Levodopa infusion combined with entacapone or tolcapone in Parkinson disease: a pilot trial

Early-morning OFF in Parkinson's disease: A systematic literature review and current therapeutics

OBJECTIVE

Early morning OFF (EMO) is one of the first motor complications to manifest and frequently signals the onset of additional motor complications in Parkinson's Disease (PD). Although EOM are frequently observed in patients with PD and many caregivers must help with their motor inability, the treatment is still unsatisfactory. The majority of research that has been conducted on the wearing-off state of patients with PD has focused on daytime symptoms; evening and early morning symptoms have received much less attention.This study aimed to review the clinical perspectives of current therapies for EMO.

MATERIALS AND METHODS

We reviewed the searching relevant publications from the key words such as morning off. A total of 456 publications were identified and we reviewed 21 clinical trials as well as other relevant clinical studies and reviews.

RESULTS

EMO are frequently disregarded or undervalued, which could have resulted in unintentional risks, inadequate management, and an increased burden of care. Oral medication is still the primary medical intervention for EMO. However, new developments in non-oral medications and advanced formulations aim to reduce the delay in experiencing the benefits of oral levodopa due to gastrointestinal problems.

CONCLUSIONS

The current therapies for EMO could be helpful in selecting a limited practical treatment. Advancements in non-oral medications and oral formulations hold promise for improving efficacy in EMO.

Clinicians' viewpoints on current paradigms of care and research in Parkinson's disease

Aim of this review is to discuss the value of current ongoing research initiatives in Parkinson's disease from the clinicians' point of view. The repeat, recent failures on progress slowing reflect the drifting apart between initially promising experimental and then disappointing clinical outcomes in the translational trials with well selected Parkinson's disease patients. A similar development concerns the emerging gap between novel developed drugs with improved pharmacokinetic behaviour and their limited use in the clinical practice following approval. Restricted regional different worldwide availability and direct, respectively indirect budget limitations for neurologists in private practice are essential hurdles. They prevent the widespread prescription of these compounds. As a result return of investment for the pharmaceutical industry becomes more and more uncertain. The interest for research on novel treatment approaches for the amelioration of motor and non motor symptoms declines. Clinicians crucially scrutinize the claim for an optimum patient care by payers and regulators.

Levodopa-Entacapone-Carbidopa Intestinal Gel in the Treatment of Advanced Parkinson's Disease: A Single Center Real-World Experience

Levodopa-entacapone-carbidopa intestinal gel infusion is a relatively new treatment option for advanced Parkinson's disease. We aimed to describe and analyze the characteristics of de novo levodopa-entacapone-carbidopa intestinal gel therapy in 20 consecutive patients with advanced Parkinson's disease. We assessed the profile of motor complications by evaluating the following: motor fluctuations, dyskinesias, and the freezing phenomenon at baseline (before the testing period) and before discharge. The treatment significantly reduced the duration of daily hours spent in off time compared with baseline pre-treatment values from a mean of 4.8 ± 0.9 h/day to a mean of 1.4 ± 0.5 h per day (p < 0.001). The duration and severity of peak-dose dyskinesia were also significantly reduced compared with baseline values. Out of the 10 patients who reported freezing, 8 did not present this complication at the pre-discharge assessment. Significant improvements were observed in Hoehn and Yahr scale scores in both the on and off states. The levodopa-entacapone-carbidopa intestinal gel therapy was well tolerated during the follow-up period immediately after initiation. Despite a relatively severe stage of the disease, all patients experienced a significant improvement in motor fluctuations, dyskinesias, and the freezing phenomenon.

Optimization of oral entacapone administration in patients undergoing levodopa-carbidopa intestinal gel treatment

BACKGROUND

Levodopa-carbidopa intestinal gel (LCIG) treatment markedly reduces motor fluctuations in patients with Parkinson's disease; however, some patients undergoing LCIG treatment may demonstrate clinical deterioration in the afternoon. Entacapone, a catechol-O-methyltransferase inhibitor, may be a promising adjunctive option for LCIG-treated patients; however, the optimal timing of oral entacapone administration to ameliorate clinical symptoms in the afternoon remains unexplored. This study aimed to investigate the optimal timing of oral entacapone administration in patients with Parkinson's disease undergoing LCIG treatment.

