Pharmacokinetics Of Aripiprazole Research Articles

Adis summary of research: Safety, tolerability and pharmacokinetics of aripiprazole 2-monthly formulation in patients with schizophrenia or bipolar I disorder

Adis summary of research: Safety, tolerability and pharmacokinetics of aripiprazole 2-monthly formulation in patients with schizophrenia or bipolar I disorder

Towards precision dosing of aripiprazole in children and adolescents with autism spectrum disorder: linking blood levels to weight gain and effectiveness.

Aripiprazole is one of the most commonly prescribed antipsychotic drugs to children and adolescents worldwide, but it is associated with serious side effects, including weight gain. This study assessed the population pharmacokinetics of aripiprazole and its active metabolite and investigated the relationship between PK parameters and BMI in children and adolescents with ASD and behavioral problems. Secondary outcomes were metabolic, endocrine, extrapyramidal and cardiac side effects and drug effectiveness. Twenty-four children and adolescents (15 males, 9 females) aged 6-18 years were included in a 24-week prospective observational trial. Drug plasma concentrations, side effects and drug effectiveness were measured at several time points during follow-up. Relevant pharmacokinetic covariates, including CYP2D6, CYP3A4, CYP3A5 and P-glycoprotein (ABCB1) genotypes, were determined. Nonlinear mixed-effects modelling (NONMEM®) was used for a population pharmacokinetic analysis with 92 aripiprazole and 91 dehydro-aripiprazole concentrations. Subsequently, model-based trough concentrations, maximum concentrations and 24-hour AUCs were analyzed to predict outcomes using generalized and linear mixed-effects models. For both aripiprazole and de-hydro-aripiprazole, one-compartment models best described the measured concentrations, with albumin and BMI as significant covariates. Of all the pharmacokinetic parameters, higher sum (aripiprazole plus dehydro-aripiprazole) trough concentrations best predicted higher BMI z-scores (P < .001) and higher Hb1Ac levels (p=0.03) during follow-up. No significant association was found between sum concentrations and effectiveness. Our results indicate a threshold with regard to safety, which suggests that therapeutic drug monitoring of aripiprazole could potentially increase safety in children and adolescents with ASD and behavioral problems.

Understanding inter-individual variability in pharmacokinetics/pharmacodynamics of aripiprazole in children with tic disorders: Individualized administration based on physiological development and CYP2D6 genotypes.

Objective: This study aims to develop a combined population pharmacokinetic (PPK) model for aripiprazole (ARI) and its main active metabolite dehydroaripiprazole (DARI) in pediatric patients with tic disorders (TD), to investigate the inter-individual variability caused by physiological and genetic factors in pharmacokinetics of ARI and optimize the dosing regimens for pediatric patients. Methods: A prospective PPK research was performed in Chinese children with TD. Totally 84 patients aged 4.83-17.33 years were obtained for the pharmacokinetic analysis. 27 CYP2D6 and ABCB1 gene alleles were detected. Moreover, the clinical efficacy was evaluated according to reduction rate of Yale Global Tic Severity Scale (YGTSS) score at the 12thweek comparing with the baseline. Monte Carlo simulations were used to evaluate and optimize dosing regimens. Results: The PPK model was established to predict the concentrations of ARI and DARI. Body weight and CYP2D6 genotype were the significant covariates affecting the clearance of ARI. The DARI/ARI metabolic ratios (MRs) of AUC24h, Cmin and Cmax at the steady state of results were ultra-rapid metabolizers (UMs) > normal metabolizers (NMs) > intermediated metabolizers (IMs). MRs could be used to distinguish UMs or IMs from other patients. The best predictor of clinical efficacy for TD was the trough concentration of ARI and the cut-off point was 101.636ng/ml. Conclusion: The pharmacokinetics of ARI and DARI in pediatric TD were significantly influenced by body weight and CYP2D6 genotype. Individualized dosing regimens were recommended for pediatric patients with TD to ensure clinical efficacy.

Influence of CYP2D6 Phenotypes on the Pharmacokinetics of Aripiprazole and Dehydro-Aripiprazole Using a Physiologically Based Pharmacokinetic Approach.

