Population Pharmacokinetic Modeling and Exposure-Response Analysis for Aripiprazole Once Monthly in Subjects With Schizophrenia

Medication burden reduction and early clinical benefit through aripiprazole once monthly in schizophrenia patients with polypharmacy

Antipsychotic polypharmacy is commonly used in clinical settings, with a growing trend in using long-acting injections to mitigate many side effects of polypharmacy. A previous study demonstrated that long-acting aripiprazole once-monthly (AOM) injection increased treatment adherence, restored functionality, and improved symptoms. However, there is insufficient evidence to demonstrate the therapeutic effects of AOM in polypharmacy practice. This observational study aimed to investigate the real-world clinical benefits and effectiveness of AOM by assessing changes in drug dosage, the number of drugs, clinical functioning, psychotic symptoms, and the duration of drug efficacy. Study participants were recruited from eight study sites, with the baseline visit marking the initiation of drug treatment. Clinical and demographic data were collected from medical records at screening, baseline, and months 1, 3, 6, 9, and 12. Over 12 months, we analyzed changes in drug dosage, the number of drugs, and scores of the Positive and Negative Syndrome Scale-6 (PANSS-6), Global Assessment of Functioning (GAF), and Clinical Global Impression-Severity (CGIS). Data from 139 participants were analyzed. Total 12-month antipsychotic doses calculated in chlorpromazine equivalents (CPE) were reduced by 32.6%. A comparison of total monthly antipsychotic doses in CPE between the first and last months showed a 24.6% reduction in the dose. Additionally, the quantity of benzodiazepine tablets/capsules, total benzodiazepine doses calculated in lorazepam equivalents, and quantity of tablets/capsules of mood stabilizers, anticholinergics, and beta blockers were significantly reduced. GAF scores increased by 14.1% over 12 months, and PANSS-6 total scores reduced by 17.3% over 12 months, with significant differences observed from month 1 and baseline, respectively. The scores steadily improved until month 9 compared to those of the previous months, continuing to improve through month 12. The CGI-S score reduced by 14.3% over 12 months, showing a significant decrease from month 1 and a steady improvement until month 6, maintaining this improvement until month 12. In conclusion, this study demonstrated the early effectiveness of AOM in treating Korean patients with schizophrenia on polypharmacy. AOM improved function and clinical symptoms in patients with schizophrenia from treatment onset and caused a decrease in the quantity and dosage of drugs taken by the patients.

A Model-Informed Drug Development Approach Supporting the Approval of an Unstudied Valbenazine Dose for Patients With Tardive Dyskinesia

Valbenazine is a highly potent and selective inhibitor of synaptic vesicular monoamine transporter 2. The current therapeutic doses of valbenazine for tardive dyskinesia (TD) are 40, 60, or 80 mg capsules, given orally, once daily (QD). While 40 and 80 mg were investigated in phase 3 KINECT® 3 trial and initially approved, the approval of valbenazine 60 mg was based on the analysis utilizing the Model-informed drug development (MIDD) approach, facilitated through the US Food and Drug Administration's MIDD Pilot Program. This study aimed to demonstrate the efficacy of 60 mg QD dose through model simulations using an established exposure-response (E-R) relationship between valbenazine active metabolite [+]-α-dihydrotetrabenazine exposure and the change from baseline in Abnormal Involuntary Movement Scale total score (AIMS-CFB). A longitudinal E-R model was constructed based on the 40 and 80 mg data from the KINECT 3 trial. The final Emax model adequately predicted dose-dependent improvement in the primary endpoint and was used to interpolate AIMS-CFB for 60 mg at week 6. The efficacy of the unstudied 60 mg dose regimen is expected to be within the range of doses studied clinically with predicted mean AIMS-CFB (95% confidence interval) of -2.69 (-3.30, -2.13) between observed mean AIMS-CFB for 40 mg of -1.92 and 80 mg of -3.39. Results from this analysis provided the key evidence to establish efficacy of 60 mg QD without the need for an additional clinical trial. The availability of valbenazine 60 mg dose fills an existing medical need for patients with TD who could benefit from this third effective dose.

