RBC and plasma levels of haloperidol and clinical response in schizophrenia

Age-related alteration of haloperidol-serum protein binding

Serum haloperidol levels were determined in 59 patients, 50-88-years-old, with psychosis, receiving long-term treatment with haloperidol. Although the total (bound and free form) haloperidol level in serum showed a linear correlation with daily dose, there was a larger variation in the relationship between free form and the daily dose compared with total because of inter-individual variation in the serum protein binding of haloperidol. The free fraction of haloperidol in serum increased with age. There was no difference in the ratio of total haloperidol level per daily dose between the adult and elderly groups, whereas the ratio of free haloperidol level per daily dose was significantly higher in the elderly than in the adult group. In the elderly, therefore, the therapeutic window of haloperidol should be assessed using free form level rather than total level, which is influenced by serum protein binding of the drug.

Haloperidol blood levels and clinical outcome: a meta-analysis of studies relevant to testing the therapeutic window hypothesis

Haloperidol, the most studied antipsychotic drug, is the only one about which reliable statements on the relationship between blood levels and clinical outcome can be made. A systematic overview was undertaken to determine whether there was an optimum blood concentration range for clinical efficacy. Eighteen published studies which provided individual patient data in tables or graphs were reviewed. Clinical benefits tended to decline when the haloperidol blood concentration was increased above 26 ng/ml. Our data support the existence of a therapeutic window between 4 and 26 ng/ml for haloperidol in the treatment of schizophrenic, schizoaffective and schizophreniform disorders.

Is there a relationship between antipsychotic blood levels and their clinical efficacy? An analysis of studies design and methodology

There are now more than 50 studies concerning neuroleptic blood levels and clinical outcome relationships. Haloperidol, the most studied, is the only antipsychotic permitting some conclusions. A number of authors suggest that the striking lack of agreement between different studies results from heterogeneity of their quality. Here, we have used a scoring system for assessing the quality of those studies. According to this system, none (0/14) of the studies having a score < 0.60 was able to show a therapeutic window, as compared to 53% (10/19) of those having a score > or = 0.60 (p = 0.002, Fisher exact test). Also, the studies able to identify the presence of a therapeutic window during haloperidol treatment were those having sample size > 20 (p = 0.06) and those whose patients were treated with fixed doses (p = 0.02). The diagnosis of schizophrenia in the studies seems not to be an exclusive condition, as compared with those also including schizophreniform and schizoaffective disorders (p = 0.12). Our qualitative analysis of haloperidol blood level publications seem to indicate that an upper limit may exist for haloperidol efficacy; values above this limit seem not to provide any supplementary clinical improvement and may even reduce therapeutic effect.

Haloperidol Concentrations in Patients With Alzheimer's Dementia

To investigate the relationship between clinical response and haloperidol blood concentrations in Alzheimer's dementia (AD) patients with behavior problems, 29 AD inpatients were assigned to a fixed oral dosage of haloperidol (0.5 mg, 1.0 mg, or 2.0 mg) every 12 hours for 3 weeks. BEHAVE-AD ratings and concentrations of plasma and RBC haloperidol and reduced haloperidol were obtained on Days 8, 15, and 22. Although no significant linear or curvilinear relationships were apparent between percent of change on BEHAVE-AD and plasma or RBC haloperidol concentrations, a good response (change ≥ 30%) was observed in 55% of the patients who entered the study.

Neuropsychological test scores and clinical response to neuroleptic drugs in schizophrenic patients

Schizophrenic patients who showed greater neuropsychological deficits on the Luria-Nebraska Pathognomonic subscale (PATH) and Trail-Making Test showed less improvement during treatment with neuroleptic drugs than patients with lower scores on these neuropsychological tests. Other neuropsychological test scores we used were not consistently related to the patients' degree of clinical improvement during neuroleptic treatment. Only a few patients evidenced severe scores on either the PATH or TM tests, suggesting that more subtle neuropsychological deficits may identify a subgroup of schizophrenics who will show a relatively poor response to treatment with standard neuroleptic drugs.