Background and ObjectivesAripiprazole is an atypical antipsychotic drug that is metabolized by cytochrome P450 (CYP) 2D6 and CYP3A4, which mainly form its active metabolite dehydro-aripiprazole. Because of the genetic polymorphism of CYP2D6, plasma concentrations are highly variable between different phenotypes. In this study, phenotype-related physiologically based pharmacokinetic models were developed and evaluated to suggest phenotype-guided dose adjustments.MethodsPhysiologically based pharmacokinetic models for single dose (oral and orodispersible formulation), multiple dose, and steady-state condition were built using trial data from genotyped healthy volunteers. Based on evaluated models, dose adjustments were simulated to compensate for genetically caused differences.ResultsPhysiologically based pharmacokinetic models were able to accurately predict the pharmacokinetics of aripiprazole and dehydro-aripiprazole according to CYP2D6 phenotypes, illustrated by a minimal bias and a good precision. For single-dose administration, 92.5% (oral formulation) and 79.3% (orodispersible formulation) of the plasma concentrations of aripiprazole were within the 1.25-fold error range. In addition, physiologically based pharmacokinetic steady-state simulations demonstrate that the daily dose for poor metabolizer should be adjusted, resulting in a maximum recommended dose of 10 mg, but no adjustment is necessary for intermediate and ultra-rapid metabolizers.ConclusionsIn clinical practice, CYP2D6 genotyping in combination with therapeutic drug monitoring should be considered to personalize aripiprazole dosing, especially in CYP2D6 poor metabolizers, to ensure therapy effectiveness and safety.

Effects of Uremic Toxins on the Binding of Aripiprazole to Human Serum Albumin.

We recently reported that aripiprazole (ARP), an antipsychotic drug, binds strongly to human serum albumin (HSA), the major drug binding protein in serum. It is known that uremic toxins that accumulate during renal disease affect the interaction between HSA and drug binding. In this study, the issue of how uremic toxins (indoxyl sulfate, indole acetic acid and p-cresyl sulfate) affect the binding of ARP to HSA was investigated. Equilibrium dialysis experiments revealed that all uremic toxins inhibited the binding of ARP to HSA although the inhibitory effects differed, depending on the specific uremic toxin. The potency of inhibition can be partially explained by the affinities of uremic toxins to HSA. Fluorescence displacement experiments suggested that ARP as well as all uremic toxins bind to site II of HSA. The inhibitory effects of the toxins on the binding of ARP for the drugs binding to the diazepam subsite are significantly larger, comparing with those for binding to arylpropionic acids subsite. Interestingly, induced circular dichroism (CD) spectra indicated that the spatial orientation of p-cresyl sulfate in the binding pocket is different from that for indoxyl sulfate and indole acetic acid. The limited findings obtained herein are important data in considering the effects of uremic toxins on the pharmacokinetics of ARP and the drugs that bind to site II on HSA, particularly drugs binding to diazepam binding site in site II.

Influence of CYP2D6 gene polymorphisms on the pharmacokinetics of aripiprazole in healthy Chinese subjects.

Background: Pharmacogenetics study was added into 2 bioequivalencetrials of aripiprazole. The correlation between CYP2D6 polymorphisms and aripiprazole pharmacokinetics (PK) was analyzed. Materials & methods: A total of 140 subjects were included. A total of26 CYP2D6 gene alleles were detected. The plasma concentration of aripiprazole was measured by liquid chromatography-tandem mass spectrometry. SPSS Statistics 21 was used to analyze the correlation between CYP2D6 polymorphisms and aripiprazole PK parameters. Results: All of the four PK parameters were significantly influenced by CYP2D6rs1058164 and rs28371699. t1/2 and area under the concentration-time curve exhibited significant difference between CYP2D6 extensive metabolizers and intermediate metabolizers. Conclusion: Aripiprazole PK was greatly influenced by CYP2D6. Attention should be paid to the possible dose adjustment for CYP2D6 intermediate metabolizer population when the drug is used in Chinese patients.

