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At least 19 recordsLinked to original sources

PubMed1992

Pharmacokinetics of haloperidol and reduced haloperidol in Chinese schizophrenic patients after intravenous and oral administration of haloperidol.

The pharmacokinetics of haloperidol were studied in eight Chinese schizophrenic patients after intravenous administration and in six of the patients who also received oral haloperidol. After intravenous dosing, haloperidol disposition was best characterized by a three compartment model. The mean elimination half-life of 54.8 h determined by model dependent analysis was similar to the mean elimination half-life of 59.9 h determined by model independent analysis. The mean plasma clearance was 21.71/h and the mean volume of distribution during the distribution phase was 1754.3 1. After oral dosing, bioavailability of haloperidol was 35 +/- 8%, suggesting extensive first pass metabolism. Determination of reduced haloperidol concentration confirmed a previous finding of significant variability in haloperidol reductive capacity in individual patients. Comparison of area under the plasma concentration-time curve of reduced haloperidol after intravenous and oral administration of haloperidol suggests that reduction of haloperidol may only account for a small portion of first pass metabolism of haloperidol. However, conversion of reduced haloperidol back to haloperidol necessitates the monitoring of both haloperidol and reduced haloperidol concentrations in clinical practice.

Administration, Oral↗

PubMed1994

Simultaneous determination of plasma haloperidol and its metabolite reduced haloperidol by liquid chromatography with electrochemical detection. Plasma levels in schizophrenic patients treated with oral or intramuscular depot haloperidol.

A simple and highly sensitive liquid chromatographic method with electrochemical detection for the simultaneous determination of haloperidol and its metabolite reduced haloperidol in human plasma has been developed. The sample preparation for the analysis involves a simple one-step extraction procedure with 10% methylene chloride in pentane. The compounds were separated on a cyano column maintained at a temperature of 40 degrees C and were detected electrochemically by a flow-through analytical cell kept at +0.95 V. The standard curve is linear over the range of 0.1 to 15 ng/ml and the lower limit of quantitation is 0.1 ng/ml for haloperidol and 0.25 ng/ml for reduced haloperidol which is equivalent to approximately 40 pg on column when 1 ml of plasma was used for the analysis. The lower limit of quantitation for reduced haloperidol can be extended to 0.1 ng/ml if 2 ml of plasma is used in the analysis. The coefficient of variation of the determination of plasma levels by this method over the standard curve concentration range was less than 10%. Commonly co-administered drugs and other neuroleptics used in conjunction with haloperidol did not interfere in the determination of either haloperidol or reduced haloperidol. This method has been successfully used for the determination of haloperidol and reduced haloperidol in plasma and their levels in patients treated with various doses oral haloperidol or intramuscular haloperidol decanoate are reported.

Administration, Oral↗

PubMed1986

Effects of smoking on haloperidol and reduced haloperidol plasma concentrations and haloperidol clearance.

Plasma concentrations of haloperidol and its reduced metabolite (reduced haloperidol) were investigated in cigarette smokers (N = 23) and nonsmokers (N = 27). Steady-state plasma concentrations were obtained 12 h post bedtime dose. Haloperidol and reduced haloperidol concentrations were determined by RIA. Reduced haloperidol was separated by selective succinylation and liquid chromatography. Patients were clinically assessed with the Clinical Global Impression Scale (CGIS). Smokers had significantly lower haloperidol and reduced haloperidol plasma concentrations than nonsmokers (P less than 0.01, P less than 0.05). Clearance of haloperidol was significantly greater in smokers compared to nonsmokers (P = 0.0052). CGIS assessments did not show significant differences between smokers and nonsmokers. Plasma concentrations should be carefully monitored when patients either start or stop smoking.

Adult↗

PubMed1996

Haloperidol and reduced haloperidol plasma concentrations after a loading dose regimen with haloperidol decanoate.

1. Haloperidol and reduced haloperidol plasma levels were measured in schizophrenic patients who received both oral (10 mg, N=16 and 20 mg, N=4) and depot haloperidol treatment 2. Patients were of Asian ethnicity and were safely and effectively converted from oral to depot therapy using a loading dose regimen using a 100 mg weekly injection interval for 4 weeks, biweekly for one month and then monthly. 3. Significant correlations were found for plasma haloperidol and reduced haloperidol levels and reduced haloperidol/haloperidol ratios between oral and depot therapy in these non-smoking patients. 4. A loading dose regimen is needed due to the long elimination half-life of decanoate of 26 days otherwise steady-state condition will not occur until 34 months of therapy. 5. Patients were maintained on monthly depot treatment for 40 weeks after the loading dose regimen and only one patient relapsed during treatment despite dosage increases. 6. The formation of reduced haloperidol remained consistent for oral and depot haloperidol treatment.

