Challenges and trends in apomorphine drug delivery systems for the treatment of Parkinson's disease

Model-based comparison of subcutaneous versus sublingual apomorphine administration in the treatment of motor fluctuations in Parkinson's disease

The objective of this study was to compare the effectiveness of subcutaneous (SC) and sublingual (SL) formulations of apomorphine for the treatment of motor fluctuations in Parkinson's disease using a pharmacokinetics (PK)/pharmacodynamics (PD) modeling approach. The PK of SC and SL apomorphine are best described by a one-compartment model with first-order absorption and a two-compartment model with delayed absorption, respectively. The PK/PD model relating apomorphine plasma concentrations to the Unified Parkinson's Disease Rating Scale (UPDRS) motor scores was described by a sigmoidal Emax model assuming effective concentration = drug concentration in an effect compartment. Apomorphine concentrations and UPDRS motor scores were simulated from the PK/PD models using 500 hypothetical subjects. UPDRS motor score change from baseline was evaluated using time to clinically relevant response, response duration, area under the curve, maximal response, and time to maximal response. Higher doses of each apomorphine formulation were associated with shorter time to response, longer response duration, and greater maximal response. Although the mean maximal responses to SC and SL apomorphine were comparable, the time to response was four times shorter (7 vs. 31 min) and time to maximal response was two times shorter (27 vs. 61 min) for 4 mg SC vs. 50 mg SL. Thus, faster onset of action was observed for the SC formulation compared to SL. These data may be useful for physicians when selecting "on demand" therapy for patients with Parkinson's disease experiencing motor fluctuations.

Management of Brain Cancer and Neurodegenerative Disorders with Polymer-Based Nanoparticles as a Biocompatible Platform

The blood-brain barrier (BBB) serves as a protective barrier for the central nervous system (CNS) against drugs that enter the bloodstream. The BBB is a key clinical barrier in the treatment of CNS illnesses because it restricts drug entry into the brain. To bypass this barrier and release relevant drugs into the brain matrix, nanotechnology-based delivery systems have been developed. Given the unstable nature of NPs, an appropriate amount of a biocompatible polymer coating on NPs is thought to have a key role in reducing cellular cytotoxicity while also boosting stability. Human serum albumin (HSA), poly (lactic-co-glycolic acid) (PLGA), Polylactide (PLA), poly (alkyl cyanoacrylate) (PACA), gelatin, and chitosan are only a few of the significant polymers mentioned. In this review article, we categorized polymer-coated nanoparticles from basic to complex drug delivery systems and discussed their application as novel drug carriers to the brain.

Hydrophobic ion pairing-based self-emulsifying drug delivery systems: a new strategy for improving the therapeutic efficacy of water-soluble drugs

INTRODUCTION

Self-emulsifying drug delivery systems (SEDDS) are formulations consisting of oil phase, emulsifiers, and co-emulsifiers, which can be spontaneously emulsified in the body to form O/W microemulsion. Traditionally, SEDDS are used commercially for the improvement of oral absorption and in vivo performances for poorly water-soluble drugs. However, SEDDS formulations were rarely reported for the delivery of water-soluble drugs. Recent studies have found that SEDDS have the potential for water-soluble macromolecular drugs by the application of the hydrophobic ion pairing (HIP) technology.

AREAS COVERED

This review summarized the characteristics of HIP complexes in SEDDS and introduced their advantages and discussed the future prospects of HIP-based SEDDS in drug delivery.

EXPERT OPINION

Hydrophobic ion pairing (HIP) is a technology that combines lipophilic structures on polar counterions to increase the lipophilicity through electrostatic interaction. Recent studies showed that HIP-based SEDDS offer an effective way to increase the mucosal permeability and improve the chemical stability for antibiotics, proteases, DNA-based drugs, and other water-soluble macromolecular drugs. It is believed that HIP-based SEDDS offer a potential and attractive method capable of delivering hydrophilic macromolecules with ionizable groups for oral administration.

