In depth characterization of physicochemical critical quality attributes of a clinical drug-dendrimer conjugate.

A deep and detailed understanding of drug-dendrimer conjugates key properties is needed to define the critical quality attributes that affect drug product performance. The characterization must be executed both in the formulation media and in biological matrices. This, nevertheless, is challenging on account of a very limited number of suitable, established methods for characterizing the physicochemical properties, stability, and interaction with biological environment of complex drug-dendrimer conjugates. In order to fully characterize AZD0466, a drug-dendrimer conjugate currently under clinical development by AstraZeneca, a collaboration was initiated with the European Nanomedicine Characterisation Laboratory to deploy a state-of-the-art multi-step approach to measure physicochemical properties. An incremental complexity characterization approach was applied to two batches of AZD0466 and the corresponding dendrimer not carrying any drug, SPL-8984. Thus, the aim of this work is to guide in depth characterization efforts in the analysis of drug-dendrimer conjugates. Additionally, it serves to highlight the importance of using the adequate complementary techniques to measure physical and chemical stability in both simple and biological media, to drive a complex drug-dendrimer conjugate product from discovery to clinical development.

The Global Characterisation of a Drug-Dendrimer Conjugate - PEGylated poly-lysine Dendrimer.

The recent emergence of drug-dendrimer conjugates within pharmaceutical industry research and development introduces a range of challenges for analytical and measurement science. These molecules are very high molecular weight (100-200kDa) with a significant degree of structural complexity. The characteristics and quality attributes that require understanding and definition, and impact efficacy and safety, are diverse. They relate to the intact conjugate, the various building blocks of these complex systems and the level of the free and bound active pharmaceutical ingredient (API). From an analytical and measurement science perspective, this necessitates the measurement of the molecular weight, impurity characterisation, the quantitation of the number of conjugated versus free API molecules, the determination of the impurity profiles of the building blocks, primary structure and both particle size and morphology. Here we report the first example of a global characterisation of a drug-dendrimer conjugate - PEGylated poly-lysine dendrimer currently under development (AZD0466). The impact of the wide variety of analytical and measurement techniques on the overall understanding of this complex molecular entity is discussed, with the relative capabilities of the various approaches compared. The results of this study are an essential platform for the research and development of the future generations of related dendrimer-based medicines.

Determining bioequivalence possibilities of long acting injectables through population PK modelling.

Long acting injectables (LAI) products are a popular intervention for treating a number of chronic conditions, with their long drug release reducing the administration frequency and thus improving patient adherence. The extended release, however, can provide a major challenge to bioequivalence (BE) testing since the long absorption half-life results in a long washout period, meaning that a traditional BE study can be many months or years in length. The unique PK profile for LAI products also means that it is critical to have appropriate metrics to summarise the plasma concentration profile. In this work, we use paliperidone as a case study to demonstrate how Population PK modelling can be utilised to explore sensitivity of summary metrics to different products. We also determine a range of products that are bioequivalent after both multiple dosing and single dosing. Finally, we show how the modelling can be used in a (virtual) PK study as an alternative approach to determining bioequivalence. This work demonstrates the potential for Population PK modelling in bioequivalence assessment, opening doors to more streamlined product development.

Design and optimisation of dendrimer-conjugated Bcl-2/xL inhibitor, AZD0466, with improved therapeutic index for cancer therapy.

Dual Bcl-2/Bcl-xL inhibitors are expected to deliver therapeutic benefit in many haematological and solid malignancies, however, their use is limited by tolerability issues. AZD4320, a potent dual Bcl-2/Bcl-xL inhibitor, has shown good efficacy however had dose limiting cardiovascular toxicity in preclinical species, coupled with challenging physicochemical properties, which prevented its clinical development. Here, we describe the design and development of AZD0466, a drug-dendrimer conjugate, where AZD4320 is chemically conjugated to a PEGylated poly-lysine dendrimer. Mathematical modelling was employed to determine the optimal release rate of the drug from the dendrimer for maximal therapeutic index in terms of preclinical anti-tumour efficacy and cardiovascular tolerability. The optimised candidate is shown to be efficacious and better tolerated in preclinical models compared with AZD4320 alone. The AZD4320-dendrimer conjugate (AZD0466) identified, through mathematical modelling, has resulted in an improved therapeutic index and thus enabled progression of this promising dual Bcl-2/Bcl-xL inhibitor into clinical development.

IMI - Oral biopharmaceutics tools project - Evaluation of bottom-up PBPK prediction success part 4: Prediction accuracy and software comparisons with improved data and modelling strategies.