Adult↗

PubMed1992

Determination of haloperidol and reduced haloperidol in the plasma and blood of patients on depot haloperidol.

We developed a sensitive HPLC assay to measure haloperidol (HA) and its metabolite, reduced haloperidol (RH), in plasma and whole blood. The conditions under which HA might be converted to RH during collection and analysis of blood were examined. Provided the blood was kept at 0 degrees C, erythrocyte ketone reductase activity was insignificant. The solid phase extraction method did not generate RH. We studied ten patients taking 25-400 mg/month of HA decanoate and one patient for 4 weeks after the daily oral dose of 120 mg HA was ceased. In the patients on depot HA, the plasma and blood concentrations of HA were not significantly different (P greater than 0.1). For the first time, RH was detected in plasma patients on depot drug, but only in three cases. In contrast, RH was present in the blood of eight of these patients. The accumulation of RH in red blood cells was also evident in the patient on oral HA, in whom the mean ratio of RH concentrations in whole blood to plasma was 3.6 +/- 1.1. Plasma concentrations of HA correlated highly with total neuroleptic activity measured by a radioreceptor assay. Compared to plasma, analysis of concentrations of HA and RH in blood has the advantages of greater sensitivity, of using smaller volumes of blood and of avoiding the efflux of HA and RH during separation of plasma and red cells.

Chromatography, High Pressure Liquid↗

PubMed1991

The measurement of haloperidol and reduced haloperidol in neonatal hair as an index of placental transfer of maternal haloperidol.

Hair samples were collected at time of delivery from three neonates and their schizophrenic mothers, who had been taking haloperidol (HP) during the perinatal period to control worsening psychotic symptoms. Maternal hair was cut into 1-cm lengths, and concentrations of HP and its major metabolite, reduced haloperidol (RHP), were measured by high-performance liquid chromatography. Neonatal hair was cut into halves, and the concentrations of HP and RHP in each half were measured. The distribution of both HP and RHP along the maternal hair paralleled the dosage of HP when hair growth was assumed to be 1 cm per month. In the upper half of hair from each of two neonates neither HP nor RHP was detected. Only HP was detected in the lower half from one, and a small peak of HP in the chromatogram was observed in the other, though under the detection limit. In the third neonate both HP and RHP were detected from both halves of hair, but the concentration of HP was larger in the lower half than in the upper. These findings suggest the possibility of monitoring the transfer of maternal HP through placenta by measuring HP and RHP concentrations in neonatal hair.

Adult↗

PubMed2001

Haloperidol for agitation in dementia.

