Irregular gastrointestinal drug absorption in Parkinson's disease

Localization Matters: Impacts of PEG-J Localization in Intestinal Levodopa Therapy for Parkinson's Disease

BACKGROUND

Real-world clinical evidence is missing to understand the resorption characteristics of levodopa through duodenal and jejunal parts of the small intestine.

OBJECTIVE

To characterize how different application sites of intestinal levodopa gel would impact on levodopa dosing and clinical outcomes.

METHODS

This multicentre retrospective analysis investigated Parkinson's disease patients (n = 111) and their change in levodopa equivalent dosage when switching from oral treatment to intestinal continuous infusion therapy while stratifying for differences in percutaneous gastrojejunostomy (PEG-J) tube localizations. We analyzed data from patients treated with both levodopa-carbidopa (LCIG) and levodopa-carbidopa-entacapone (LECIG) intestinal gel.

RESULTS

In dichotomic analysis, duodenal and jejunal tube positions showed similar levodopa equivalent dosages changes from baseline (P = 0.143). This was similar when subdividing patients for LCIG and LECIG treatment. In duodenal PEG-J positions, 44.4% of patients showed persistent motor fluctuations compared to 21.9% in jejunal placements (P = 0.026). In duodenal positions, fluctuations most often persisted when the PEG-J tube was placed proximally into the duodenum. In jejunal localizations, several patients displayed a satisfactory outcome from the primary intervention but experienced dislocation of the PEG-J tube to a duodenal position. This was associated with re-emergence of motor fluctuations in a majority of them.

CONCLUSIONS

Our real-world data suggest that LCIG and LECIG are absorbed similarly in both duodenal and jejunal portions of the small intestine. However, clinical data suggest, that jejunal positioning is critical to the stabilization of dopaminergic motor fluctuations.

Potential and challenges in application of physiologically based pharmacokinetic modeling in predicting diarrheal disease impact on oral drug pharmacokinetics

Physiologically based pharmacokinetic (PBPK) modeling is a physiologically relevant approach that integrates drug-specific and system parameters to generate pharmacokinetic predictions for target populations. It has gained immense popularity for drug-drug interaction, organ impairment, and special population studies over the past 2 decades. However, an application of PBPK modeling with great potential remains rather overlooked-prediction of diarrheal disease impact on oral drug pharmacokinetics. Oral drug absorption is a complex process involving the interplay between physicochemical characteristics of the drug and physiological conditions in the gastrointestinal tract. Diarrhea, a condition common to numerous diseases impacting many worldwide, is associated with physiological changes in many processes critical to oral drug absorption. In this Minireview, we outline key processes governing oral drug absorption, provide a high-level overview of key parameters for modeling oral drug absorption in PBPK models, examine how diarrheal diseases may impact these processes based on literature findings, illustrate the clinical relevance of diarrheal disease impact on oral drug absorption, and discuss the potential and challenges of applying PBPK modeling in predicting disease impacts. SIGNIFICANCE STATEMENT: Pathophysiological changes resulting from diarrheal diseases can alter important factors governing oral drug absorption, contributing to suboptimal drug exposure and treatment failure. Physiologically based pharmacokinetic (PBPK) modeling is an in silico approach that has been increasingly adopted for drug-drug interaction potential, organ impairment, and special population assessment. This Minireview highlights the potential and challenges of using physiologically based pharmacokinetic modeling as a tool to improve our understanding of how diarrheal diseases impact oral drug pharmacokinetics.

Development and In Vitro Characterization of Azadirachta Indica Gum Grafted Polyacrylamide Based pH-Sensitive Hydrogels to Improve the Bioavailability of Lansoprazole

The present study intended to develop a pH-responsive hydrogel based on Neem gum (Ng) to improve Lansoprazole (LSP) oral bioavailability. Azadirachta Indica seed extract was used to obtain Ng. pH-responsive hydrogel formulations (F1-F9) were prepared using different Ng ratios, Acrylamide (AAm), and methylene-bis-acrylamide (MBA). The formulated hydrogels were characterized through FTIR, thermal analysis, swelling ratio, SEM, sol-gel ratios, In-Vitro drug release, and cytotoxicity analysis. Azadirachta Indica was extracted to produce a powder containing 21.5 % Ng. Prepared hydrogels showed maximum swelling at pH 7.4, whereas the swelling at an acidic pH was insignificant. LSP-loaded hydrogel demonstrated a regulated release of LSP for up to 24 h and indicated a Super Case II transport release mechanism. During the cytotoxic evaluation, the delivery system showed minimal cytotoxicity towards normal cells, while percent cytotoxicity was carried out for a longer duration (up to 96 h). The present study revealed Azadirachta indica gum-based pH-responsive hydrogel as a promising technique for precisely delivering LSP.

Therapeutic drug monitoring in Parkinson's disease

A patient-tailored therapy of the heterogeneous, neuropsychiatric disorder of Parkinson's disease (PD) aims to improve dopamine sensitive motor symptoms and associated non-motor features. A repeated, individual adaptation of dopamine substituting compounds is required throughout the disease course due to the progress of neurodegeneration. Therapeutic drug monitoring of dopamine substituting drugs may be an essential tool to optimize drug applications. We suggest plasma determination of levodopa as an initial step. The complex pharmacology of levodopa is influenced by its short elimination half-life and the gastric emptying velocity. Both considerably contribute to the observed variability of plasma concentrations of levodopa and its metabolite 3-O-methyldopa. These amino acids compete with other aromatic amino acids as well as branched chain amino acids on the limited transport capacity in the gastrointestinal tract and the blood brain barrier. However, not much is known about plasma concentrations of levodopa and other drugs/drug combinations in PD. Some examples may illustrate this lack of knowledge: Levodopa measurements may allow further insights in the phenomenon of inappropriate levodopa response. They may result from missing compliance, interactions e.g. with treatments for other mainly age-related disorders, like hypertension, diabetes, hyperlipidaemia, rheumatism or by patients themselves independently taken herbal medicines. Indeed, uncontrolled combination of compounds for accompanying disorders as given above with PD drugs might increase the risk of side effects. Determination of other drugs used to treat PD in plasma such as dopamine receptor agonists, amantadine and inhibitors of catechol-O-methyltransferase or monoamine oxidase B may refine and improve the value of calculations of levodopa equivalents. How COMT-Is change levodopa plasma concentrations? How other dopaminergic and non-dopaminergic drugs influence levodopa levels? Also, delivery of drugs as well as single and repeated dosing and continuous levodopa administrations with a possible accumulation of levodopa, pharmacokinetic behaviour of generic and branded compounds appear to have a marked influence on efficacy of drug treatment and side effect profile. Their increase over time may reflect progression of PD to a certain degree. Therapeutic drug monitoring in PD is considered to improve the therapeutic efficacy in the course of this devastating neurologic disorder and therefore is able to contribute to the patients' precision medicine. State-of-the-art clinical studies are urgently needed to demonstrate the usefulness of TDM for optimizing the treatment of PD.