Interaction of Aripiprazole With Human α1-Acid Glycoprotein

We recently reported that aripiprazole binds strongly to human albumin. In continuing our investigations, we investigated the mechanism responsible for the binding and the related interactions of aripiprazole with α1-acid glycoprotein (AGP). The extrinsic Cotton effects for the binding of aripiprazole and its derivatives to AGP were generated, but the magnitudes of the induced circular dichroism intensities did not correlate with those for the binding affinities. It therefore appears that the binding mode of aripiprazole with AGP is somewhat complicated, compared with that of albumin. Isothermal titration calorimetry data obtained for the binding of aripiprazole with AGP were different from that for albumin systems in that the 3 driving reactions, entropy-driven, enthalpy-driven, and the entropy-enthalpy mixed type, were all found for the AGP system, but not albumin. Moreover, the weak binding mode of aripiprazole with the 2 proteins were supported by a molecular docking model analysis. The concentration of albumin in plasma is about 50 times higher than those of AGP, but AGP levels in plasma are increased by about 10 times under inflammatory disease. Therefore, the involvement of these 2 plasma proteins should be considered in more depth for understanding the pharmacokinetics of aripiprazole.

Phenoconversion of CYP2D6 by inhibitors modifies aripiprazole exposure.

The efficacy of aripiprazole therapy and the risk of adverse reactions are influenced by substantial inter-individual variability in aripiprazole metabolizing capacity. In vitro studies assigned the potential role in aripiprazole metabolism to CYP2D6 and CYP3A enzymes; therefore, the association between the steady-state aripiprazole plasma concentrations and patients' CYP2D6 and CYP3A statuses (CYP2D6, CYP3A4, and CYP3A5 genotypes, and CYP3A4 expression) and/or co-medication with CYP function modifying medications has been investigated in 93 psychiatric patients on stable aripiprazole therapy. The patients' CYP2D6 genotype had a major effect on aripiprazole plasma concentrations, whereas contribution of CYP3A genotypes and CYP3A4 expression to aripiprazole clearance were considered to be minor or negligible. The role of CYP3A4 expression in aripiprazole metabolism did not predominate even in the patients with nonfunctional CYP2D6 alleles. Furthermore, dehydroaripiprazole exposure was also CYP2D6 genotype-dependent. Dehydroaripiprazole concentrations were comparable with aripiprazole levels in patients with functional CYP2D6 alleles, and 35% or 22% of aripiprazole concentrations in patients with one or two non-functional CYP2D6 alleles, respectively. The concomitant intake of CYP2D6 inhibitors, risperidone, metoprolol, or propranolol was found to increase aripiprazole concentrations in patients with at least one wild-type CYP2D6*1 allele. Risperidone and 9-hydroxy-risperidone inhibited both dehydrogenation and hydroxylation of aripiprazole, whereas metoprolol and propranolol blocked merely the formation of the active dehydroaripiprazole metabolite, switching towards the inactivation pathways. Patients'CYP2D6 genotype and co-medication with CYP2D6 inhibitors can be considered to be the major determinants of aripiprazole pharmacokinetics. Taking into account CYP2D6 genotype and co-medication with CYP2D6 inhibitors may improve the outcomes of aripiprazole therapy.

Association between aripiprazole pharmacokinetics and CYP2D6 phenotypes: A systematic review and meta-analysis.

The FDA has provided recommendations for aripiprazole use in CYP2D6 poor metabolizers (PMs); however, PMs make up <1% of the Asian population and no recommendation has been provided for intermediate metabolizers (IMs), who comprise a considerable proportion of the Asian population (64%-70% occurrence of CYP2D6*10). This study aimed to investigate the characteristics of aripiprazole metabolism in IMs and other phenotypes by conducting the first meta-analysis of the association among CYP2D6 phenotypes and aripiprazole pharmacokinetics (PK). We searched four electronic databases for studies published through February 2018, investigating the association between aripiprazole and CYP2D6 gene polymorphisms. Gene polymorphism information was extracted, and CYP2D6 phenotypes were determined according to a unified classification standard. The associations between three aripiprazole PK-related outcomes and CYP2D6 phenotype were analysed. Meta-analyses were used to compare ultra-rapid metabolizers (UMs) vs extensive metabolizers (EMs), EMs vs IMs and IMs vs poor metabolizers (PMs) for each outcome. The aripiprazole serum concentration funnel plot and the Egger's and Begg's tests were used to assess publication bias. Altogether, 10 studies were included in this analysis (n=649). Aripiprazole serum concentration differed significantly between EMs and IMs (EM vs IM pooled SMD: -0.383; 95% CI: -0.735 to -0.031, P=0.03<0.05), but not between IMs and PMs (IM vs PM pooled SMD: -0.425; 95% CI: -0.933 to 0.082, P=0.10>0.05). However, aripiprazole plus dehydroaripiprazole serum level did not significantly differ among EMs, IMs and PMs (EM vs IM pooled SMD: -0.285; 95% CI: -0.724 to 0.154, P=0.20>0.05; IM vs PM pooled SMD: -0.302; 95%CI: -0.810 to 0.205, P=0.24>0.05). Overall, aripiprazole serum level and the sum level of aripiprazole plus dehydroaripiprazole in different phenotypes followed the trend UMs<EMs<IMs<PMs, whereas dehydroaripiprazole serum level followed the trend UMs<EMs>IMs>PMs. Aripiprazole serum concentration differed significantly between EMs and IMs, but not between PMs. Whether this has clinical significance requires further evaluation by randomized trials.