BACKGROUND: Agitation includes wandering, crying out, abusive vocalization, and assaultive behavior and occurs in up to 70% of patients with dementia. Although the neuroleptic haloperidol has been used for decades to control disruptive behavior in psychotic and demented patients, the effectiveness of this drug for agitated dementia remains in question. The first meta-analysis on the effectiveness of haloperidol for agitated dementia, published in 1990, was limited in scope and was unable to provide clear guidelines for the use of haloperidol for demented patients who are agitated. Meta-analyses in 1998 and 2000 examined haloperidol compared with other neuroleptics as well as with placebo and omitted a number of databases, including non-English language publications. To determine the effect of haloperidol, compared with placebo, in the control of agitated dementia and to make recommendations for future research in this area a more widely based, yet more highly focussed review was carried out. OBJECTIVES: The main objective was to determine whether evidence supports the use of haloperidol to treat agitation in demented patients. SEARCH STRATEGY: The CDCIG Specialized Register was searched to identify all available reports on haloperidol treatment of agitated dementia. SELECTION CRITERIA: We examined randomized, placebo-controlled trials, with concealed allocation, where subjects' dementia and agitation were assessed. Trials involving treatment of less than one week were not included. DATA COLLECTION AND ANALYSIS: 1. Two reviewers extracted data from included trials. 2. Data were pooled, where possible, and analysed using appropriate statistical methods. 3. Odds ratios or average differences were calculated. 4. Only 'intention to treat' data were included. Where a cross-over design was employed (Devanand, 1998), only the initial phase of the study was used to compare haloperidol versus placebo. 5. Sensitivity analysis was applied to heterogeneity of results and to gauge the effect of the included studies of small sample size. 6. In addition to the overall meta-analysis, individual analyses of the reports were carried out to examine the effect of degree of dementia, dose of haloperidol, and duration of therapy on agitated dementia. Analysis included the following groups: All patients treated with haloperidol compared with placebo. MAIN RESULTS: There were five included trials. All studies stated "intention to treat" analysis of their results. Three studies were from the United States, and two studies were from Europe. Two studies examined patients with various forms of dementia, and three studies included only patients with diagnosed Alzheimer's dementia. 1. Overall meta-analysis of the response of agitated patients to haloperidol, compared with controls, showed no improvement in agitation. There is some evidence that haloperidol helps to control aggression. Adverse reactions and dropouts were more frequent among haloperidol treated patients, compared with controls. This meta-analysis provided no information about the relationship between the degree of dementia, the kind of agitation manifested, or the dosage and duration of therapy with haloperidol and response to treatment of demented patients with agitation. 2. The results of this meta-analysis were too broad to permit specific recommendations for treatment of agitated dementia with haloperidol. 3. Higher dose haloperidol, or prolonged haloperidol (12 weeks compared with 3 - 6 weeks) was associated with increased side effects, largely related to Parkinsonian symptoms of rigidity and bradykinesia. REVIEWER'S CONCLUSIONS: 1. Haloperidol appeared to provide no improvement in agitation among demented patients compared with placebo, but side effects were frequent. 2. Dropout rates were higher for haloperidol compared with placebo treated patients, suggesting that side effects led to discontinuation of treatment in some patients. 3. Because of the wide focus of this meta-analysis, not enough information was provided to permit recommendations linking haloperidol treatment of agitated dementia to degree of dementia, manifestations of agitation, or dosage and duration of treatment of haloperidol. 4. Individual analysis of reports indicated that higher dose haloperidol (more than 2 mg per day) may have been more effective than lower dose haloperidol (less than 2 mg per day) in controlling aggression, but not other manifestations of agitation, among patients with mild to moderate dementia. 5. Similar analysis suggested that prolonged therapy with haloperidol (more than 3 - 6 wks) or higher dosage (more than 2 mg per day) was more likely to result in side effects than were short term therapy (3 weeks) or lower dose haloperidol (less than 2 mg per day). 6. The reports provided too little information to permit interpretation of the effect of degree or type of dementia on response to haloperidol. Except for a favorable response of aggression to haloperidol, no other manifestations of agitated dementia were found to have improved following therapy with haloperidol, compared with controls.

Aggression↗

PubMed1995

Haloperidol and reduced haloperidol-induced exacerbation of the dystonia produced by the kappa opioid U50,488H in guinea-pigs is associated with inhibition of sigma binding sites: behavioural and autoradiographical studies.

A single dose of haloperidol and reduced haloperidol has been found to exacerbate the dystonic response produced by U50,488H (trans-(+/-)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl) -cyclohexyl]-benzeacetamide methane sulphonate) in guinea-pigs [8]. The present study sought to correlate the behavioural effect of haloperidol and reduced haloperidol with their effect on inhibition of sigma binding sites in guinea-pig brain using receptor binding and semi-quantitative autoradiography. In the first experiments, groups of guinea-pigs were injected with saline (control, n = 12), haloperidol (0.1 and 1 mg/kg i.p., n = 5) or reduced haloperidol (0.1 and 1 mg/kg i.p., n = 5) 1, 3 and 10 days before, followed by U50,488H (10 mg/kg s.c.) and the effect on the dystonic response rated using a behavioural rating scale [8]. In the second experiments, animals (n = 5) were injected with saline, haloperidol and reduced haloperidol as above and killed 1, 3 and 10 days later, their brains removed, dissected and tissue sections processed for sigma binding site autoradiography using [3H]3-(3-hydroxyphenyl)-N-(n-propyl)piperidine ([3H]-3-PPP). Triplicate tissue sections were wiped using GF/C filters and radioactivity counted. Injection of haloperidol and reduced haloperidol 1, 3 and 10 days earlier exacerbated the dystonic response by decreasing the latency to maximal dystonia and increasing the duration of the response at each dose tested compared with saline-treated animals. These effects of haloperidol and reduced haloperidol on latency and duration were time-related since the effect at 1 > 3 > 10 days. In addition, [3H]-3-PPP binding was inhibited by haloperidol and reduced haloperidol in a dose-and time-related manner. For example, % inhibition of [3H]-3-PPP binding for haloperidol (1 mg/kg) > haloperidol (0.1 mg/kg) and % inhibition of binding (mean +/- SEM) produced by haloperidol (0.1 mg/kg) at 1 (96.1 +/- 2.4) > 3 (74.8 +/- 4.8) > 10 days (36.2 +/- 1.6). Similar results were obtained for haloperidol (1 mg/kg) and reduced haloperidol (0.1 and 1 mg/kg). [3H]-3-PPP autoradiography confirmed these binding data. The results indicate that the exacerbation by sigma ligands of the dystonia produced by U50,488H was associated with the degree of inhibition of [3H]-3-PPP binding.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗

PubMed1994

Effects of haloperidol and reduced haloperidol on binding to sigma sites.

The s.c. administration of a single dose of 0.1 mg/kg of reduced haloperidol to guinea pigs produced a marked inhibition of the binding of [3H]dextromethorphan and [3H]3-(3-hydroxyphenyl)-N-(n-propyl)piperidine ([3H](+)-3-PPP) to brain. The inhibition was still evident 10 days later, and it was accompanied by residual brain levels of reduced haloperidol, and much lower levels of haloperidol. Scatchard and computer-assisted analysis demonstrated that the inhibition was due to a reduction in the number of binding sites without changes in the affinity. In the rat, haloperidol and reduced haloperidol also produced a rapid inhibition of binding to sigma sites. Interestingly, the brain of the reduced haloperidol-treated rats contained both haloperidol and reduced haloperidol, but the levels of reduced haloperidol in the haloperidol-treated rats were undetectable. However, the inhibition observed was of comparable magnitude, indicating that the haloperidol remaining in the brain is also inhibitory. In vitro experiments showed that the inhibition produced by haloperidol and reduced haloperidol was apparently competitive, but when brain membranes were preincubated with either drug, the inhibition was noncompetitive. By contrast, the inhibition produced by dextromethorphan was always competitive. Moreover, the inhibition produced by haloperidol and reduced haloperidol could not be reversed by washing. This investigation strongly suggests that the inhibition observed after the administration of haloperidol or reduced haloperidol is not a classic agonist-induced receptor down-regulation. The results indicated that the inhibition produced is a complex phenomenon, and suggest the formation of a slowly reversible or irreversible complex with reduced haloperidol or haloperidol.

Animals↗

PubMed2001

Plasma concentrations of haloperidol are related to CYP2D6 genotype at low, but not high doses of haloperidol in Korean schizophrenic patients.

AIMS: This study was carried out to evaluate the influence of CYP2D6 genotype on the steady state plasma concentrations of haloperidol and reduced haloperidol in Korean schizophrenic patients. METHODS: One hundred and twenty Korean schizophrenic patients treated with various, clinically determined, doses of haloperidol (range 3-60, median 20 mg day-1) during monotherapy were recruited. CYP2D6 genotypes were determined by analysis of the CYP2D6*10 allele using allele-specific PCR and the CYP2D6*5 allele by long-PCR. Steady state plasma concentrations of haloperidol and reduced haloperidol were analysed by h.p.l.c. RESULTS: Twenty-three (19.2%), 60 (50.0%), 1 (0.8%), 33 (27.5%) and 3 patients (2.5%) possessed the CYP2D6 genotypes *1/*1, *1/*10, *1/*5, *10/*10 and *10/*5, respectively. The allele frequencies of CYP2D6*1, *10 and *5 were 44.6%, 53.8% and 1.7%, respectively. Significant relationships between dose and plasma concentrations of haloperidol (linear; r2 = 0.60, P < 0.0001) and reduced haloperidol (quadratic equation; r(2) = 0.67) were observed. Overall, the concentrations normalized for dose (C/D) of haloperidol were significantly different between the CYP2D6*1/*1, *1/*10 and *10/*10 genotype groups (one-way ANOVA; P = 0.028). No significant differences between the genotype groups were found with respect to the C/D of reduced haloperidol (P = 0.755). However, in patients with daily doses less than 20 mg, significant differences in the C/D of haloperidol (P = 0.003), but not of reduced haloperidol, were found between the three major genotype groups. In patients with doses higher than 20 mg, no differences were found between the genotype groups for either haloperidol or reduced haloperidol. 68 patients (57%) used benztropine, an antimuscarinic agent. All four patients with a *5 allele (one together with *1 and three with *10) were found to use benztropine. The patients homozygous for the *1 allele seemed to need less benztropine than the patients with one or two mutated alleles (Fisher's exact test; P = 0.036). CONCLUSIONS: The dose-corrected steady state plasma concentrations of haloperidol, but not of reduced haloperidol, were significantly different between the CYP2D6*1/*1, *1/*10 and *10/*10 genotype groups when doses lower than 20 mg haloperidol were given. No differences were found at higher doses. These results suggest the involvement of CYP2D6 in the metabolism of haloperidol at low doses of haloperidol (< 20 mg daily), while another enzyme, probably CYP3A4, contributes at higher doses.

