Double-blind comparison of haloperidol decanoate and fluphenazine decanoate effectiveness, side-effects, dosage and serum levels during a six months' treatment for relapse prevention

Oral and long-acting antipsychotics for relapse prevention in schizophrenia-spectrum disorders: a network meta-analysis of 92 randomized trials including 22,645 participants

According to current evidence and guidelines, continued antipsychotic treatment is key for preventing relapse in people with schizophrenia-spectrum disorders, but evidence-based recommendations for the choice of the individual antipsychotic for maintenance treatment are lacking. Although oral antipsychotics are often prescribed first line for practical reasons, long-acting injectable antipsychotics (LAIs) are a valuable resource to tackle adherence issues since the earliest phase of disease. Medline, EMBASE, PsycINFO, CENTRAL and CINAHL databases and online registers were searched to identify randomized controlled trials comparing LAIs or oral antipsychotics head-to-head or against placebo, published until June 2021. Relative risks and standardized mean differences were pooled using random-effects pairwise and network meta-analysis. The primary outcomes were relapse and dropout due to adverse events. We used the Cochrane Risk of Bias tool to assess study quality, and the CINeMA approach to assess the confidence of pooled estimates. Of 100 eligible trials, 92 (N=22,645) provided usable data for meta-analyses. Regarding relapse prevention, the vast majority of the 31 included treatments outperformed placebo. Compared to placebo, "high" confidence in the results was found for (in descending order of effect magnitude) amisulpride-oral (OS), olanzapine-OS, aripiprazole-LAI, olanzapine-LAI, aripiprazole-OS, paliperidone-OS, and ziprasidone-OS. "Moderate" confidence in the results was found for paliperidone-LAI 1-monthly, iloperidone-OS, fluphenazine-OS, brexpiprazole-OS, paliperidone-LAI 1-monthly, asenapine-OS, haloperidol-OS, quetiapine-OS, cariprazine-OS, and lurasidone-OS. Regarding tolerability, none of the antipsychotics was significantly worse than placebo, but confidence was poor, with only aripiprazole (both LAI and OS) showing "moderate" confidence levels. Based on these findings, olanzapine, aripiprazole and paliperidone are the best choices for the maintenance treatment of schizophrenia-spectrum disorders, considering that both LAI and oral formulations of these antipsychotics are among the best-performing treatments and have the highest confidence of evidence for relapse prevention. This finding is of particular relevance for low- and middle-income countries and constrained-resource settings, where few medications may be selected. Results from this network meta-analysis can inform clinical guidelines and national and international drug regulation policies.

Maintenance Treatment With Long-Acting Injectable Antipsychotics for People With Nonaffective Psychoses: A Network Meta-Analysis

OBJECTIVE

This study compared relapse prevention and acceptability of long-acting injectable (LAI) antipsychotics in the maintenance treatment of adults with nonaffective psychoses.

METHODS

The authors searched MEDLINE, Embase, PsycINFO, CINAHL, CENTRAL, and online registers for randomized controlled trials published until June 2020. Relative risks and standardized mean differences were pooled using random-effects pairwise and network meta-analysis. The primary outcomes were relapse rate and all-cause discontinuation ("acceptability"). The quality of included studies was rated with the Cochrane Risk of Bias tool, and the certainty of pooled estimates was measured with GRADE (Grading of Recommendations Assessment, Development, and Evaluation).

RESULTS

Of 86 eligible trials, 78 (N=11,505) were included in the meta-analysis. Regarding relapse prevention, most of the 12 LAIs included outperformed placebo. The largest point estimates and best rankings of LAIs compared with placebo were found for paliperidone (3-month formulation) and aripiprazole. Moderate to high GRADE certainty for superior relapse prevention compared with placebo was also found for (in descending ranking order) risperidone, pipothiazine, olanzapine, and paliperidone (1-month formulation). In head-to-head comparisons of LAIs, only haloperidol was inferior to aripiprazole, fluphenazine, and paliperidone. For acceptability, most LAIs outperformed placebo, with moderate to high GRADE certainty for (in descending ranking order) zuclopenthixol, aripiprazole, paliperidone (3-month formulation), olanzapine, flupenthixol, fluphenazine, and paliperidone (1-month formulation). In head-to-head comparisons, only LAI aripiprazole had superior acceptability to other LAIs (bromperidol, fluphenazine, paliperidone [1-month formulation], pipothiazine, and risperidone).

