Clinical pharmacokinetics of the depot antipsychotics

Switching to long-acting injectable antipsychotics: pharmacological considerations and practical approaches

INTRODUCTION

Long-acting injectable antipsychotics (LAIs) are an effective, but potentially underutilized treatment option in schizophrenia and other severe mental illnesses. Prescribing information typically focuses on how to initiate treatment from the corresponding oral formulations. However, in clinical practice other scenarios, such as switching from other oral antipsychotics or other LAIs, occur frequently, requiring guidance.

AREAS COVERED

Pharmacodynamic properties of antipsychotics and their relation to rebound symptoms. Pharmacokinetic properties of LAIs and their implications for switching approaches. Specific approaches to switching to LAIs.

EXPERT OPINION

The LAI landscape has evolved significantly in the last decade with more formulations available, longer dosing intervals, and extended indications. However, currently available LAIs have various shortcomings, e.g. short dosing intervals, need for oral supplementation, loading regimens, deep intramuscular injection and/or restricted indications. Recent improvements include a one-day initiation option for aripiprazole lauroxil, aripiprazole monohydrate once-monthly, risperidone in situ microparticles and subcutaneous risperidone. Future LAI developments should focus on longer dosing intervals, subcutaneous administration, expansion of LAIs beyond currently available antipsychotic agents and indications beyond schizophrenia and bipolar disorder. In the future, LAIs might become a first-line treatment after initial oral stabilization for chronic mental disorders with need for maintenance treatment and presence of significant non-adherence.

Risperidone ISM as a New Option in the Clinical Management of Schizophrenia: A Narrative Review

Antipsychotics are the cornerstone of schizophrenia treatment. Lack of treatment adherence encouraged the development of injectable long-acting antipsychotics. However, second-generation or atypical antipsychotics require a loading dose at the start of treatment and eventually oral supplementation to achieve therapeutic plasma levels. This review discusses the evidence emerging from studies evaluating the pharmacokinetics, efficacy and safety of the intramuscular formulation of risperidone based on in situ microparticles (ISM). ISM® technology applied to risperidone allows therapeutic levels of the active moiety to be achieved within 2 h of intramuscular administration without the need for loading doses or oral supplementation, leading to a constant release over the whole dosing period. Risperidone ISM showed significant antipsychotic efficacy versus placebo in the Positive and Negative Syndrome Scale (PANSS) total score (p < 0.0001) and on the subscales of positive symptoms after 8 days, negative symptoms in 8 weeks, and general psychopathology during the 12 weeks of treatment. The improvement was also statistically significant (p < 0.0001) against placebo in the Clinical Global Impressions-Severity of Illness scale (CGI-S) score at the end of the treatment. Risperidone ISM was generally well tolerated and the most frequently reported adverse events were similar to those observed with other risperidone formulations. There is clinical evidence that these results are maintained in the long term. In conclusion, four-weekly risperidone ISM (75 mg and 100 mg) is an adequate antipsychotic for treating schizophrenia, both in the short term when an exacerbation has recently occurred and for long-term maintenance, since it provides rapid onset of action and sustained efficacy, as well as being safe and well tolerated.

Consideration of Long-Acting Injectable Antipsychotics for Polypharmacy Regimen in the Treatment of Schizophrenia: Put It on the Table or Not?

Antipsychotic monotherapy (APM) is considered best-acceptable treatment option regardless of antipsychotic class and formulation types for treating schizophrenia. However, antipsychotic polypharmacy (APP) has been also widely utilized in routine clinical practice. Despite APP has some clinical benefits it has also numerous pitfalls in relation with increased total number and doses of APs leading to adverse events as well as decrease of treatment adherence and persistence resulting in poor clinical outcomes. Recent introduction of long-acting injectable antipsychotics (LAIs) to the market has offered a chance for better medication adherence/persistence and also provided a simplification of treatment regime leading to more stabilized treatment for schizophrenia patients. When we cannot stay away from APP in the treatment of schizophrenia, clinicians need to find more proper APP regimens and thereby utilization of APP in efficient way should be a practical strategy to benefit schizophrenia patient in a real world treatment setting. With this regard, LAIs can be one of available APP regimen for treatment of schizophrenia in routine practice since their clinical utility and pharmacokinetic stability over oral APs have been well-elaborated today. However, when we have to commence LAIs as a part of APP with oral APs or other LAIs, every effort should be made before doing so whether or not validated and available treatment options or other clinical factors were not done or evaluated yet. Any treatment guidelines do not support APP regardless of the formulation of APP regimen or address two or more LAIs for treatment of schizophrenia till today.

Evaluating parameters affecting drug fate at the intramuscular injection site

Intramuscular (IM) injections are a well-established method of delivering a variety of therapeutics formulated for parenteral administration. While the wide range of commercial IM pharmaceuticals provide a wealth of pharmacokinetic (PK) information following injection, there remains an inadequate understanding of drug fate at the IM injection site that could dictate these PK outcomes. An improved understanding of injection site events could improve approaches taken by formulation scientists to identify therapeutically effective and consistent drug PK outcomes. Interplay between the typically non-physiological aspects of drug formulations and the homeostatic IM environment may provide insights into the fate of drugs at the IM injection site, leading to predictions of how a drug will behave post-injection in vivo. Immune responses occur by design after e.g. vaccine administration, however immune responses post-injection are not in the scope of this article. Taking cues from existing in vitro modelling technologies, the purpose of this article is to propose "critical parameters" of the IM environment that could be examined in hypothesis-driven studies. Outcomes of such studies might ultimately be useful in predicting and improving in vivo PK performance of IM injected drugs.

