Apomorphine therapy in Parkinson's disease and future directions

Memory enhancing and neuroprotective effects of apomorphine in a rat model of dementia

Oxidative stress from generation of increased reactive oxygen species or has been reported to play an important role in dementia. Oxidative stress due to free radicals of oxygen or reactive oxygen species could be precipitating factors in the etiology of dementia. Apomorphine has been reported to have neuroprotective effects. To monitor memory enhancing and neuroprotective effects of apomorphine, we determined the antioxidant enzymes activities, lipid peroxidation, acetylcholine esterase (AChE) activity in brain and plasma, following repetitive administration of apomorphine in rat model of dementia. Biogenic amine levels were also monitored in hippocampus. Repeated administration of scopolamine was taken as an animal model of dementia. Decreased glutathione peroxidase, superoxide dismutase and catalase activities were observed in these animal models of dementia. While increased lipid peroxidation was also observed in the brain and plasma samples. The results showed significant effects of apomorphine. The activities of antioxidant enzymes displayed increased activities in both brain and plasma. Glutathione peroxidase and catalase activities were found to be significantly higher in brain and plasma of apomorphine treated rats. Superoxide dismutase (SOD) was significantly decreased in plasma of scopolamine injected rats; and a decreased tendency (non-significant) of SOD in brain was also observed. AChE activity in brain and plasma was significantly decreased in scopolamine treated rats. Learning and memory of rats in the present study was assessed by Morris Water Maze (MWM). Short-term memory and long-term memory was impaired significantly in scopolamine treated rats, which was prevented by apomorphine. Moreover, a marked decrease in biogenic amines was also found in the brain of scopolamine treated rats and was reverted in apomorphine treated rats. Results showed that scopolamine-treatment induced memory impairment and induced oxidative stress in rats as compared to saline-treated controls. These impairments were significantly restored by apomorphine administration. In conclusion, our data suggests that apomorphine at the dose of 1 mg/kg could be a potential therapeutic agent to treat dementia and related disorders.

Long-term safety, tolerability and efficacy of apomorphine sublingual film in patients with Parkinson's disease complicated by OFF episodes: a phase 3, open-label study

BACKGROUND

Apomorphine sublingual film (SL-APO) is an on-demand treatment for OFF episodes in patients with Parkinson's disease (PD).

OBJECTIVE

To assess the long-term (≥ 3 years) safety/tolerability and efficacy of SL-APO.

METHODS

Study CTH-301 ( http://www.

CLINICALTRIALS

gov NCT02542696; registered 2015-09-03) was a phase 3, multicentre, open-label study of SL-APO in PD patients with motor fluctuations, comprised of a dose-titration and long-term safety phase. All participants received SL-APO. The primary endpoint was safety/tolerability (treatment-emergent adverse events [TEAEs]) during the long-term safety phase. Efficacy assessments included the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III (motor examination), assessed at weeks 24, 36 and 48 during the first year of the long-term safety phase.

RESULTS

496 patients were included and 120 (24.2%) completed the long-term safety phase. Mean duration of SL-APO exposure was 294.3 days. TEAEs related to study drug were experienced by 65.3% of patients (most common: nausea [6.0%], stomatitis [1.8%], lip swelling [1.8%], dizziness [1.6%], oral mucosal erythema [1.6%], mouth ulceration [1.6%]). TEAEs leading to study drug withdrawal were experienced by 34.0% of patients (most common: nausea [5.4%], lip swelling [4.5%], mouth ulceration [2.6%], stomatitis [2.3%]). A clinically meaningful reduction in MDS-UPDRS part III score was observed as soon as 15 min following administration of SL-APO, with peak effects observed approximately 30 min post-dose and sustained up to 90 min post-dose; results were consistent over 48 weeks.

CONCLUSIONS

SL-APO was generally well tolerated and efficacious over the long term as an on-demand treatment for OFF episodes in patients with PD.

Advances in the Therapeutic Use of Non-Ergot Dopamine Agonists in the Treatment of Motor and Non-Motor Symptoms of Parkinson's Disease

Dopamine (DA) agonists, as an excellent dopamine replacement therapy for patients with early and advanced Parkinson's disease (PD), play a vital role in controlling motor and several nonmotor symptoms. Besides, the application of DA agonists may delay levodopa therapy and the associated risk of motor complications. Indeed, each DA agonist has unique pharmacokinetic and pharmacodynamic characteristics and therefore has different therapeutic efficacy and safety profile. The comorbidities, significant non-motor manifestations, concomitant medications, and clinical features of PD individuals should guide the selection of a specific DA agonist to provide a more patient-tailored treatment option. Thorough knowledge of DA agonists helps clinicians better balance clinical efficacy and side effects. Therefore, this review refers to recent English-written articles on DA agonist therapy for PD patients and summarizes the latest findings on non-ergot DA agonists as well as the advantages and disadvantages of each compound to help clinicians in the selection of a specific DA agonist. In addition, novel D1/D5 partial agonists and new formulations of DA agonists are also discussed.