CONCLUSIONS

LAI formulations of paliperidone (3-month formulation), aripiprazole, olanzapine, and paliperidone (1-month formulation) showed the highest effect sizes and certainty of evidence for both relapse prevention and acceptability. Results from this network meta-analysis should inform frontline clinicians and guidelines.

Therapeutic Drug Monitoring of Long-Acting Injectable Antipsychotic Drugs

BACKGROUND

The use of therapeutic drug monitoring (TDM) to guide treatment with long-acting injectable (LAI) antipsychotics, which are increasingly prescribed, remains a matter of debate. The aim of this review was to provide a practical framework for the integration of TDM when switching from an oral formulation to the LAI counterpart, and in maintenance treatment.

METHODS

The authors critically reviewed 3 types of data: (1) positron emission tomography data evaluating dopamine (D2/D3) receptor occupancy related to antipsychotic concentrations in serum or plasma; D2/D3 receptors are embraced as target sites in the brain for antipsychotic efficacy and tolerability, (2) pharmacokinetic studies evaluating the switch from oral to LAI antipsychotics, and (3) pharmacokinetic data for LAI formulations. Based on these data, indications for TDM and therapeutic reference ranges were considered for LAI antipsychotics.

RESULTS

Antipsychotic concentrations in blood exhibited interindividual variability not only under oral but also under LAI formulations because these concentrations are affected by demographic characteristics such as age and sex, genetic peculiarities, and clinical variables, including comedications and comorbidities. Reported data combined with positron emission tomography evidence indicated a trend toward lower concentrations under LAI administration than under oral medications. However, the available evidence is insufficient to recommend LAI-specific therapeutic reference ranges.

CONCLUSIONS

Although TDM evidence for newer LAI formulations is limited, this review suggests the use of TDM when switching an antipsychotic from oral to its LAI formulation. The application of TDM practice is more accurate for dose selection than the use of dose equivalents as it accounts more precisely for individual characteristics.

Classics in Chemical Neuroscience: Haloperidol

The discovery of haloperidol catalyzed a breakthrough in our understanding of the biochemical basis of schizophrenia, improved the treatment of psychosis, and facilitated deinstitutionalization. In doing so, it solidified the role for chemical neuroscience as a means to elucidate the molecular underpinnings of complex neuropsychiatric disorders. In this Review, we will cover aspects of haloperidol's synthesis, manufacturing, metabolism, pharmacology, approved and off-label indications, and adverse effects. We will also convey the fascinating history of this classic molecule and the influence that it has had on the evolution of neuropsychopharmacology and neuroscience.

A systematic review and meta-analysis of the effect of depot antipsychotic frequency on compliance and outcome

BACKGROUND

Depot antipsychotics are commonly used to improve adherence and clinical outcomes such as relapse and readmission. Dosing regimens vary but are commonly two- and four-weekly. To date, the effect of administration at two-weekly or four-weekly intervals on outcome has not been examined in a meta-analysis.

AIMS

A systematic review and meta-analysis on whether the frequency of depot antipsychotic administration (e.g., two- vs four-weekly) makes any difference to compliance and outcome.

METHODS

A systematic search of Medline, EMBASE and PsycInfo for RCTs that compared the frequency of depot administration (e.g., two- vs four-weekly) for an equivalent dose. Outcomes were compliance, psychiatric symptomatology, quality of life, adverse drug reactions (ADRs), patient preference, admission rates, bed-days and costs.

RESULTS

Seven studies from eight papers (n=3994) were found covering olanzapine, paliperidone, risperidone, haloperidol and fluphenazine enanthate/decanoate with follow-up of up to one year. Meta-analyses were possible for psychotic symptoms and ADRs. There were no differences in psychotic symptoms or quality of life between two- and four-weekly doses. Health service use was not reported. For ADRs, the only significant difference detected was that two-weekly injections were less likely to lead to site pain (RR 0.16, 95% CI 0.07-0.38; 2 studies n=1667). There were no differences in other ADRs.