Clinical response and plasma haloperidol levels in chronic and subchronic schizophrenia

Levels of haloperidol were determined by radioimmunoassay (RIA) in 30 schizophrenic patients (diagnosed according to the criteria of DSM-III), who were treated with fixed doses of this neuroleptic for a period of 21 days. An inverted U-shaped relationship was found between the percent improvement observed in the BPRS global score and the steady state of haloperidol. The interval of effective concentration of haloperidol was set between 12.0 and 35.5 ng/ml. However, the limits of such an interval found in the subchronic schizophrenic subgroup (SS) ranged from 7.4 to 24.9 ng/ml, whereas in the chronic schizophrenic subgroup (CS), it ranged from 14.8 to 38.5 ng/ml. This finding suggests that the interval of effective concentrations may vary as a function of the number of years of evolution of the subjects' illness. This may be compatible with the development of tolerance in the mesolimbic and/or mesocortical dopaminergic systems as a response to prolonged neuroleptic treatments.

Hyperactivity of associations in psychosis

Disordered associative processes have long been regarded as central to the psychological description of psychotic states such as acute schizophrenia. Previous work is briefly summarised concerning the idea that hyperactive associative processes of thought underlie many of the symptoms of psychosis. The idea is developed further, with respect to several features of the psychotic state. Schneiderian symptoms are seen as a consequence of hyperactive associations of thought, combined with perceptual hypersensitivity characteristic of many psychotic individuals. Anxiety in psychotic states is seen as arising from the great ambiguity of mental images when associations are loosened. A vicious circle between high anxiety and hyperactive associations is postulated. The slow and variable response to neuroleptic treatment is seen as being determined in part by the dynamics of change of the memories acquired during a period of hyperactive associations.

Neuroleptic plasma concentrations and clinical response: in search of a therapeutic window

There is much interest in finding a therapeutic window for commonly used neuroleptics so that dosage can be individualized and side effects minimized. The authors review specific requirements of good study design and survey the literature that has investigated the relationship between therapeutic response and plasma concentrations of neuroleptics. The evidence from a number of fixed-dose haloperidol studies suggests, but does not yet prove, the existence of a therapeutic window for this compound.

Serum haloperidol levels and clinical response in chronic, treatment-resistant schizophrenic patients

Eleven chronic treatment-resistant schizophrenic in-patients were treated with haloperidol (HPL) or placebo with a fixed ascending dose schedule for 20 weeks. Seven patients relapsed and were withdrawn and five of these re-entered, single-blind, on known active treatment. Two weekly clinical ratings and weekly serum HPL levels were carried out throughout the study. More patients on placebo dropped out and at an earlier stage than those on active treatment but the difference was not statistically significant. Despite wide individual variations in both serum HPL levels and clinical response, these were positively correlated. HPL appeared to be of more value in the prevention of relapse than in symptom reduction. Overall, the clinical response was poor and a 'therapeutic window' could not be demonstrated either for the group as a whole or in any individual patient. There was no additional therapeutic benefit in exceeding serum HPL levels of 20 ng/ml in any of our patients. Since this serum level was achieved by daily doses of 10-40 mg HPL and the relationship between dose and serum level is linear, the use of serum HPL estimations is not likely to be of value in the routine clinical management of treatment-resistant patients.