Sublingual apomorphine therapy as an alternative to complex continuous infusion pumps in advanced Parkinson's disease treatment: a district nurse-led intervention

In the UK, Parkinson's disease (PD) is estimated to affect an annual incidence of 15-20 per 100 000 of the population over the age of 60. Service users living with advanced-stage PD require the use of apomorphine, which is generally used to control symptoms. The district nursing service plays a key role in monitoring and in the administration of apomorphine therapy. Although apomorphine is effective, skin problems such as nodules are commonly reported adverse events that can complicate efficiency of treatment. A sublingual delivery route to apomorphine has been known for years as a feasible alternative to subcutaneous route. Collaboration between the multidisciplinary team is essential to meet the complex needs of service users with advanced PD. However, due to the increase in demands of the district nurse service, this time crucial intervention can be unpredictable to meet. An alternative route can enable district nurses to become less task-orientated. However, an increased risk of oral cavity related adverse events should be taken into consideration with the sublingual administration of apomorphine.

A deep eutectic-based, self-emulsifying subcutaneous depot system for apomorphine therapy in Parkinson's disease

Parkinson’s disease (PD) is a progressive disorder of the central nervous system that affects motor control. While subcutaneous injection of apomorphine (Apokyn) is clinically used to alleviate intermittent episodes of dyskinesia, the treatment requires multiple injections of the drug per day, significantly deterring patient compliance. We introduce a deep eutectic-based ternary solvent system that self-emulsifies in situ following subcutaneous injection and entraps apomorphine, allowing a 48-h duration of detectable drug concentration in the plasma of pigs, which is a remarkable improvement over the clinical comparator. The results from the animal studies support the self-emulsifying system as a potent, long-lasting therapeutic for PD patients and potentially for other therapeutics that have a similar delivery challenge.

Apomorphine, a dopamine agonist, is a highly effective therapeutic to prevent intermittent off episodes in advanced Parkinson’s disease. However, its short systemic half-life necessitates three injections per day. Such a frequent dosing regimen imposes a significant compliance challenge, especially given the nature of the disease. Here, we report a deep eutectic-based formulation that slows the release of apomorphine after subcutaneous injection and extends its pharmacokinetics to convert the current three-injections-a-day therapy into an every-other-day therapy. The formulation comprises a homogeneous mixture of a deep eutectic solvent choline-geranate, a cosolvent n-methyl-pyrrolidone, a stabilizer polyethylene glycol, and water, which spontaneously emulsifies into a microemulsion upon injection in the subcutaneous space, thereby entrapping apomorphine and significantly slowing its release. Ex vivo studies with gels and rat skin demonstrate this self-emulsification process as the mechanism of action for sustained release. In vivo pharmacokinetics studies in rats and pigs further confirmed the extended release and improvement over the clinical comparator Apokyn. In vivo pharmacokinetics, supported by a pharmacokinetic simulation, demonstrate that the deep eutectic formulation reported here allows the maintenance of the therapeutic drug concentration in plasma in humans with a dosing regimen of approximately three injections per week compared to the current clinical practice of three injections per day.

Patient Centricity Driving Formulation Innovation: Improvements in Patient Care Facilitated by Novel Therapeutics and Drug Delivery Technologies

Innovative formulation technologies can play a crucial role in transforming a novel molecule to a medicine that significantly enhances patients' lives. Improved mechanistic understanding of diseases has inspired researchers to expand the druggable space using new therapeutic modalities such as interfering RNA, protein degraders, and novel formats of monoclonal antibodies. Sophisticated formulation strategies are needed to deliver the drugs to their sites of action and to achieve patient centricity, exemplified by messenger RNA vaccines and oral peptides. Moreover, access to medical information via digital platforms has resulted in better-informed patient groups that are requesting consideration of their needs during drug development. This request is consistent with health authority efforts to upgrade their regulations to advance age-appropriate product development for patients. This review describes formulation innovations contributingto improvements in patient care: convenience of administration, preferred route of administration, reducing dosing burden, and achieving targeted delivery of new modalities.