Prolongation of the gastric residence time of caffeine after administration in fed state: Comparison of effervescent granules with an extended release tablet

The aim of the present study was to investigate the gastroretentive capacity of different formulation principles. This was indirectly determined by the absorption behavior of caffeine from the dosage forms. A slow and continuous appearance of caffeine in the saliva of healthy volunteers was used as a parameter for a prolonged gastric retention time. For this purpose, a four-way study was conducted with twelve healthy volunteers using the following test procedures: (1) Effervescent granules with 240 mL of still water administered in fed state, (2) effervescent granules with 20 mL of still water in fed state, (3) extended release (ER) tablet with 240 mL of still water in fed state, and (4) effervescent granules with 240 mL of still water in fasted state. The initial rise of the caffeine concentrations was more pronounced after the intake of the effervescent granules in the fed state compared to that of the ER tablets. However, tmax tended to be shorter in the fed study arms following administration of the ER tablet compared to the granules. Overall, the application of active pharmaceutical ingredients formulated as effervescent granules seems to be a promising approach to increase their gastric residence time after intake in fed state.

Model-based optimization of controlled release formulation of levodopa for Parkinson's disease

Levodopa is currently the standard of care treatment for Parkinson's disease, but chronic therapy has been linked to motor complications. Designing a controlled release formulation (CRF) that maintains sustained and constant blood concentrations may reduce these complications. Still, it is challenging due to levodopa's pharmacokinetic properties and the notion that it is absorbed only in the upper small intestine (i.e., exhibits an "absorption window"). We created and validated a physiologically based mathematical model to aid the development of such a formulation. Analysis of experimental results using the model revealed that levodopa is well absorbed throughout the entire small intestine (i.e., no "absorption window") and that levodopa in the stomach causes fluctuations during the first 3 h after administration. Based on these insights, we developed guidelines for an improved CRF for various stages of Parkinson's disease. Such a formulation is expected to produce steady concentrations and prolong therapeutic duration compared to a common CRF with a smaller dose per day and a lower overall dose of levodopa, thereby improving patient compliance with the dosage regime.

Impact of outpatient gastroenterology consult on pharmacotherapy and management of gastrointestinal symptoms in Parkinson's Disease

Background & aims

Gastrointestinal (GI) symptoms are common in Parkinson's Disease (PD) patients, and GI dysmotility is thought to induce motor fluctuations, requiring escalation of levodopa therapy. The role of GI consultation in managing such symptoms, however, is unclear. In this study, we investigate the possible association between GI dysmotility symptoms and escalated LEDD therapy, as well as factors associated with GI consultation for PD symptom management.

Methods

This was a retrospective case-study of 248 PD patients evaluated by outpatient neurology at Massachusetts General Brigham Healthcare from 2018 to 2022. Logistic regression, t-test, and Fisher exact tests were performed to identify factors associated with GI consult, change in LEDD with consult, and association of consultation with GI diagnoses and treatments, respectively.

Results

Among 248 PD patients, 12.9% received GI consultation despite 96.8% having GI symptoms. Bloating was the primary symptom associated with receiving GI consultation (OR 3.59 [95% CI 1.47-8.88], p = 0.005). GI consultation increased the odds of receiving GI-specific medications (78.2% vs 46.3%, p = 0.001) and specialized GI diagnoses like gastroparesis (9.4% vs 0.46%, p < 0.001) and pelvic floor dysfunction (15.6% vs 0%, p < 0.0001). Interestingly, LEDD tended not to change after GI consultation, and dysmotility symptoms, including bloating, did not predict need for higher LEDD.

Conclusions

While treating symptoms of dysmotility may not ameliorate levodopa-based motor fluctuations as much as previously thought, GI consultations are underutilized in PD, and patients who receive GI consultation are more likely to have changes in GI diagnosis and treatment.

Clinical Use of On-Demand Therapies for Patients with Parkinson's Disease and OFF Periods

On-demand therapies for Parkinson's disease (PD) provide rapid, reliable relief for patients experiencing OFF periods; however, practical guidelines on the use of these therapies are not generally available. This paper reviews the use of on-demand treatments. Motor fluctuations occur in nearly all patients with PD after long-term use of levodopa. As the goal of PD treatment is to provide good ON time, on-demand treatments that have a more rapid reliable onset than the slower-acting oral medications provide rapid relief for OFF periods. All current on-demand treatments bypass the gastrointestinal tract, providing dopaminergic therapy directly into the blood stream by subcutaneous injection, through the buccal mucosa, or by inhalation into the pulmonary circulation. On-demand treatments are fast acting (10- to 20-min onset), with maximum, reliable, and significant responses reached within 30 min after administration. Oral medications pass through the gastrointestinal tract and thus have slower absorption owing to gastroparesis and competition with food. On-demand therapies, by providing fast-acting relief, can have a positive impact on a patient's quality of life when patients are experiencing OFF periods.

A review of studies on gut microbiota and levodopa metabolism

Parkinson's disease (PD) is the second most common neurodegenerative disease globally. Levodopa (L-dopa) has been the cornerstone for treating Parkinson's since the 1960s. However, complications such as "wearing-off" and dyskinesia inevitably appear with disease progression. With the further development of microbiomics in recent years, It has been recognized that gut microbiota plays a crucial role in Parkinson's disease pathogenesis. However, Little is known about the impact of gut microbiota in PD treatment, especially in levodopa metabolism. This review examines the possible mechanisms of gut microbiota, such as Helicobacter pylori, Enterobacter faecalis, and Clostridium sporogenes, affecting L-dopa absorption. Furthermore, we review the current status of gut microbiota intervention strategies, providing new insights into the treatment of PD.

Role of dopamine agonists in Parkinson's disease therapy

Dopamine agonists are an important component of Parkinson's therapy. When weighing up the various therapy options, therapy with levodopa has recently been increasingly preferred due to its stronger efficacy and the ostensibly lower rate of side effects. The advantage of the lower incidence of motor complications during therapy with dopamine agonists was neglected. The occurrence of side effects can be explained by the different receptor affinity to the individual dopaminergic and non-dopaminergic receptors of the individual dopamine agonists. However, the different affinity to individual receptors also explains the different effect on individual Parkinson symptoms and can, therefore, contribute to a targeted use of the different dopamine agonists. Since comparative studies on the differential effect of dopamine agonists have only been conducted for individual substances, empirical knowledge of the differential effect is of great importance. Therefore, the guidelines for the treatment of Parkinson's disease do not consider the differential effect of the dopamine agonists. The historical consideration of dopamine agonists within Parkinson's therapy deserves special attention to be able to classify the current discussion about the significance of dopamine agonists.