Effect of sinapic acid on aripiprazole pharmacokinetics in rats: Possible food drug interaction

Dietary supplements and foods can interact with various drugs, leading to possible clinical concerns. This study aimed to investigate the effect of orally administered sinapic acid (SA) on the pharmacokinetics of aripiprazole (APZ) in rats and its possible modulatory effects on hepatic cytochrome P450 (CYP3A2 and CYP2D6) expression in the liver tissues. Single dose and multiple dose parallel groups of wistar rats were categorized into six groups (n = 6 each) which abstained from food for 12 h prior to the experiment, while water was allowed ad libitum. The investigation was carried out for single dose: Group I was treated with normal saline orally for 15 days (normal control). Group II was administered normal saline orally for 15 days and received APZ (3 mg/kg p.o.) on day 15. Group III received SA (20 mg/kg p.o.) for 15 days and received APZ (3 mg/kg p.o.) on day 15. Group IV was treated with SA (20 mg/kg p.o.) for 15 days. For the multiple dose study, Group I was treated with normal saline orally for 15 days (normal control); Group II received APZ (3 mg/kg p.o.) daily for 15 days; Group III was administered with SA (20 mg/kg p.o.) and APZ (3 mg/kg p.o.) for 15 days and Group IV received SA (20 mg/kg p.o.) for 15 days. The group I and IV were kept common in single and multiple dose groups. After last APZ dose, plasma samples were collected and APZ concentrations were determined using an UPLC-MS/MS technique. The pharmacokinetic parameters were calculated using a non-compartmental analysis. The concomitant administration of APZ with SA (as single or multiple dose) resulted in an increase in APZ absorption and a decrease on its systemic clearance. This was associated with a reduction in CYP3A2 and CYP2D6 protein expressions by 33–43% and -71–68% after the single and multiple co-administration, which are two enzymes responsible of the metabolism of APZ. Therefore, a reduction in the metabolic clearance appears to be the mechanism underlying the drug interaction of dietary supplement containing SA with APZ. Therefore, the concomitant administration of SA and APZ should be carefully viewed. Further investigations are required to assess the clinical significance of such observations in humans.

Population Pharmacokinetic Analysis and Model-Based Simulations of Aripiprazole for a 1-Day Initiation Regimen for the Long-Acting Antipsychotic Aripiprazole Lauroxil.

