Successful treatment with olanzapine and aripiprazole of a schizophrenic patient who developed priapism after switching from risperidone to paliperidone.

BACKGROUND: Ischemic priapism is a rare pathological condition, and delayed intervention can result in irreversible sequelae. Most cases are attributed to the use of antipsychotics. The blockade of α1-adrenergic receptors is thought to be associated with the disease onset, although data supporting this hypothesis are lacking. No consensus regarding the optimal choice of medication is available. CASE PRESENTATION: A 59-year-old man with schizophrenia, who had been receiving long-acting injections of risperidone, developed ischemic priapism after receiving paliperidone treatment. Following improvement in ischemic priapism, we administered a combination of aripiprazole and olanzapine, which improved his psychiatric symptoms. We did not observe any recurrence of ischemic priapism. CONCLUSIONS: Switching the antipsychotic drug causing ischemic priapism to patients having a relatively low affinity for α1-adrenergic receptors may enable the treatment of schizophrenia without recurrence of ischemic priapism. In addition to the affinity for α1-adrenergic receptor, differences in metabolic enzyme types and antipsychotic doses may be involved in the occurrence of ischemic priapism. Accumulating evidence is necessary to establish guidelines for selecting medication of patients with ischemic priapism.

Combining ion-pair strategy and percutaneous permeation enhancers to develop sustained-release paliperidone patch.

In this study, a sustained-release paliperidone (PAL) patch was developed using a combination of ion-pair strategy and percutaneous permeation enhancers (PPEs). The ion-pair strategy was used to improve drug-adhesive miscibility and control drug release. PPEs were used to break SC barrier function to facilitate drug skin permeation. The in vitro skin permeation experiments using single-factor experiments and Box-Behnken design gave the optimized formulation, a 55 µm adhesive thickness patch with 7 % (w/w) PAL-LA (Lauric acid), 9.7 % (w/w) Plurol® Oleique CC 497 (POCC). Moreover, the pharmacokinetic study confirmed its potential in sustained-release transdermal patch with longer MRT0-t (18.35 ± 3.11 h) and higher BA (63.14 %) than the gavage group (Cmax = 6.64 ± 2.61 µg/mL, MRT0-t = 2.88 ± 1.06 h, BA = 45.70 %) without significant increasing Cmax. The mechanism study revealed that forming ion-pairs effectively modulated drug's physicochemical properties and doubly ionic H-bond strength to improve drug miscibility in patches. To summarize, a sustained-release patch of PAL was successfully developed, which provided a strategy for sustained-release patches with good drug-polymer miscibility, drug controlled-release, and feasible drug utilization features.

Drug-induced hyponatraemia and possible related signals: Analysis of 659 cases reported to the Spanish Pharmacovigilance System and disproportionality analysis.