Pharmacokinetic Characteristics of Long-Acting Injectable Antipsychotics for Schizophrenia: An Overview

The availability of long-acting injectable (LAI) antipsychotics for the treatment of schizophrenia provides clinicians with options that deliver continuous drug exposure and may improve adherence compared with daily oral antipsychotics. However, all LAI antipsychotics have unique formulations and pharmacokinetic characteristics that have implications for medication selection, administration interval, and injection site. This review outlines key differences in drug formulations and pharmacokinetics among LAI antipsychotics. A systematic search of the PubMed database was conducted to identify physical and formulation properties and pharmacokinetic data of commercially available LAI antipsychotics, including flupentixol decanoate, fluphenazine decanoate, haloperidol decanoate, zuclopenthixol decanoate, aripiprazole monohydrate, aripiprazole lauroxil, olanzapine pamoate, paliperidone palmitate, risperidone microspheres, and risperidone polymeric microspheres. Additional information was obtained from package inserts and product monographs. Relevant data on drug properties, administration details, pharmacokinetic parameters, and oral dose equivalencies of LAI antipsychotics are summarized. Based on our analysis, formulation characteristics (e.g., vehicle medium) and administration characteristics (e.g., injection site) can affect rate of absorption and adverse effects and may factor into whether oral supplementation or an additional injection is needed. Dose adjustments may be necessary based on potential drug-drug interactions, and approximate dose equivalence with oral formulations can help inform titration when switching from oral to LAI formulations. Clinicians administering LAI antipsychotics should consider these formulation and pharmacokinetic factors to maximize clinical impact and to adjust to an individual patient's needs and treatment goals.

Neural Responsivity to Food Cues in Patients With Unmedicated First-Episode Psychosis

IMPORTANCE

Schizophrenia is associated with a reduced life expectancy of 15 to 20 years owing to a high prevalence of cardiometabolic disorders. Obesity, a key risk factor for the development of cardiometabolic alterations, is more prevalent in individuals with schizophrenia. Although obesity is linked to the altered reward processing of food cues, no studies have investigated this link in schizophrenia without the confounds of antipsychotics and illness chronicity.

OBJECTIVE

To investigate neural responsivity to food cues in first-episode psychosis without the confounds of antipsychotic medication or illness chronicity.

DESIGN, SETTING, AND PARTICIPANTS

A case-control study was conducted from January 31, 2015, to September 30, 2018, in London, United Kingdom, of 29 patients with first-episode psychosis who were not taking antipsychotic medication and 28 matched controls.

MAIN OUTCOMES AND MEASURES

Participants completed a food cue paradigm while undergoing a functional magnetic resonance imaging scan. Neural activation was indexed using the blood oxygen level-dependent hemodynamic response. The Dietary Instrument for Nutrition Education was used to measure diet, and the International Physical Activity Questionnaire was used to measure exercise.

RESULTS

There were no significant differences in age, sex, or body mass index between the 29 patients (25 men and 4 women; mean [SD] age, 26.1 [4.8] years) and 28 controls (22 men and 6 women; mean [SD] age, 26.4 [5.5] years). Relative to controls, patients consumed more saturated fat (t46 = -3.046; P = .004) and undertook less high-intensity (U = 304.0; P = .01) and low-intensity (U = 299.5; P = .005) weekly exercise. There were no group differences in neural responses to food vs nonfood cues in whole-brain or region-of-interest analyses of the nucleus accumbens, insula, or hypothalamus. Body mass index was inversely correlated with the mean blood oxygen level-dependent signal in the nucleus accumbens in response to food vs nonfood cues in controls (R = -0.499; P = .01) but not patients (R = 0.082; P = .70).

CONCLUSIONS AND RELEVANCE

Relative to controls, patients with first-episode psychosis who were not taking antipsychotic medication consumed more saturated fat and showed an altered association between body mass index and neural response to food cues in the absence of differences in neural responses to food cues. These findings highlight how maladaptive eating patterns and alterations in the association between body mass index and neural responses to food cues are established early in the course of schizophrenia.

Long-Acting Injectable Second-Generation Antipsychotics: An Update and Comparison Between Agents

Schizophrenia is a chronic medical condition with periods of remission and relapses over a patient's lifetime. Antipsychotic medications represent the mainstay of treatment for this disease. Long-acting injectable (LAI) formulations of antipsychotics are an attractive alternative to their oral counterparts, as they enhance patient adherence. A number of second-generation antipsychotics (SGAs) are available in LAI formulations. These include paliperidone, aripiprazole, olanzapine, and risperidone. This article reviews the most recently developed and approved of these formulations-aripiprazole monohydrate, aripiprazole lauroxil, and paliperidone palmitate. While all were initially available as once-monthly formulations, a paliperidone palmitate 3-monthly injection formulation has been approved and is the first LAI agent to extend the dosing administration beyond the typical monthly time period. In addition, aripiprazole lauroxil every 6-week and 8-week administration preparations have been developed. LAI preparations of the SGAs have all demonstrated superiority over placebo and are comparable to their oral counterparts in terms of safety and tolerability, if injection site reactions are not taken into account. First-generation antipsychotic LAI preparations (e.g., haloperidol decanoate) have recently been compared with SGA LAI agents, and both formulations demonstrated comparable efficacy with the expected adverse events seen with each drug. Despite their availability, barriers to the use of LAIs remain. Education of both patients and clinicians on the use of LAI formulations and the continued development of these agents are important steps in ensuring these medications are available to the patients they would be most likely to benefit.

Converting oral to long-acting injectable antipsychotics: a guide for the perplexed

There has been increasing recognition that antipsychotic nonadherence is common across all stages of schizophrenia, starting from the first episode. Moreover, numerous meta-analyses of the existing literature indicate superiority of long-acting injectable (LAI) over oral antipsychotics when one adjusts for the greater illness severity and duration among patients in LAI antipsychotic trials. The increasing availability of LAI antipsychotic options has raised interest in converting patients from oral medication; however, the successful transition from oral to the comparable LAI antipsychotic requires an understanding of the current extent of antipsychotic exposure, the kinetics of the LAI preparation, and the expected plasma levels achieved by the LAI formulation. The purpose of this article is to provide, in a concise format, the essential information for converting patients to the LAI forms of haloperidol, fluphenazine, risperidone, paliperidone, olanzapine, and aripiprazole from the comparable oral medication, and how the use of plasma antipsychotic levels can be invaluable for this process.