Development and Validation of a New LC-MS/MS Bioanalytical Method for the Simultaneous Determination of Levodopa, Levodopa Methyl Ester, and Carbidopa in Human Plasma Samples

Levodopa (L-DOPA) treatment, combined with the administration of dopa-decarboxylase inhibitors (DDCIs), is still the most effective symptomatic treatment of Parkinson's disease (PD). Although its efficacy in the early stage of the disease has been confirmed, its complex pharmacokinetics (PK) increases the variability of the intra-individual motor response, thus amplifying the risk of motor/non-motor fluctuations and dyskinesia. Moreover, it has been demonstrated that L-DOPA PK is strongly influenced by several clinical, therapeutic, and lifestyle variables (e.g., dietary proteins). L-DOPA therapeutic monitoring is therefore crucial to provide personalized therapy, hence improving drug efficacy and safety. To this aim, we have developed and validated an ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method to quantify L-DOPA, levodopa methyl ester (LDME), and the DDCI carbidopa in human plasma. The compounds were extracted by protein precipitation and samples were analyzed with a triple quadrupole mass spectrometer. The method showed good selectivity and specificity for all compounds. No carryover was observed, and dilution integrity was demonstrated. No matrix effect could be retrieved; intra-day and inter-day precision and accuracy values met the acceptance criteria. Reinjection reproducibility was assessed. The described method was successfully applied to a 45-year-old male patient to compare the pharmacokinetic behavior of an L-DOPA-based medical treatment involving commercially available Mucuna pruriens extracts and an LDME/carbidopa (100/25 mg) formulation.

Gastrointestinal barriers to levodopa transport and absorption in Parkinson's disease

Levodopa is the gold standard for the symptomatic treatment of Parkinson's disease (PD). There are well documented motor and non-motor fluctuations, however, that occur almost inevitably once levodopa is started after a variable period in people with PD. Whilst brain neurodegenerative processes play a part in the pathogenesis of these fluctuations, a range of barriers across the gastrointestinal (GI) tract can alter levodopa pharmacokinetics, ultimately contributing to non-optimal levodopa response and symptoms fluctuations. GI barriers to levodopa transport and absorption include dysphagia, delayed gastric emptying, constipation, Helicobacter pylori infection, small intestinal bacterial overgrowth and gut dysbiosis. In addition, a protein-rich diet and concomitant medication intake can further alter levodopa pharmacokinetics. This can result in unpredictable or sub-optimal levodopa response, 'delayed on' or 'no on' phenomena. In this narrative review, we provided an overview on the plethora of GI obstacles to levodopa transport and absorption in PD and their implications on levodopa pharmacokinetics and development of motor fluctuations. In addition, management strategies to address GI dysfunction in PD are highlighted, including use of non-oral therapies to bypass the GI tract.

Patient-specific in vitro drug release testing coupled with in silico PBPK modeling to forecast the in vivo performance of oral extended-release levodopa formulations in Parkinson's disease patients

Biorelevant in vitro release models are valuable analytical tools for oral drug development but often tailored to gastrointestinal conditions in 'average' healthy adults. However, predicting in vivo performance in individual patients whose gastrointestinal conditions do not match those of healthy adults would be of great value for optimizing oral drug therapy for such patients. This study focused on establishing patient-specific in vitro and in silico models to predict the in vivo performance of levodopa extended-release products in Parkinsońs disease patients. Current knowledge on gastrointestinal conditions in these patients was incorporated into model development. Relevant in vivo pharmacokinetic data and patient-specific in vitro release data from a novel in vitro test setup were integrated into patient-specific physiologically-based pharmacokinetic models. AUC, c_max and t_max of the computed plasma profiles were calculated using PK-Sim®. For the products studied, levodopa plasma concentration-time profiles modeled using this novel approach compared far better with published average plasma profiles in Parkinsońs disease patients than those derived from in vitro release data obtained from the 'average' healthy adult setup. Although further work is needed, results of this study highlight the importance of addressing patient-specific gastrointestinal conditions when aiming to predict drug release in such specific patient groups.

Management of dysphagia and gastroparesis in Parkinson's disease in real-world clinical practice - Balancing pharmacological and non-pharmacological approaches

Gastrointestinal (GI) issues are commonly experienced by patients with Parkinson's disease (PD). Those that affect the lower GI tract, such as constipation, are the most frequently reported GI problems among patients with PD. Upper GI issues, such as swallowing dysfunction (dysphagia) and delayed gastric emptying (gastroparesis), are also common in PD but are less well recognized by both patients and clinicians and, therefore, often overlooked. These GI issues may also be perceived by the healthcare team as less of a priority than management of PD motor symptoms. However, if left untreated, both dysphagia and gastroparesis can have a significant impact on the quality of life of patients with PD and on the effectiveness on oral PD medications, with negative consequences for motor control. Holistic management of PD should therefore include timely and effective management of upper GI issues by utilizing both non-pharmacological and pharmacological approaches. This dual approach is key as many pharmacological strategies have limited efficacy in this setting, so non-pharmacological approaches are often the best option. Although a multidisciplinary approach to the management of GI issues in PD is ideal, resource constraints may mean this is not always feasible. In 'real-world' practice, neurologists and PD care teams often need to make initial assessments and treatment or referral recommendations for their patients with PD who are experiencing these problems. To provide guidance in these cases, this article reviews the published evidence for diagnostic and therapeutic management of dysphagia and gastroparesis, including recommendations for timely and appropriate referral to GI specialists when needed and guidance on the development of an effective management plan.