Adult↗

PubMed1999

Reduced haloperidol does not interfere with the antipsychotic activity of haloperidol in the treatment of acute schizophrenia.

The aim of this study was to investigate the effect of reduced haloperidol, the main metabolite of the antipsychotic drug haloperidol, on psychopathology improvement and extrapyramidal adverse effects in acute schizophrenia. The steady-state pharmacokinetics of reduced haloperidol was studied. Serum concentrations of reduced haloperidol (C(RH)) and haloperidol (C(H)) were measured in an open clinical trial over 6 weeks of treatment in 57 acutely schizophrenic patients. Psychopathology was measured by the Brief Psychiatric Rating Scale and several subscales. The assay of extrapyramidal adverse effects was conducted by means of the Extrapyramidal Symptom Rating Scale. A significant serum concentration-therapeutic effect relationship (SCTER) of haloperidol of the same data has been demonstrated. In our study, the influence of the metabolite reduced haloperidol on the antipsychotic activity of haloperidol was analysed by means of regression analysis of the residuals of the SCTER of haloperidol with C(RH). In addition, the steady-state pharmacokinetics of reduced haloperidol and direct relationships between C(RH) and the metabolite ratio C(RH)/C(H) with psychopathology improvement and extrapyramidal adverse effects were investigated. Reduced haloperidol was not found to interfere with the antipsychotic action of the parent drug. Patients with elevated C(RH) or elevated metabolite ratio C(RH)/C(H) did not show consistently lower clinical improvements compared with the fitting curve of the SCTER of haloperidol and therefore no significant relationship between C(RH) and the residuals of the SCTER of haloperidol was detected. Furthermore, no significant result was found in the analysis of the direct relationships of C(RH) and C(RH)/C(H) with clinical variables which, for example, indicate decreased outcome with increased C(RH). In contrast, because of the pharmacokinetic dependence of C(RH) and C(H), a trend for a bisigmoidal relationship with C(RH) emerged for some outcome variables which was traced as an epiphenomenon from the bisigmoidal SCTER of the parent drug (e.g. change of hostility after 3 weeks). No relationship of reduced haloperidol with extrapyramidal adverse effects could be detected. It is concluded that serum concentrations of reduced haloperidol are of minor value for the interpretation of data of therapeutic drug monitoring of haloperidol in patients with acute schizophrenia. Reduced haloperidol does not act as a 'false neuroleptic'.

Acute Disease↗

PubMed1985

Interconversions of haloperidol and reduced haloperidol in guinea pig and rat liver microsomes.

An alcohol metabolite of haloperidol, reduced haloperidol, is present in the tissues of haloperidol-treated patients. We have studied whether rat and guinea pig liver microsomes have the capability to reduce haloperidol and thus serve as models for human haloperidol metabolism. Interestingly, the rat microsomes did not reduce haloperidol, but possessed an NADPH-dependent, carbon monoxide-inhibited mechanism to oxidize the reduced haloperidol back to haloperidol. Guinea pig microsomes efficiently reduced haloperidol molecules in a fashion not dependent on nicotinamide cofactors and not inhibited by carbon monoxide. Both of these activities were confined to the microsomal fraction. In guinea pigs, reduction of haloperidol was observed also in kidney slices, whereas brain slices proved inactive. Reduced haloperidol was also oxidized to haloperidol to a small extent in guinea pig microsomes. These in vitro experiments confirm our findings in vivo, which showed that in rats haloperidol is not reduced, while guinea pigs have a very active mechanism for reducing haloperidol. Thus, guinea pigs constitute a model for human haloperidol metabolism, and they should be used for further characterization of the reductive drug-metabolizing system.