INTRODUCTION: Hyponatraemia has negative effects on cognitive function and gait stability and is a risk factor for osteoporosis, falls, fractures and hospital mortality. Acute hyponatraemia can lead to neurological dysfunction due to cerebral oedema. Its rapid correction can also be fatal, leading to osmotic demyelination syndrome. For some antiepileptics, thiazides, benzodiazepines or antidepressants this reaction is widely described. Knowing which drugs are most likely to cause hyponatraemia will allow early detection and prevention of its complications, as well as individualising the prescription of these drugs according to the patient's characteristics. OBJECTIVE: The main objectives are to identify potential new safety signals related to hyponatraemia and to analyse the cases of hyponatraemia reported to the Spanish Pharmacovigilance System for Medicines for Human Use (SEFV-H). METHOD: A disproportionality and a descriptive analysis of individual case safety reports (ICSR) was performed in the SEFV-H database (FEDRA). RESULTS: Six hundred and fifty-nine cases of suspected drug-induced hyponatraemia were found (0.6% of the total database). Over the 5 years period studied, there was a 57% increase in the number of hyponatraemia reports in Spain. Most of the reported cases were serious (93%). Patients were most often women (63.7%) and elderly (71.9%). The time to onset ranged from 1 to 7030 days (median, 79 days) and approximately 70% of the total occurred within the first year of treatment. Five hundred and forty-six patients (82.9%) showed complete recovery after the withdrawal of the suspected medicine. Diuretics (reported in 57.7% of the cases), antidepressants (in 25%), drugs acting on renin angiotensin system (in 24%) and antiepileptics (in 20.2%) were the most frequent involved drugs. Disproportionate reporting has been found for almost all the substances most frequently reported, higher for amiloride and oxcarbazepine. Regarding new safety signals, the Reporting Odds Ratio (ROR) (95% CI) was found to be statistically significant for valsartan [7.7 (5.1-11.5)], olmesartan [7.3 (4.7-11.1)], amlodipine [3.4 (2.1-5.4)], pregabalin [2.5 (1.4-4.5)], irbesartan [18.6 (9.6-35.9)], paliperidone [2.7 (1.3-5.7)], ritonavir [2.4 (1.1-5.5)], atosiban [29.7 (8.6-102.2)], melphalan [9.7 (3.5-26.8)] and clozapine [4.4 (1.6-11.8)]. These active ingredients do not include this reaction on their SPC and comply with the EMA criteria for a safety signals. CONCLUSION: There are increasing reports of drug-induced hyponatraemia. It can be serious and seems to most often affect women over 65 years of age who take more than 1 medication. The time to onset varies and can be very long, so patient monitoring should be continuous throughout treatment. Hydrochlorothiazide is the drug with the highest number of reported cases in our setting. In terms of disproportionate reporting, diuretics leads the list, followed by antiepileptics as oxcarbazepine and eslicarbazepine. Safety signals were found for several drugs, more plausibly for pregabalin and paliperidone, thus a possible association between these drugs and hyponatraemia/SIAD is identified. This signal must be further studied. Meanwhile healthcare professionals should pay attention to this possibility. The reporting of suspected ADRs is essential to understand the risks associated with medicines once they are on the market.

Health-Care Utilisation and Costs of Transition from Paliperidone Palmitate 1-Monthly to 3-Monthly Treatment for Schizophrenia: A Real-World, Retrospective, 24-Month Mirror-Image Study.

Introduction: Poor adherence to antipsychotics in patients with schizophrenia is a leading cause of relapse and functional deterioration. Long-acting injectable paliperidone may reduce relapse risks, health-care utilisation, and health-care costs in these patients. Methods: In this 24-month mirror-image study, we compared health-care utilization and costs before and after the initiation of paliperidone palmitate 3-monthly (PP3M) treatment in patients with schizophrenia spectrum disorders. Before the initiation of PP3M, the patients received paliperidone 1-monthly (PP1M) treatment. The primary study outcomes were changes in health-care utilisation and costs over the study period. Results: This study included 34 patients with schizophrenia spectrum disorders. During the 12-months period after the initiation of PP3M treatment, the mean duration of hospitalisation decreased from 57.7 to 28.5 days (p = 0.03). Moreover, significant reductions were noted in emergency room visits (PP1M vs PP3M: 0.3 vs 0.0, respectively; p = 0.05) and health-care costs (PP1M vs PP3M: 107,328.8 vs 57,848.6, respectively; p = 0.03). Conclusion: PP3M may significantly reduce hospitalisation duration, emergency room visits, and health-care costs in patients with schizophrenia.

Clinical effectiveness of paliperidone palmitate 3-monthly and 1-monthly as monotherapy in patients with schizophrenia: A retrospective cohort study based on the Medicaid claims database.

