A pharmacovigilance study of pharmacokinetic drug interactions using a translational informatics discovery approach.

BACKGROUND: While the pharmacokinetic (PK) mechanisms for many drug interactions (DDIs) have been established, pharmacovigilance studies related to these PK DDIs are limited. Using a large surveillance database, a translational informatics approach can systematically screen adverse drug events (ADEs) for many DDIs with known PK mechanisms. METHODS: We collected a set of substrates and inhibitors related to the cytochrome P450 (CYP) isoforms, as recommended by the United States Food and Drug Administration (FDA) and Drug Interactions Flockhart table™. The FDA's Adverse Events Reporting System (FAERS) was used to obtain ADE reports from 2004 to 2018. The substrate and inhibitor information were used to form PK DDI pairs for each of the CYP isoforms and Medical Dictionary for Regulatory Activities (MedDRA) preferred terms used for ADEs in FAERS. A shrinkage observed-to-expected ratio (Ω) analysis was performed to screen for potential PK DDI and ADE associations. RESULTS: We identified 149 CYP substrates and 62 CYP inhibitors from the FDA and Flockhart tables. Using FAERS data, only those DDI-ADE associations were considered that met the disproportionality threshold of Ω > 0 for a CYP substrate when paired with at least two inhibitors. In total, 590 ADEs were associated with 2085 PK DDI pairs and 38 individual substrates, with ADEs overlapping across different CYP substrates. More importantly, we were able to find clinical and experimental evidence for the paclitaxel-clopidogrel interaction associated with peripheral neuropathy in our study. CONCLUSION: In this study, we utilized a translational informatics approach to discover potentially novel CYP-related substrate-inhibitor and ADE associations using FAERS. Future clinical, population-based and experimental studies are needed to confirm our findings.

The Complex Management of Atrial Fibrillation and Cancer in the COVID-19 Era: Drug Interactions, Thromboembolic Risk, and Proarrhythmia.

PURPOSE OF REVIEW: Cardiotoxicity by anticancer agents has emerged as a multifaceted issue and is expected to affect both mortality and morbidity. This review summarizes clinical challenges in the management of oncological patients requiring anticoagulants for atrial fibrillation (AF) also considering the current outbreak of the COVID-19 (coronavirus disease 2019) pandemic, since this infection can add challenges to the management of both conditions. Specifically, the aims are manyfold: (1) describe the evolving use of direct oral anticoagulants (DOACs) in AF patients with cancer; (2) critically appraise the risk of clinically important drug-drug interactions (DDIs) between DOACs and oral targeted anticancer agents; (3) address expected DDIs between DOACs and candidate anti-COVID drugs, with implications on management of the underlying thrombotic risk; and (4) characterize the proarrhythmic liability in cardio-oncology in the setting of COVID-19, focusing on QT prolongation. RECENT FINDINGS: AF in cardio-oncology poses diagnostic and management challenges, also due to the number of anticancer drugs recently associated with AF onset/worsening. Oral targeted drugs can potentially interact with DOACs, with increased bleeding risk mainly due to pharmacokinetic DDIs. Moreover, the vast majority of oral anticancer agents cause QT prolongation with direct and indirect mechanisms, potentially resulting in the occurrence of torsade de pointes, especially in susceptible patients with COVID-19 receiving additional drugs with QT liability. Oncologists and cardiologists must be aware of the increased bleeding risk and arrhythmic susceptibility of patients with AF and cancer due to DDIs. High-risk individuals with COVID-19 should be prioritized to target preventive strategies, including optimal antithrombotic management, medication review, and stringent monitoring.

The current understanding of the interactions between nanoparticles and cytochrome P450 enzymes - a literature-based review.

Nanoparticles (NPs) have wide spectrum applications in the areas of industry and biomedicine. However, concerns about their toxic and negative impacts on the environments as well as human health have been raised. Cytochrome P450s (CYPs) are involved in endogenous and exogenous metabolism. Modulations of CYP can adversely damage drug metabolism, detoxification of xenobiotics and animal physiology functions. This article focused on NPs-CYP interactions for humans and animals available in the literature. It was found that different NPs process specific inhibitory potencies against CYPs involved in drug metabolism. Moreover, NPs were able to modify the expression of CYPs genes or protein in humans and other animals, which highlighted their detoxification functions. Nonetheless, changes of CYPs responsible for hormone synthesis and metabolism resulted in endocrine disturbances. Hence, there is a need to screen newly developed NPs to evaluate their interactions with CYPs. The future studies should further strategize the in vitro approaches to reveal the molecular mechanisms behind interactions by taking full considerations of the interference of co-factors, buffers, substrates and metabolites with NPs. Moreover, in vivo studies should compare the influences of NPs via different administration routes and different duration of treatments to reveal the physiological significance.