METHODS

Pharmacokinetic analysis and symptom assessment were performed on three days: a day without entacapone administration, day with oral entacapone administration at 13:00, and day with oral entacapone administration at 15:00.

RESULTS

Eight LCIG-treated patients were enrolled, of whom seven completed this study. The relative plasma concentrations of levodopa with entacapone administration at 13:00 were gradually increased, especially at 18:00 and were significantly higher than those without entacapone administration (127.10 ± 25.06% vs. 97.51 ± 22.20%). The relative plasma concentrations of 3-O-methyldopa were gradually increased without entacapone administration, whereas those with entacapone administration at 13:00 were lower than those without entacapone administration, especially at 17:00 (97.47 ± 3.70% vs. 110.71 ± 9.84%). Administering oral entacapone at 15:00 increased and decreased the relative plasma concentrations of levodopa and 3-O-methyldopa, respectively, but without significant difference. The "Off" time was shorter with entacapone administration at 13:00 (0.43 ± 0.79 h) and at 15:00 (0.57 ± 0.79 h) than that without entacapone administration (1.14 ± 1.46 h).

CONCLUSIONS

The concomitant use of oral entacapone in the early afternoon may be effective in improving afternoon symptoms in patients undergoing LCIG treatment.

Clinical benefit of MAO-B and COMT inhibition in Parkinson's disease: practical considerations

Inhibitors of monoamine oxidase B (MAO-B) and catechol-O-methyltransferase (COMT) are major strategies to reduce levodopa degradation and thus to increase and prolong its effect in striatal dopaminergic neurotransmission in Parkinson's disease patients. While selegiline/rasagiline and tolcapone/entacapone have been available on the market for more than one decade, safinamide and opicapone have been approved in 2015 and 2016, respectively. Meanwhile, comprehensive data from several post-authorization studies have described the use and specific characteristics of the individual substances in clinical practice under real-life conditions. Here, we summarize current knowledge on both medication classes, with a focus on the added clinical value in Parkinson's disease. Furthermore, we outline practical considerations in the treatment of motor fluctuations and provide an outlook on ongoing studies with MAO-B and COMT inhibitors.

Off-time Treatment Options for Parkinson's Disease

Motor fluctuations (MF) are deemed by patients with Parkinson's disease (PD) as the most troublesome disease feature resulting from the increasing impairment in responsiveness to dopaminergic drug treatments. MF are characterized by the loss of a stable response to levodopa over the nychthemeron with the reappearance of motor (and non-motor) parkinsonian clinical signs at various moments during the day and night. They normally appear after a few years of levodopa treatment and with a variable, though overall increasing severity, over the disease course. The armamentarium of first-line treatment options has widened in the last decade with new once-a-daily compounds, including a catechol O-methyltransferase inhibitor - Opicapone-, two MAO-B inhibitors plus channel blocker - Zonisamide and Safinamide and one amantadine extended-release formulation - ADS5012. In addition to apomorphine injection or oral levodopa dispersible tablets, which have been available for a long time, new on-demand therapies such as apomorphine sublingual or levodopa inhaled formulations have recently shown efficacy as rescue therapies for Off-time treatment. When the management of MF becomes difficult in spite of oral/on-demand options, more complex therapies should be considered, including surgical, i.e. deep brain stimulation, or device-aided therapies with pump systems delivering continuous subcutaneous or intestinal levodopa or subcutaneous apomorphine formulation. Older and less commonly used ablative techniques (radiofrequency pallidotomy) may also be effective while there is still scarce data regarding Off-time reduction using a new lesional approach, i.e. magnetic resonance-guided focused ultrasound. The choice between the different advanced therapies options is a shared decision that should consider physician opinion on contraindication/main target symptom, patients' preference, caregiver's availability together with public health systems and socio-economic environment. The choice of the right/first add-on treatment is still a matter of debate as well as the proper time for an advanced therapy to be considered. In this narrative review, we discuss all the above cited aspects of MF in patients with PD, including their phenomenology, management, by means of pharmacological and advanced therapies, on-going clinical trials and future research and treatment perspectives.