Background and ObjectivesAripiprazole lauroxil (AL), a long-acting injectable antipsychotic for the treatment of schizophrenia, requires 21 days of oral aripiprazole supplementation upon initiation (21-day initiation regimen). An alternative 1-day initiation regimen utilizing a nano-crystalline milled dispersion of AL (ALNCD) plus a single 30 mg oral aripiprazole dose achieved aripiprazole concentrations associated with therapeutic doses of aripiprazole in the same time frame as the 21-day initiation regimen when starting AL (441 or 882 mg). A population pharmacokinetic (PopPK) model was developed to describe aripiprazole pharmacokinetics following administration of ALNCD, AL and oral aripiprazole, and evaluate dosing scenarios likely to be encountered in clinical practice.MethodsIn total, 12,768 plasma aripiprazole concentrations from 343 patients (from 4 clinical studies) were included in the PopPK analysis and used to construct the model.ResultsConcomitant administration of the 1-day initiation regimen with all approved AL dosing regimens (441, 662, or 882 mg monthly, 882 mg every 6 weeks, or 1064 mg every 2 months) is predicted to achieve aripiprazole concentrations associated with therapeutic doses of AL using the 21-day initiation regimen within 4 days, maintaining these concentrations until the next AL dose. Administration of the first AL injection 10 days after the 1-day initiation regimen resulted in median aripiprazole concentrations just before the second dose of AL ≥ 77% of that when coadministered on the same day. Coadministration of AL with a single ALNCD injection was predicted to be effective in rapidly re-establishing concentrations associated with therapeutic doses of AL following dose delay.ConclusionsModel-based simulations demonstrate that the 1-day initiation regimen is suitable for starting treatment with all AL doses, allowing a window of ≤ 10 days between initiation and AL administration. ALNCD may also be used to re-establish concentrations associated with therapeutic doses of AL in conjunction with a delayed AL dose.Electronic supplementary materialThe online version of this article (10.1007/s13318-018-0488-4) contains supplementary material, which is available to authorized users.

Influence of CYP2D6, CYP3A4, CYP3A5 and ABCB1 Polymorphisms on Pharmacokinetics and Safety of Aripiprazole in Healthy Volunteers.

The aim of this study was to investigate the effect of polymorphisms in cytochrome P450 (CYP) 2D6, CYP3A4 and CYP3A5 enzymes and in P-glycoprotein (P-gp) on the pharmacokinetics and safety of aripiprazole and, its active metabolite, dehydro-aripiprazole, in 148 healthy volunteers from six bioequivalence trials receiving a single oral dose of aripiprazole. The plasma concentrations of both analytes were measured by LC-MS/MS. CYP2D6 (*3,*4,*5,*6,*7,*9 and copy number variations), CYP3A4 (*20 and *22), CYP3A5*3 and C3435T, C1236T and G2677T/A in ABCB1 gene were determined. As the number of active CYP2D6 alleles decreased, AUC0-t , Cmax and t1/2 of aripiprazole were higher and clearance of aripiprazole, AUC0-t of dehydro-aripiprazole and ratio dehydro-aripiprazole/aripiprazole were lower. AUC0-t of aripiprazole of poor metabolizer (PM) subjects was increased by 50% compared to extensive metabolizers (EM), and AUC0-t of dehydro-aripiprazole was decreased by 33%. ABCB1 1236TT subjects had a lower clearance of aripiprazole (p=0.023) and AUC0-t (p=0.039) and Cmax of dehydro-aripiprazole (p=0.036) compared to C/C. CYP3A5*3/*3 subjects had a 10% lower ratio dehydro-aripiprazole/aripiprazole than *1/*3 (p=0.019). Adverse drug reactions (ADRs) had a directly proportional relationship with AUC0-t of aripiprazole (p=0.001), especially nausea/vomiting, which were more common in women (p=0.005). Women and CYP3A5*1/*1 subjects showed more often dizziness (p=0.034; p=0.009). Pharmacokinetics of aripiprazole is affected by CYP2D6 phenotype but also by sex and C1236T (ABCB1 gene), while dehydro-aripiprazole pharmacokinetics is affected by CYP2D6 and C1236T. The ratio dehydro-aripiprazole/aripiprazole was influenced by CYP2D6 phenotype and CYP3A5*3. Concentrations of aripiprazole, sex, CYP3A5*3 and CYP2D6 were involved in the development of ADRs.

Validated LC–MS/MS Method for Simultaneous Determination of Aripiprazole and its Three Metabolites in Human Plasma