CONCLUSIONS

There were surprisingly little data on the effect of dosing frequency for an equivalent dose on clinical outcomes. There is a need for long-term studies of a wide range of outcomes including cost-effectiveness. Claims for advantages of new preparations over others require careful evaluation.

Fluphenazine decanoate (depot) and enanthate for schizophrenia

BACKGROUND

Intramuscular injections (depot preparations) offer an advantage over oral medication for treating schizophrenia by reducing poor compliance. The benefits gained by long-acting preparations, however, may be offset by a higher incidence of adverse effects.

OBJECTIVES

To assess the effects of fluphenazine decanoate and enanthate versus oral anti-psychotics and other depot neuroleptic preparations for individuals with schizophrenia in terms of clinical, social and economic outcomes.

SEARCH METHODS

We searched the Cochrane Schizophrenia Group's Trials Register (February 2011 and October 16, 2013), which is based on regular searches of CINAHL, BIOSIS, AMED, EMBASE, PubMed, MEDLINE, PsycINFO, and registries of clinical trials.

SELECTION CRITERIA

We considered all relevant randomised controlled trials (RCTs) focusing on people with schizophrenia comparing fluphenazine decanoate or enanthate with placebo or oral anti-psychotics or other depot preparations.

DATA COLLECTION AND ANALYSIS

We reliably selected, assessed the quality, and extracted data of the included studies. For dichotomous data, we estimated risk ratio (RR) with 95% confidence intervals (CI). Analysis was by intention-to-treat. We used the mean difference (MD) for normal continuous data. We excluded continuous data if loss to follow-up was greater than 50%. Tests of heterogeneity and for publication bias were undertaken. We used a fixed-effect model for all analyses unless there was high heterogeneity. For this update. we assessed risk of bias of included studies and used the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach to create a 'Summary of findings' table.

MAIN RESULTS

This review now includes 73 randomised studies, with 4870 participants. Overall, the quality of the evidence is low to very low.Compared with placebo, use of fluphenazine decanoate does not result in any significant differences in death, nor does it reduce relapse over six months to one year, but one longer-term study found that relapse was significantly reduced in the fluphenazine arm (n = 54, 1 RCT, RR 0.35, CI 0.19 to 0.64, very low quality evidence). A very similar number of people left the medium-term studies (six months to one year) early in the fluphenazine decanoate (24%) and placebo (19%) groups, however, a two-year study significantly favoured fluphenazine decanoate (n = 54, 1 RCT, RR 0.47, CI 0.23 to 0.96, very low quality evidence). No significant differences were found in mental state measured on the Brief Psychiatric Rating Scale (BPRS) or in extrapyramidal adverse effects, although these outcomes were only reported in one small study each. No study comparing fluphenazine decanoate with placebo reported clinically significant changes in global state or hospital admissions.Fluphenazine decanoate does not reduce relapse more than oral neuroleptics in the medium term (n = 419, 6 RCTs, RR 1.46 CI 0.75 to 2.83, very low quality evidence). A small study found no difference in clinically significant changes in global state. No difference in the number of participants leaving the study early was found between fluphenazine decanoate (17%) and oral neuroleptics (18%), and no significant differences were found in mental state measured on the BPRS. Extrapyramidal adverse effects were significantly less for people receiving fluphenazine decanoate compared with oral neuroleptics (n = 259, 3 RCTs, RR 0.47 CI 0.24 to 0.91, very low quality evidence). No study comparing fluphenazine decanoate with oral neuroleptics reported death or hospital admissions.No significant difference in relapse rates in the medium term between fluphenazine decanoate and fluphenazine enanthate was found (n = 49, 1 RCT, RR 2.43, CI 0.71 to 8.32, very low quality evidence), immediate- and short-term studies were also equivocal. One small study reported the number of participants leaving the study early (29% versus 12%) and mental state measured on the BPRS and found no significant difference for either outcome. No significant difference was found in extrapyramidal adverse effects between fluphenazine decanoate and fluphenazine enanthate. No study comparing fluphenazine decanoate with fluphenazine enanthate reported death, clinically significant changes in global state or hospital admissions.