Cytochrome P450 interactions are common and consequential in Massachusetts hospital discharges.

Despite the recognition that drug-drug interactions contribute substantially to preventable health-care costs, the prevalence of such interactions related to the cytochrome P450 system in clinical practice remains poorly characterized. This study drew retrospective hospital discharge cohorts from a large health claims data set and a large health system data set. For every hospital discharge, frequency of co-occurrence of substrates and inducers or inhibitors at cytochrome P450 2D6, 2C19, 3A4 and 1A2 were determined. A total of 124 520 individuals in the state of Massachusetts (health claims cohort) and 77 026 individuals in two large academic medical centers (electronic health record (EHR) cohort) were examined. In the claims cohort, 35 157 (28.2%) exhibited at least one CYP450 drug-drug interaction at hospital discharge, whereas in the EHR cohort, 36 750 (47.7%) had at least one interaction. The most commonly affected CYP450 systems were 2C19 and 2D6, with putative interactions observed in at least 10% of individuals at discharge in each cohort. Odds of hospital readmission within 90 days among those discharged with at least one interaction were 10-16% greater, with mean health-care cost $574/month greater over the subsequent year, after adjusting for age, sex, insurance type, total number of medications prescribed, Charlson comorbidity score and presence or absence of a psychiatric diagnosis. These two distinct clinical data types show that CYP450 drug-drug interactions are prevalent and associated with greater probability of early hospital readmission and greater health-care cost, despite the widespread availability and application of drug-drug interaction checking software.

Effect of valproic acid on perampanel pharmacokinetics in patients with epilepsy.

We prospectively examined the effect of antiepileptic (AED) cotherapy on steady state plasma concentrations of perampanel (PMP) in epileptic patients. We classified AEDs as strong enzyme inducers (carbamazepine, phenobarbital, phenytoin, oxcarbazepine), not strong enzyme inducers/not inhibitors (levetiracetam, lamotrigine, topiramate, rufinamide, lacosamide, zonisamide, clobazam), and enzyme inhibitors (valproic acid [VPA]). The main outcome was the comparison of PMP plasma concentration to weight-adjusted dose ratio (C/D; [µg/mL]/mg kg-1  d-1 ) among comedication subgroups. From 79 patients (42 females, 37 males) aged (mean ± standard deviation) 33 ± 13 years (range = 12-66 years), 114 plasma samples were collected. Twenty-eight patients (44 samples) were cotreated with enzyme inducers (group A), 21 (27 samples) with not strong enzyme inducers/not inhibitors (group B), 21 (31 samples) with not strong enzyme inducers/not inhibitors + VPA (group C), and 9 (12 samples) with enzyme inducers + VPA (group D). PMP C/D was reduced (-56%, P < .001) in group A (1.79 ± 0.80) versus group B (4.05 ± 2.16) and increased (P < .001) in group C (6.72 ± 4.04) compared with groups A (+275%), B (+66%), and D (2.76 ± 2.00, +143%). Our study documents the unpublished higher PMP C/D in patients cotreated with VPA. These findings have both theoretical relevance, suggesting better characterization of PMP metabolic pathways with ad hoc studies, and clinical usefulness in managing patients on AED polytherapy.

A Chemoproteomic Platform To Assess Bioactivation Potential of Drugs.

Reactive metabolites (RM) formed from bioactivation of drugs can covalently modify liver proteins and cause mechanism-based inactivation of major cytochrome P450 (CYP450) enzymes. Risk of bioactivation of a test compound is routinely examined as part of lead optimization efforts in drug discovery. Here we described a chemoproteomic platform to assess in vitro and in vivo bioactivation potential of drugs. This platform enabled us to determine reactivity of thousands of proteomic cysteines toward RMs of diclofenac formed in human liver microsomes and living animals. We pinpointed numerous reactive cysteines as the targets of RMs of diclofenac, including the active (heme-binding) sites on several key CYP450 isoforms (1A2, 2E1 and 3A4 for human, 2C39 and 3A11 for mouse). This general platform should be applied to other drugs, drug candidates, and xenobiotics with potential hepatoxicity, including environmental organic substances, bioactive natural products, and traditional Chinese medicine.