Aripiprazole, a partial agonist of dopamine D2 receptors, is primarily metabolized to active dehydroaripiprazole and then converted to its urinary metabolites 1-(2,3-dichlorophenyl) piperazine (DCPP) and 3,4-dihydro-7-(3′carboxy) propoxy-2(1H) quinolinone (DCPQ). This study aimed to develop a simultaneous determination method for aripiprazole and its three metabolites in human plasma using isocratic liquid chromatography coupled to tandem mass spectrometry and then to apply it to pharmacokinetic analyses. The pretreatments for human plasma involve protein precipitation using acetonitrile under basic conditions. Aripiprazole and its metabolites were separated on an octadecylsilyl column filled with 3-µm particles using an isocratic mixture of 30% acetonitrile containing 0.1% formic acid with a total run time of 10 min. The mass spectrometer was run in the positive ion multiple reaction monitoring mode. The calibration curves were linear over the plasma concentration ranges 2–2000 ng mL−1 for aripiprazole, and 1–1000 ng mL−1 for dehydroaripiprazole, DCPP, and DCPQ. The lower limits of quantification in human plasma were 2 ng mL−1 for aripiprazole and 1 ng mL−1 for the metabolites. Their pretreatment recoveries were 88.3–102.7%. The intra-assay precision and accuracy were within 1.7–9.6 and 86.9–105.9% and inter-assay precision and accuracy were within 3.1–9.1 and 87.4–102.4%, respectively. The plasma concentrations of aripiprazole, dehydroaripiprazole, DCPP, and DCPQ ranged from 42.8 to 1369, 1.01–548, 1.02–46.1, and 1.69–475 ng mL−1, respectively, in 20 schizophrenia patients. In conclusion, this simultaneous determination method with acceptable analytical performance can be helpful for evaluating the pharmacokinetics of aripiprazole including the determination of its metabolites, in clinical research.

Population pharmacokinetics of aripiprazole in healthy Korean subjects.

Aripiprazole is widely used to treat schizophrenia and bipolar disorder. This study aimed to develop a combined population pharmacokinetic model for aripiprazole in healthy Korean subjects and to identify the significant covariates in the pharmacokinetic variability of aripiprazole. Aripiprazole plasma concentrations and demographic data were collected retrospectively from previous bioequivalence studies that were conducted in Chonbuk National University Hospital. Informed consent was obtained from subjects for cytochrome P450 (CYP) genotyping. The population pharmacokinetic parameters of aripiprazole were estimated using nonlinear mixed-effect modeling with first-order conditional estimation with interaction method. The effects of age, sex, weight, height, and CYP genotype were assessed as covariates. A total of 1,508 samples from 88 subjects in three bioequivalence studies were collected. The two-compartment model was adopted, and the final population model showed that the CYP2D6 genotype polymorphism, height and weight significantly affect aripiprazole disposition. The bootstrap and visual predictive check results were evaluated, showing that the accuracy of the pharmacokinetic model was acceptable. A population pharmacokinetic model of aripiprazole was developed for Korean subjects. CYP2D6 genotype polymorphism, weight, and height were included as significant factors affecting aripiprazole disposition. The population pharmacokinetic parameters of aripiprazole estimated in the present study may be useful for individualizing clinical dosages and for studying the concentration-effect relationship of the drug.

Pharmacokinetics of a New Orally Disintegrating Tablet Formulation of Aripiprazole 15 mg Administered Without Water in Healthy Middle-aged Korean Subjects

PurposeThe main objective of this study was to compare the pharmacokinetic properties and relative bioavailability of two 15-mg aripiprazole formulations (an orally disintegrating tablet [ODT] as the test drug and a conventional tablet as the reference drug) in healthy middle-aged Korean subjects. MethodsThis study was conducted in a population of healthy middle-aged Korean subjects as a randomized, open-label, single-dose, 2-sequence, 2-period crossover trial. After administration of a single dose of a 15-mg aripiprazole standard tablet with 240 mL water or an aripiprazole 15-mg ODT without water, blood samples were collected at specific time intervals from 0 to 240 hours. Concentrations of aripiprazole in plasma were analyzed by using a LC-MS/MS method of detection. Data on the pharmacokinetic parameters were recorded, and the 90% CIs of the ratios of the geometric means of the parameters were determined from the logarithmically transformed data by using an ANOVA model. FindingsThirty-nine healthy middle-aged Korean subjects were enrolled (mean age, 52.7 years; mean height, 167 cm; mean weight, 67.6 kg); 33 participants completed the study (29 male subjects and 4 female subjects). The 90% CIs of the geometric means ratio (test drug/reference drug) of Cmax, AUC0–last, and AUC0–∞ values were 0.95 to 1.14, 0.98 to 1.09, and 0.97 to 1.08, respectively. All of the subjects who experienced adverse events recovered without sequelae, and no serious adverse events were observed. ImplicationsThe aripiprazole pharmacokinetics was similar for the ODT and standard tablet of 15-mg aripiprazole in these healthy middle-aged Korean subjects. The aripiprazole ODT formulation is therefore expected to offer a convenient alternative for patients who have difficulty swallowing tablets without water. The study was registered at http://cris.nih.go.kr (registration number: KCT0001677).