The contribution of the in-vivo fate of an oil depot to drug absorption

Sustained release of lipophilic compounds can be achieved with oil depots. These parenteral formulations are generally injected in the vastus lateralis and deltoid muscle. It is known that the absorption rate differs between these two muscles. The reason for this is not fully understood. The aim of the current study was to investigate the fate of an oil depot in different tissues to elucidate whether the disappearance rate of oil is the cause of observed differences in absorption rate. A study with healthy volunteers was conducted to determine 1.0mL oil depots in the vastus lateralis and deltoid muscle for two weeks. The spatial distribution of the oil depots was determined using MRI. Additionally, a study in rats was conducted to microscopically examine the oil immediately and after 31days of injection. All rats were injected with a 0.1mL oil depot with and without benzyl alcohol (BOH), a commonly used excipient in oil depots. In humans, it was shown that all oil depots were equal in volume and surface area directly after injection. Moreover, the disappearance rate for all oil depots was similar; within one week there was no depot visible anymore by MRI. This in contrast to the depots in rats, which were still microscopically visible after 31days. It is concluded from these observations that the oil is dispersed to small droplets in the course of time. The resulting increase in surface area does not lead to an increase in absorption rate however. The results of this paper show that the variation in drug absorption as found for the two muscles is not caused by a distinction in surface areas or disappearance rates of the oil depots. Therefore, it is argued that the local tissue drainage (e.g. lymph flow) plays a considerable role in drug absorption from oil depots, whereby the lymph flow differs between the muscles.

Aripiprazole Lauroxil: Pharmacokinetic Profile of This Long-Acting Injectable Antipsychotic in Persons With Schizophrenia

BACKGROUND

Aripiprazole lauroxil is an extended-release prodrug of aripiprazole for intramuscular injection, approved for schizophrenia treatment. We developed a population pharmacokinetic (PopPK) model to characterize aripiprazole lauroxil PK and evaluate dosing scenarios likely to be encountered in clinical practice.

METHODS

Data from 616 patients with schizophrenia, collected from 5 clinical studies, were used to construct the PopPK model. The model was subsequently used to evaluate various dose levels and frequency and the impact of dosing delay on aripiprazole concentrations.

FINDINGS

The results of the model indicate that aripiprazole is released into the systemic circulation after 5 to 6 days, and release continues for an additional 36 days. The slow increase in aripiprazole concentration after injection necessitates the coadministration of oral aripiprazole for 21 days with the first injection. Based on the PopPK model simulations, a dosing interval of 882 mg every 6 weeks results in aripiprazole concentrations that fall within the concentration range associated with the efficacious aripiprazole lauroxil dose range (441-882 mg dosed monthly). A 662-mg monthly dose also resulted in aripiprazole concentrations within the efficacious dose range. Aripiprazole lauroxil administration results in prolonged exposure, such that dose delays of 2 to 4 weeks, depending on the dose regimen, do not require oral aripiprazole supplementation upon resumption of dosing.

CONCLUSIONS

This PopPK model and model-based simulations were effective means for evaluating aripiprazole lauroxil dosing regimens and management of missed doses. Such analyses play an important role in determining the use of this long-acting antipsychotic in clinical practice.

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.

Plasma Antipsychotic Drug Concentrations: Practical Clinical Considerations

The practical application of plasma antipsychotic moni toring to achieve dose optimization remains problematic. Despite numerous studies attempting to establish antipsychotic dosing guidelines based on target plasma concentration ranges, a therapeutic window for most neuroleptics remains elusive and drug individualiza tion is still most often empirically determined. Drug concentration testing for all antipsychotics is commercially available, but at present, only haloperidol and clozapine appear to provide clinically useful plasma values. Reasons for obtaining levels include suspected noncompliance, pharmacokinetic drug interactions, toxicity, and cases in which difficulty arises in distinguishing between drug-induced toxicity and underlying pathology. Accordingly, antipsychotic plasma concentration monitoring offers potential to improve therapeutic outcomes only when interpreted carefully in conjunction with the patient's overall clinical status. Copyright © 1996 by W.B. Saunders Company

Fundamental understanding of drug absorption from a parenteral oil depot

Oil depots are parenteral drug formulations meant for sustained release of lipophilic compounds. Until now, a comprehensive understanding of the mechanism of drug absorption from oil depots is lacking. The aim of this paper was to fill this gap. A clinical study with healthy volunteers was conducted. An oil depot with nandrolone decanoate and benzyl alcohol was subcutaneously administered in the upper arm of female volunteers. Pharmacokinetic profiles of both substances were related to each other and to literature data. Benzyl alcohol absorbs much more rapidly than nandrolone. In detail, it appears that benzyl alcohol enters the central compartment directly, while nandrolone decanoate is recovered in serum after a lag time. This lag time is also seen in literature data, although not reported explicitly. The absorption of nandrolone is enhanced by the presence of benzyl alcohol. This is most likely an effect of altered oil viscosity and partition coefficient between the oil and aqueous phase. The absorption rate constant of compounds is found to be related to the logP of the solubilized prodrug. The absorption rate is however not only determined by the physico-chemical properties of the formulation but also by the tissue properties. Here, it is argued that lymphatic flow must be considered as a relevant parameter.

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.

Understanding depot antipsychotics: an illustrated guide to kinetics

Long-acting injectable (LAI) antipsychotics can have considerable advantages over oral medications for the management of patients with schizophrenia. Despite the high prevalence of treatment nonadherence with oral pharmacotherapy, LAI antipsychotics are significantly underutilized in this patient population. The availability of newer LAI antipsychotic preparations combined with a resurgent interest in the use of typical antipsychotics has rekindled awareness of the value of LAI medications. This article is intended to provide a visual understanding of the various kinetic profiles of LAI antipsychotics to facilitate initiation and greater use of these agents.

Long-acting injectable aripiprazole: how might it fit in our tool box?