Nanotechnology Approaches for Enhanced CNS Drug Delivery in the Management of Schizophrenia

Schizophrenia is a neuropsychiatric disorder mainly affecting the central nervous system, presented with auditory and visual hallucinations, delusion and withdrawal from society. Abnormal dopamine levels mainly characterise the disease; various theories of neurotransmitters explain the pathophysiology of the disease. The current therapeutic approach deals with the systemic administration of drugs other than the enteral route, altering the neurotransmitter levels within the brain and providing symptomatic relief. Fluid biomarkers help in the early detection of the disease, which would improve the therapeutic efficacy. However, the major challenge faced in CNS drug delivery is the blood-brain barrier. Nanotherapeutic approaches may overcome these limitations, which will improve safety, efficacy, and targeted drug delivery. This review article addresses the main challenges faced in CNS drug delivery and the significance of current therapeutic strategies and nanotherapeutic approaches for a better understanding and enhanced drug delivery to the brain, which improve the quality of life of schizophrenia patients.

On-Demand Therapy for OFF Episodes in Parkinson's Disease

Levodopa is the most effective therapy for Parkinson's disease; however, chronic treatment is associated with the development of OFF episodes, in which there is a return of parkinsonian features following a dose of levodopa and prior to the onset of benefit from the subsequent dose. OFF episodes can be a major source of disability for PD patients and frequently result in depression, apathy and an unwillingness to participate in social activities. Most currently available medical and surgical therapies are designed to reduce total daily OFF time but do not provide a rapid and reliable "on-demand" therapy for individual OFF episodes. Indeed, responses to individual doses of levodopa during an acute OFF episode are unreliable, frequently leading to partial-ON, delayed-ON, or no-ON responses even at different times in the same patient. There are now 3 therapies that are available for the on-demand treatment of OFF episodes; subcutaneous injection of apomorphine, sublingual apomorphine film, and inhaled levodopa. The first has not enjoyed widespread use in the PD community, whereas the latter 2 therapies have only recently been approved. This review will consider the currently available on-demand therapies and their potential advantages and disadvantages. © 2021 International Parkinson and Movement Disorder Society.

Population pharmacokinetic analysis of apomorphine sublingual film or subcutaneous apomorphine in healthy subjects and patients with Parkinson's disease

Apomorphine is an on-demand treatment of "OFF" episodes in patients with Parkinson's disease (PD). A joint parent-metabolite population pharmacokinetic (PK) model characterized apomorphine and apomorphine-sulfate following administration of apomorphine sublingual film (APL) and two formulations of subcutaneous apomorphine. Overall, 2485 samples from 87 healthy subjects and 71 patients with PD and "OFF" episodes were analyzed using nonlinear mixed-effects modeling. Apomorphine PK was adequately described by a two-compartment model with first-order transit absorption via both routes of administration and first-order metabolism to apomorphine-sulfate with one-compartment disposition and first-order elimination. Bioavailability of apomorphine sublingual film was ~ 18% relative to subcutaneous apomorphine. Among covariates tested, only body weight had a large effect on apomorphine exposure (maximum plasma concentration and area under the concentration-time curve [AUC_0-∞ ]), with greater weight resulting in lower exposure. Model-predicted apomorphine exposure was similar between apomorphine sublingual film 30 mg and subcutaneous apomorphine 5 mg (median AUC_0-24 , 66.7 ng•h/mL, geometric mean ratio of 0.99; 90% confidence interval [CI], 0.96-1.03) and was comparable between apomorphine sublingual film 35 mg and subcutaneous apomorphine 6 mg (median AUC_0-24 , 75.4 and 80.0 ng•h/mL, respectively; geometric mean ratio of 0.94; 90% CI, 0.90-0.97) administered every 2 h for a maximum of 5 doses per day. In a typical patient with PD, predicted apomorphine exposure increased with increasing doses of apomorphine sublingual film; however, the increase was less than dose proportional. Similar apomorphine exposure was predicted in patients with mild renal impairment versus normal renal function. PK properties of apomorphine sublingual film support its administration for a wide range of patients with PD and "OFF" episodes, regardless of demographic and clinical characteristics.