The effect of resveratrol on pharmacokinetics of aripiprazole in vivo and in vitro

1. The objective of this study were to investigate the effect of orally administered resveratrol on the pharmacokinetics of aripiprazole (APZ) in rat, and the inhibitory effects of resveratrol on APZ dehydrogenation activity in liver microsomes and human cytochrome P450 3A4 and 2D6.2. Twenty-five healthy male Sprague–Dawley rats were randomly divided into five groups: A (control group), B (multiple dose of 200 mg/kg resveratrol), C (multiple dose of 100 mg/kg resveratrol), D (a single dose of 200 mg/kg resveratrol) and E (a single dose of 100 mg/kg resveratrol). A single dose of 3 mg/kg APZ administered orally 30 min after administration of resveratrol. In addition, CYP2D6*1, CYP3A4*1, human and rat liver microsomes were performed to determine the effect of resveratrol on the metabolism of APZ in vitro.3. The multiple dose of 200 or 100 mg/kg resveratrol significantly increased the AUC and Cmax of APZ. The resveratrol also obviously decreased the CL, but without any significant difference on t1/2 in vivo. On the other hand, resveratrol showed inhibitory effect on CYP3A4*1, CYP2D6*1, human and rat microsomes, the IC50 of resveratrol was 6.771, 87.87, 45.11 and 35.59 μmol l−1, respectively.4. Those results indicated more attention should be paid when APZ was administrated combined with resveratrol.

Relative bioavailability and safety of aripiprazole lauroxil, a novel once-monthly, long-acting injectable atypical antipsychotic, following deltoid and gluteal administration in adult subjects with schizophrenia

Aripiprazole lauroxil is a linker lipid ester of aripiprazole for extended-release intramuscular (IM) injection. This multicenter, randomized, open-label study evaluated the pharmacokinetics (PK), relative bioavailability, and tolerability of a single IM deltoid or gluteal injection of aripiprazole lauroxil in adult subjects with chronic stable schizophrenia or schizoaffective disorder. Forty-six subjects were randomized 1:1 to aripiprazole lauroxil 441mg IM in the deltoid or gluteal muscle. Samples were collected through 89days post-dose to measure levels of aripiprazole lauroxil, N-hydroxymethyl aripiprazole, aripiprazole, and dehydro-aripiprazole. Forty-three (93.5%) subjects completed all study assessments; most were CYP2D6 extensive or immediate metabolizers (96%); two (4%) were poor metabolizers. The PK of aripiprazole following aripiprazole lauroxil was characterized by a steady rise in plasma concentrations (Tmax 44–50days), a broad peak, and prolonged exposure attributable to the dissolution of aripiprazole lauroxil and formation rate-limited elimination of aripiprazole (t1/2=15.4–19.2days). Deltoid vs. gluteal administration resulted in slightly higher Cmax aripiprazole concentrations [1.31 (1.02, 1.67); GMR 90% CI]; total exposure (AUCinf) was similar between sites of administration [0.84 (0.57, 1.24)]. N-hydroxymethyl-aripiprazole and dehydro-aripiprazole exposures were 10% and 33–36%, respectively, of aripiprazole exposure following aripiprazole lauroxil. The most common adverse events were injection site pain in 20 subjects (43.5%) and headache in 6 subjects (13.0%) of mild intensity occurring at a similar rate with deltoid and gluteal administration. Exposure ranges with deltoid and gluteal administration overlapped, suggesting that these sites may be used interchangeably. Despite a higher incidence of adverse events, deltoid muscle provides a more accessible injection site and could facilitate patient acceptance.