AUTHORS' CONCLUSIONS

There are more data for fluphenazine decanoate than for the enanthate ester. Both are effective antipsychotic preparations. Fluphenazine decanoate produced fewer movement disorder effects than other oral antipsychotics but data were of low quality, and overall, adverse effect data were equivocal. In the context of trials, there is little advantage of these depots over oral medications in terms of compliance but this is unlikely to be applicable to everyday clinical practice.

Comparison of physician-rating and self-rating scales for patients with major depressive disorder

Physician-rating scales remain the standard in antidepressant clinical trials. The current study aimed to examine the discrepancies between physician-rating scales and self-rating scales for symptoms and functioning, before and after treatment, in newly hospitalized patients. A total of 131 acutely ill inpatients with major depressive disorder were enrolled to receive 20 mg of fluoxetine daily for 6 weeks. Symptom severity and functioning were assessed at baseline and again at week 6. Symptom severity was rated using the 17-item Hamilton Depression Rating Scale (HDRS-17) and the Zung Self-rating Depression Scale (ZDS). Functioning was measured by the Global Assessment of Functioning (GAF) and the Work and Social Adjustment Scale (WSAS). Pearson correlation coefficients (r) between HDRS-17 and ZDS and between GAF and WSAS were calculated at week 0 and week 6. Sensitivity to change was measured using effect sizes. One-hundred twelve patients completed the 6-week trial. After 6 weeks of treatment, correlations between HDRS-17 and ZDS or correlations between GAF and WSAS became larger from baseline to end point. All correlations were statistically significant (P < 0.001). Effect sizes measured by physician-rating scales (ie, HDRS-17 and GAF) were larger than by self-rating scales (ie, ZDS and WSAS). Correlations between baseline physician-rating scale scores and self-rating scale scores improved after 6 weeks of treatment. Physician-rating scales had larger effect sizes than self-rating scales. Physician-rating scales were more sensitive in detecting symptom or functional changes than self-rating scales.

The role of long-acting injectable antipsychotics in schizophrenia: a critical appraisal

Despite their widespread use, long-acting injectable (LAI) antipsychotics (APs) are often regarded with some negativity because of the assumption of punishment, control and insufficient evolution towards psychosocial development of patients. However, LAI APs have proved effective in schizophrenia and other severe psychotic disorders because they assure stable blood levels, leading to a reduction of the risk of relapse. Therapeutic opportunities have also arisen after introduction of newer, second-generation LAI APs in recent years. Newer LAI APs are more readily dosed optimally, may be better tolerated and are better suited to integrated rehabilitation programmes. This review outlines the older and newer LAI APs available for the treatment of schizophrenia, with considerations of past and present pharmacological and therapeutic issues. Traditional, evidence-based approaches to systematic reviews and randomized clinical trials are of limited utility in this area so this paper's blending of experimental trials with observational research is particularly appropriate and effective.

Evaluation of the in vitro cytogenotoxicity profile of antipsychotic drug haloperidol using human peripheral blood lymphocytes

Haloperidol (HLP) is a potent antipsychotic drug that is commonly used for the treatments of schizophrenia and bipolar disorders but has a tendency to cause adverse effects. In the present study, the cyto/genotoxic potential of clinically relevant concentrations of HLP was evaluated in human peripheral blood lymphocytes (HPBLs) as sensitive biomarkers of exposure. HLP was administered as HLP hydrochloride in the final concentrations of 5, 10 and 20 ng/ml for 4 and 24 h period. Cytotoxicity was determined using differential staining of HPBLs with acridine orange and ethidium bromide while chromosomal aberrations, micronucleus and comet assays were applied to estimate the chromosomal and DNA damage after the treatment. The results of the present study indicate that HLP is capable of inducing cyto/genotoxicity in tested cells. Present study has also confirmed the need for further cytogenetic research and regular patient monitoring to minimize the risk of any possible adverse events.

Psychopharmacology and adverse effects of antipsychotic long-acting injections: a review

BACKGROUND

Depot antipsychotics are widely used in clinical practice. Long-acting formulations of second-generation antipsychotics are now being developed and introduced.