AIM: Real-world data (RWD) for paliperidone palmitate (PP) three-monthly (PP3M) is lacking based on Japan label requirements. This study evaluated the clinical effectiveness of PP3M versus PP once-monthly (PP1M) in patients with schizophrenia administered according to Japan label requirements. METHODS: Retrospective analyses were conducted using RWD from Merative™ MarketScan® Multi-State Medicaid (MDCD) claims database (June 2015-December 2022). Adult patients with schizophrenia switching from PP1M to PP3M were included. Patients transitioning to PP3M were matched with patients who continued with PP1M using propensity score matching (PSM) at 1:1 ratio. Primary hypothesis aimed to investigate non-inferiority of PP3M versus PP1M in terms of relapse-free status at 24 months from index PP injection. Outcome measures were proportions of relapse-free patients at 24 months, time to relapse, treatment persistence, and adherence. RESULTS: Total 4252 eligible adult schizophrenia patients on PP (PP3M:582; PP1M:3670) were identified. After PSM, each PP cohort comprised 562 matched individuals. Estimated proportion of relapse-free patients was higher in PP3M (85.7%) versus PP1M (77.9%), per Japan PP label. PP3M demonstrated superiority to PP1M after testing for non-inferiority in terms of achieving relapse-free status at 24 months, with an estimated difference of 7.8% (95% CI: 1.7%-13.9%). PP3M cohort had lower risk of relapse (HR: 0.605; CI: 0.427-0.856), longer treatment persistence, and higher treatment adherence versus PP1M cohort. CONCLUSIONS: Findings suggests that patients who switched to PP3M might be able to reduce risk of relapse compared to those who continued PP1M after aligning particularly with Japan's label requirements.

Transformative Outcomes With Paliperidone Long-Acting Injection in Severe Treatment-Resistant Schizophrenia: A Case Report and Literature Review.

Treatment-resistant schizophrenia (TRS) presents considerable challenges in contemporary psychiatric practice due to inadequate response to conventional antipsychotic treatments. Paliperidone, the primary active metabolite of risperidone, particularly in its long-acting injectable (LAI) form, has emerged as a promising option for TRS due to its consistent medication delivery, reducing symptom exacerbation and relapse associated with oral dosing fluctuations. This case report presents the clinical journey of a 42-year-old female diagnosed with schizophrenia at age 15. Despite numerous hospital admissions and trials of various oral and injectable antipsychotics, including clozapine and electroconvulsive therapy (ECT), her symptoms persisted. During her last admission, her condition showed minimal improvement despite extensive pharmacological interventions. Introducing paliperidone LAI while tapering off other antipsychotics led to significant improvements within four weeks. The patient exhibited reduced hallucinatory behaviour, delusions, and disorganized behaviour. Follow-up assessments confirmed sustained progress, with the patient showing increased engagement in daily activities and reduced irritability and suspiciousness. This case underscores the potential efficacy of paliperidone LAI in managing TRS. The patient's notable improvement highlights the importance of personalized treatment plans and continuous monitoring in complex psychiatric conditions. Its favourable safety and tolerability profile further supports its use as a long-term treatment option for TRS, potentially leading to enhanced patient compliance and overall quality of life. The significant symptomatic relief and functional improvement observed advocate for the consideration of paliperidone LAI as a promising therapeutic option for TRS, with the potential to be considered in the future among the first-line treatments for TRS.

Healthcare utilization and economics evaluation of paliperidone palmitate once-monthly in schizophrenia: a one-year, real-world, and retrospective mirror image study in China.

Background: Investigation and analysis of the changes in healthcare resources and burden of schizophrenia in the real world before and after switching from oral antipsychotics (OAPs) to paliperidone palmitate once-monthly (PP1M) could provide evidence to clinicians and patients for choosing treatment modality and data support for health policy optimization. Methods: The first dosage of PP1M was set as mirror point, and patients with mirror point between January 2020 and June 2022 were recruited in the study. The differences in treatment patterns, healthcare resource utilization, and costs within one year before and after the mirror point were compared. Results: A total of 72 patients transitioning from OAPs to PP1M (mean age, 35.33 years; 43.06% female) were included in the study. Of the 72 patients, the application of PP1M resulted in a significant reduction in the hospitalization times, emergency room visits, and direct medical costs (P < 0.001), while the pharmacy cost and total cost increased by 222.57% (P < 0.001) and 16.35% (P < 0.001), respectively; PP1M accounted for 88.48% of the pharmacy cost. For patients with ≥1 hospitalization during the OAPs phase (n = 25), the number of hospitalizations, hospitalization days and hospitalization expenses decreased by more than 90% (P < 0.001). Total one-year expenses decreased by 37.67% (P < 0.001), and pharmacy expenses increased by 185.21% (P < 0.001). For patients with no hospitalizations during the OAPs phase (n = 47), emergency and outpatient visits decreased by 70% (P < 0.001) and 30.27% (P < 0.05), respectively, while the total cost increased by 117.56% (P < 0.001), and the pharmacy cost increased by 260.15% (P < 0.001) after initiation of PP1M treatment. Conclusion: After the transition to PP1M, the number of hospitalizations and outpatient and emergency department visits reduced, and healthcare resources were conserved. Switching to PP1M may be more economically beneficial for patients with prior hospitalizations while on OAP regimens. The high price of PP1M might be an obstacle to its widespread use.