Optimizing levodopa therapy, when and how? Perspectives on the importance of delivery and the potential for an early combination approach

INTRODUCTION

There is currently a resurgence of levodopa as the initial treatment of choice for most patients with Parkinson's disease, albeit at lower doses than previously used. The addition of adjuvant treatments (including MAO-B inhibitors, COMT inhibitors and dopamine agonists) is an established strategy to reduce motor complications that develop with sustained levodopa therapy.

AREAS COVERED

In this narrative review, the authors discuss the evidence underpinning current levodopa optimization strategies, during early disease and once motor complications occur. To support the discussion, the authors performed a broad PubMed search with the terms 'levodopa/L-dopa/L-Dopa, and Parkinson's disease,' restricted to clinical trials. There is now a wealth of evidence that improving levodopa delivery to the brain improves outcomes and we discuss how agents can be combined earlier in the course of disease to leverage the full potential of this strategy.

EXPERT OPINION

Levodopa remains the cornerstone of antiparkinsonian therapy. Several promising advances in formulation have been made and include novel extended-release oral drugs as well as non-oral delivery systems. However, evidence has long suggested that anti-parkinsonian medications may be better used in combination earlier in the disease, and consequently patients will benefit from low doses of several agents rather than ever larger levodopa doses.

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.

Clinical Pharmacology of Entacapone (Comtan) From the FDA Reviewer

This new drug application was first submitted to the US Food and Drug Administration (FDA) by the Orion Corporation from Finland on January 2, 1998. The final clinical pharmacology review was completed on September 3, 1999. Entacapone is a potent and specific peripheral catechol-O-methyltransferase inhibitor. It has been shown to improve the clinical benefits of levodopa plus an aromatic L-amino acid decarboxylase inhibitor when given to patients with Parkinson's disease and end-of-dose deterioration in the response to levodopa (the "wearing-off" phenomenon). The drug indication is for Parkinson's disease as an adjunct therapy to levodopa/carbidopa. This is a combination drug with carbidopa (aromatic amino acid decarboxylation inhibitor) and entacapone. It is rapidly absorbed after oral administration of a single dose, with peak time generally reached within 1 hour. It is noted that no accumulation of plasma entacapone was detected after 8 daily doses. The maximum daily dose is 2000 mg. In this paper, the clinical pharmacology review of the drug is presented from the perspective of a clinical pharmacologist who reviewed this new drug application at the FDA. It should be noted that all the information in this paper is publicly available on the FDA website and in its literature.