AIMS

To review the pharmacology, pharmacokinetics and adverse effect profiles of currently available antipsychotic long-acting injections (LAIs).

METHOD

The psychopharmacological properties of first- and second-generation antipsychotic LAIs are reviewed using data available up to October 2008.

RESULTS

First-generation antipsychotic (FGA) LAIs are associated with a high rate of acute and chronic movement disorders. Risperidone LAI is better tolerated in this respect, but is associated with hyperprolactinaemia and weight gain. Olanzapine LAI causes weight gain and other metabolic effects but appears not to be associated with an important incidence of movement disorders.

CONCLUSIONS

Dosing of LAIs is complicated by delayed release of drug, changes in plasma levels without change in dose, and by the lack of data establishing clear dose requirements. All LAIs offer the prospect of assured adherence (although patients may still default on treatment) but their use is complicated by adverse effects, complex pharmacokinetics and confusion over dose-response relationships.

Depot fluphenazine decanoate and enanthate for schizophrenia

BACKGROUND

Intramuscular injections (depot preparations) offer an advantage over oral medication for treating schizophrenia by reducing poor compliance. The benefits gained by long acting preparations, however, may be offset by a higher incidence of adverse effects.

OBJECTIVES

To investigate the clinical effects of fluphenazine decanoate and enanthate.

SEARCH STRATEGY

For this update we searched the Cochrane Schizophrenia Group's Register (May 2002).

SELECTION CRITERIA

We considered all relevant randomised clinical controlled trials focusing on people with schizophrenia comparing fluphenazine decanoate or enanthate with placebo or oral anti-psychotics or other depot preparations.

DATA COLLECTION AND ANALYSIS

We reliably selected, quality rated and data extracted studies. For dichotomous data we estimated relative risk (RR) with 95% confidence intervals (CI), and, where possible, the number needed to treat/harm (NNT/H). Analysis was by intention-to-treat. We used the weighted mean difference (WMD) for normal continuous data. Tests of heterogeneity and for publication bias were undertaken.

MAIN RESULTS

This review now includes 70 randomised studies. Compared with placebo, fluphenazine decanoate did not reduce relapse over 6 months to 1 year, but one longer term study found that relapse was significantly reduced in the fluphenazine arm (n=54, RR 0.35, CI 0.2 to 0.6, NNT 2 CI 2 to 4). Fluphenazine decanoate does not reduce relapse more than oral neuroleptics (n=419, 6 RCTs, RR relapse 26-52 weeks 1.46 CI 0.8 to 2.8) or other depot antipsychotics (n=581, 11 RCTs, RR relapse 26-52 weeks 0.82 CI 0.6 to 1.2). Relapse rates over 6 months to 1 year were not significantly different between standard dosage of fluphenazine decanoate over a low dose group (n=523, 4 RCTs, RR 2.09 CI 0.6 to 7.1). Movement disorders were significantly less for people receiving fluphenazine decanoate compared with oral neuroleptics (n=259, 3 RCTs, RR 0.47 CI 0.2 to 0.9, NNT 14 CI 10 to 82). For fluphenazine enanthate there were limited data but no clear difference in global change (0 to 5 weeks) when compared with oral neuroleptics (n=31, 1 RCTs, RR 0.67 CI 0.3 to 1.7), and in relapse rates over 6-26 weeks between fluphenazine enanthate and other depots. Compared with placebo, giving the enanthate caused no more people to need need anticholinergic drugs (n=25, 1 RCT, RR 9.69 CI 0.6 to 163.0) and movement disorders, tardive dyskinesia, tremor, blurred vision and dry mouth were equally prevalent when enanthate was compared with other depot neuroleptics.

AUTHORS' CONCLUSIONS

There are more data for fluphenazine decanoate than for the enanthate ester. Both are effective antipsychotic preparations. In the context of trials, there is little advantage of these depots over oral medications in terms of compliance but this is unlikely to be applicable to everyday clinical practice.

Depot haloperidol decanoate for schizophrenia

BACKGROUND

The mainstay of treatment for schizophrenia is the antipsychotic group of drugs. These are usually given orally but compliance with medication given by this route may be difficult to quantify. Problems with treatment adherence are common. The development of depot injections in the 1960s gave rise to their extensive use as a means of long-term maintenance treatment. Haloperidol decanoate is one depot drug available in clinical practice.