Levodopa–entacapone–carbidopa intestinal gel infusion in advanced Parkinson’s disease: real-world experience and practical guidance

As Parkinson’s disease (PD) progresses, treatment needs to be adapted to maintain symptom control. Once patients develop advanced PD, an optimised regimen of oral and transdermal medications may no longer provide adequate relief of OFF periods and motor complications can emerge. At this point, patients may wish to consider a device-aided therapy (DAT) that provides continuous dopaminergic stimulation to help overcome these issues. Levodopa–entacapone–carbidopa intestinal gel (LECIG) infusion is a recently developed DAT option. The aim of this article is twofold: (1) to give an overview of the pharmacokinetics of LECIG infusion and clinical experience to date of its use in patients with advanced PD, including real-world data and patient-reported outcomes from a cohort of patients treated in Sweden, the first country where it was introduced, and (2) based on that information to provide practical guidance for healthcare teams starting patients on LECIG infusion, whether they are transitioning from oral medications or from other DATs, including recommendations for stepwise dosing calculation and titration. In terms of clinical efficacy, LECIG infusion has been shown to have a similar effect on motor function to standard levodopa–carbidopa intestinal gel (LCIG) infusion but, due to the presence of entacapone in LECIG, the bioavailability of levodopa is increased such that lower overall levodopa doses can be given to achieve therapeutically effective plasma concentrations. From a practical standpoint, LECIG infusion is delivered using a smaller cartridge and pump system than LCIG infusion. In addition, for patients previously treated with LCIG infusion who have an existing percutaneous endoscopic transgastric jejunostomy (PEG-J) system, this is compatible with the LECIG infusion system. As it is a relatively new product, the long-term efficacy and safety of LECIG infusion remain to be established; however, real-world data will continue to be collected and analysed to provide this information and help inform future clinical decisions.

3D Printed Mini-Floating-Polypill for Parkinson's Disease: Combination of Levodopa, Benserazide, and Pramipexole in Various Dosing for Personalized Therapy

Therapy for Parkinson’s disease is quite challenging. Numerous drugs are available for symptomatic treatment, and levodopa (LD), in combination with a dopa decarboxylase inhibitor (e.g., benserazide (BZ)), has been the drug of choice for years. As the disease progresses, therapy must be supplemented with a dopamine agonist (e.g., pramipexole (PDM)). Side effects increase, as do the required dose and dosing intervals. For these specific requirements of drug therapy, the 3D printing method fused deposition modelling (FDM) was applied in this study for personalized therapy. Hot melt extrusion was utilized to produce two different compositions into filaments: PDM and polyvinyl alcohol for rapid drug release and a fixed combination of LD/BZ (4:1) in an ethylene-vinyl acetate copolymer matrix for prolonged drug release. Since LD is absorbed in the upper gastrointestinal tract, a formulation that floats in gastric fluid was desired to prolong API absorption. Using the FDM 3D printing process, different polypill geometries were printed from both filaments, with variable dosages. Dosage forms with 15−180 mg LD could be printed, showing similar release rates (f2 > 50). In addition, a mini drug delivery dosage form was printed that released 75% LD/BZ within 750 min and could be used as a gastric retentive drug delivery system due to the floating properties of the composition. The floating mini-polypill was designed to accommodate patients’ swallowing difficulties and to allow for individualized dosing with an API release over a longer period of time.

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.

Preliminary Investigation of Linum usitatissimum Mucilage-Based Hydrogel as Possible Substitute to Synthetic Polymer-Based Hydrogels for Sustained Release Oral Drug Delivery

The aim of this study was to investigate the potential of Linum usitatissimum mucilage, a natural polymer, in developing a sustained release hydrogel for orally delivered drugs that require frequent dosing. For this purpose, nicorandil (a model drug)-loaded hydrogels with various feed ratios of Linum usitatissimum mucilage, acrylamide (monomer) and methylene bis-acrylamide (crosslinker) were prepared. The newly synthesized hydrogel formulations were probed fundamentally with respect to swelling behaviour, solvent penetration, and the release of the drug from the hydrogels. Later, the selected formulations were further characterized by Fourier-transform infrared spectroscopy, thermal analysis, X-ray diffraction analysis, and scanning electron microscopy. The swelling coefficient demonstrated a linear relation with the polymer ratio; however, an inverse behaviour in the case of monomer and crosslinker was observed. The drug release studies, performed at pH 1.2 and 4.5 and considering the dynamic environment of GIT, demonstrated that all formulations followed the Korsmeyer–Peppas model, displaying a slow drug release via diffusion and polymer erosion. FTIR analysis confirmed the successful grafting of acrylamide on linseed mucilage. Furthermore, scanning electron microscopy revealed a clear surface morphology with folds and pinholes in the hydrogel. Therefore, based upon the in-vitro outcomes, it can be concluded that a promising sustained release hydrogel can be prepared from natural polymer, Linum usitatissimum mucilage, offering many-fold benefits over the conventional synthetic polymers for oral delivery of drugs.

Inhaled Levodopa (CVT-301) for the Treatment of Parkinson Disease: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Purpose

of Review: To investigate the efficacy and safety of CVT-301 for motor fluctuation in Parkinson’s disease (PD).

Recent Findings:

This study demonstrated that the CVT-301 group had a higher proportion of patients achieving an ON state than the placebo group (OR=2.68; 95% CI: 1.86-3.86; p<0.00001). Moreover, CVT-301 had also shown to improve motor function by UPDRS-III score (SMD=3.83; 95% CI: 2.44-5.23; p<0.00001) and promote an overall improvement of PD by PGIC self-rating (OR=2.95; 95% CI: 1.78-4.9; p<0.00001). The most common adverse events encountered were respiratory symptoms (OR=12.18; 95% CI: 5.01-29.62; p<0.00001) and nausea (OR=3.95; 95% CI: 1.01-15.41; p=0.05).

Summary:

CVT-301 had the potential to be an alternative or even a preferred treatment for motor fluctuation in PD patients.

Synthesis, characterization and in-vitro prolonged release of L-DOPA using a novel amphiphilic hydrogel based on sodium alginate-polypyrrole

As a serious neurodegenerative disorder, the prevalence of Parkinson's disease is predicted to dramatically increase in the coming decades. Despite the development of numerous drugs for its treatment, oral administration of levodopa has remained the simplest and most effective pharmacological approach in the management of Parkinson's disease. In this research, the levodopa-imprinted hydrogel was synthesized by reverse emulsion polymerization in the presence of levodopa followed by modification with polypyrrole. The antioxidant activity of amphiphilic non-levodopa-imprinted hydrogel was studied by 2,2-Diphenyl-1-picrylhydrazyl active radicals, which indicated 100% efficiency in the applied amount. Amphiphilic non-levodopa-imprinted hydrogel cytotoxicity was evaluated by MTT assay, which confirmed no significant toxicity after 24 and 48 h even at high concentrations. Moreover, in vitro releasing property of the levodopa-imprinted hydrogel was studied in the pH range of 4 to 7.4, which reached 60 and 80% within 160 h, respectively.