Schizophrenia is a severe mental illness with a lifetime prevalence of approximately one percent worldwide. Maintenance antipsychotic treatment has been effective in preventing relapses in long-term follow-up studies. Logically it can be proposed that long-acting injectable antipsychotics (LAI) might reduce both unintentional and intentional nonadherence. Long-acting injectable aripiprazole was approved for the treatment of schizophrenia by the U.S. FDA on 28th February 2013 and will be marketed under the name Abilify Maintena. Aripiprazole LAI (ALAI) is a lyophilized powder that needs to be reconstituted with sterile water to form an injectable suspension without affecting the original molecule. The monthly injection interval is very attractive since patients prefer fewer injections. From a tolerability perspective, ALAI appears to be both weight neutral and lacking metabolic side effects. This can confer an advantage over the other currently available second-generation antipsychotic LAIs. Simple constitution with sterile water and no requirement to refrigerate make storage and administration easier. Like all medications, there are always potential disadvantages to ALAI. There is a period of oral coverage, while not as long as for long-acting risperidone microspheres (RLAI), that is required. Care must be taken to review concomitant medications for the presence of metabolic inducers and inhibitors. One would also expect some patients to be sensitive to extrapyramidal symptoms, especially akathisia which is well documented in the oral preparation. All things considered, we welcome our new tool, ALAI, to our work-place and predict both clinical practice and post marketing analysis and studies will discover its true value.

Oral versus Long-Acting Injectable Antipsychotics in the Treatment of Schizophrenia and Special Populations at Risk for Treatment Nonadherence: A Systematic Review

Long-acting injectable antipsychotics (LAIs) should offer better efficacy and tolerability, compared to oral antipsychotics due to improved adherence and more stable pharmacokinetics. However, data on LAIs has been mixed, with some studies finding that they are more effective and tolerable than oral antipsychotics, and others finding the contrary. One possibility for the disparate results may be that some studies administered different antipsychotics in the oral and injectable form. The present systematic review examined the efficacy and tolerability of LAIs versus their oral equivalents in randomized and naturalistic studies. In addition, it examined the impact of LAIs on special populations such as patients with first-episode psychosis, substance use disorders, and a history of violence or on involuntary outpatient commitment. Randomized studies suggest that not all LAIs are the same; for example, long-acting risperidone may be associated with equal or less side effects than oral risperidone, whereas fluphenazine decanoate and enanthate may be associated with equal or more side effects than oral fluphenazine. They also suggest that LAIs reduce risk of relapse versus oral antipsychotics in schizophrenia outpatients when combined with quality psychosocial interventions. For their part, naturalistic studies point to a larger magnitude of benefit for LAIs, relative to their oral equivalents particularly among first-episode patients.

Dosing and switching strategies for paliperidone palmitate: based on population pharmacokinetic modelling and clinical trial data

Paliperidone palmitate is a second-generation, long-acting injectable (LAI) antipsychotic recently approved by the US FDA and European Medicines Agency for use in patients with schizophrenia. This article reviews the recommended dosing regimens for initiation and maintenance treatment with paliperidone palmitate in adult patients with schizophrenia. We also address issues of switching to paliperidone palmitate from other antipsychotics, managing missed doses and dosing in special patient populations. The dosing recommendations that were approved by the FDA and other regulatory agencies around the world are based on the results of population pharmacokinetic (PK) simulations and data from clinical trials that are presented in this review. A one-compartment disposition model with zero/first-order absorption best described the PK of paliperidone palmitate. Population PK models for extended-release paliperidone and long-acting risperidone were also developed and we report the results from these models. The PK profiles for 5000 patients were simulated after paliperidone palmitate injections. The population median and 90% prediction intervals of the simulated plasma concentration versus time profiles after multiple doses are graphically displayed in this review. Based on the data from model-based PK simulations, the approved recommended initiation regimen for paliperidone palmitate is 150 mg equivalent (mg eq.) paliperidone (paliperidone palmitate 234 mg) on day 1 followed by 100 mg eq. paliperidone (paliperidone palmitate 156 mg) on day 8, each administered into the deltoid muscle, using a 1-inch 23-gauge needle in those weighing <90 kg and a 1.5-inch 22-gauge needle in those weighing ≥90 kg. No oral supplementation is required. Monthly maintenance dosing is in the range of 25-150 mg eq. paliperidone (paliperidone palmitate 39-234 mg; recommended dose of 75 mg eq. paliperidone [paliperidone palmitate 117 mg]) injected into the deltoid (needle size is weight adjusted) or gluteal (using a 1.5-inch 22-gauge needle) muscle. The day 8 dose may be administered ±2 days and monthly doses ±7 days, without a clinically significant impact on plasma concentrations. The re-initiation schedule in patients whose last maintenance dose was >6 weeks previously is dependent upon the duration of time since the last paliperidone palmitate injection. In patients with mild renal impairment (creatinine clearance [CL(CR)]: 50-80 mL/min), dosage should be adjusted. No dose adjustment is required in patients with mild or moderate hepatic impairment; no data currently exist regarding severe hepatic impairment. Elderly patients with normal renal function should receive the same dosage as younger adult patients with normal renal function. In the event of an age-related decline in CL(CR), dosage should be adjusted accordingly. Paliperidone palmitate can be initiated the day after discontinuing previous oral antipsychotic treatment. In patients switching from other LAIs (including long-acting risperidone), paliperidone palmitate dosing should be initiated at the time of what would have been the next scheduled injection of the previous LAI, and continued monthly thereafter. In summary, following initiation dosing, paliperidone palmitate is administered on a monthly basis. It is the first of the second-generation antipsychotics to be available and approved with this dosing regimen. Population PK modelling presented in this review has helped provide practical guidance for administering this novel LAI antipsychotic.

Smoking and tardive dyskinesia in male patients with chronic schizophrenia

Interactions between smoking and movement disorders include the contrasting associations of more cigarette smoking with reductions in Parkinson's disease and increases in tardive dyskinesia (TD) symptoms. Here we examine the relationship between smoking and TD in a large sample of inpatients with schizophrenia. We used cross-sectional naturalistic methods to analyze the prevalence and severity of neuroleptic-induced TD in relation to cigarette smoking among 764 male chronic and medicated inpatients meeting DSM-IV criteria for schizophrenia. We administered a detailed questionnaire including general information, medical and psychological conditions, and smoking behaviors. We evaluated TD severity using the abnormal involuntary movement scale (AIMS) and psychopathology using the Positive and Negative Syndrome Scale (PANSS). The main statistical analyses used cross-tabulations for the prevalence of TD by smoking and multivariate regression analyses for continuous measures (AIMS and PANSS). We found that the prevalence of TD did not significantly differ between smokers (41%=237/578) and non-smokers (37%=69/186). Secondary outcomes showed a significant association between the AIMS total score and age, duration of illness and hospitalization times. Thus, smoking was not associated with TD in male Chinese schizophrenics, but consistent with previous reports, older patients with a longer duration of illness and more hospitalizations showed greater severity of TD.