Animals↗

PubMed1999

Effects of itraconazole on the steady-state plasma concentrations of haloperidol and its reduced metabolite in schizophrenic patients: in vivo evidence of the involvement of CYP3A4 for haloperidol metabolism.

The effects of itraconazole, a potent inhibitor of cytochrome P450 (CYP) 3A4, on the steady-state plasma concentrations of haloperidol and reduced haloperidol were examined in schizophrenic patients. Thirteen schizophrenic patients treated with haloperidol 12 or 24 mg/day received 200 mg/day of itraconazole for 7 days. Plasma concentrations of haloperidol and reduced haloperidol were measured by high-performance liquid chromatography together with clinical assessment by the Brief Psychiatric Rating Scale (BPRS) and the Udvalg for Kliniske Undersogelser side effect rating scale just before and during itraconazole treatment and 1 week after its discontinuation. Plasma concentrations of haloperidol and reduced haloperidol during the itraconazole treatment (16.9 +/- 11.2 and 6.1 +/- 6.6 ng/mL, respectively) were significantly (p < 0.01) higher than those observed before itraconazole treatment (13.0 +/- 7.9 and 4.9 +/- 5.1 ng/mL) or 1 week after its discontinuation (13.5 +/- 8.2 and 4.9 +/- 5.0 ng/mL). No change was found in clinical symptoms assessed by BPRS, whereas neurologic side effects were significantly (p < 0.05) increased during itraconazole coadministration. The elevated plasma concentrations of haloperidol and reduced haloperidol during itraconazole coadministration were likely due to the inhibitory effects of itraconazole on the metabolism of haloperidol and reduced haloperidol. Thus, this study may provide in vivo evidence of involvement of CYP3A4 in the metabolism of haloperidol and possibly in that of reduced haloperidol. Deterioration of neurologic side effects during itraconazole treatment may result from the increased plasma concentrations of haloperidol and reduced haloperidol during itraconazole treatment.

Adult↗

PubMed1984

Reduced haloperidol: effects on striatal dopamine metabolism and conversion to haloperidol in the rat.

Acute injection of rats with either haloperidol or reduced haloperidol (1 mg/kg, IP) greatly increased the striatal concentrations of the acidic dopamine metabolites, indicating enhanced turnover of dopamine. The effect of reduced haloperidol was almost as great as that of haloperidol. Reduced haloperidol, however, was much less efficient (about 400 times) than haloperidol in displacing [3H]spiperone binding to striatal membranes in vitro. In agreement with the above results, reduced haloperidol was found to be oxidized to haloperidol, so that 2 h after injection of reduced haloperidol the concentrations of haloperidol and reduced haloperidol were equal in the striatum. The apparent conversion of reduced haloperidol to haloperidol was much quicker in liver than in plasma or brain, and it is suggested that the conversion primarily occurs in the liver. Before drawing any definite conclusion about the possible central activity of reduced haloperidol, further studies with other animal species are needed.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1993

Prolonged haloperidol and reduced haloperidol plasma concentrations after decanoate withdrawal.

Haloperidol and reduced haloperidol plasma concentrations were measured in twelve schizophrenic patients upon cessation of haloperidol decanoate (HLD) treatment. Each patient received HLD 100 mg every 4 weeks for five injections. After the fifth injection, HLD was discontinued. Haloperidol and reduced haloperidol plasma concentrations were obtained prior to cessation and at weeks 1, 3, 4, 5, 7, 9, 11, and 13 post-injection. Haloperidol and reduced haloperidol plasma concentrations were assayed by HPLC. Both haloperidol and reduced haloperidol plasma concentrations were detectable 13 weeks post HLD discontinuation. Maximal haloperidol plasma concentrations were observed at one week post cessation and gradually declined. The mean elimination half-life for haloperidol was 27.4 +/- 8.6 days (range 19.0-47.0 days). Reduced haloperidol plasma concentrations declined very slowly. Our results show that both haloperidol and reduced haloperidol plasma concentrations can remain for extended time periods after HLD is discontinued.