Population Pharmacokinetics and Dosing Simulations for Aripiprazole 2-Month Ready-to-Use Long-Acting Injectable in Adult Patients With Schizophrenia or Bipolar I Disorder

A ready-to-use (RTU) long-acting injectable (LAI) formulation of aripiprazole monohydrate for administration once every 2 months, available in 960 mg (Ari 2MRTU 960) or 720 mg doses, has been developed for the treatment of schizophrenia or bipolar I disorder. A previously developed and validated population pharmacokinetic model for characterizing aripiprazole plasma concentrations following administration of oral aripiprazole or aripiprazole once-monthly (AOM) intramuscular injection was expanded to include the RTU LAI formulation of aripiprazole (Ari RTU LAI). Overall, 8899 aripiprazole pharmacokinetic samples from 1191 adults from 10 clinical trials were included in the final combined analysis data set. Aripiprazole plasma concentration-time profiles were simulated for various Ari RTU LAI initiation and maintenance scenarios in 1000 virtual patients. Diagnostic plots demonstrated that the final population pharmacokinetic model, which incorporated data for oral aripiprazole, AOM, and Ari RTU LAI, adequately described aripiprazole concentrations following Ari RTU LAI administration. Absorption of Ari RTU LAI was modeled by a parallel zero-order and lagged first-order process. Simulations across multiple scenarios were performed to inform dosing recommendations, including various treatment initiation regimens for a 2-monthly formulation of Ari RTU LAI in patients with or without prior stabilization on oral aripiprazole, and for patients switching from AOM. Additional simulations accounted for missed/delayed doses, cytochrome (CYP) 2D6 metabolizer status, and concomitant use of CYP2D6 or CYP3A4 inhibitors. Overall, simulations across a variety of scenarios demonstrated an Ari RTU LAI pharmacokinetic exposure profile that was comparable to AOM, with a longer dosing interval.

Towards precision medicine of long-acting aripiprazole through population pharmacokinetic modelling

Population pharmacokinetic (popPK) models constitute a valuable tool for characterizing the pharmacokinetic properties of once-monthly long-acting injectable aripiprazole (LAI aripiprazole) and quantifying the sources of variability in drug exposure. Our aim is to develop a popPK model of both aripiprazole and its metabolite dehydro-aripiprazole in patients treated with LAI aripiprazole, and to personalize the dosing regimen of aripiprazole across different sub-groups of patients. This is a prospective study investigating the pharmacokinetics of LAI aripiprazole. A total of 93 patients were included, 21 for model development and 71 for external model evaluation. A one-compartment model with linear absorption and elimination adequately described both aripiprazole and dehydro-aripiprazole concentrations. The weight of the patients has been shown to be the factor that most influences the absorption. However, the metabolizing phenotype for CYP2D6 and the concomitant treatment with strong inhibitors of this cytochrome have been shown to be the covariates that most influence total drug exposure. This is the first popPK model developed for LAI aripiprazole that includes aripiprazole and its main active metabolite, dehydroaripiprazole. It provides a personalized dosage recommendation that maximizes the probability of achieving optimal therapeutic concentrations and minimizes the difficulties associated with trial-and-error therapeutic strategies carried out in clinical practice.

Long-Acting Injectable Second-Generation Antipsychotics in Seriously Ill Patients with Schizophrenia: Doses, Plasma Levels, and Treatment Outcomes

This research studies the dose-plasma level (PL) relationship of second-generation antipsychotics, together with the treatment outcomes achieved, in seriously ill people with schizophrenia. An observational, prospective, one-year follow-up study was carried out with patients (N = 68) with severe schizophrenia treated with paliperidone three-month (PP3M) or aripiprazole one-month (ARIM). Participants were divided into standard-dose or high-dose groups. PLs were divided into "standard PL" and "high PL" (above the therapeutic reference range, TRR) groups. The dose/PL relationship, and severity, hospitalizations, tolerability, compliance, and their relationship with doses and PLs were evaluated. There was no clear linear relationship between ARIM or PP3M doses and the PLs achieved. In half of the subjects, standard doses reached PLs above the TRR. The improvements in clinical outcomes (decrease in clinical severity and relapses) were related to high PLs, without worse treatment tolerability or adherence. All participants remained in the study, regardless of dose or PL. Clinical severity and hospitalizations decreased significantly more in those patients with high PLs. Considering the non-linear dose-PL relationship of ARIM and PP3M in people with severe schizophrenia, PLs above the TRR are linked to better treatment outcomes, without worse tolerability. The need in a notable number of cases for high doses to reach those effective PLs is highlighted.