Predictors of smoking severity in patients with schizophrenia and alcohol use disorders

The goal of the present study was to identify predictors of smoking severity in patients with schizophrenia and co-occurring alcohol use disorders (AUD). Our hypothesis was that negative symptoms of schizophrenia, severity of depression, male gender, drinking severity, and recreational drug use were associated with increased smoking. Clinical data, including demographic variables, alcohol and substance use severity, psychiatric medications, severity of depression, positive and negative symptoms of schizophrenia were analyzed in a cohort of 90 patients with schizophrenia or schizoaffective disorder and AUD. Eighty-eight percent of participants were smokers, they smoked an average of 15 cigarettes/day. Zero-inflated negative binomial (ZINB) regression analyses demonstrated that alcohol use severity, gender, and severity of negative symptoms were not predictive of the number of cigarettes smoked. Smoking severity was positively related to Caucasian race, psychosis severity (Positive and Negative Syndrome Scale [PANSS] general score), and medications (conventional antipsychotics). Subjects who used recreational drugs smoked less. In summary, severe, treatment resistant schizophrenia, and conventional antipsychotic treatment is associated with heavy smoking in patients with schizophrenia and AUD regardless of gender or alcohol use.

Long-acting injectable antipsychotics in the treatment of schizophrenia: their role in relapse prevention

IMPORTANCE OF THE FIELD

Antipsychotic medications are the cornerstone of treatment in schizophrenia, and a large body of data confirms the value of ongoing and continuous antipsychotic pharmacotherapy in controlling symptoms and preventing relapse. However, nonadherence with antipsychotic treatment is a significant issue, with estimates as high as 90%.

AREAS COVERED IN THIS REVIEW

This review focuses on long-acting injectable (LAI) antipsychotics and their role in the treatment of schizophrenia. The existing literature, with an emphasis on clinical evidence, is assessed. This includes both reviews and specific trials that examine LAIs and compare them with oral agents, with measures ranging from relapse and rehospitalization to adherence. Both advantages and limitations (e.g., challenges in terms of dose titration and time to steady state) are examined.

WHAT THE READER WILL GAIN

This overview serves as an update for clinicians wishing to understand LAIs better, including the newer second-generation antipsychotics (SGAs) with this formulation available, and their potential role in the long-term treatment of individuals with schizophrenia.

TAKE HOME MESSAGE

Despite identified advantages, LAIs are not used as widely as might be expected. It would seem that clinicians are at least partly responsible for this, influenced by our own misperceptions (e.g., that LAIs are not acceptable to patients) and, perhaps, misinformation (e.g., increased side effect risk). As clinicians, we may well be shortchanging LAIs if we position them as a treatment of last resort for the multi-episode, nonadherent, 'revolving door' patient, especially given recent evidence underscoring their potential benefits in first-episode patients. The search for new and more effective antipsychotics will continue, but we are reminded that suboptimal outcomes may have as much to do with nonadherence as inadequate treatments. Evidence has established that LAI antipsychotics demonstrate distinct benefits in this regard, and we would be remiss if we did not exploit this already available strategy. As well as additional research, we need to rethink how we position these agents in our treatment algorithms if we are to maximize their potential.

Prodrugs available on the Brazilian pharmaceutical market and their corresponding bioactivation pathways

The aim of this paper was to emphasize the importance of prodrug design to therapy, by examining examples available on the Brazilian pharmaceutical market. The principles of prodrug design are briefly discussed herein. Examples of prodrugs from many important therapeutic classes are shown and their advantages relative to the drugs they are derived from are also discussed. Considering the importance of these therapeutic classes, from both therapy and economic standpoints, prodrug design is a very valuable aspect in the research of new drugs and for the pharmaceutical industry as a whole.

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.

Adherence to treatment and therapeutic strategies in schizophrenic patients: the ADHERE study

AIM

To assess the degree of compliance and adherence to treatment during the follow-up of schizophrenic outpatients after a new therapeutic strategy had been initiated.

METHODS

A multicenter, retrospective, prospective, observational study of 1,848 outpatients with schizophrenia or schizoaffective disorders (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria) was conducted. Patients were treated either with oral or injectable conventional or second generation antipsychotics, and were followed up for 3 months at mental health centers. Patient compliance with the pharmacological treatment was assessed by the use of questionnaires, scales, medication accountability, and the Medication Event Monitoring System. Patients were considered compliant if they reported a high compliance rate (> or = 80%).

RESULTS

At baseline only 29% of patients on oral medication were compliant compared with 79% of patients on injectable medication (injection counting) (OR= 9.11; 95% CI 6.02-13.77; P<.0001). At the 3 month visit, 84% of patients had changed their treatment and in these, the compliance rate of those on injectable medication was 94% versus 87% of patients taking oral medication (OR= 2.47; 95% CI 1.21-5.05; P=.022).

CONCLUSION

The use of long-acting injectable antipsychotics, which improves compliance rates and patient follow-up, should facilitate the management of Spanish patients with schizophrenia in mental health centers.

Critical factors influencing the in vivo performance of long-acting lipophilic solutions--impact on in vitro release method design

Parenteral long-acting lipophilic solutions have been used for decades and might in the future be used in the design of depots with tailored delivery characteristics. The present review highlights major factors influencing the in vivo performance of lipophilic solutions. Furthermore, an account is given of the characteristics of employed in vitro release methods with a focus on the "state" of sink condition, the stirring conditions, and the oil-water interfacial area. Finally, the capability of in vitro release data to predict the in vivo performance of drug substances administrated in the form of lipophilic solutions is discussed. It is suggested that as long as the major rate-limiting in vivo release mechanism is governed by the drug partitioning between the oil vehicle and the tissue fluid, the use of in vitro release testing in quality control appears to be realistic. With increasing lipophilicity of the drug substances and longer duration of action, the in vivo drug release process may become more complex. As discussed, practical analytical problems together with the inability of release methods to mimic two or more concomitant in vivo events may constitute severe impediments for establishment of in vitro in vivo correlations.