Apomorphine Targets the Pleiotropic Bacterial Regulator Hfq

Hfq is a bacterial regulator with key roles in gene expression. The protein notably regulates translation efficiency and RNA decay in Gram-negative bacteria, thanks to its binding to small regulatory noncoding RNAs. This property is of primary importance for bacterial adaptation and survival in hosts. Small RNAs and Hfq are, for instance, involved in the response to antibiotics. Previous work has shown that the E. coli Hfq C-terminal region (Hfq-CTR) self-assembles into an amyloid structure. It was also demonstrated that the green tea compound EpiGallo Catechin Gallate (EGCG) binds to Hfq-CTR amyloid fibrils and remodels them into nonamyloid structures. Thus, compounds that target the amyloid region of Hfq may be used as antibacterial agents. Here, we show that another compound that inhibits amyloid formation, apomorphine, may also serve as a new antibacterial. Our results provide an alternative in order to repurpose apomorphine, commonly used in the treatment of Parkinson’s disease, as an antibiotic to block bacterial adaptation to treat infections.

Prolonged Delivery of Apomorphine Through the Buccal Mucosa, Towards a Noninvasive Sustained Administration Method in Parkinson's Disease: In Vivo Investigations in Pigs

In the current work, prolonged systemic delivery of apomorphine via buccal mucosa was shown to be a promising treatment for Parkinson's disease as a substitute for clinically utilized subcutaneous infusions. Due to extensive 'first-pass' metabolism, apomorphine is administered parenterally to bypass liver metabolism. Drawbacks of parenteral administration cause low patient compliance and adherence to treatment. On the other hand, while also bypassing the liver, delivery through buccal mucosa has a superior safety profile, is less costly, lacks pain and discomfort, and possesses excellent accessibility, overall augmenting patient compliance. Current in vivo study in pigs showed: (1) steady plateau levels of apomorphine in plasma were obtained 30 min following administration and remained constant for 8 h until a delivery device was removed, (2) bioavailability of apomorphine was 55%-80% as opposed to <2% peroral and (3) simulation of the pharmacokinetic profile obtained in pigs predicted therapeutically relevant levels of apomorphine in human. Furthermore, antipyrine was incorporated as a permeation marker to enable mechanistic investigation of apomorphine release from the delivery device and its permeation through the buccal mucosa. In addition, limitations of an Ussing diffusion chamber as an ex vivo research tool were also discussed.

Adjunctive Therapies in Parkinson's Disease: How to Choose the Best Treatment Strategy Approach

End-of-dose motor fluctuations are regarded as one of the core troublesome symptoms by patients with Parkinson's disease (PD). Treatment of levodopa (L-dopa)-induced motor fluctuations is still an unmet medical need. L-dopa is the gold standard in the treatment of motor PD symptoms; notwithstanding, a wide range of adjunct therapies are currently available for the treatment of end-of-dose motor fluctuations. Additionally, device-aided therapies, such as deep brain stimulation, L-dopa-carbidopa intestinal gel infusion, and on-demand injection or continuous apomorphine infusion, may be considered when oral treatments are not sufficient to control motor fluctuations. In spite of the several evidence-based reviews and guidelines available, there is no agreement on which add-on therapy should be started first or its optimal timing. Equally challenging is the choice and timing between device-aided therapies. Herein, we propose a general overview of oral and device-aided treatments for PD patients with end-of-dose motor fluctuations, offering two possible algorithms that can guide clinicians during the therapeutic decision process.

The Many Faces of Apomorphine: Lessons from the Past and Challenges for the Future

Apomorphine is now recognized as the oldest antiparkinsonian drug on the market. Though still underused, it is increasingly prescribed in Europe for patients with advanced Parkinson's disease (PD) with motor fluctuations. However, its history is far from being limited to movement disorders. This paper traces the history of apomorphine, from its earliest empirical use, to its synthesis, pharmacological development, and numerous indications in human and veterinary medicine, in light of its most recent uses and newest challenges. From shamanic rituals in ancient Egypt and Mesoamerica, to the treatment of erectile dysfunction, from being discarded as a pharmacological tool to becoming an essential antiparkinsonian drug, the path of apomorphine in the therapeutic armamentarium has been tortuous and punctuated by setbacks and groundbreaking discoveries. Throughout history, three main clinical indications stood out: emetic (gastric emptying, respiratory disorders, aversive conditioning), sedative (mental disorders, clinical anesthesia, alcoholism), and antiparkinsonian (fluctuations). New indications may arise in the future, both in PD (palliative care, nonmotor symptoms, withdrawal of oral dopaminergic medication), and outside PD, with promising work in neuroprotection or addiction.