Study on influence of piperine treatment on the pharmacokinetics of diclofenac in healthy volunteers.

1. Diclofenac sodium (DIC) is a widely used anti-inflammatory drug and its administration in humans receiving long-term therapy with herbal drugs containing piperine (PIP) may occur, which leads to drug-phytochemical interactions. The purpose of the present study was to investigate the influence of PIP treatment on the pharmacokinetics of DIC in healthy volunteers. 2. The open-label, two period, sequential study was conducted in 12 healthy volunteers. PIP 20 mg was administered once daily for 10 days during treatment phase. A single dose of DIC 100 mg was administered during control and after treatment phases under fasting conditions. The blood samples were collected after DIC dosing at predetermined time intervals and analyzed by HPLC. 3. Treatment with PIP significantly enhanced maximum plasma concentration (Cmax) (2.24-3.68 µg/mL, p < 0.05), area under the curve (AUC) (7.09-11.81 µg h/mL, p < 0.05), half-life (T1/2) (1.23-1.65 h, p < 0.05) and significantly decreased elimination rate constant (Kel) (0.62-0.41 h-1, p < 0.05), apparent oral clearance (CL/F) (7.57-4.52 L/h, p < 0.05) of DIC as compared to that of control phase. 4. The results suggest that the altered pharmacokinetics of DIC might be attributed to PIP mediated inhibition of CYP2C9 enzyme, which indicates the clinically significant interaction present between DIC and PIP. Therefore, the combination therapy of DIC along with PIP may represent a novel approach to reduce dosage and result in reduced incidence of gastrointestinal side effects seen with DIC alone at higher doses.

Population pharmacokinetics of ospemifene and safety evaluation of pharmacokinetic alterations caused by intrinsic and extrinsic factors
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PURPOSE: To develop a population pharmacokinetic (PPK) model to assess factors influencing ospemifene pharmacokinetics and to assess safety for pharmacokinetic alteration observed in drug development. METHOD: A PPK model was constructed using pooled ospemifene concentrations. Covariates considered before start of the analysis were: age, race, body weight, BMI, albumin, alanine amino-transferase, bilirubin, and creatinine clearance. The expected distribution of ospemifene concentration was derived for the 4 cases in phase-1 studies that increased ospemifene exposure: administration to severe renal impairment subjects (case 1), administration to moderate hepatic impairment subjects (case 2), coadministration with ketoconazole (case 3), or coadministration with fluconazole (case 4). Safety information in a long-term safety trial was used to assess the potential changes in risk of adverse events with ospemifene-exposure increase. RESULTS: The PPK parameter estimates were 9.16 L/h for CL/F, 34.3 L for V2/F, 16.4 L/h for Q/F, 250 L for V3/F, and 0.522 h-1 for ka, based on the final model. Distributions of estimated AUC in a phase-3 study largely covered the expected distribution for case 1, case 2, or case 3, but did not overlap the expected distribution for case 4. The incidences of adverse events were not associated with ospemifene exposure in the long-term safety study. CONCLUSIONS: We developed an ospemifene PPK model and identified no relevant covariate in the PPK analysis. The drug appears safe to use in renal impairment, moderate hepatic impairment, and when coadministered with ketoconazole. Ospemifene should not be administered with fluconazole.
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Efavirenz and the CNS: what we already know and questions that need to be answered.

The NNRTI efavirenz has long been one of the most frequently employed antiretroviral drugs in the multidrug regimens used to treat HIV infection, in accordance with its well-demonstrated antiretroviral efficacy and favourable pharmacokinetics. However, growing concern about its adverse effects has sometimes led to efavirenz being replaced by other drugs in the initial treatment selection or to switching of therapy to efavirenz-free regimens in experienced patients. Neurological and neuropsychiatric reactions are the manifestations most frequently experienced by efavirenz-treated patients and range from transitory effects, such as nightmares, dizziness, insomnia, nervousness and lack of concentration, to more severe symptoms including depression, suicidal ideation or even psychosis. In addition, efavirenz has recently been associated with mild/moderate neurocognitive impairment, which is of specific relevance given that half of the patients receiving ART eventually suffer some form of HIV-associated neurocognitive disorder. The mechanisms responsible for efavirenz-induced neurotoxicity are unclear, although growing evidence points to disturbances in brain mitochondrial function and bioenergetics. This review offers a comprehensive overview of the current evidence on the interaction that efavirenz displays with the CNS, including the penetration and concentration of the drug in the brain. We discuss the prevalence, types and specificities of its side effects and recently uncovered cellular mechanisms that may be involved in their development.