Newly Approved and Investigational Drugs for Motor Symptom Control in Parkinson's Disease

Motor symptoms are a core feature of Parkinson’s disease (PD) and cause a significant burden on patients’ quality of life. Oral levodopa is still the most effective treatment, however, the motor benefits are countered by inherent pharmacologic limitations of the drug. Additionally, with disease progression, chronic levodopa leads to the appearance of motor complications including motor fluctuations and dyskinesia. Furthermore, several motor abnormalities of posture, balance, and gait may become less responsive to levodopa. With these unmet needs and our evolving understanding of the neuroanatomic and pathophysiologic underpinnings of PD, several advances have been made in defining new therapies for motor symptoms. These include newer levodopa formulations and drug delivery systems, refinements in adjunctive medications, and non-dopaminergic treatment strategies. Although some are in early stages of development, these novel treatments potentially widen the available options for the management of motor symptoms allowing clinicians to provide an individually tailored care for PD patients. Here, we review the existing and emerging interventions for PD with focus on newly approved and investigational drugs for motor symptoms, motor fluctuations, dyskinesia, and balance and gait dysfunction.

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.

Therapeutic Devices for Motor Symptoms in Parkinson’s Disease: Current Progress and a Systematic Review of Recent Randomized Controlled Trials

Background

Pharmacotherapy is the first-line treatment option for Parkinson’s disease, and levodopa is considered the most effective drug for managing motor symptoms. However, side effects such as motor fluctuation and dyskinesia have been associated with levodopa treatment. For these conditions, alternative therapies, including invasive and non-invasive medical devices, may be helpful. This review sheds light on current progress in the development of devices to alleviate motor symptoms in Parkinson’s disease.

Methods

We first conducted a narrative literature review to obtain an overview of current invasive and non-invasive medical devices and thereafter performed a systematic review of recent randomized controlled trials (RCTs) of these devices.

Results

Our review revealed different characteristics of each device and their effectiveness for motor symptoms. Although invasive medical devices are usually highly effective, surgical procedures can be burdensome for patients and have serious side effects. In contrast, non-pharmacological/non-surgical devices have fewer complications. RCTs of non-invasive devices, especially non-invasive brain stimulation and mechanical peripheral stimulation devices, have proven effectiveness on motor symptoms. Nearly no non-invasive devices have yet received Food and Drug Administration certification or a CE mark.

Conclusion

Invasive and non-invasive medical devices have unique characteristics, and several RCTs have been conducted for each device. Invasive devices are more effective, while non-invasive devices are less effective and have lower hurdles and risks. It is important to understand the characteristics of each device and capitalize on these.

Management strategies of sexual dysfunctions in Parkinson's disease

Sexual dysfunctions (SD) are frequent and highly disabling nonmotor manifestations of Parkinson's disease (PD) but are also potentially treatable. Neurologists should actively discuss, recognize and treat sexual health issues as an integral part of the management of the disease. In this chapter, we provide recommendations for managing and treating both primary and secondary SD in PD. Many sexual problems can be, at least partially, improved by adjusting the treatment of motor, nonmotor symptoms and comorbidities. Although some treatments of primary SD are evidence-based, many therapeutic options have not been yet systematically studied in patients with PD. The development of new treatments and repurposing of existing remedies in patients with PD remain an unmet need.

A Randomized Trial Assessing the Safety, Pharmacokinetics, and Efficacy During Morning Off of AZ-009

Background

Inhalation of apomorphine could be a faster‐acting and more user‐friendly alternative to subcutaneous injection for treating off periods in Parkinson's disease (PD).

Objective

The aim of this study was to compare the safety and pharmacokinetics of inhaled apomorphine (AZ‐009) with subcutaneous apomorphine (APO‐go PEN) in healthy volunteers (HVs) and to examine the safety, pharmacokinetics, and efficacy of AZ‐009 in patients with PD.

Methods

In part A of this study, eight HVs received 1 mg AZ‐009 and 2 mg subcutaneous apomorphine in a randomized crossover manner. In the subsequent single ascending dose parts in HVs (part B, n = 16) and patients with PD (part C, n = 25), participants were randomized to placebo or AZ‐009 up to 4 mg. In patients, after medication withdrawal, Movement Disorder Society‐Unified Parkinson's Disease Rating Scale part III and on/off states were assessed predose and postdose.