Novel long-acting treatment for schizophrenia based on paliperidone dissolving and implantable microarray patches.

Schizophrenia is a severe mental disorder that affects millions of people worldwide. Several atypical antipsychotic medications, including paliperidone (PPD), has been developed and proven effective in treating it. To date, four PPD extended-release products have been launched commercially, providing up to six months of therapeutic effect with a single administration. However, the need for hospital injections by professional healthcare workers not only lead to poor patients' adherence, but also put additional pressure on the healthcare system. Therefore, three PPD microarray patch (PPD MAP) systems based on dissolving microneedle technology and implantable microneedle technology were developed in this work. The two dissolving microarray patch systems contained either PPD crude drug (PPD DMAP-CD) or PPD nanocrystal (PPD DMAP-NC) and the implantable MAP contained PPD crude drug (PPD IMAP). All three types of PPD MAPs showed excellent mechanical and insertion properties as they achieved over 256 µm insertion depth in skin model. In vitro release study showed that PPD released from IMAP in a much more sustained manner (up to 14 days) than PPD did from DMAPs (7 days), with only 20 % initial burst release from IMAP compared with 43-71 % from DMAPs. The MAP dissolution study showed that both DMAPs can be immediately dissolved within less than 3 min once inserted into the skin, indicating a faster action potential compared with IMAP. Ex vivo delivery study showed that 1.68 ± 0.23 mg, 1.39 ± 0.07 mg, and 1.18 ± 0.12 mg were delivered from DMAP-CD, DMAP-NC and IMAP, respectively, demonstrating that over 50 % and up to 70 % of PPD in the MAPs can be delivered into the skin. The IMAP offers most sustained release of PPD whereas DMAP-NC exhibits fastest PPD release (11.19 % vs 20.01 % into Franz cell receiver compartment over 24 h). This work presents a promising alternative for the sustained delivery of antipsychotic drugs, allowing for patient self-administration and extended release concurrently. Patients may potentially use both DMAP and IMAP to achieve a sustained release of PPD while also avoid having an initial therapeutic lag.

Long-term stability of five atypical antipsychotics (risperidone, olanzapine, paliperidone, clozapine, quetiapine) and the antidepressant mirtazapine in human serum assessed by a validated SPE LC-MS/MS method.

Long-term sample stability of five atypical antipsychoticdrugs risperidone, paliperidone, clozapine, quetiapine and olanzapine and the antidepressant drug mirtazapine in serum was studied by use of a newly developed and validated analytical method based on solid-phase extraction and liquid chromatography-tandem mass spectrometry. Ascorbic acid was used as an antioxidative agent to stabilize olanzapine during storage and sample preparation. We assessed analyte stability on long-term storage in serum samples at 25°C, 5°C, -20°C and -80°C, and during five freeze-thaw cycles. Analytes were stable for 23 days at room temperature except for olanzapine and mirtazapine (17 days). All analytes were stable for at least 30 days at 5°C. All analytes were stable for 270 days at -20°C, except for paliperidone and mirtazapine with 60 days and 180 days, respectively. All analytes were stable for 270 days at -80°C. Furthermore, all analytes were stable for five freeze-thaw cycles. We recommend storage at -80°C when samples drawn for analysis of antipsychotic drugs are stored for more than 60 days, whereas a temperature of -20°C is sufficient for storage less than 60 days.