A technology evaluation of CVT-301 (Inbrija): an inhalable therapy for treatment of Parkinson's disease

Introduction: The most widely used pharmacological treatment for Parkinson's disease is levodopa, the precursor for dopamine formation in the brain. Over time, the effectiveness of levodopa declines, and patients experience motor fluctuations, or OFF periods. A levodopa formulation administered via a capsule-based oral inhaler provides a new delivery mechanism for levodopa that provides rapid relief of OFF periods.Areas covered: CVT-301 is a dry powder formulation designed to supply levodopa to the systemic circulation via pulmonary absorption. The technology, pharmacokinetics, efficacy, and safety data of this formulation are presented.Expert opinion: Oral inhalation is a novel method of administration for levodopa that bypasses the gastrointestinal tract, allowing levodopa to enter the systemic circulation rapidly and more reliably than oral medications. Gastrointestinal dysfunction, a common feature of Parkinson's disease, can lead to impaired absorption of oral medications. Pulmonary delivery rapidly elevates levodopa plasma concentrations to provide relief of OFF periods for patients receiving oral levodopa.

Oral Health Disorders in Parkinson's Disease: More than Meets the Eye

Despite clinical evidence of poor oral health and hygiene in Parkinson’s disease (PD) patients, the mouth is often overlooked by both patients and the medical community, who generally focus on motor or psychiatric disorders considered more burdensome. Yet, oral health is in a two-way relationship with overall health—a weakened status triggering a decline in the quality of life. Here, we aim at giving a comprehensive overview of oral health disorders in PD, while identifying their etiologies and consequences. The physical (abnormal posture, muscle tone, tremor, and dyskinesia), behavioral (cognitive and neuropsychiatric disorders), and iatrogenic patterns associated with PD have an overall detrimental effect on patients’ oral health, putting them at risk for other disorders (infections, aspiration, pain, malnutrition), reducing their quality of life and increasing their isolation (anxiety, depression, communication issues). Interdisciplinary cooperation for prevention, management and follow-up strategies need to be implemented at an early stage to maintain and improve patients’ overall comfort and condition. Recommendations for practice, including (non-)pharmacological management strategies are discussed, with an emphasis on the neurologists’ role. Of interest, the oral cavity may become a valuable tool for diagnosis and prognosis in the near future (biomarkers). This overlooked but critical issue requires further attention and interdisciplinary research.

On demand therapy for Parkinson's disease patients: Opportunities and choices

Levodopa is the most effective symptomatic treatment for Parkinson's disease (PD), but a major treatment challenge is that over time, many patients experience periods of return of PD symptoms intermittently through the day, known as OFF periods. OFF periods typically manifest as a return of motor symptoms but can also involve non-motor symptoms and these periods can disrupt good control despite optimization of the oral levodopa regimen. OFF periods emerge in large measure due to a shortening of the duration of clinical benefit from oral levodopa, thought to be related to a progressive loss of dopamine neurons and their ability to store and release levodopa-derived dopamine over many hours. The problem is further compounded by impaired absorption of oral levodopa due to gastroparesis and other factors limiting its uptake in the small intestine, including competition for uptake by meals and their protein content. On-demand therapies are now available for the treatment of OFF episodes in PD and are administered intermittently, on an as-needed basis, on top of the patient's maintenance medication regimen. To be useful, an on-demand medication should take effect more rapidly and reliably than oral levodopa. Options for on-demand therapy for OFF periods have recently increased with the approval of levodopa inhalation powder and sublingual apomorphine as alternatives to the older option of subcutaneous apomorphine injection, each of which avoids the gastrointestinal tract and its potential for absorption delay. On-demand therapy is now available for patients experiencing episodic or intermittent need for rapid and reliable onset of benefit. On-demand therapy may also provide an alternative to more invasive treatment such as infusion of levodopa/carbidopa intestinal gel and for patients whose OFF episodes are not controlled despite deep brain stimulation.

The Long-Term Impact of Levodopa/Carbidopa Intestinal Gel on 'Off'-time in Patients with Advanced Parkinson's Disease: A Systematic Review

INTRODUCTION

Levodopa/carbidopa intestinal gel (LCIG; carbidopa/levodopa enteral suspension) has been widely used and studied for the treatment of motor fluctuations in levodopa-responsive patients with advanced Parkinson's disease (PD) when other treatments have not given satisfactory results. Reduction in 'off'-time is a common primary endpoint in studies of LCIG, and it is important to assess the durability of this response. This systematic literature review was conducted to qualitatively summarise the data on the long-term effects of LCIG therapy on 'off'-time.

METHODS

Studies were identified by searching PubMed, EMBASE and Ovid on 30 September 2019. Studies were included if they reported on patients with PD, had a sample size of ≥ 10, LCIG was an active intervention and 'off'-time was reported for ≥ 12 months after initiation of LCIG treatment. Randomised clinical trials, retrospective and prospective observational studies, and other interventional studies were included for selection. Data were collected on: 'off'-time (at pre-specified time periods and the end of follow-up), study characteristics, Unified Parkinson's Disease Rating Scale (UPDRS) II, III and IV total scores, dyskinesia duration, quality of life scores, non-motor symptoms and safety outcomes.

RESULTS

Twenty-seven studies were included in this review. The improvement in 'off'-time observed shortly after initiating LCIG was maintained and was statistically significant at the end of follow-up in 24 of 27 studies. 'Off'-time was reduced from baseline to end of follow-up by 38-84% and was accompanied by a clinically meaningful improvement in quality of life. Stratified analysis of 'off'-time demonstrated mean relative reductions of 47-82% at 3-6 months and up to 83% reduction at 3-5 years of follow-up. Most studies reported significant improvements in activities of daily living and motor complications. Most frequent adverse events were related to the procedure or the device.

CONCLUSION

In one of the largest qualitative syntheses of published LCIG studies, LCIG treatment was observed to provide a durable effect in reducing 'off'-time.

INFOGRAPHIC

Video Abstract.

An evaluation of the efficacy and value of CVT-301 for the treatment of Parkinson's disease

Introduction: Levodopa is the most effective drug in the treatment of Parkinson's disease, but its chronic treatment is linked to the occurrence of motor complications with fluctuations of motor performance and dyskinesia. Unpredictable OFF episodes can be severe and disabling and current rescue medications cannot always be used safely. Rescue therapy is characterized by a rapid and predictable ON response and the safety profile of levodopa will represent a major advantage for patients affected by unresponsive OFF episodes.Areas covered: CVT-301 is a new inhaled formulation of LD recently developed as a self-administered treatment for OFF periods. Herein, the pharmacodynamic and pharmacokinetic properties, efficacy, and safety of CVT-301 are reviewed.Expert opinion: CVT-301 may offer several potential advantages including increased systemic bioavailability through pulmonary absorption, rapid onset of action, avoidance of first-pass drug metabolism, and less plasma level variability. It should be noted that the delivery device used has been described as relatively simple to use, but the few steps required to prepare and self-administer the dose can be challenging for PD patients during their OFF state. Additionally, resolution of an OFF episode requires the administration of two capsules of CVT-301, which further complicates the use of the device.