Melatonin Interaction Resulting in Severe Sedation.

PURPOSE: Natural health products (NHPs), including melatonin, are widely used products. Despite the widespread assumption that all NHPs are safe, they contain pharmacologically active substances and can therefore have adverse effects and/or interact with pharmaceuticals. OBJECTIVE: To investigate the mechanism underlying NHP interactions identified through the Pharmacy SONAR active surveillance study. METHODS: Active surveillance was undertaken in community pharmacies to identify adverse events in patients who had recently taken NHPs together with conventional pharmaceuticals. For suspected NHP-pharmaceutical interactions, the possible mechanism of action was explored by in vitro analysis of samples of different products to identify cytochrome P450 enzyme (CYP) inhibition potential. RESULTS: Active surveillance identified a 19-year-old male taking citalopram, nortriptyline and oxycodone concomitantly and who experienced severe sedation when melatonin was added to this regimen. In vitro analysis involving several melatonin products showed product-dependent inhibition of CYP1A2, CYP2C19 and CYP3A7. CONCLUSION: The adverse event was likely due to a primary pharmacokinetic interaction between melatonin and citalopram; although mechanistically, interactions affecting cytochrome P450-mediated metabolism may have occurred with all of these health products. A pharmacodynamic interaction may also be possible, but beyond the capacity of this study to establish.

Mechanism-based inhibition of CYPs and RMs-induced hepatoxicity by rutaecarpine.

1. Rutaecarpine, a quinolone alkaloid isolated from the unripe fruit of Evodia rutaecarpa, is one of the main active components used in a variety of clinical applications, including the treatment of hypertension and arrhythmia. However, its hepatotoxicity has also been reported in recent years. 2. Reactive metabolites (RMs) play a vital role in drug-induced liver injury. Rutaecarpine has a secondary amine structure that may be activated to RMs. The aim of the study was to investigate the inhibition of rutaecarpine on CYPs and explore the possible relationship between RMs and potential hepatotoxicity. 3. A cell counting kit-8 cytotoxicity assay indicated that rutaecarpine can decrease the primary rat hepatocyte viability, increase lactate dehydrogenase and reactive oxygen species, reduce JC-1, and cause cell stress and membrane damage. The indexes were significantly restored by adding ABT, an inhibitor of CYPs. A cocktail assay showed that CYP1A2, CYP2C9, CYP2C19, CYP2E1 and CYP3A4 can be inhibited by rutaecarpine in human liver microsomes. The IC50 values of CYP1A2 with and without NADPH were 2.2 and 7.4 µM, respectively, which presented a 3.3 shift. The results from a metabolic assay indicated that three mono-hydroxylated metabolites and two di-hydroxylated metabolites were identified and two GSH conjugates were also trapped. 4. Rutaecarpine can inhibit the activities of CYPs and exhibit a potential mechanism-based inhibition on CYP1A2. RMs may cause herb-drug interactions, providing important information for predicting drug-induced hepatotoxicity.

The effects of Andrographis paniculata (Burm.f.) Nees extract and diterpenoids on the CYP450 isoforms' activities, a review of possible herb-drug interaction risks.

Andrographis paniculata (Burm.f.) Nees is a popular medicinal plant and its components are used in various traditional product preparations. However, its herb-drug interactions risks remain unclear. This review specifically discusses the various published studies carried out to evaluate the effects of Andrographis paniculata (Burm.f.) Nees plant extracts and diterpenoids on the CYP450 metabolic enzyme and if the plant components pose a possible herb-drug interaction risk. Unfortunately, the current data are insufficient to indicate if the extracts or diterpenoids can be labeled as in vitro CYP1A2, CYP2C9 or CYP3A4 inhibitors. A complete CYP inhibition assay utilizing human liver microsomes and the derivation of relevant parameters to predict herb-drug interaction risks may be necessary for these isoforms. However, based on the current studies, none of the extracts and diterpenoids exhibited CYP450 induction activity in human hepatocytes or human-derived cell lines. It is crucial that a well-defined experimental design is needed to make a meaningful herb-drug interaction prediction.