Pharmacokinetics and efficacy of a direct switch from conventional depot to risperidone long-acting injection in Chinese patients with schizophrenic and schizoaffective disorders

AIMS

This 12-week open-label study was designed to investigate the pharmacokinetics and efficacy of a direct switch from a conventional depot to long-acting injectable risperidone in patients with schizophrenia and schizoaffective disorder.

METHODS

Men or women from 18 to 65 years old with a diagnosis of schizophrenia or schizoaffective disorder were eligible for participation if they had been treated with conventional depot for at least 8 weeks before study entry. Intramuscular long-acting risperidone was administered starting from 25 mg, with the dose flexibly adjusted every two weeks for 12 weeks from week 4.

RESULTS

Of the 25 patients enrolled in this study, 21 completed at least one post-baseline assessment and were thus included in the analysis. The mean serum concentration of risperidone plus 9-hydroxyrisperidone was 29.1 ng/mL at the 12th week after switching, with an average injection dose of 31.25 mg long-acting risperidone every two weeks. The levels of active moiety of risperidone seemed to be higher in Chinese patients compared to those in Caucasian patients. Positive and Negative Syndrome Scale total scores (from 67.5 to 56.4; P = 0.002), scores for negative symptoms (P = 0.006) and general symptoms (P = 0.001) were improved significantly 12 weeks after the switch. Mean Extrapyramidal Symptom Rating Scale scores were improved significantly from 20.1 to 5.5 (P < 0.001). Significantly decreased levels of cholesterol and triglyceride were found at the 12th week. The levels of fasting glucose, low-density lipoprotein, high-density lipoprotein and bodyweight remained unchanged.

CONCLUSIONS

These findings suggest that switching from conventional depot to long-acting risperidone is feasible with the advantage of symptom reduction and side-effect profile decrement.

Risperidone long-acting injection: a review of its long term safety and efficacy

A long-acting form of the second-generation antipsychotic drug risperidone is now broadly available for the treatment of schizophrenia and closely related psychiatric conditions. It combines the advantage of previously available depot formulations for first-generation drugs with the favorable characteristics of the modern "atypical" antipsychotics, namely higher efficacy in the treatment of the negative symptoms of schizophrenia and reduced motor disturbances. Published clinical studies show an objective clinical efficacy (as per psychiatric symptom scores and relapse data) that exceeds that of oral atypical antipsychotics when patients are switched to the long-acting injectable form, a low incidence of treatment-emergent extrapyramidal side effects, and very good acceptance by patients. Available data for maintenance treatment of bipolar disorder show equivalence with the oral form instead of superiority, but are still limited. As it seems likely that efficacy benefits are mostly due to the fact that the injectable form reduces the demand for patient compliance to one physician visit every 2 weeks instead of self-administration on a daily or twice-daily basis, additional potential could exist in other psychiatric disorders where atypical antipsychotic drugs are of benefit but where patient adherence to treatment schedules is typically low.

Serum concentrations of risperidone and 9-OH risperidone following intramuscular injection of long-acting risperidone compared with oral risperidone medication

OBJECTIVE

To compare serum concentrations of risperidone, 9-hydroxy (OH) risperidone and risperidone plus 9-OH risperidone, as well as the 9-OH risperidone/risperidone ratio in patients receiving depot and oral risperidone.

METHOD

Serum concentrations from 78 patients receiving three different doses of risperidone depot were measured and compared with serum concentrations from 82 patients taking three different doses of oral risperidone.

RESULTS

Patients receiving risperidone depot had significantly lower serum concentrations of risperidone plus 9-OH risperidone than patients taking oral risperidone. More interestingly, the 9-OH risperidone/risperidone ratio was also significantly lower in patients receiving risperidone depot than in patients taking oral risperidone.

CONCLUSION

Serum concentrations of risperidone plus 9-OH risperidone may be a rather poor indication of the antipsychotic efficacy of risperidone unless their ratio is also considered.

The "inverted cup" -- a novel in vitro release technique for drugs in lipid formulations

The aim of this study was to develop a membrane-free in vitro release method for drugs in lipid formulations. It was intended to be applicable to as wide a range as possible of preparations, independently of their polarity and viscosity. The principle of the novel technique is to keep the sample suspended in the release medium in an inverted glass cup, allowing a possible phase transition or swelling. Thirteen formulations containing bupivacaine, lidocaine and/or prilocaine in lipid vehicles with different physical properties were prepared and examined. When possible, in vitro release profiles obtained by the new method were compared to profiles obtained by earlier techniques. For three formulations of either bupivacaine or lidocaine in polar lipid formulations, in vitro release profiles were evaluated in relation to in vivo data, from nerve block and pharmacokinetic studies in rats. Preparations that could be investigated both by the "inverted cup" and by the earlier published "single drop" technique generally showed good agreement between the two release profiles. In the case of the polar lipid formulations, arterial blood concentration curves in rats could reasonably be predicted from the in vitro release profiles. In conclusion, the "inverted cup" technique should potentially be applicable to a wide range of lipid formulations of drugs, both for physico-chemical characterisation and for obtaining in vitro -- in vivo correlations.

Therapeutic drug monitoring of patients on risperidone depot

Risperidone depot is the first long-acting atypical antipsychotic to be registered in Norway. The combination of antipsychotic efficacy for negative symptoms, reduction of adverse effects and assured delivery of medication is expected to improve patient compliance and thus reduce the rate of hospitalization. Nevertheless, clinicians have reported that risperidone depot has shown poor antipsychotic response in a number of patients. We therefore performed a retrospective, naturalistic study in search of a pharmacokinetic explanation for this reported lack of response. The study is based on data from therapeutic drug monitoring (TDM) of 46 patients on risperidone depot and 50 patients on oral risperidone. There was a significantly lower mean total serum drug level of risperidone and its active metabolite 9-OH risperidone among patients receiving standard doses of risperidone depot (25-50 mg/14 days) compared with patients on oral risperidone (2-6 mg/day). About 25% of patients receiving risperidone depot showed total serum drug levels below established reference range (30-120 nmol/l), even when steady state was presumed. In contrast, only 6% of patients on oral risperidone had a total serum drug level under this reference range. There was a wide range in total serum drug levels among patients in both groups. Explanations for these findings may be skewed selection of patients, flaws in the injection procedure, or unpredictable absorption of the active moiety from injection site. There is, however, only a presumed relationship between serum drug level and antipsychotic efficacy for risperidone.