COMT Inhibitors in the Management of Parkinson's Disease

Levodopa treatment remains the gold standard for Parkinson's disease, but shortcomings related to the pharmacological profile, notably, oral administration and the consequent occurrence of motor complications, have led to the development of several add-on levodopa treatments or to research to improve the method of delivery. Motor fluctuations, and to a lesser extent non-motor fluctuations, concern half of the patients with Parkinson's disease after 5 years of disease and patients identified them as one of their most bothersome symptoms. Catechol-O-methyl transferase inhibitors (COMT-Is) are one of the recommended first-line levodopa add-on therapies for the amelioration of end-of dose motor fluctuations in patient with advanced Parkinson's disease. Currently, two peripheral COMT-Is are considered as first-line choices - entacapone (ENT), which was approved by the US Food and Drug Administration in 1999 and the European Committee in 1998; and opicapone (OPC), which was approved by the European Committee in 2016. A second-line COMT-I that requires regular hepatic monitoring, tolcapone (TOL), was approved by the Food and Drug Administration in 1998 and the European Committee in 1997. Of note, OPC also received Food and Drug Administration approval in 2021, but it is still only marketed in a few countries, including Germany, UK, Spain, Portugal, Italy, Japan, and USA, while ENT and TOL have a wider market. Our narrative review summarizes the pharmacokinetic/pharmacodynamic properties, clinical efficacy in terms of motor fluctuations, motor/non-motor symptoms, quality of life, and safety data of these three COMT-Is, as evidenced by randomized clinical trials, as well as by real-life observational studies. Overall, a phase III non-inferiority trial showed a similar effect between ENT and OPC on off-time (-60.8 min/day and -40.3 min/day, vs placebo, respectively), with a possible additional off-time reduction of 39 min/day, obtained when there is a switch from ENT to OPC. Concomitantly, TOL can reduce off-time by an average of 98 min/day. A significant though discrete concomitant reduction on the Unified Parkinson's Disease Rating Scale motor section (2-3 points) is obtained with all three drugs vs placebo. Data on quality of life are fewer and more heterogeneous, with positive results obtained especially in open-label studies. Effects on non-motor symptoms were investigated as secondary outcome only in a few studies, frequently by means of non-specific scales and a benefit was observed in open-label studies. Dopaminergic adverse effects were the most frequent, dyskinesia being the most common for the three drugs eventually requiring levodopa dose reductions. No urine discoloration and a very low incidence of diarrhea were found with OPC compared with ENT and TOL. Regular hepatic monitoring is needed only for TOL. A combination of COMT-Is with new formulations of levodopa, including the subcutaneous, intrajejunal, or new extended-release formulation, merits further exploration to improve the management of both mild and severe motor fluctuations.

Advanced Parkinson's Disease Treatment Simplification and Long-Term Outcomes with Levodopa Carbidopa Intestinal Gel: COSMOS Romanian Subanalysis

The aim of the COmedication Study assessing Mono- and cOmbination therapy with levodopa-carbidopa inteStinal gel (COSMOS) was to assess the use of levodopa/carbidopa intestinal gel (LCIG) as monotherapy in patients with advanced Parkinson’s disease (APD) in routine clinical practice. COSMOS was an international observational study with one cross-sectional visit and retrospective data collection. In Romania, 95 adult patients with APD on LCIG treatment for at least 12 months were enrolled and stratified according to their LCIG therapy after 12 months: monotherapy (without any add-on PD medication), monotherapy with night PD medication and LCIG + add-on medication. Compared to the moment of LCIG initiation, the percentage of patients on monotherapy increased at three months after LCIG initiation and remained constant up to 12 months, when 30.5% of the patients were on LCIG monotherapy and 11.6% were on monotherapy with night medication. “Off” time and “On” time with dyskinesia decreased from LCIG initiation to patient visit in all groups. LCIG monotherapy with or without night medication may provide a simplified treatment option for selected APD patients, with long-term efficacy similar to that of LCIG plus add-on medication.

Opicapone and Levodopa-Carbidopa Intestinal Gel Infusion: The Way Forward Towards Cost Savings for Healthcare Systems?

Combined catechol-O-methyl-transferase-inhibition and Levodopa-Carbidopa intestinal gel (LCIG) infusion has the potential to reduce LCIG daily dose and the costs of this therapy. In this retrospective analysis, we report on Parkinson's disease (PD) patients on LCIG with concomitant Opicapone. In 11 patients, the introduction of Opicapone led to LCIG daily dose being reduced by 24.8% (p = 0.05) without any significant worsening of dyskinesia. Three patients withdrew from Opicapone due to side effects or inefficacy. LCIG daily dose reduction could lead to cost savings of £142,820.63/year in the United Kingdom while maintaining clinical care.