Neuroleptic blood levels and clinical response

Gas chromatography and radioreceptor assay technologies made possible the measurement of nanogram quantities of neuroleptic in the blood. They revealed large differences in blood concentrations among patients receiving the same oral dose. This led to the hope that measuring neuroleptic concentrations would allow more effective oral dosing for individual psychotic patients. Early attempts to study neuroleptic concentration/clinical response patterns, using chlorpromazine, produced confusing results. Many of the studies had serious design flaws, and were complicated by the many active metabolites of chlorpromazine. Adequate blood level/response studies should use fixed drug dosage schedules, drug-responsive patients, and neuroleptics without active metabolites. Brain concentration of drug is probably better reflected by erythrocyte than by plasma concentration. Therefore, recent investigators have usually used erythrocyte haloperidol or butaperazine concentrations to study level/response relationships. These recent studies strongly suggest an "optimal concentration" level/response pattern for haloperidol and butaperazine. Patients tend to respond best to moderate concentrations of neuroleptic, and nonresponse can be due to either too low or too high concentrations. In the latter case, decreasing the oral dose should be seriously considered. Blood level findings remain preliminary. The clinician should continue to fine-tune his clinical skills, using neuroleptic blood concentrations to complement his clinical judgment, in the attempt to determine the lowest effective dose for the individual patient.

Radio receptor assay of serum neuroleptic levels in psychiatric patients

The radioreceptor assay for the measurement of neuroleptic drugs in serum has been used to study the relationship between dose and serum level in schizophrenic patients receiving these drugs. The assay was found to be reproducible and capable of detecting neuroleptics in the sera of patients receiving a range of both oral and depot drugs, with the exception of trifluoperazine spansules. Linear correlations were obtained between daily dose and serum level for each drug both in individual patients on different doses and between patients on a stable dose. Extrapyramidal side effects were related to the serum neuroleptic level within, but not between, patients. The assay may be of use in clinical practice, including the assessment of compliance or poor response to neuroleptics.

Plasma level monitoring of antipsychotic drugs. Clinical utility

The steady-state plasma concentrations of antipsychotic drugs show large interpatient variations but remain relatively stable from day to day in each individual patient. Monitoring of antipsychotic drug concentrations in plasma might be of value provided the patients are treated with only 1 antipsychotic drug. Some studies have reported a relationship between therapeutic response and serum antipsychotic drug 'concentrations' as measured using the radioreceptor assay (RRA) method, which measures dopamine receptor-blocking activity in plasma. Most studies, however, have failed to demonstrate such a relationship, and the RRA does not seem to provide the generally useful tool for plasma concentration monitoring of antipsychotic drugs that was hoped for initially. A lack of correlation between dopamine receptor-blocking activity in plasma and therapeutic response may be due to differences in the blood-brain distribution of both antipsychotic drugs and their active metabolites. Chemical assay methods (e.g. GLC and HPLC) have been used in studies which examined the relationships between therapeutic response and antipsychotic drug concentrations in red blood cells and in plasma. It seems that for these drugs, measuring red blood cell concentrations does not offer any significant advantage over measuring plasma concentrations. Reasonably controlled studies of plasma concentration-response relationships using randomly allocated, fixed dosages of chlorpromazine, fluphenazine, haloperidol, perphenazine, sulpiride, thioridazine and thiothixene have been published but often involve relatively few patients. A correlation between therapeutic response and plasma concentrations of thioridazine and its metabolites has not been demonstrated, and plasma level monitoring of thioridazine and its metabolites therefore appears to have no clinical value. Clinical behavioural deterioration concomitant with high plasma concentrations of chlorpromazine and haloperidol have been reported. A dosage reduction might be considered after 2 to 4 weeks' treatment in non-responders who have plasma chlorpromazine concentrations above 100 to 150 micrograms/L or plasma haloperidol concentrations above 20 to 30 micrograms/L. Non-responders and good responders to chlorpromazine treatment, however, have plasma drug concentrations in the same range, and a therapeutic range of plasma chlorpromazine levels has not been defined. Therapeutic plasma haloperidol concentrations (i.e. 'window') in the range of 5 to 20 micrograms/L have been reported by some investigators, but others have found no such relationship.(ABSTRACT TRUNCATED AT 400 WORDS)

Lateral ventricular enlargement and clinical response in schizophrenia

The relationship between enlargement of the lateral ventricles in the brains of schizophrenic patients and clinical response to neuroleptic treatment, as assessed by the ventricle-brain ratio (VBR) and psychopathology scores, was studied in a sample of 39 patients with schizophrenia or schizoaffective psychosis during a drug-free washout and after 3 1/2 weeks of treatment with either haloperidol or thioridazine. There was a weak, but statistically significant positive relationship between VBR and improvement on BPRS Psychosis factor scores after 3 1/2 weeks of treatment, and a negative correlation between VBR and baseline (washout) scores on the BPRS Anergia factor. Patients with enlarged VBRs, as defined by two criteria, also tended to show a better response to neuroleptics than patients below these criterion values.

