases in spontaneous locomotor activity produced by haloperidol. Animals received nicotine (0.1 mg/kg) alone or in conjunction with haloperidol (0.1 or 0.4 mg/kg) and were tested in Digiscan Animal Monitors. Haloperidol produced a dose-related decrease in locomotion. Nicotine significantly potentiated the hypoactivity produced by both doses of haloperidol. These results indicated that: 1) nicotine produces a significant potentiation of both the catalepsy and locomotor decreases following haloperidol and 2) the Digiscam Animal Activity Monitors may provide a more sensitive assessment of the interaction between nicotine and haloperidol than the catalepsy bat test. These data suggest that adjunct treatment with nicotine may prove useful for treating neuroleptic responsive disorders such as Tourette Syndrome, schizophrenia and Huntington's disease.

Animals↗

8-OH DPAT can restore the locomotor stimulant effects of cocaine blocked by haloperidol.

In the first experiment, separate groups of rats (n = 7) were treated with either saline, cocaine (10 mg/kg), haloperidol (0.1 mg/kg), or cocaine (10 mg/kg) plus haloperidol (0.1 mg/kg). Locomotor behavior was measured in an open-field environment, and cocaine induced a reliable locomotor stimulant effect compared to saline-treated animals. Haloperidol produced a progressive decline in locomotion over the 5 test days. Haloperidol also blocked cocaine stimulant effects compared to cocaine-treated animals. In the second experiment, five groups (n = 7) of animals were treated either with saline, cocaine (10 mg/kg), 8-OH DPAT (0.2 mg/kg), 8-OH DPAT (0.2 mg/kg) plus haloperidol (0.1 mg/kg), or 8-OH DPAT (0.2 mg/kg) plus haloperidol 0.1 mg/kg plus cocaine (10 mg/kg). Over the course of 5 days of treatment, cocaine induced a locomotor stimulant effect. Saline and 8-OH DPAT animals did not differ in terms of locomotion. The 0.1 mg/kg haloperidol plus 0.2 mg/kg 8-OH DPAT treatment decreased locomotion compared to the saline group, but the group given 0.2 mg/kg 8-OH DPAT plus 0.1 mg/kg haloperidol plus cocaine (10 mg/kg) exhibited a locomotor stimulant effect equivalent to the cocaine group. In a third experiment, it was found that the 0.2 mg/kg 8-OH DPAT treatment did not enhance the locomotor stimulant effect of cocaine. Thus, the 8-OH DPAT treatment was able to restore a cocaine locomotor stimulant effect in animals treated with haloperidol without directly enhancing the locomotor stimulant effects of cocaine. In Experiments 2 and 3, entries into the central zone of the open field were measured. Cocaine reliably increased central zone entries. The 8-OH DPAT treatment, however, selectively blocked this behavioral effect of cocaine suggesting a qualitative influence of 5-HT(1A) receptors upon cocaine, independent of locomotion activation by cocaine. Ex vivo measurements of dopamine and 5-hydroxytryptamine metabolism in limbic tissue were consistent with the established effects of cocaine, haloperidol, and 8-OH DPAT upon dopamine and 5-hydroxytryptamine neurotransmission. In addition, measurement of cocaine brain concentration indicated that neither haloperidol or 8-OH DPAT affected cocaine concentration in brain.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

The effects of olanzapine, risperidone, and haloperidol on plasma prolactin levels in patients with schizophrenia.

BACKGROUND: There is relatively little comparative information on elevations in plasma prolactin level (PRL) with conventional versus novel antipsychotic agents. OBJECTIVE: This paper examines the comparative effects on PRL of olanzapine, risperidone, and haloperidol based on data from 3 multicenter, double-blind, randomized clinical trials. Magnitude of response, dose dependency, time course, effects of sex and age, and response to switching from haloperidol to olanzapine are assessed. METHODS: The effects of olanzapine, risperidone, and haloperidol on PRL were assessed in patients with schizophrenia or related psychoses participating in 3 double-blind clinical trials: (1) a 6-week acute trial comparing olanzapine 5 to 20 mg/d (n = 1,336) and haloperidol 5 to 20 mg/d (n = 660), with a 1-year, open-label olanzapine extension for responders; (2) a 54-week study comparing olanzapine 5 to 20 mg/d (n = 21), risperidone 4 to 10 mg/d (n = 21), and haloperidol 5 to 20 mg/d (n = 23) in early illness; and (3) a 28-week study comparing olanzapine 10 to 20 mg/d (n = 172) and risperidone 4 to 12 mg/d (n = 167). RESULTS: PRL elevations were significantly greater with risperidone than with either olanzapine or haloperidol in study 2. and significantly greater than with olanzapine in study 3 (all, P < 0.001). PRL elevations were significantly greater with haloperidol than with olanzapine in study 1 (P < 0.001 ). A dose-response relationship was not consistently confirmed with any of the drug treatments. Risperidone-associated PRL elevations peaked relatively early in treatment. In haloperidol- and risperidone-treated patients, the mean change in PRL was greater in women than in men. PRL decreased significantly when treatment was switched from haloperidol to olanzapine. CONCLUSIONS: This side-by-side analysis of 3 independent studies suggests that with the 3 antipsychotic drugs studied, PRL is elevated moderately by olanzapine (mean change, 1-4 ng/mL), intermediately by haloperidol (mean change, approximately 17 ng/mL), and strongly by risperidone (mean change, 45-80 ng/mL). No consistent dose-response relationship was observed, and the time course and sex-dependency of the response differed between the 3 agents. Patients with haloperidol-induced hyperprolactinemia may benefit from a switch to olanzapine. Long-term studies examining the health consequences of chronic hyperprolactinemia during antipsychotic treatment are needed.

Antipsychotic Agents↗