A Bayesian framework for virtual comparative trials and bioequivalence assessments.

Introduction: In virtual bioequivalence (VBE) assessments, pharmacokinetic models informed with in vitro data and verified with small clinical trials' data are used to simulate otherwise unfeasibly large trials. Simulated VBE trials are assessed in a frequentist framework as if they were real despite the unlimited number of virtual subjects they can use. This may adequately control consumer risk but imposes unnecessary risks on producers. We propose a fully Bayesian model-integrated VBE assessment framework that circumvents these limitations. Methods: We illustrate our approach with a case study on a hypothetical paliperidone palmitate (PP) generic long-acting injectable suspension formulation using a validated population pharmacokinetic model published for the reference formulation. BE testing, study power, type I and type II error analyses or their Bayesian equivalents, and safe-space analyses are demonstrated. Results: The fully Bayesian workflow is more precise than the frequentist workflow. Decisions about bioequivalence and safe space analyses in the two workflows can differ markedly because the Bayesian analyses are more accurate. Discussion: A Bayesian framework can adequately control consumer risk and minimize producer risk . It rewards data gathering and model integration to make the best use of prior information. The frequentist approach is less precise but faster to compute, and it can still be used as a first step to narrow down the parameter space to explore in safe-space analyses.

Anismus-A Very Unusual Extrapyramidal Side Effect of Paliperidone Palmitate in an Adolescent with Schizo-Affective Disorder.

Here, authors report on an interesting case of an adolescent with a diagnosis of schizo-affective disorder, maintained on LAI paliperidone palmitate that developed an unusual dystonic reaction in form of anismus that masquerade as constipation and faecal impaction. To our knowledge, this is one of the earliest reports of antipsychotic-induced anismus notably in adolescent population. Clinicians should be mindful of unusual forms of dyskinesias that might be associated with high-potency antipsychotic use.

Assessing the Clinical Efficacy of Therapeutic Drug Monitoring for Risperidone and Paliperidone in Patients with Schizophrenia: Insights from a Clinical Data Warehouse.

This study investigated the usage patterns and impact of therapeutic drug monitoring (TDM) for risperidone and paliperidone in patients diagnosed with schizophrenia, utilizing retrospective real-world data sourced from a single center's Clinical Data Warehouse. Our study cohort comprised patients diagnosed with schizophrenia undergoing treatment with either risperidone or paliperidone. Data on demographic characteristics, comorbidities, medication utilization, and clinical outcomes were collected. Patients were categorized into two groups: those undergoing TDM and those not undergoing TDM. Additionally, within the TDM group, patients were further stratified based on their risperidone and paliperidone concentrations relative to the reference range. The findings revealed that patients in the TDM group received higher risperidone and paliperidone doses (320 mg/day and 252 mg/day, p = 0.0045) compared to their non-TDM counterparts. Nevertheless, no significant disparities were observed in hospitalization rates, duration of hospital stays, or compliance between the two groups (p = 0.9082, 0.5861, 0.7516, respectively). Subgroup analysis within the TDM cohort exhibited no notable distinctions in clinical outcomes between patients with concentrations within or surpassing the reference range. Despite the possibility of a selection bias in assigning patients to the groups, this study provides a comprehensive analysis of TDM utilization and its ramifications on schizophrenia treatment outcomes.

Protective Effect of Hyperprolactinemia on Oxidative Stress in Patients with Psychotic Disorder on Atypical Antipsychotics Risperidone and Paliperidone: A Cross-Sectional Study.