Adult↗

PubMed1997

Haloperidol serum concentrations and D2 dopamine receptor occupancy during low-dose treatment with haloperidol decanoate.

The aim of this study was to examine the relationship between serum concentrations of haloperidol and central D2 receptor occupancy in eight schizophrenic patients treated with low doses of haloperidol decanoate. The accompanying psychopathology was assessed. During a 4-week interval after administration of haloperidol decanoate (dose range 30-70 mg), serum concentrations of haloperidol were determined once a week by using a sensitive high-performance liquid chromatography method. The patients' D2 receptor occupancy was determined with single-photon emission computed tomography on two separate occasions. One week after depot administration the mean haloperidol serum concentration was 7.3 nmol/l (range 3.9-22.7 nmol/l) and the mean D2 receptor occupancy was 75% (range 52-100%). After 4 weeks the mean haloperidol serum concentration had decreased to 1.8 nmol/l (range 0-5.7 nmol/l) and the mean D2 receptor occupancy to 53% (range 12-89%). Differences were seen in two subgroups, defined by their history of neuroleptic exposure before inclusion into the study. Patients treated with depots of haloperidol decanoate for months showed higher D2 receptor occupancy and corresponding higher serum haloperidol concentrations at week 4 than did patients who had a history of oral haloperidol treatment. Because the difference in the dynamics of D2 receptor occupancy could be reflected by corresponding serum concentrations of haloperidol, it seems useful to involve haloperidol drug monitoring as a possible surrogate marker for D2 receptor occupancy in optimizing low-dose treatment with haloperidol decanoate.

Adult↗

PubMed1992

Oxidative stress induced by administration of the neuroleptic drug haloperidol is attenuated by higher doses of haloperidol.

The effect of haloperidol administration on lipid peroxidation and glutathione/protein thiol homeostasis in the brain was examined 4 h following subcutaneous administration of a single dose of haloperidol; 1.0, 1.5, 2.0 or 2.5 mg/kg b.wt. Glutathione (GSH) levels decreased significantly in cortex, striatum and midbrain after haloperidol administration. Maximal decrease of GSH was observed in the striatum. The depleted GSH was recoverable as protein glutathione mixed disulfide (Pr-SSG) with concomitant loss of protein thiols (Pr-SH) in all the regions of the brain examined. Administration of 1.5 mg/kg b.wt. of haloperidol resulted in significant depletion of GSH in striatum and midbrain as compared to that after administration of the lower dose of 1.0 mg/kg b.wt. of haloperidol. However, administration of higher doses of haloperidol (2.0 and 2.5 mg/kg b.wt.) did not result in greater depletion of GSH; the GSH levels were not significantly different from that observed following the administration of 1.5 mg/kg b.wt. of haloperidol. However, Pr-SSG levels increased dose-dependently following haloperidol administration. The total GSH recovered as sum of GSH and Pr-SSG was significantly higher than controls in striatum and midbrain following administration of higher doses of haloperidol, namely, 2.0 and 2.5 mg/kg b.wt. The depleted GSH was not recoverable as glutathione disulfide (GSSG). GSSG levels were not significantly different from controls 4 h after administration of 1.5 mg/kg b.wt. of haloperidol. The levels of malondialdehyde (indicative of lipid peroxidation) increased significantly as compared to control levels (280-220%) following administration of 1.0 and 1.5 mg/kg b.wt. of haloperidol.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Comparison of haloperidol and reduced haloperidol plasma levels in four different ethnic populations.

1. Plasma haloperidol and reduced haloperidol concentration were measured in four ethnic populations. 2. Plasma samples were obtained under steady-state conditions and obtained 10-12 hours post bedtime dose and prior to the morning dose. 3. Haloperidol and reduced haloperidol plasma levels were assayed by radioimmunoassay and liquid chromatography. 4. A wide interpatient variability between haloperidol dose and plasma concentration was observed for each ethnic group. 5. The Chinese group differed from the other ethnic populations. 6. A nonlinear relationship was observed between haloperidol and reduced haloperidol plasma levels in each ethnic group. Further, the relationship of haloperidol to reduced haloperidol plasma levels differed for each ethnic group. These results suggest that various ethnic groups could metabolize haloperidol and reduced haloperidol differently.

Black or African American↗