OBJECTIVES

To assess the effects of haloperidol decanoate versus oral anti-psychotics and other depot antipsychotic preparations for people with schizophrenia in terms of clinical, social and economic outcomes.

SEARCH STRATEGY

Relevant trials were identified by searching Biological Abstracts (1982-1998), Cochrane Library (Issue 2, 1998), Cochrane Schizophrenia Group's Register (June 1998), EMBASE (1980-1998), MEDLINE (1966-1998) and PsycLIT (1974-1998). References of all identified trials were also inspected for more studies.

SELECTION CRITERIA

All relevant randomised trials focusing on people with schizophrenia where haloperidol decanoate, oral anti-psychotics or other depot preparations were compared. Outcomes such as death, clinically significant change in global function, mental state, relapse, hospital admission, adverse effects and acceptability of treatment were sought.

DATA COLLECTION AND ANALYSIS

Studies were reliably selected, quality rated and data extracted. For dichotomous data Mantel-Haenszel odds ratios (OR) with the 95% confidence intervals (CI) were estimated. Where possible, the number needed to treat statistic (NNT) was calculated. Analysis was by intention-to-treat. Normal continuous data were summated using the weighted mean difference (WMD). Scale data were presented only for those tools that had attained pre-specified levels of quality.

MAIN RESULTS

In a haloperidol decanoate versus placebo comparison, two small studies reported that significantly fewer people on depot left early (OR 0.09 CI 0.03-0.21, NNT 2 CI 1-3) or experienced no important improvement in mental state (OR 0. 04 CI 0.01-0.15). Zississ (1982) suggested that those taking haloperidol decanoate would need less additional antipsychotic medication (OR 0.14 Cl 0.04-0.55, NNT 2 CI 1-5). Haloperidol decanoate was compared to oral haloperidol in a single trial that showed no differences in global impression, mental state or side effects ( approximately approximately Zuardi 1983 approximately approximately , n=22). Compliance with medication was not reported in this study. Eight trials compared haloperidol decanoate to other depot neuroleptics and again no differences were found for the outcomes of death, global impression, mental state, behaviour, or side effects.

REVIEWER'S CONCLUSIONS

Haloperidol decanoate may have a substantial effect in improving the symptoms and behaviour associated with schizophrenia in comparison to placebo, but data are remarkably sparse. There are no discernible differences between the depot form of haloperidol and its oral equivalent. For those needing and willing to take the drug, the means of administration is then a matter of individual choice and clinical judgement. As there are no clear differences between haloperidol decanoate and other depots, the choice of depot medication could also be individually tailored and patient preference exercised. Well-conducted and reported randomised trials are needed comparing haloperidol decanoate with other depots but the comparison of haloperidol decanoate to oral antipsychotics is a priority.

Long-term depot antipsychotics. A risk-benefit assessment

The main advantage of depot antipsychotic medication is that it overcomes the problem of covert noncompliance. Patients receiving depot treatment who refuse their injection or fail to receive it for any other reason can be immediately identified and appropriate action taken. In the context of a carefully monitored management programme, depot treatment can have a major impact on compliance and, consequently, the risk of relapse and hospitalisation can be reduced. Another major advantage is that the considerable individual variation in bioavailability and metabolism with oral antipsychotic drugs is markedly reduced with depot treatment. A better correlation between the dose administered and the concentration of medication found in blood or plasma is achieved with depot treatment, and thus, the clinician has greater control over the amount of drug being delivered to the site of activity. A further benefit of depot treatment is the achievement of stable plasma concentrations over long periods, allowing injections to be given every few weeks. However, this also represents a potential disadvantage in that there is a lack of flexibility of administration. Should adverse effects develop, the drug cannot be rapidly withdrawn. Furthermore, adjustment to the optimal dose becomes a long term strategy. The controlled studies of low dose maintenance therapy with depot treatment suggest that it can take months or years for the consequences of dose reduction, in terms of increased risk of relapse, to become manifest. When weighing up the risks and benefits of long term antipsychotic treatment for the individual patient with schizophrenia, the clinician must take into account the nature, severity and frequency of past relapses, and the degree of distress and disability related to any adverse effects. However, the clinical decision to prescribe either a depot or an oral antipsychotic for maintenance treatment will probably rest largely on an assessment of the risk of poor compliance in the particular patient. There is no convincing evidence that the range, nature or severity of adverse effects reported with depot treatment is significantly different from that seen with oral treatment, and depot treatment has been shown to be as good or better than oral medication in preventing or postponing relapse. Furthermore, when adjusting the dose or frequency of depot injection, to improve control of psychotic symptoms or reduce adverse effects, the clinician can be confident that the dose prescribed is the dose being received by the patient.