Oral drug absorption is a complex process depending on many factors, including the physicochemical properties of the drug, formulation characteristics and their interplay with gastrointestinal physiology and biology. Physiological-based pharmacokinetic (PBPK) models integrate all available information on gastro-intestinal system with drug and formulation data to predict oral drug absorption. The latter together with in vitro-in vivo extrapolation and other preclinical data on drug disposition can be used to predict plasma concentration-time profiles in silico. Despite recent successes of PBPK in many areas of drug development, an improvement in their utility for evaluating oral absorption is much needed. Current status of predictive performance, within the confinement of commonly available in vitro data on drugs and formulations alongside systems information, were tested using 3 PBPK software packages (GI-Sim (ver.4.1), Simcyp® Simulator (ver.15.0.86.0), and GastroPlus™ (ver.9.0.00xx)). This was part of the Innovative Medicines Initiative (IMI) Oral Biopharmaceutics Tools (OrBiTo) project. Fifty eight active pharmaceutical ingredients (APIs) were qualified from the OrBiTo database to be part of the investigation based on a priori set criteria on availability of minimum necessary information to allow modelling exercise. The set entailed over 200 human clinical studies with over 700 study arms. These were simulated using input parameters which had been harmonised by a panel of experts across different software packages prior to conduct of any simulation. Overall prediction performance and software packages comparison were evaluated based on performance indicators (Fold error (FE), Average fold error (AFE) and absolute average fold error (AAFE)) of pharmacokinetic (PK) parameters. On average, PK parameters (Area Under the Concentration-time curve (AUC0-tlast), Maximal concentration (Cmax), half-life (t1/2)) were predicted with AFE values between 1.11 and 1.97. Variability in FEs of these PK parameters was relatively high with AAFE values ranging from 2.08 to 2.74. Around half of the simulations were within the 2-fold error for AUC0-tlast and around 90% of the simulations were within 10-fold error for AUC0-tlast. Oral bioavailability (Foral) predictions, which were limited to 19 APIs having intravenous (i.v.) human data, showed AFE and AAFE of values 1.37 and 1.75 respectively. Across different APIs, AFE of AUC0-tlast predictions were between 0.22 and 22.76 with 70% of the APIs showing an AFE > 1. When compared across different formulations and routes of administration, AUC0-tlast for oral controlled release and i.v. administration were better predicted than that for oral immediate release formulations. Average predictive performance did not clearly differ between software packages but some APIs showed a high level of variability in predictive performance across different software packages. This variability could be related to several factors such as compound specific properties, the quality and availability of information, and errors in scaling from in vitro and preclinical in vivo data to human in vivo behaviour which will be explored further. Results were compared with previous similar exercise when the input data selection was carried by the modeller rather than a panel of experts on each in vitro test. Overall, average predictive performance was increased as reflected in smaller AAFE value of 2.8 as compared to AAFE value of 3.8 in case of previous exercise.

Novel application of synchrotron x-ray computed tomography for ex-vivo imaging of subcutaneously injected polymeric microsphere suspension formulations.

PURPOSE: Subcutaneously or intramuscularly administered biodegradable microsphere formulations have been successfully exploited in the management of chronic conditions for over two decades, yet mechanistic understanding of the impact of formulation attributes on in vivo absorption rate from such systems is still in its infancy. METHODS: Suspension formulation physicochemical attributes may impact particulate deposition in subcutaneous (s.c.) tissue. Hence, the utility of synchrotron X-ray micro-computed tomography (µCT) for assessment of spatial distribution of suspension formulation components (PLG microspheres and vehicle) was evaluated in a porcine s.c. tissue model. Optical imaging of dyed vehicle and subsequent microscopic assessment of microsphere deposition was performed in parallel to compare the two approaches. RESULTS: Our findings demonstrate that synchrotron µCT can be applied to the assessment of microsphere and vehicle distribution in s.c. tissue, and that microspheres can also be visualised in the absence of contrast agent using this approach. The technique was deemed superior to optical imaging of macrotomy for the characterisation of microsphere deposition owing to its non-invasive nature and relatively rapid data acquisition time. CONCLUSIONS: The method outlined in this study provides a proof of concept feasibility for µCT application to determining the vehicle and suspended PLG microspheres fate following s.c. injection. A potential application for our findings is understanding the impact of injection, device and formulation variables on initial and temporal depot geometry in pre-clinical or ex-vivo models that can inform product design. Graphical abstract.

Predicting bioavailability of monoclonal antibodies after subcutaneous administration: Open innovation challenge.