Results

AZ‐009 was rapidly absorbed with peak plasma concentrations at 2 minutes, as compared to 30 minutes for subcutaneous apomorphine. Adverse events for AZ‐009 were comparable to subcutaneous apomorphine, except for mild and transient throat irritation. Adverse events limited AZ‐009 dose escalation in HVs to 3 mg. Patients tolerated up to 4 mg. In patients with PD, 2, 3, and 4 mg AZ‐009 reduced mean Movement Disorder Society‐Unified Parkinson's Disease Rating Scale part III score (standard deviation) by 10.7 (13.6), 12.8 (7.9), and 10.3 (3.7) points, respectively, compared to 4.8 (4.9) after placebo at 10 minutes postdose. The percentage of patients achieving full on within 45 minutes postdose increased dose dependently: 0% (placebo), 17% (2 mg), 50% (3 mg), and 83% (4 mg).

Conclusions

AZ‐009 appears to be a rapid‐acting and reasonably well‐tolerated formulation for treating off periods. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Touchscreen-based finger tapping: Repeatability and configuration effects on tapping performance

Parkinson’s disease (PD) is a progressive neurodegenerative disease that affects almost 2% of the population above the age of 65. To better quantify the effects of new medications, fast and objective methods are needed. Touchscreen-based tapping tasks are simple yet effective tools for quantifying drug effects on PD-related motor symptoms, especially bradykinesia. However, there is no consensus on the optimal task set-up. The present study compares four tapping tasks in 14 healthy participants. In alternate finger tapping (AFT), tapping occurred with the index and middle finger with 2.5 cm between targets, whereas in alternate side tapping (AST) the index finger with 20 cm between targets was used. Both configurations were tested with or without the presence of a visual cue. Moreover, for each tapping task, within- and between-day repeatability and (potential) sensitivity of the calculated parameters were assessed. Visual cueing reduced tapping speed and rhythm, and improved accuracy. This effect was most pronounced for AST. On average, AST had a lower tapping speed with impaired accuracy and improved rhythm compared to AFT. Of all parameters, the total number of taps and mean spatial error had the highest repeatability and sensitivity. The findings suggest against the use of visual cueing because it is crucial that parameters can vary freely to accurately capture medication effects. The choice for AFT or AST depends on the research question, as these tasks assess different aspects of movement. These results encourage further validation of non-cued AFT and AST in PD patients.

Inhaled levodopa for intermittent treatment of OFF episodes in patients with Parkinson's disease

Introduction: Many patients with advanced Parkinson's disease (PD) have inadequate control of motor symptoms despite optimized treatment. Predictable and unpredictable OFF periods severely interfere with the quality of life. A drug that easily and rapidly reverts the OFF state is still needed. Subcutaneous apomorphine, the only approved drug for this indication, although efficacious, is not widely used probably due to its potential side effects and complicated administration.Levodopa is the most efficacious drug for the treatment of PD motor symptoms. However, issues related to the oral route and intestinal absorption in later disease stages render this route lengthy and inefficacious.Areas covered: Literature on the development of an inhaled formulation of levodopa has been reviewed. Significant advances in the field of pulmonary delivery systems and in dry powders have enabled the development of a new formulation of levodopa that can be inhaled and adequate blood levels rapidly achieved, bypassing intestinal absorption. Several clinical trials have reported efficacy, safety, and tolerability data. Some pulmonary-related adverse events have been reported but are mostly mild.Expert opinion: This new way of administering levodopa is likely to be very welcome and may fill a gap for OFF rescue treatments, at least for some patients.

Continuous Drug Delivery Aiming Continuous Dopaminergic Stimulation in Parkinson's Disease

Continuous dopaminergic stimulation in Parkinson's disease (PD) has several advantages over pulsatile, non-continuous, stimulation. These therapies currently consist of pump-based and transcutaneous therapies and are based on a more constant delivery of the dopaminergic drug resulting in continuous dopaminergic stimulation and a more stable treatment effect. Several clinical and experimental observations have shown that continuous stimulation of dopaminergic receptors induces fewer complications, such as dyskinesia, compared to pulsatile stimulation. Currently available non-oral pharmacological continuous therapies in PD include the transdermal Rotigotine (RTG) patch, infusion therapies with Apomorphine and Intrajejunal Levodopa (IJLI) and the Rivastigmine patch. Here we aim to provide a concise review of these current therapies and discuss ongoing and future developments of continuous non-oral pharmacological dopaminergic therapies in PD.