Survey of reference ranges and clinical measurements for psychoactive drugs in serum

Thirty-three members of the United Kingdom National External Quality Assessment Scheme for measurement of psychoactive drugs in serum responded to a questionnaire concerning 31 tricyclic, antipsychotic, and selective serotonin re-uptake inhibitor drugs. Considerable variation was found between laboratories in their reference ranges and in the observed range of measured drug concentrations in clinical samples. For the lower end of the reference range, the median ratio between the highest and lowest values reported was 6.8, while for the top end of the range, the median ratio was 3.6. Observed clinical values were significantly less than reference range values at the lower end of the range and significantly higher at upper-range values by median values of -57% and +47%, respectively. The median ratio between maximum and minimum measurements reported by laboratories was 10.0 for both the lowest non-zero measurements and the highest non-toxicological concentrations. The variation in clinical range values did not differ significantly from that in reference range values. The ratios take no account of local variation in patient groups and treatment regimens.

Modification of in vitro drug release rate from oily parenteral depots using a formulation approach

Rate constants for transfer of naproxen and lidocaine from different oils and oil mixtures to aqueous buffer, pH 6.00, were determined using the rotating dialysis cell. Significantly different first-order rate constants related to attainment of equilibrium, k(obs), were derived depending on the type of oil/oil mixtures used in the release experiments. For the drugs a linear correlation was found between logk(obs) and the logarithm of the partition coefficient P(app): logk(obs)=-0.68 logP(app)-0.25 (k(obs) in h(-1), n=26). A linear relationship was observed between the calculated and experimentally determined P(app) values for the oil mixtures investigated. The specific rate constants, k(ow) and k(wo), related to the partition process were derived from the determined k(obs) and P(app) values. The rate constant k(ow) representing the rate of transfer of the solute from the oil phase to the aqueous buffer was shown to be strongly dependent on the partition coefficient according to the relationship: logk(ow)=-0.68 logP(app)-log(P(app)+1)-0.25 (k(ow) in h(-1), n=26). In particular, diminished release rates were seen for oil mixtures containing castor oil most likely afforded by hydrogen bonding between the solute and the hydroxy groups of the latter vegetable oil. In this study it has been possible to alter P(app) for a specific compound up to a factor of 10 by variation of the composition of the oil vehicle. Such a span of P(app) values results in in vitro release rates differing a factor of 37. Thus, by proper design of the oil vehicle composition it should be possible to modify the release rate for a specific compound within certain limits.

Sensitive method for the simultaneous measurement of fluphenazine decanoate and fluphenazine in plasma by high-performance liquid chromatography with coulometric detection

A highly sensitive and specific high-performance liquid chromatographic method with coulometric detection was developed for the simultaneous assay of fluphenazine decanoate and fluphenazine in plasma. The extraction and sample clean-up procedures are simple, rapid to execute, yet yield chromatograms relatively free of any interference from endogenous plasma constituents, such that the extraordinary sensitivity of the coulometric detector can be exploited fully. This is the first analytical procedure for the simultaneous determination of fluphenazine decanoate and fluphenazine. The detection limits for both fluphenazine decanoate and fluphenazine were 0.1 ng/ml plasma and the limits of quantitation were 0.25 ng/ml plasma. Standard curves from 0.25 to 10 ng/ml were linear with coefficients of variation < 10%. The method was applied to measure plasma levels of fluphenazine decanoate and fluphenazine in patients under medication with 25-50 mg biweekly intramuscular (i.m.) injections of fluphenazine decanoate. It was possible to monitor the plasma levels of fluphenazine in all cases. Fluphenazine decanoate was present in measurable concentration in the plasma of 4 out of 5 patients who received biweekly i.m. injections of 50 mg fluphenazine decanoate. In a pilot experiment with a dog, the method was used to follow fluphenazine decanoate and fluphenazine plasma levels up to 13 days, at least, after i.m. single dose (10 mg/kg).

Imaging of dopamine receptors with [123I]iodobenzamide single-photon emission-computed tomography in neuroleptic malignant syndrome

With the tracer [123I]iodobenzamide ([123I]-IBZM), it is possible to image dopamine receptor occupancy with single-photon emission-computed tomography (SPECT). We report follow-up examinations with IBZM-SPECT in neuroleptic malignant syndrome (NMS) to display D2-receptor availability in the acute phase and during the course of remission. A 27-year-old man was admitted with severe akinesia, rigor, tachycardia, fever, and elevated creatine phosphokinase level (CK) after neuroleptic medication. NMS was diagnosed, and treatment was started with dantrolene, amantadine, and dopamine agonists. IBZM-SPECT examination was performed on days 6, 34, 90, 107, 131, and 201. In the acute state of NMS, there was no binding of IBZM to D2-receptors. SPECT reached almost normal values on day 131, but clinical examination still showed a mild parkinsonian syndrome. With SPECT, the D2-receptor occupancy in NMS could be successfully shown in correlation with extrapyramidal signs. IBZM-SPECT may therefore serve to monitor D2-receptor occupancy in patients at risk for NMS.

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.

Severe rhinorrhea and respiratory distress in a neonate exposed to fluphenazine hydrochloride prenatally

OBJECTIVE

To report a case of respiratory distress with severe rhinorrhea in a newborn exposed prenatally to fluphenazine hydrochloride.

CASE SUMMARY

The safety of phenothiazines during pregnancy and the effect on the fetus and newborn are not well known. We describe a newborn who had severe rhinorrhea, vomiting, and respiratory distress after being exposed in utero to fluphenazine hydrochloride. Sepsis, choanal atresia, and congenital syphilis were excluded as causative factors for rhinorrhea. The rhinorrhea and upper airway obstruction responded to treatment with pseudoephedrine.

CONCLUSIONS

Severe rhinorrhea, vomiting, and respiratory distress that occurred in this infant have not been reported previously following prenatal fluphenazine hydrochloride exposure. Awareness of this problem would be helpful to clinicians and should be considered in the differential diagnosis of rhinorrhea in newborns.