Major psychosis and dopamine: controversial features and some suggestions

Three problems with the dopamine hypothesis of major psychosis are pointed out: the long time-course of neuroleptic therapy; the absence of tolerance to the antipsychotic effects of neuroleptic drugs, or of a supersensitivity psychosis on drug withdrawal; and the absence of potent psychotogenic properties in the direct dopamine agonists. A resolution of these paradoxes is suggested relying on a role for dopamine in learning processes at a relatively high (cognitive) functional level. The hypothesis proposed is also used to explain the origin of some of the more distinctive psychotic symptoms.

Plasma and red cell levels of thioridazine and clinical response in schizophrenia

The relationship of plasma and red blood cell (RBC) levels of thioridazine to clinical response in schizophrenia was evaluated in a fixed-dose study. Steady-state plasma and RBC levels of thioridazine, mesoridazine, and sum of thioridazine and mesoridazine, determined by gas-liquid chromatography, were not significantly correlated with clinical response as measured by improvement on the Brief Psychiatric Rating Scale. RBC thioridazine levels were not substantially more strongly correlated with clinical response than plasma levels.

Clinical efficacy, extrapyramidal symptoms and serum levels: influence of administration schedules and concomitant drugs on serum bromperidol concentrations

Bromperidol (4 or 12 mg per day) was administered to 18 newly admitted schizophrenics and 29 chronic schizophrenic inpatients once or four times a day and the two dose schedules were compared. The bromperidol levels in the four-times-a-day group were significantly higher than those in the once-a-day group and the daily variation in the serum level of the agent was markedly wider in the latter than in the former patients. The incidence and severity of extrapyramidal symptoms were not significantly different between the two. A clear relationship was not present between the serum levels and the development of extrapyramidal symptoms. The bromperidol serum values were not correlated with the therapeutic response but, at more than 5 ng per ml, there might be a positive correlation between the bromperidol levels and clinical efficacy in the newly admitted schizophrenics. As for concomitant medication, levomepromazine may raise the bromperidol serum level. An anti-parkinson drug failed to depress the bromperidol level.

Reduced haloperidol in the post-mortem brains of haloperidol-treated patients

We measured the concentrations of haloperidol and its reduced alcohol metabolite in human post-mortem tissues with high-performance/liquid chromatography using electrochemical detection. Both haloperidol and reduced haloperidol were detected and quantified in the occipital cortex of nine schizophrenic patients with a history of haloperidol treatment, but not in six samples from nontreated subjects. Reduced haloperidol concentrations were below the detection limit of the assay in several tissues of rats and mice even after 10 days of haloperidol treatment. The results suggest that reduced haloperidol is present in the brains of haloperidol-treated patients at slightly higher concentrations than haloperidol itself. Further studies are warranted to establish the possible biological importance of this haloperidol metabolite.

Prolactin response to single and multiple doses of haloperidol in schizophrenic patients

Serum prolactin and blood levels of haloperidol were assessed in schizophrenic patients after single acute oral doses of haloperidol and during fixed dose treatment with this medication. Although significant intrapatient correlations between prolactin responses to different doses of haloperidol were found, no statistically significant interpatient relationship between haloperidol dose and prolactin response emerged. There were statistically significant relationships between steady-state plasma and red cell haloperidol levels (measured by radioreceptor or gas liquid chromatographic techniques) and serum prolactin response, but not between blood levels after the acute haloperidol dose and prolactin response.