Leveraging Oral Drug Development to a Next Level: Impact of the IMI-Funded OrBiTo Project on Patient Healthcare

A thorough understanding of the behavior of drug formulations in the human gastrointestinal (GI) tract is essential when working in the field of oral drug development in a pharmaceutical company. For orally administered drug products, various GI processes, including disintegration of the drug formulation, drugrelease, dissolution, precipitation, degradation, dosage form transit and permeation, dictate absorption into the systemic circulation. These processes are not always fully captured in predictive in vitro and in silico tools, as commonly applied in the pre-clinical stage of formulation drug development. A collaborative initiative focused on the science of oral biopharmaceutics was established in 2012 between academic institutions and industrial companies to innovate, optimize and validate these in vitro and in silico biopharmaceutical tools. From that perspective, the predictive power of these models can be revised and, if necessary, optimized to improve the accuracy toward predictions of the in vivo performance of orally administered drug products in patients. The IMI/EFPIA-funded "Oral Bioavailability Tools (OrBiTo)" project aimed to improve our fundamental understanding of the GI absorption process. The gathered information was integrated into the development of new (or already existing) laboratory tests and computer-based methods in order to deliver more accurate predictions of drug product behavior in a real-life setting. These methods were validated with the use of industrial data. Crucially, the ultimate goal of the project was to set up a scientific framework (i.e., decision trees) to guide the use of these new tools in drug development. The project aimed to facilitate and accelerate the formulation development process and to significantly reduce the need for animal experiments in this area as well as for human clinical studies in the future. With respect to the positive outcome for patients, high-quality oral medicines will be developed where the required dose is well-calculated and consistently provides an optimal clinical effect. In a first step, this manuscript summarizes the setup of the project and how data were collected across the different work packages. In a second step, case studies of how this project contributed to improved knowledge of oral drug delivery which can be used to develop improved products for patients will be illustrated.

Directly Compressed Tablets: A Novel Drug-Containing Reservoir Combined with Hydrogel-Forming Microneedle Arrays for Transdermal Drug Delivery

Microneedle (MN) patches consist of a hydrogel-forming MN array and a drug-containing reservoir. Drug-containing reservoirs documented in the literature include polymeric films and lyophilized wafers. While effective, both reservoir formulations are aqueous based, and so degradation can occur during formulation and drying for drugs inherently unstable in aqueous media. The preparation and characterization of novel, nonaqueous-based, directly compressed tablets (DCTs) for use in combination with hydrogel-forming MN arrays are described for the first time. In this work, a range of drug molecules are investigated. Precipitation of amoxicillin (AMX) and primaquine (PQ) in conventional hydrogel-forming MN arrays leads to use of poly(vinyl alcohol)-based MN arrays. Following in vitro permeation studies, in vivo pharmacokinetic studies are conducted in rats with MN patches containing AMX, levodopa/carbidopa (LD/CD), and levofloxacin (LVX). Therapeutically relevant concentrations of AMX (≥2 µg mL^-1 ), LD (≥0.5 µg mL^-1 ), and LVX (≥0.2 µg mL^-1 ) are successfully achieved at 1, 2, and 1 h, respectively. Thus, the use of DCTs offers promise to expand the range of drug molecules that can be delivered transdermally using MN patches.

Gastrointestinal dysfunction in the synucleinopathies

Interest in gastrointestinal dysfunction in Parkinson's disease has blossomed over the past 30 years and has generated a wealth of investigation into this non-motor aspect of the disorder, research that has encompassed its pathophysiology, its clinical features, and its impact on quality of life. The question of gastrointestinal dysfunction in the other synucleinopathies has not received nearly as much attention, but information and knowledge are growing. In this review, the current knowledge, controversies, and gaps in our understanding of the pathophysiology of gastrointestinal dysfunction in Parkinson's disease and the other synucleinopathies will be addressed, and extended focus will be directed toward the clinical problems involving saliva management, swallowing, gastric emptying, small intestinal function, and bowel function that are so problematic in these disorders.

Parkinson disease and the gut: new insights into pathogenesis and clinical relevance

The classic view portrays Parkinson disease (PD) as a motor disorder resulting from loss of substantia nigra pars compacta dopaminergic neurons. Multiple studies, however, describe prodromal, non-motor dysfunctions that affect the quality of life of patients who subsequently develop PD. These prodromal dysfunctions comprise a wide array of gastrointestinal motility disorders including dysphagia, delayed gastric emptying and chronic constipation. The histological hallmark of PD - misfolded α-synuclein aggregates that form Lewy bodies and neurites - is detected in the enteric nervous system prior to clinical diagnosis, suggesting that the gastrointestinal tract and its neural (vagal) connection to the central nervous system could have a major role in disease aetiology. This Review provides novel insights on the pathogenesis of PD, including gut-to-brain trafficking of α-synuclein as well as the newly discovered nigro-vagal pathway, and highlights how vagal connections from the gut could be the conduit by which ingested environmental pathogens enter the central nervous system and ultimately induce, or accelerate, PD progression. The pathogenic potential of various environmental neurotoxicants and the suitability and translational potential of experimental animal models of PD will be highlighted and appraised. Finally, the clinical manifestations of gastrointestinal involvement in PD and medications will be discussed briefly.

Population pharmacokinetics of levodopa gel infusion in Parkinson's disease: effects of entacapone infusion and genetic polymorphism

Levodopa-entacapone-carbidopa intestinal gel (LECIG) provides continuous drug delivery through intrajejunal infusion. The aim of this study was to characterize the population pharmacokinetics of levodopa following LECIG and levodopa-carbidopa intestinal gel (LCIG) infusion to investigate suitable translation of dose from LCIG to LECIG treatment, and the impact of common variations in the dopa-decarboxylase (DDC) and catechol-O-methyltransferase (COMT) genes on levodopa pharmacokinetics. A non-linear mixed-effects model of levodopa pharmacokinetics was developed using plasma concentration data from a double-blind, cross-over study of LCIG compared with LECIG in patients with advanced Parkinson’s disease (n = 11). All patients were genotyped for rs4680 (polymorphism of the COMT gene), rs921451 and rs3837091 (polymorphisms of the DDC gene). The final model was a one compartment model with a high fixed absorption rate constant, and a first order elimination, with estimated apparent clearances (CL/F), of 27.9 L/h/70 kg for LCIG versus 17.5 L/h/70 kg for LECIG, and apparent volume of distribution of 74.4 L/70 kg. Our results thus suggest that the continuous maintenance dose of LECIG, on a population level, should be decreased by approximately 35%, to achieve similar drug exposure as with LCIG. An effect from entacapone was identified on all individuals, regardless of COMT rs4680 genotype. The individuals with higher DDC and COMT enzyme activity showed tendencies towards higher levodopa CL/F. The simultaneous administration of entacapone to LCIG administration results in a 36.5% lower apparent levodopa clearance, and there is a need for lower continuous maintenance doses, regardless of patients’ COMT genotype.