Monitoring plasma levels of fluphenazine during chronic therapy with fluphenazine decanoate

This study was conducted to examine the interpatient variability in steady-state plasma concentrations of fluphenazine by repeat depot intramuscular administration, and to determine the relationship between these concentrations and clinical state. Steady-state pre-dose concentrations of fluphenazine in plasma were measured using a sensitive and specific gas chromatography/mass spectrometry (GC/MS) assay in 24 patients with schizophrenia who were receiving continuous treatment with depot intramuscular fluphenazine decanoate. Clinical response was measured using the Andreasen Scale for positive and negative symptoms. Steady-state plasma concentrations of fluphenazine ranged from undetectable (< 0.1 ng/ml) to 27.9 ng/ml, with a median of 0.5 ng/ml. No significant associations were found between plasma concentration and dosage, or age and sex of the patient. Steady-state plasma concentrations in patients taking anticholinergic agents were significantly higher than in patients not receiving such drugs (P < 0.05 by Mann-Whitney U-test). Poorer control, expressed as the sum of the negative symptom scores or the sum of the positive and negative symptom scores, was related to higher log transformed plasma concentration of fluphenazine and higher fluphenazine decanoate dosage. The log transformed plasma concentrations of fluphenazine and the fluphenazine decanoate dosages were weakly related. Patients receiving another antipsychotic drug in addition to fluphenazine decanoate tended to have poorer clinical control and higher dosages of fluphenazine decanoate. These results indicate the useful role that plasma level monitoring can fulfil in identifying patients who are therapy-resistant despite high plasma levels.

Neuroleptic-induced vacuous chewing movements in rodents: incidence and effects of long-term increases in haloperidol dose

Rats treated chronically with neuroleptics develop vacuous chewing movements (VCMs), similar in some respects to tardive dyskinesia (TD) in man. The VCM syndrome was used as a model of TD to examine the ability of increased neuroleptic doses to produce long-term suppression of dyskinetic movements. The incidence and persistence of the VCM syndrome in individual rats were also assessed to look for affected and unaffected subgroups. Rats were initially treated for 15 weeks and haloperidol decanoate. For the next 21 weeks, half the group received a 50-150% increase in dose while the other half continued to receive the same dose. Animals were also followed during a 28-week withdrawal period. Total VCM ratings showed a skewed distribution, with some rats exhibiting few movements while others developed marked and persistent movements. Increasing doses did not suppress VCMs, nor did they exacerbate movements during the withdrawal period. To the extent that the VCM syndrome models TD, the absence of long-term suppression of the VCM syndrome suggests that, at this dosage range, increasing depot neuroleptic doses may not be a useful long-term strategy for TD suppression.

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.

Factors affecting rehospitalisation rates of chronic schizophrenic patients living in the community

Eighty-eight [corrected] patients selected from a depot neuroleptic clinic in the hospital outpatients department were assessed clinically on various demographic and clinical variables with a view to determining the factors that may contribute to high rates of rehospitalisation amongst schizophrenics in remission. It was found that rehospitalisation rates during the preceding 5 years correlated with an early age of onset of illness, severity of positive and affective symptoms, current neuroleptic dose and total AIMS score, all reflecting the severity of underlying psychotic disorder and the neuroleptic treatment required to treat the psychosis. Poor compliance with neuroleptic prophylaxis was not found to be of importance in contributing to high relapse rates in this sample. It was concluded that patients who repeatedly relapse may do so because of the clinical characteristics of their illness.

Clinical pharmacokinetics of antipsychotics

The antipsychotics are a chemically diverse group of heterocyclic compounds, which ameliorate many symptoms of schizophrenia. Most of the antipsychotics are very lipophilic and cross lipoidal membranes freely. When administered orally, they are well absorbed and undergo substantial pre-systemic elimination (bioavailability: 10-70%), are highly bound to plasma proteins (75-99%) and tissues, and are extensively distributed (VD: 100-1000 L). Primary route of elimination for most of antipsychotics is hepatic metabolism and biotransformation produces active metabolites. There is no linear relationship between the concentration of parent compound and different metabolites, and clinical relevance of pharmacologically active metabolites is not well understood. There are wide interindividual variabilities in pharmacokinetics, which result in large differences in steady-state plasma concentrations on the same dose regimen. The existence of optimal therapeutic ranges for most antipsychotics remains controversial. One of the major problems is the lack of well-designed studies that involve sufficient numbers of patients to clearly establish a therapeutic range for these drugs and is further complicated by the presence of a large number of pharmacologically active metabolites. However, the pronounced interindividual kinetic variabilities, combined with problems of noncompliance and drug interactions, and the delayed onset of clinical response in relation to initiation of treatment with antipsychotics are reasons why drug monitoring in conjunction with clinical status of the patient can be useful. Indications for antipsychotic drug monitoring include lack of response, non-compliance, toxicity, and drug interactions when other drugs are coadministered.

Dosaging patterns in schizophrenia with depot, oral and combined neuroleptic therapy

A group of patients with chronic schizophrenia were evaluated according to the form of neuroleptic treatment they were receiving: depot, oral or combined (depot/oral or oral/oral). The patients treated with the combined therapy received significantly higher dosages of neuroleptic than those treated with either depot or oral therapy, which did not differ from each other. Daily maintenance dosages were generally well above recent guidelines.

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.

Rationalizing neuroleptic polypharmacy in chronic schizophrenics: effects of changing to a single depot preparation

This study investigated the effects of transferring patients on combined depot and oral neuroleptics to a single depot preparation; a secondary objective was to assess the effects of transferring patients from one depot neuroleptic to another. It was found that, whereas transferring from one depot preparation (flupenthixol) to another (fluphenazine) had no clear disadvantage for the patients, changing over from a combined oral and depot (fluphenazine) regimen to equivalent doses of depot alone resulted in an unacceptably high rate of relapse. The reasons for this may relate to either the unique pharmacokinetics of these drugs or subtle qualitative differences between them. It is suggested that caution is necessary whenever attempts are made to rationalize polypharmacy in schizophrenic patients.