Factors to Consider in the Selection of Dopamine Agonists for Older Persons with Parkinson's Disease

Dopamine agonists (DAs) are frequently used in the management of Parkinson's disease (PD), a complex multisystem disorder influenced substantially by age-related factors. Over 80% of PD patients present after age 60 years and may have clinical features exacerbated by age-related comorbidities or decline in physiological compensatory mechanisms. Pharmacotherapy for motor symptoms in older persons is more likely to involve exclusive use of levodopa combined with a peripheral decarboxylase inhibitor throughout the course of the illness. Non-ergot DAs, such as pramipexole, rotigotine and ropinirole, may be used as de novo monotherapy for the control of motor symptoms in older persons, although they are less efficacious than levodopa therapy. DAs may also be considered as adjunct therapy in older persons when motor symptoms are no longer adequately controlled by levodopa or when motor fluctuations and dyskinesia appear. DAs may be used cautiously in older persons with cognitive impairment and orthostatic hypotension but should be avoided when there is a history or risk of psychosis or impulse control disorders.

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.

ND0701, A Novel Formulation of Apomorphine for Subcutaneous Infusion, in Comparison to a Commercial Apomorphine Formulation: 28-Day Pharmacokinetic Study in Minipigs and a Phase I Study in Healthy Volunteers to Assess the Safety, Tolerability, Pharmacokinetics and Relative Bioavailability

BACKGROUND

Subcutaneous apomorphine is used for the treatment of Parkinson's disease (PD); however, infusion site reactions are a common adverse event (AE), which can lead to treatment discontinuation. Apomorphine formulations that are more tolerable and convenient for use are needed.

OBJECTIVE

Our aim was to compare the toxicity and bioavailability of ND0701, a new concentrated formulation of apomorphine free base, with one of the commercially available apomorphine HCl formulations (APO-go^®, Britannia Pharmaceuticals Ltd).

METHODS

(1) Preclinical study: 16 minipigs were randomly assigned to placebo, APO-go^®, and ND0701 groups, and treated for 28 days. Pharmacokinetic, clinical, and pathological assessments were performed. (2) Phase I study: 18 healthy volunteers participated in an open-label, two-sequence, randomized, three single-dose, partial crossover study to compare the pharmacokinetics, safety, and tolerability of ND0701 with APO-go^® (1%).

RESULTS

(1) Preclinical study: No systemic toxicity was observed in apomorphine-treated minipigs, but local skin reactions were observed at the infusion sites. These effects were less frequent and less severe and recovery was more rapid for ND0701 compared with APO-go^®. (2) Phase I study: Both formulations were safe and well tolerated under the conditions of the study and no severe or serious treatment-emergent AEs were reported. Infusion site nodules were reported more frequently, with higher severity, and recovered slower at APO-go^®-treated sites compared with ND0701-treated sites. Bioavailability of apomorphine was comparable between the two formulations.

CONCLUSION

Based on these pilot studies, ND0701 appears to be superior to APO-go^® in terms of tolerability and safety, while maintaining comparable bioavailability with APO-go^®, and shows promise as a future treatment for PD.

Magnetic Resonance Imaging as a Noninvasive Method for Longitudinal Monitoring of Infusion Site Reactions Following Administration of a Novel Apomorphine Formulation

Infusion site reactions are common following subcutaneous infusion of drugs. Such reactions can lead to discontinuation of the treatment. Therefore, assessment of such reactions is essential during preclinical safety studies, and magnetic resonance imaging (MRI) can assist in evaluation. Here, in vivo and ex vivo MRI evaluations were used in addition to classical histopathology to assess the infusion site reaction to ND0701, a novel formulation of apomorphine base developed for the treatment of Parkinson’s disease, in comparison to the commercial apomorphine hydrochloride (HCl) formulation. Both formulations, each at two concentrations, were continuously administered subcutaneously for 20 hr to each of 3 male and 3 female domestic pigs. Based on MRI evaluations, there was a gradual decrease in the volume of the subcutaneous lesions over 4 weeks, with smaller lesions and quicker resolution with ND0701 at concentrations 2.5- to 5-fold higher when compared to the commercial apomorphine HCl formulation. Histopathological evaluation of ND0701 revealed only minimal inflammation at the sites of infusion, whereas the commercial apomorphine HCl caused persistent inflammatory reactions and necrosis. This study provides support to the use of MRI in preclinical testing of subcutaneous drugs when evaluating local site reactions.