Aripiprazole 2-month ready-to-use 960 mg (Ari 2MRTU): review of its possible role in schizophrenia therapy

Most patients with schizophrenia need life-long treatment. There is therefore a continued need for effective and tolerable treatment options. A 2-monthly LAI formulation of aripiprazole, Aripiprazole 2-Month Ready-to-Use 960 mg (Ari 2MRTU 960) has recently been approved in the US. Here, the possible role in therapy for this new treatment option is discussed in a narrative review. PubMed was searched for literature on long-acting injectables with a focus on patient-reported outcomes and real-world evidence on extended injection intervals (2-3 months). Dopamine D2 partial agonists, one of which is aripiprazole, exhibit favorable tolerability and safety properties. Additionally, there are many advantages in using long-acting injectable formulations such as enhanced treatment persistence and stability of patients as well as reduced rates of relapses, hospitalizations, and death. Some of these advantages become more pronounced with longer injection intervals. Additional advantages of longer injection intervals are more room for non-medication-related communication between healthcare professionals and patients, patient and physician preferences, reduced caregiver burden, and easier transitioning from inpatient to outpatient treatment. Taken together, since aripiprazole may be a good treatment choice for many patients based on its favorable safety and tolerability profile, and given the advantages of LAI treatment over oral treatment and the advantages of reduced dosing frequency, Ari 2MRTU 960 may become an important treatment option for many clinically stable patients with schizophrenia.

Aripiprazole Plasma Concentrations Delivered from Two 2-Month Long-Acting Injectable Formulations: An Indirect Comparison

Aripiprazole 2-month ready-to-use 960 mg (Ari 2MRTU 960) is a novel long-acting injectable (LAI) formulation of aripiprazole monohydrate for administration once every 2 months, developed for the treatment of schizophrenia or maintenance monotherapy treatment of bipolar I disorder in adults (indication will vary by country). Aripiprazole lauroxil 1064 mg (AL 1064) is an LAI formulation of aripiprazole lauroxil, an aripiprazole prodrug, for administration once every 2 months, indicated for the treatment of schizophrenia in adults. This analysis provides an indirect comparison of aripiprazole plasma concentrations following multiple doses of either formulation. Clinical trial data were used to determine average steady-state aripiprazole plasma concentration (Cavg,ss), maximum aripiprazole plasma concentration (Cmax), and other pharmacokinetic parameters of either formulation following four administrations (96 patients received Ari 2MRTU 960; 28 patients received AL 1064). All pharmacokinetic parameters were considered in the context of a minimum aripiprazole therapeutic concentration (Cmin) of ≥95 ng/mL. An exposure-response analysis using data from two Phase III trials of aripiprazole once-monthly (an aripiprazole monohydrate LAI, administered monthly), showed that patients with a Cmin ≥95 ng/mL are 4.41 times less likely to relapse than patients with a Cmin <95 ng/mL. A similar analysis has not been performed for AL 1064. However, consensus guidelines for therapeutic drug monitoring recommend a range of 100-350 ng/mL for aripiprazole. Following four administrations, mean (standard deviation [SD]) Cavg,ss over the 2-month dosing interval was 263 (133) ng/mL for Ari 2MRTU 960 and 140.7 (57.3) ng/mL for AL 1064. Mean (SD) Cmax during the fourth dosing interval was 342 (157) ng/mL for Ari 2MRTU 960 and 188.8 (79.8) ng/mL for AL 1064. This indirect comparison showed that, following four administrations, Ari 2MRTU 960 and AL 1064 delivered mean aripiprazole plasma concentrations that remained above the minimum therapeutic concentration of aripiprazole over the 2-month dosing interval.