Clinical implications of gastric complications on levodopa treatment in Parkinson's disease

Disorders of the gastrointestinal (GI) tract are common and distressing nonmotor symptoms of Parkinson's disease (PD) that can adversely affect levodopa absorption and lead to OFF periods, also known as motor fluctuations. Gastroparesis, which is primarily defined as delayed gastric emptying (DGE), and Helicobacter pylori infection, which is present with increased frequency in PD, are among the most common and important GI disorders reported in PD that may impair oral levodopa absorption and increase OFF time. Symptoms of gastroparesis include nausea, vomiting, postprandial bloating, fullness, early satiety, abdominal pain, and weight loss. DGE has been reported in a substantial fraction of individuals with PD. Symptoms of H. pylori infection include gastritis and peptic ulcers. Studies have found that DGE and H. pylori infection are correlated with delayed peak levodopa plasma levels and increased incidence of motor fluctuations. Therapeutic strategies devised to minimize the potential that gastric complications will impair oral levodopa absorption and efficacy in PD patients include treatments that circumvent the GI tract, such as apomorphine injection, levodopa intestinal gel delivery, levodopa inhalation powder, and deep brain stimulation. Other strategies aim at improving gastric emptying in PD patients, primarily including prokinetic agents.

From medications to surgery: advances in the treatment of motor complications in Parkinson's disease

Motor complications are responsible for the large burden of disability and poor quality of life in Parkinson’s disease (PD). The pulsatile nature of stimulation with oral dopaminergic therapies due to relatively short pharmacokinetic profiles and dysfunctional gastrointestinal absorption have been attributed to the development of PD motor complications. In this review, we will provide an overview of the pharmacologic and surgical therapies currently available and under investigation for the treatment of motor fluctuations and dyskinesia.

Pharmacokinetics of Rytary®, An Extended-Release Capsule Formulation of Carbidopa-Levodopa

Parkinson's disease (PD) is a chronic progressive neurological disorder characterized by resting tremor, rigidity, bradykinesia, gait disturbance, and postural instability. Levodopa, the precursor to dopamine, coadministered with carbidopa or benserazide, aromatic amino acid decarboxylase inhibitors, is the most effective and widely used therapeutic agent in the treatment of PD. With continued levodopa treatment, a majority of patients develop motor complications such as dyskinesia and motor 'on-off' fluctuations, which are, in part, related to the fluctuations in plasma concentrations of levodopa. A new extended-release (ER) carbidopa-levodopa capsule product (also referred to as IPX066) was developed and approved in the US as Rytary^® and in the EU as Numient^®. The capsule formulation is designed to provide an initial rapid absorption of levodopa comparable to immediate-release (IR) carbidopa-levodopa, and to subsequently provide stable levodopa concentrations with reduced peak-to-trough excursions in plasma concentrations in order to reduce motor fluctuations associated with pulsatile stimulation of dopamine receptors and to minimize dyskinesia. Phase III studies of this ER carbidopa-levodopa capsule formulation in patients with PD have shown a significant reduction in 'off' time compared with IR carbidopa-levodopa and carbidopa-levodopa-entacapone. We present a review of the clinical pharmacokinetics and pharmacodynamics of this ER product of carbidopa-levodopa in healthy subjects and in patients with PD.

DA-9701 on gastric motility in patients with Parkinson's disease: A randomized controlled trial

INTRODUCTION

To evaluate the effect of DA-9701, a novel prokinetic drug, on gastric motility evaluated by magnetic resonance imaging in patients with Parkinson's disease (PD).

METHODS

Forty PD patients were randomly allocated to receive either domperidone or DA-9701. Their gastric functions were evaluated using magnetic resonance imaging before and after 4-week treatment period. Information on levodopa daily dose, disease duration, and Unified PD Rating Scale scores was collected. In 18 patients (domperidone: 9, DA-9701: 9), plasma levodopa concentrations were determined. Primary outcome was assessed by a one-sided 95% confidence interval to show non-inferiority of DA-9701 vs. domperidone with a pre-determined non-inferiority margin of -10%.

RESULTS

Thirty-eight participants (19 men and 19 women; mean age, 67.1 years) completed the study protocol (domperidone: DA-9701 = 19:19). Gastric emptying rate at 120 min (2-hr GER) was comparable between the 2 groups; it was not correlated with levodopa daily dose or disease duration or Unified PD Rating Scale scores (all p > 0.05). DA-9701 was not inferior to domperidone in changes of 2-hr GERs before and after the treatment (absolute difference, 4.0 %; one-sided 95% confidence interval, - 3.7 to infinity). However, a significant increase in 2-hr GER was observed only in DA-9701 group (54.5% and 61.8%, before and after treatment, respectively, p < 0.05). Plasma levodopa concentration showed an insignificant but increasing trend in DA-9701 group. There were neither adverse reactions nor deteriorations of parkinsonian symptoms observed in the study participants.

CONCLUSION

DA-9701 can be used for the patients with PD to enhance gastric motility without aggravating PD symptoms (ClinicalTrials.gov number: NCT03022201).

Molecular basis of dopamine replacement therapy and its side effects in Parkinson's disease

There is currently no cure for Parkinson's disease. The symptomatic therapeutic strategy essentially relies on dopamine replacement whose efficacy was demonstrated more than 50 years ago following the introduction of the dopamine precursor, levodopa. The spectacular antiparkinsonian effect of levodopa is, however, balanced by major limitations including the occurrence of motor complications related to its particular pharmacokinetic and pharmacodynamic properties. Other therapeutic strategies have thus been developed to overcome these problems such as the use of dopamine receptor agonists, dopamine metabolism inhibitors and non-dopaminergic drugs. Here we review the pharmacology and molecular mechanisms of dopamine replacement therapy in Parkinson's disease, both at the presynaptic and postsynaptic levels. The perspectives in terms of novel drug development and prediction of drug response for a more personalised medicine will be discussed.