Effect of valproate on the plasma concentrations of aripiprazole in bipolar patients

Objective. There is very limited documentation available on the effects of valproate co-medication on the pharmacokinetics of aripiprazole in a naturalistic setting. The aim of the present study was to investigate the effect of co-medication with valproate on serum concentrations of aripiprazole in bipolar disorder patients in a clinical setting. Method. Plasma samples of bipolar disorder patients (n = 69) on a stable dose of aripiprazole 20 mg/day were analyzed by a liquid chromatography-mass spectrometry method in a routine therapeutic drug monitoring setting. Therapeutic drug monitoring was done for the entire study group before and after valproate co-administration. Results. We observed a statistically significant difference between the aripiprazole monotherapy and aripiprazole-valproate combination with respect to total aripiprazole plasma levels (p < 0.01). However, no statistically significant differences were noted in aripiprazole levels between the first week and the second week of valproate co-administration. Conclusion. In conclusion, concurrent treatment with valproate resulted in changes in the total aripiprazole plasma levels by 23%. But a lower total aripiprazole concentration during co-medication with valproate, caused by protein binding displacement, is reported being clinically insignificant in previous studies. The results from these studies are important in order to clarify clinical safety and efficacy.

A rapid and selective LC–MS/MS method for the quantification of aripiprazole in beagle dog plasma and its application to a pharmacokinetic study

A rapid, selective and cost-effective ultra-performance liquid chromatography-tandem mass spectrometric method was developed and validated for the determination of aripiprazole in beagle dog plasma. UPLC analysis was carried out under the following conditions: a Kinetex C18 column (50 mm × 2.1 mm i.d., 1.7 µm particle size), mobile phase of acetonitrile and 5 mM ammonium acetate with gradient elution and flow rate of 0.2 mL/min. Aripiprazole and an internal standard (papaverine) were extracted by liquid–liquid extraction with ethyl ether. The total run time was 4 min. The analyte was detected using an electrospray ionization tandem mass spectrometry in the multiple reaction monitoring mode. The chromatograms showed good resolution and sensitivity as well as no interference from the beagle dog plasma. The calibration curves were linear over the concentration range, 1.0–100 ng/mL using a 100 μL plasma sample, with correlation coefficients >0.998. The intra- and inter-day assay precision as well as the accuracy fulfilled the international requirements. The lower limit of quantification for aripiprazole in beagle dog plasma was 1 ng/mL, which is sensitive enough for pharmacokinetic studies. Stability studies revealed that aripiprazole in beagle dog plasma was stable during storage as well as during the assay procedure. The validated method was successfully applied to an examination of the pharmacokinetics of aripiprazole in beagle dogs following a single oral dose of an aripiprazole (10 mg) tablet. This method allows laboratory researchers to simply determine aripiprazole in plasma.

Impact of genetic deficiencies of P-glycoprotein and breast cancer resistance protein on pharmacokinetics of aripiprazole and dehydroaripiprazole

1. We investigated how deficiencies in P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) affect the pharmacokinetics of atypical antipsychotics aripiprazole and its active metabolite (dehydroaripiprazole) using normal Friend leukemia virus strain B (FVB) mice, BCRP knockout (Bcrp[−/−]) mice, and P-gp and BCRP triple knockout (Mdr1a/1b[−/−]Bcrp[−/−]) mice.2. While plasma concentrations of aripiprazole and dehydroaripiprazole after oral administration were slightly higher in both Bcrp(−/−) and Mdr1a/1b(−/−)/Bcrp(−/−) mice than in normal FVB mice, the difference was not marked. The increase in absolute bioavailability (F) compared with normal mice (approximately 1.3-fold increase) was comparable between Bcrp(−/−) and Mdr1a/1b(−/−)/Bcrp(−/−) mice. This finding suggests that BCRP may be involved in the intestinal absorption of aripiprazole in mice, albeit with minimal contribution to absorption at best.3. In contrast, the brain-to-plasma concentration ratio (Kp,brain) for aripiprazole and dehydroaripiprazole after oral administration was significantly higher in Mdr1a/1b(−/−)/Bcrp(−/−) mice than in normal mice, whereas Bcrp(−/−) mice exhibited Kp,brain values similar to those in normal mice. In addition, the Kp,brain values in Mdr1a/1b(−/−)/Bcrp(−/−) mice were not drastically different from those previously reported in Mdr1a/1b(−/−) mice, suggesting that brain penetration of aripiprazole and dehydroaripiprazole can be affected by P-gp, but with little synergistic effect of BCRP.