A Randomized, Open-Label, Multiple-Dose, Parallel-Arm, Pivotal Study to Evaluate the Safety, Tolerability, and Pharmacokinetics of Aripiprazole 2-Month Long-Acting Injectable in Adults With Schizophrenia or Bipolar I Disorder

BACKGROUND

Aripiprazole 2-month ready-to-use 960 mg (Ari 2MRTU 960) is a new long-acting injectable antipsychotic formulation for gluteal administration every 2 months, currently being investigated for the treatment of schizophrenia and bipolar I disorder (BP-I). The objectives of this trial were to evaluate the safety and tolerability of Ari 2MRTU 960, and the similarity of aripiprazole plasma concentrations following administration of Ari 2MRTU 960 or aripiprazole once-monthly 400 mg (AOM 400), in adults with schizophrenia or BP-I.

METHODS

This was a 32-week open-label study. Eligible participants were randomized 1:1 to receive Ari 2MRTU 960 every 56 ± 2 days (four injections scheduled) or AOM 400 every 28 ± 2 days (eight injections scheduled). Participants received overlapping oral antipsychotic treatment with the first administration of study drug (there was no oral overlap for participants stabilized on AOM 400). Safety, tolerability, and pharmacokinetics (PK) were evaluated throughout the study. Primary safety endpoints included reported adverse events, injection site reactions, and extrapyramidal symptoms. Primary PK endpoints were plasma concentration of aripiprazole 56 days after the fourth dose of Ari 2MRTU 960 and 28 days after the eighth dose of AOM 400, and area under the concentration-time curve (AUC) from Day 0 to 56 postdose after the fourth dose of Ari 2MRTU 960, or AUC from Day 0 to 28 after the seventh and eighth doses of AOM 400.

RESULTS

Of the 266 participants enrolled (schizophrenia, n = 185; BP-I, n = 81), 132 were randomized to receive Ari 2MRTU 960 and 134 were randomized to receive AOM 400. The majority (66.2%) of participants were male; 72.9% were Black or African American, and mean age was 47.3 years; demographic characteristics and baseline disease characteristics were generally well balanced between groups. Study completion rate was 77.3% in the Ari 2MRTU 960 group and 68.7% in the AOM 400 group. The incidence of treatment-emergent adverse events (TEAEs) was similar between Ari 2MRTU 960 (71.2%) and AOM 400 (70.9%). The most frequently reported TEAEs were increased weight (Ari 2MRTU 960: 22.7%; AOM 400: 20.9%) and injection-site pain (Ari 2MRTU 960: 18.2%; AOM 400: 9.0%). The geometric means ratio (GMR) of aripiprazole plasma concentrations on the last day following the final dosing for Ari 2MRTU 960 versus AOM 400 was 1.011 (90% confidence interval [CI] 0.893-1.145), and the GMR of aripiprazole plasma exposure (area under the concentration-time curve) over the fourth Ari 2MRTU 960 dosing interval versus the seventh and eighth AOM 400 dosing intervals was 1.006 (90% CI 0.851-1.190).

CONCLUSIONS

Ari 2MRTU 960 was generally well tolerated in adults with schizophrenia or BP-I, with a safety profile comparable with that of AOM 400, and aripiprazole exposure equivalent to that with AOM 400 (ClinicalTrials.gov identifier: NCT04030143, registered on 23 July 2019).

Differences in autonomic nervous system activity between long-acting injectable aripiprazole and oral aripiprazole in schizophrenia

BACKGROUND

Distinct oral atypical antipsychotics have different effects on autonomic nervous system (ANS) activity. Among them, oral aripiprazole has been linked to dysfunction of the ANS in schizophrenia. Long-acting injectable aripiprazole is a major treatment option for schizophrenia, but the effect of the aripiprazole formulation on ANS activity remains unclear. In this study, we compared ANS activity between oral aripiprazole and aripiprazole once-monthly (AOM) in schizophrenia.

METHODS

Of the 122 patients with schizophrenia who participated in this study, 72 received oral aripiprazole and 50 received AOM as monotherapy. We used power spectral analysis of heart rate variability to assess ANS activity.

RESULTS

Patients who received oral aripiprazole showed significantly diminished sympathetic nervous activity compared with those who received AOM. Multiple regression analysis revealed that the aripiprazole formulation significantly influenced sympathetic nervous activity.

CONCLUSION

Compared with oral aripiprazole, AOM appears to have fewer adverse effects, such as sympathetic nervous dysfunction.