Several studies indicate the impact of antipsychotics like risperidone and paliperidone on oxidative stress parameters, yet data remain inconsistent. We investigated the link between these medications, hyperprolactinemia (HPRL), and oxidative stress. This study was conducted at the Psychiatry Clinic, University Clinical Center, Kragujevac, between November 2022 and August 2023. Inclusion criteria comprised diagnosed psychotic disorders from the ICD-10-based F20-F29 spectrum and clinical stability on risperidone/paliperidone for ≥12 weeks with no recent dose adjustments. Exclusion criteria included pregnancy, breastfeeding, relevant medical conditions, or co-therapy with prolactin-secreting drugs. Data encompassed drug choice, administration method, therapy duration, and daily dose. Prolactin (PRL) levels, oxidative stress parameters (TBARS, H2O2, O2-, NO2-), and antioxidant system (CAT, GSH, SOD) were assessed. Of 155 subjects, women exhibited significantly higher PRL levels (p < 0.001) and symptomatic HPRL (p < 0.001). Drug choice and regimen significantly influenced TBARS (p < 0.001), NO2- (p < 0.001), O2- (p = 0.002), CAT (p = 0.04), and GSH (p < 0.001) levels. NO2- levels were affected by drug dose (p = 0.038). TBARS (p < 0.001), O2- (p < 0.001), and SOD (p = 0.022) inversely correlated with PRL levels, suggesting PRL's protective role against oxidative stress. The female sex association with higher PRL levels implies additional factors influencing PRL's antioxidant role. Antipsychotic choice and dosage impact PRL and oxidative stress markers, necessitating further exploration.

Health economics study of paliperidone palmitate in the treatment of schizophrenia: a 12-month cohort study.

BACKGROUND: To analyze the economic benefits of paliperidone palmitate in the treatment of schizophrenia. METHODS: We collected 546 patients who met the diagnostic criteria for schizophrenia according to the 《International Statistical Classification of Diseases and Related Health Problems,10th》(ICD-10). We gathered general population data such as gender, age, marital status, and education level, then initiated treatment with paliperidone palmitate. Then Follow-up evaluations were conducted at 1, 3, 6, 9, and 12 months after the start of treatment to assess clinical efficacy, adverse reactions, and injection doses. We also collected information on the economic burden before and after 12 months of treatment, as well as the number of outpatient visits and hospitalizations in the past year to analyze economic benefits. RESULTS: The baseline patients totaled 546, with 239 still receiving treatment with paliperidone palmitate 12 months later. After 12 months of treatment, the number of outpatient visits per year increased compared to before (4 (2,10) vs. 12 (4,12), Z=-5.949, P < 0.001), while the number of hospitalizations decreased (1 (1,3) vs. 1 (1,2), Z = 5.625, P < 0.001). The inpatient costs in the direct medical expenses of patients after 12 months of treatment decreased compared to before (5000(2000,12000) vs. 3000 (1000,8050), P < 0.05), while there was no significant change in outpatient expenses and direct non-medical expenses (transportation, accommodation, meal, and family accompanying expenses, etc.) (P > 0.05); the indirect costs of patients after 12 months of treatment (lost productivity costs for patients and families, economic costs due to destructive behavior, costs of seeking non-medical assistance) decreased compared to before (300(150,600) vs. 150(100,200), P < 0.05). CONCLUSION: Palmatine palmitate reduces the number of hospitalizations for patients, as well as their direct and indirect economic burdens, and has good economic benefits.

Safety and Efficacy of Paliperidone Palmitate in Pediatric Patients with Autism and Intellectual Disability.

This retrospective chart review examines the safety, tolerability and effectiveness of long acting injectable paliperidone palmitate (P-LAI) targeting irritability in twenty-six youth and transition-aged individuals with autism spectrum disorder (ASD) and/or intellectual disability (ID) over a 3-year window. Clinical response was evaluated via prospectively assigned Clinical Global Impressions Severity (CGI-S) and Improvement (CGI-I) scales as well as number of hospital presentations. P-LAI was well tolerated with only 3 patients stopping P-LAI due to side effects. The average duration of P-LAI treatment was 21.1 months. Difficulty with medication compliance was the most common reason for initiating P-LAI. There was a statistically significant improvement in CGI-I, CGI-S and hospital visits and no change in BMI noted. Given the potential difficulty of medication administration in this population, this evidence of safety, tolerability as well as preliminary data supporting effectiveness is an important addition to the literature regarding psychopharmacologic management of irritability in youth with ASD and ID.