Depot antipsychotic drugs. Place in therapy

The pharmacokinetics of depot antipsychotic medications are such that an intramuscular injection given at intervals of from 1 to 4 weeks will produce adequate plasma concentrations that are sufficient to prevent relapse over the dosage interval. Such medication is useful in patients who do not reliably take their oral medication. The pharmacokinetics and clinical actions of various depot formulations of antipsychotic drugs have been extensively studied. Unfortunately, patients who do not reliably take their oral medications are unlikely to volunteer for controlled studies. This is because the same factors that influence a patient to not cooperate with the physician in taking the medication as prescribed will also interfere with their willingness to volunteer for research protocols. Thus, evidence from blinded controlled trials may not necessarily reflect the actual patient population at risk. We feel that particularly important evidence of efficacy of depot vs oral medication comes from mirror-image studies. In these trials, the number of hospitalisations after initiation of depot medication is compared with that observed when the patient was solely taking oral medication. Studies of this type show that depot medication substantially reduces the rate of relapse. There is considerable evidence about how long depot medications should be used. For many patients, depot medication to prevent relapse in schizophrenia should be used for the life of the patient. As the conventional antipsychotic agents are replaced by a new generation of agents, the need for depot formulations will continue, and the knowledge gained about the current formulations should transfer to future generations of drugs.

Pharmacokinetics of haloperidol and fluphenazine decanoates in chronic schizophrenia

In a double-blind comparison of haloperidol decanoate and fluphenazine decanoate given 4-weekly for 60 weeks as maintenance therapy in 38 chronic schizophrenic in-patients, plasma haloperidol, fluphenazine and prolactin levels were measured at regular intervals by radioimmunoassay. After the first injection, the mean plasma haloperidol level was highest at week 1 and fell gradually towards week 4. Mean pre-dose haloperidol levels changed little after week 8. Results suggested an absorption half-life of 4 weeks, although, in three cases steady state was only achieved after 11 monthly injections. Steady state levels of both haloperidol and fluphenazine correlated highly with dose. In two sub-groups observed at steady state, both drugs produced a biphasic pattern of plasma drug concentration between injections, a rapid rise on day 1 followed by stable elevated levels and a gradual return to pre-injection concentration by the end of week 4. In the fluphenazine sub-group there was a second peak on day 7 and a steeper decline, so that the mean area-under-curve in week 4 was 64% of that in week 1. Drug injections at steady state induced an increase in prolactin secretion in all of the fluphenazine sub-group and in half of those receiving haloperidol. Plasma prolactin changes resembled those for drug concentrations, but differences in times of peaks on day 1 resulted in weak correlations. Fluphenazine appeared more potent than haloperidol in provoking prolactin secretion.

Haloperidol decanoate: a depot antipsychotic

This article reviews the role of a new depot antipsychotic dosage form, haloperidol decanoate (HD), in relationship to other comparable pharmacotherapies (oral and injectable). The chemistry, indications, contraindications, and pharmacokinetics of HD are discussed. The available clinical research in humans is presented and evaluated with respect to efficacy, adverse effects, and dosing. HD is clearly an effective antipsychotic dosage form. Certainly, HD can improve compliance and possibly outcome for selected patients. HD should be reserved for chronic relapsing schizophrenic patients who have responded to oral haloperidol. Considering the pharmacokinetics, potential risks, and cost of HD, the clinician needs to be prepared with recommendations to effect optimal use of HD (guidelines are presented).

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.