Despite the increasing trend towards subcutaneous delivery of monoclonal antibodies, factors influencing the subcutaneous bioavailability of these molecules remain poorly understood. To address critical knowledge gaps and issues during development of subcutaneous dosage forms for monoclonal antibodies, the Subcutaneous Drug Delivery and Development Consortium was convened in 2018 as a pre-competitive collaboration of recognized industry experts. One of the Consortium's eight problem statements highlights the challenges of predicting human bioavailability of subcutaneously administered monoclonal antibodies due to a lack of reliable in vitro and preclinical in vivo predictive models. In this paper, we assess the current landscape in subcutaneous bioavailability prediction for monoclonal antibodies and discuss the gaps and opportunities associated with bioavailability models for biotherapeutics. We also issue an open challenge to industry and academia, encouraging the development of reliable models to enable subcutaneous bioavailability prediction of therapeutic large molecules in humans and improve translation from preclinical species.

Nonclinical safety and pharmacokinetics of Miglyol 812: A medium chain triglyceride in exenatide once weekly suspension.

Exenatide, a glucagon-like peptide-1 receptor agonist was originally developed as either a twice daily or once weekly injectable therapeutic for patients with type 2 diabetes. Exenatide QW suspension was developed for use with an autoinjector device, in which the microspheres are suspended in Miglyol 812, a mixture of medium chain triglycerides (MCTs). MCTs are a class of lipids whose fatty acid chains contain from six to 12 carbon atoms (medium chain fatty acids or MCFAs). While MCTs are edible oils present in many foods, including foodstuffs containing coconut and palm kernel oils, limited information is available regarding the oral and subcutaneous bioavailability of MCTs as well as safety following subcutaneous injection. These studies were designed to investigate the non-clinical pharmacokinetics and safety of MCTs. In a single dose pharmacokinetic study, MCFAs were rapidly detected in the plasma of rats following oral administration of either Miglyol 812 or tricaprylin at doses of 10 or 9.48 g kg-1 , respectively. Following subcutaneous dosing with Miglyol 812, MCFAs were rapidly absorbed with a similar profile to that following oral dosing. Furthermore, the toxicity of Miglyol 812 alone was evaluated in a 3 month repeat dose toxicology studies in cynomolgus monkeys. In this study, weekly subcutaneous doses of 0.15 g kg-1 did not elicit any treatment-related effects in cynomolgus monkeys. In conclusion, these studies alongside the available literature data show that Miglyol 812 is a safe excipient for use in subcutaneously administered therapeutics.

Lean methodology: an evidence-based practice approach for healthcare improvement.

Lean methodology, an evidence-based practice approach adopted from Toyota, is grounded on the pillars of respect for people and continuous improvement. This article describes the use of Lean methodology to improve healthcare outcomes for patients with community-acquired pneumonia. Nurse practitioners and other clinicians should be knowledgeable about this methodology and become leaders in Lean transformation.

An investigation into the utility of a multi-compartmental, dynamic, system of the upper gastrointestinal tract to support formulation development and establish bioequivalence of poorly soluble drugs.

In recent years mechanical systems have been developed that more closely mimic the full dynamic, physical and biochemical complexity of the GI Tract. The development of these complex systems raises the possibility that they could be used to support formulation development of poorly soluble compounds and importantly may be able to replace clinical BE studies in certain circumstances. The ability of the TNO Simulated Gastro-Intestinal Tract Model 1 (TIM-1) Dynamic Artificial Gastrointestinal System in the 'lipid membrane' configuration to support the development of Biopharmaceutics Classification System Class 2 compounds was investigated by assessing the performance of various AZD8055 drug forms and formulations in the TIM-1 system under standard fasting and achlorhydric physiological conditions. The performance data were compared with exposure data from the phase 1 clinical study. Analysis of the AZD8055 plasma concentrations after tablet administration supported the conclusions drawn from the TIM-1 experiments and confirmed that these complex systems can effectively support the product development of poorly soluble drugs. Particularly, the TIM-1 system was able to show that AZD8055 exposure would increase in an approximately dose proportional manner and not be limited by the solubility or dissolution. Additionally, the investigations also showed that the exposure produced by a solution and a tablet would be the same. Specific instances when the TIM-1 system may not be predictive of clinical product performance have also been identified.

Dynamic study of oxidative stress in renal dialysis patients based on breath ethane measured by optical spectroscopy.

The application of optical spectroscopy for rapid accurate measurement of breath biomarkers has opened up new possibilities for monitoring and diagnostics in recent years. Here, we report on how our recent advances in optical detection of ethane have enabled us to record dynamic breath ethane patterns for patients undergoing kidney dialysis. Ethane is well established as a breath biomarker for free radical induced cell degradation. Moreover, renal dialysis is known to induce such oxidative attack, and our measurements may offer insight into the nature of this assault. Specifically, we have discovered that patients undergo significant breath ethane elevation at the beginning of each dialysis session. We have found an inverse relationship between the magnitude of this effect and number of months patients have been receiving treatment. We comment on how further refinements of our technology will allow a more detailed evaluation of the ethane elevation effect and ultimately lead to the assessment of potential interventions.