Inhibitory effects of curcumin on activity of cytochrome P450 2C9 enzyme in human and 2C11 in rat liver microsomes.

Cytochrome P450 2C9 (CYP2C9), one of the most important phase I drug metabolizing enzymes, could catalyze the reactions that convert diclofenanc into diclofenac 4'-hydroxylation. Evaluation of the inhibitory effects of compounds on CYP2C9 is clinically important because inhibition of CYP2C9 could result in serious drug-drug interactions. The objective of this work was to investigate the effects of curcumin on CYP2C9 in human and cytochrome P450 2C11 (CYP2C11) in rat liver microsomes. The results showed that curcumin inhibited CYP2C9 activity (10 µmol L(-1) diclofenac) with half-maximal inhibition or a half-maximal inhibitory concentration (IC50) of 15.25 µmol L(-1) and Ki = 4.473 µmol L(-1) in human liver microsomes. Curcumin's mode of action on CYP2C9 activity was noncompetitive for the substrate diclofenanc and uncompetitive for the cofactor NADPH. In contrast to its potent inhibition of CYP2C9 in human, diclofenanc had lesser effects on CYP2C11 in rat, with an IC50 ≥100 µmol L(-1). The observations imply that curcumin has the inhibitory effects on CYP2C9 activity in human. These in vitro findings suggest that more attention should be paid to special clinical caution when intake of curcumin combined with other drugs in treatment.

Chloramphenicol significantly affects the pharmacokinetics of oral methadone in Greyhound dogs.

OBJECTIVE: To assess the effects of cytochrome P450 (CYP) inhibitors (ketoconazole, chloramphenicol, trimethoprim, fluoxetine, cimetidine and medetomidine) in various combinations on the pharmacokinetics of oral methadone in Greyhound dogs to determine the specific effects of the different inhibitors and if a clinically relevant interaction occurs. STUDY DESIGN: Non-randomized, sequential design. ANIMALS: Six healthy Greyhound dogs (three male, three female). METHODS: Canine CYP inhibitors (ketoconazole, chloramphenicol, trimethoprim, fluoxetine, cimetidine and medetomidine) were administered in varying combinations prior to the administration of oral methadone. Plasma was obtained from each dog to enable the determination of methadone and CYP inhibitor drug concentrations using liquid chromatography with either mass spectrometry or ultraviolet detection. RESULTS: Significant increases in the area under the curve (AUC) and maximum plasma concentrations (CMAX ) of methadone occurred in all groups administered chloramphenicol. The AUC (6 hours ng mL(-1)) and CMAX (6 ng mL(-1)) of methadone significantly increased to 541 hours ng mL(-1) and 47.8 ng mL(-1), respectively, when methadone was administered with chloramphenicol as a sole inhibitor. There were no significant effects of CYP inhibitors other than chloramphenicol on methadone pharmacokinetics, which suggests that chloramphenicol was primarily responsible for the pharmacokinetic interaction. CONCLUSIONS AND CLINICAL RELEVANCE: This study demonstrated significant effects of chloramphenicol on the pharmacokinetics of oral methadone. Further studies should investigate the effects of chloramphenicol on methadone pharmacokinetics in multiple dog breeds and examine whether oral methadone would be an effective analgesic in dogs. In addition, the safety of chloramphenicol and its effects on the pharmacokinetics of parenteral methadone warrant assessment.

Pharmacoepidemiologic and in vitro evaluation of potential drug-drug interactions of sulfonylureas with fibrates and statins.