Levodopa in Parkinson's Disease: Current Status and Future Developments

BACKGROUND

Ever since the pioneering reports in the 60s, L-3,4-Dioxyphenylalanine (levodopa) has represented the gold standard for the treatment of Parkinson's Disease (PD). However, long-term levodopa (LD) treatment is frequently associated with fluctuations in motor response with serious impact on patient quality of life. The pharmacokinetic and pharmacodynamic properties of LD are pivotal to such motor fluctuations: discontinuous drug delivery, short half-life, poor bioavailability, and narrow therapeutic window are all crucial for such fluctuations. During the last 60 years, several attempts have been made to improve LD treatment and avoid long-term complications.

METHODS

Research and trials to improve the LD pharmacokinetic since 1960s are reviewed, summarizing the progressive improvements of LD treatment.

RESULTS

Inhibitors of peripheral amino acid decarboxylase (AADC) have been introduced to achieve proper LD concentration in the central nervous system reducing systemic adverse events. Inhibitors of catechol-O-methyltransferase (COMT) increased LD half-life and bioavailability. Efforts are still being made to achieve a continuous dopaminergic stimulation, with the combination of oral LD with an AADC inhibitor and a COMT inhibitor, or the intra-duodenal water-based LD/ carbidopa gel. Further approaches to enhance LD efficacy are focused on new non-oral administration routes, including nasal, intra-duodenal, intrapulmonary (CVT-301) and subcutaneous (ND0612), as well as on novel ER formulations, including IPX066, which recently concluded phase III trial.

CONCLUSION

New LD formulations, oral compounds as well as routes have been tested in the last years, with two main targets: achieve continuous dopaminergic stimulation and find an instant deliver route for LD.

l-Dopa responsiveness is associated with distinctive connectivity patterns in advanced Parkinson's disease

BACKGROUND

Neuronal loss and dopamine depletion alter motor signal processing between cortical motor areas, basal ganglia, and the thalamus, resulting in the motor manifestations of Parkinson's disease. Dopamine replacement therapy can reverse these manifestations with varying degrees of improvement.

METHODS

To evaluate functional connectivity in patients with advanced Parkinson's disease and changes in functional connectivity in relation to the degree of response to l-dopa, 19 patients with advanced Parkinson's disease underwent resting-state functional magnetic resonance imaging in the on-medication state. Scans were obtained on a 3-Tesla scanner in 3 × 3 × 2.5 mm³ voxels. Seed-based bivariate regression analyses were carried out with atlas-defined basal ganglia regions as seeds, to explore relationships between functional connectivity and improvement in the motor section of the UPDRS-III following an l-dopa challenge. False discovery rate-corrected P was set at < 0.05 for a 2-tailed t test.

RESULTS

A greater improvement in UPDRS-III scores following l-dopa administration was characterized by higher resting-state functional connectivity between the prefrontal cortex and the striatum (P = 0.001) and lower resting-state functional connectivity between the pallidum (P = 0.001), subthalamic nucleus (P = 0.003), and the paracentral lobule (supplementary motor area, mesial primary motor, and primary sensory areas).

CONCLUSIONS

Our findings show characteristic basal ganglia resting-state functional connectivity patterns associated with different degrees of l-dopa responsiveness in patients with advanced Parkinson's disease. l-Dopa exerts a graduated influence on remapping connectivity in distinct motor control networks, potentially explaining some of the variance in treatment response. © 2017 International Parkinson and Movement Disorder Society.

Levodopa-carbidopa enteral suspension in advanced Parkinson's disease: clinical evidence and experience

The duration of action of oral levodopa becomes shorter as Parkinson's disease (PD) progresses. Patients with advanced PD may develop potentially disabling motor fluctuations and abnormal involuntary movement (dyskinesia), which cannot be managed with optimized oral or transdermal PD medications. The progressively worsening symptoms can have a substantial impact on the patient quality of life (QoL). Levodopa-carbidopa intestinal gel (LCIG) is delivered continuously via a percutaneous endoscopic gastrostomy with a jejunal extension (PEG-J). LCIG is licensed for the treatment of levodopa-responsive advanced PD in individuals experiencing severe motor fluctuations and dyskinesia when available combinations of antiparkinsonian medications have not given satisfactory results. Initial evidence for the efficacy and tolerability of LCIG came from a number of small-scale studies, but recently, three prospective studies have provided higher quality evidence. A 12-week double-blind comparison of LCIG with standard levodopa therapy, a 52-week open-label study extension of the double-blind study, and a 54-week open-label safety study, demonstrated significant improvements in 'off' time and 'on' time without troublesome dyskinesia, and QoL measures that were maintained in the longer term. There are also observations that LCIG may be effective treatment for nonmotor symptoms (NMS) although the evidence is limited. There is a need for further research on the efficacy of LCIG in reducing NMS, dyskinesia and improving QoL. This review surveys the clinical evidence for the effectiveness and tolerability of LCIG in the management of advanced PD and highlights some practical considerations to help optimize treatment.

Conversion to IPX066 from Standard Levodopa Formulations in Advanced Parkinson's Disease: Experience in Clinical Trials

Background:

Due to the short half-life of levodopa, immediate-release carbidopa-levodopa (IR CD-LD) produces fluctuating LD concentrations, contributing to a risk of eventual motor complications. IPX066 was designed to rapidly attain therapeutic LD concentrations and maintain them to allow a dosing interval of ∼6 hours.

Objective:

To extensively analyze the dosing data collected in IPX066 studies during open-label conversions from IR CD-LD alone or with entacapone (CLE) and identify patterns relevant for managing conversion in the clinical setting.

Methods:

Patients had ≥2.5 hours/day of “off” time despite a stable IR or CLE regimen. Suggested initial dosing conversion tables based on prior LD daily dosage were provided.

Results:

Of 450 patients previously treated with IR CD-LD and 110 with CLE, 87.3% and 82.7% completed conversion to IPX066, respectively. At the end of conversion, average IPX066 LD daily dosages were higher than pre-conversion dosages, with a mean conversion ratio of 2.1±0.6 for IR CD-LD and 2.8±0.8 for CLE; >90% of patients took IPX066 3 or 4 times/day, compared with a median of 5 times/day at baseline in both studies. After conversion, daily “off” time significantly decreased, with no significant increase in troublesome dyskinesia. The most common adverse event reported during conversion was nausea, with an incidence of 5.3% for conversion from IR and 7.3% from CLE.

Conclusions:

Among PD patients with substantial “off” time, a majority were safely converted to IPX066. The sustained LD profile from the IPX066 formulation allowed an increase in LD dose accompanied by improved motor functions, without increased troublesome dyskinesia.