Clinical outcomes with paliperidone palmitate 3-monthly injection as monotherapy: observational 3-year follow-up of patients with schizophrenia.

BACKGROUND: Paliperidone palmitate 3-monthly (PP3M) has been tested in 1-year controlled studies. The aim of this study was to examine the relapse outcomes with PP3M monotherapy at 3 years in patients with schizophrenia. METHODS: This was an observational, non-interventional study of patients started on PP3M according to their clinical need. All patients had a diagnosis of schizophrenia (ICD-10 F20) and were between 18 and 65 years of age. The study took place in a mental health facility in South East London, UK. RESULTS: Among the 166 patients who started PP3M, 97 (58%) met inclusion criteria and were observed for 36 months. In total, five patients (5%) experienced a relapse (defined as step-up in clinical care) while on PP3M. There were no relapses between months 18 and 36. Of the original 97 patients, 56 (58%) remained on PP3M monotherapy at 3 years, and 71 (73%) remained on either PP3M or paliperidone palmitate one-monthly. Reasons for discontinuation of PP3M included patient refusal (n = 11, 33% of discontinuations) and adverse effects in (n = 8, 24%). CONCLUSION: PP3M is a highly effective monotherapy treatment for reducing relapse in people with schizophrenia.

Hyaluronidase impacts exposures of long-acting injectable paliperidone palmitate in rodent models.

A significant challenge in the development of long-acting injectable drug formulations, especially for anti-infective agents, is delivering an efficacious dose within a tolerable injection volume. Co-administration of the extracellular matrix-degrading enzyme hyaluronidase can increase maximum tolerable injection volumes but is untested for this benefit with long-acting injectable formulations. One concern is that hyaluronidase could potentially alter the tissue response surrounding an injection depot, a response known to be important for drug release kinetics of long-acting injectable formulations. The objective of this pilot study was to evaluate the impact of co-administration of hyaluronidase on the drug release kinetics, pharmacokinetic profiles, and injection site histopathology of the long-acting injectable paliperidone palmitate for up to four weeks following intramuscular injection in mouse and rat models. In both species, co-administration of hyaluronidase increased paliperidone plasma exposures the first week after injection but did not negate the overall long-acting release nature of the formulation. Hyaluronidase-associated modification of the injection site depot was observed in mice but not in rats. These findings suggest that further investigation of hyaluronidase with long-acting injectable agents is warranted.

Evaluating the 6-month formulation of paliperidone palmitate: a twice-yearly injectable treatment for schizophrenia in adults.

INTRODUCTION: Paliperidone Palmitate is the only antipsychotic that has been developed in three different intramuscular long-acting injectable (LAI) dosing regimen: monthly (PP1M), quarterly (PP3M), and from 2020 also twice-yearly (PP6M). The latter was approved for the maintenance treatment of adults with schizophrenia and clinically stabilized with PP1M or PP3M. AREAS COVERED: Data from studies evaluating efficacy in the maintenance treatment of schizophrenia with PP6M are reviewed. Since no post-marketing safety studies are currently available, data from spontaneous reporting system databases, FAERS and Eudravigilance, are analyzed and the reported treatment-emergent adverse events of PP6M are discussed. EXPERT OPINION: The efficacy of PP6M is comparable to that of PP3M in terms of relapses prevention in patients with schizophrenia previously stabilized on PP3M or PP1M. Also, the maintenance of clinical efficacy in the long term has been demonstrated. Data from pharmacovigilance analyses, as well as from phase 3 studies, show that PP6M is generally well tolerated, consistently with PP3M safety data. PP6M allows a longer dosing interval than any other LAI antipsychotics, potentially reducing nonadherence and disease relapses. In future, an increase in the prescription rates of PP6M is expected and real-world efficacy and tolerability studies will be conducted.