AIMS: To examine whether initiation of fibrates or statins in sulfonylurea users is associated with hypoglycaemia, and examine in vitro inhibition of cytochrome P450 (CYP) enzymes by statins, fenofibrate and glipizide. METHODS: We used healthcare data to conduct nested case-control studies of serious hypoglycaemia (i.e. resulting in hospital admission or emergency department treatment) in persons taking glipizide or glyburide, and calculated adjusted overall and time-stratified odds ratios (ORs) and 95% confidence intervals (CIs). We also characterized the in vitro inhibition of CYP enzymes by statins, fenofibrate and glipizide using fluorometric CYP450 inhibition assays, and estimated area under the concentration-time curve ratios (AUCRs) for the drug pairs. RESULTS: We found elevated adjusted overall ORs for glyburide-fenofibrate (OR 1.84, 95% CI 1.37, 2.47) and glyburide-gemfibrozil (OR 1.57, 95% CI 1.25, 1.96). The apparent risk did decline over time as might be expected from a pharmacokinetic mechanism. Fenofibrate was a potent in vitro inhibitor of CYP2C19 (IC50 = 0.2 µm) and CYP2B6 (IC50 = 0.7 µm) and a moderate inhibitor of CYP2C9 (IC50 = 9.7 µm). The predicted CYP-based AUCRs for fenofibrate-glyburide and gemfibrozil-glyburide interactions were only 1.09 and 1.04, suggesting that CYP inhibition is unlikely to explain such an interaction. CONCLUSIONS: Use of fenofibrate or gemfibrozil together with glyburide was associated with elevated overall risks of serious hypoglycaemia. CYP inhibition seems unlikely to explain this observation. We speculate that a pharmacodynamic effect of fibrates (e.g. activate peroxisome proliferator-activator receptor alpha) may contribute to these apparent interactions.

Association of CYP1A1 and CYP1B1 inhibition in in vitro assays with drug-induced liver injury.

Drug-induced liver injury (DILI) is one of the major causes for the discontinuation of drug development and withdrawal of drugs from the market. Since it is known that reactive metabolite formation and being substrates or inhibitors of cytochrome P450s (P450s) are associated with DILI, we systematically investigated the association between human P450 inhibition and DILI. The inhibitory activity of 266 DILI-positive drugs (DILI drugs) and 92 DILI-negative drugs (no-DILI drugs), which were selected from Liver Toxicity Knowledge Base (US Food and Drug Administration), against 8 human P450 forms was assessed using recombinant enzymes and luminescent substrates, and the threshold values showing the highest balanced accuracy for DILI discrimination were determined for each P450 enzyme using receiver operating characteristic analyses. The results showed that among the P450s tested, CYP1A1 and CYP1B1 were inhibited by DILI drugs more than no-DILI drugs with a statistical significance. We found that 91% of drugs that showed inhibitory activity greater than the threshold values against CYP1A1 or CYP1B1 were DILI drugs. The results of internal 5-fold cross-validation confirmed the usefulness of CYP1A1 and CYP1B1 inhibition data for the threshold-based discrimination of DILI drugs. Although the contribution of these P450s to drug metabolism in the liver is considered minimal, our present findings suggest that the assessment of CYP1A1 and CYP1B1 inhibition is useful for screening DILI risk of drug candidates at the early stage of drug development.

Cannabis and Cannabinoids: Kinetics and Interactions.

Cannabis sativa and related products are widely used, but their potential to cause significant clinical interactions remains unclear, particularly for cannabinoid-enriched or otherwise concentrated products. The pharmacokinetics of most cannabis products is not known. Where information is known, there is wide variation. Extrapolation of limited clinical data is complicated by the complexity and variability of cannabis products as well as their delivery through various routes of administration. In vitro evidence shows that the major cannabinoids are substrates for numerous metabolic enzymes, including the cytochrome P450 metabolizing enzymes. Whereas many consumers consider cannabis products to be safe relative to alternative prescription or narcotic drugs, clinical reports of cannabis-related drug interactions and adverse events are increasing in frequency. Patients using these products, whether for medical or nonmedical purposes, together with conventional therapeutic agents may be at increased risk of adverse events, including therapeutic failure, and require enhanced monitoring.

Administration of a long-acting antipsychotic injection to a child while managing contraindicated polypharmacy interactions and transition between services.

Second-generation antipsychotics are used to treat a variety of psychiatric symptoms and illnesses as well as the behavioural aspects of various neurodevelopmental disorders. However, there is reluctance in using second-generation long-acting injectable antipsychotics in child psychiatry services. We present a case of a 12-year-old child whose presentation and medication regime warranted the use of aripiprazole long-acting injection against a backdrop of potential CYP P450 enzyme interactions as a consequence of polypharmacy. The case also describes the difficulties encountered working across different health sectors and agencies and highlights the ongoing need for skills-based Continuous Professional Development for Child and Adolescent Mental Health Services-based nursing staff.