Initial Experience of the Levodopa-Entacapone-Carbidopa Intestinal Gel in Clinical Practice

Patients in fluctuating stages of Parkinson’s disease (PD) require device-aided treatments. Continuous infusion of levodopa–carbidopa intestinal gel (LCIG) is a well-proven option in clinical practice. We now report the first clinical experience of levodopa–entacapone–carbidopa intestinal gel (LECIG) therapy. An observational study of the first patients to start LECIG in our clinic was performed. Twenty-four patients (11 females, 13 males) were included. The median age was 71.5 years, and the median duration since PD diagnosis was 15.5 years. The median treatment duration was 305 days. Median doses were: 6.0 mL as morning dose, 2.5 mL/h as infusion rate, and 1.0 mL as extra dose. Half of the patients were switched directly from LCIG. These patients express improvements in the size and weight of the pump. Furthermore, most of them considered the new pump to be improved regarding user-friendliness. Six patients discontinued LECIG, three due to diarrhea, one due to hallucinations and two deceased (one cardiac arrest and one COVID-19). LECIG has shown to be possible to use in patients with PD, efficacy and safety as expected. Patients are generally happy with the size and usability of the pump, but some technical improvements of the software are warranted, as well as larger, prospective studies.

Entacapone scavenges peroxynitrite and protects against kidney and liver injuries induced by renal ischemia/reperfusion in rats

BACKGROUND

Acute kidney injury (AKI), secondary to renal ischemia/reperfusion (I/R), is a serious problem associated with high mortality. The pathophysiology of AKI after renal I/R involves peroxynitrite production; hence, scavenging this metabolite may rescue AKI. Entacapone is a catechol-O-methyl transferase (COMT) inhibitor which elicits antioxidant activity by scavenging peroxynitrite. Therefore, we hypothesized that the peroxynitrite scavenging activity of entacopone protects against AKI after renal I/R injury in rats.

METHODS

Male Wistar rats were given either entacapone or a well-known peroxynitrite scavenger (FeTPPS) daily for 10 days before I/R procedures. I/R was induced by occluding both renal pedicles for 45 min followed by reperfusion for 24 h.

RESULTS

Pre-treatment with either entacapone or FeTPPS improved renal function as indicated by a significant reduction in serum creatinine and urea when compared to I/R group (P < 0.05). I/R injury increased renal levels of NO (4-folds, P < 0.05), iNOS (4-folds, P < 0.05), and 3-nitrotyrosine (5-folds, P < 0.05) compared to sham control. These effects were abrogated in animals pre-treated with entacapone or FeTPPS before being subjected to I/R (P < 0.05). In addition, entacapone or FeTPPS significantly inhibited I/R-induced elevation in renal TNF-α levels (78% and 58%, respectively) and caspase-3 activity (72% and 56%, respectively) indicating the reduction of both inflammation and apoptosis in the kidney (P < 0.05). The two drugs also improved kidney and liver functions in rats with renal I/R injury.

CONCLUSION

Our study showed that entacapone and FeTPPS protected against AKI and remote liver damage associated with renal I/R and this effect might be due to scavenging peroxynitrite and reducing nitrosative stress.

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.

Long-term safety and effectiveness of levodopa-carbidopa intestinal gel infusion

INTRODUCTION

Levodopa-carbidopa intestinal gel (LCIG) infusion has demonstrated to improve motor fluctuations. The aim of this study is to assess the long-term safety and effectiveness of LCIG infusion in advanced Parkinson's disease (PD) patients with motor fluctuations and its effect in nonmotor symptoms.

METHODS

Adverse events (AE) and their management, clinical motor, and nonmotor aspects were assessed up to 10 years. Thirty-seven patients were treated with LGIC; in three subsets of patients, specific batteries of tests were used to assess cognitive and behavior assessment for 6 months, quality of sleep for 6 months, and quality of life and caregiver burden for 1 year.

RESULTS

There was a high number of AE, but manageable, most of mild and moderate severity. All patients experienced significant improvement in motor fluctuations with a reduction in mean daily off time of 4.87 hr after 3 months (n = 37) to 6.25 hr after 9 years (n = 2). Diskynesias remained stables in 28 patients (75.7%) and improved in 5 patients (13.5%). There was no neuropsychological deterioration, but an improvement in attentional functions, voluntary motor control, and semantic fluency. Quality of sleep did not worsen, and there was an improvement in the subjective parameters, although overnight polysomnography did not change. There was a significant sustained improvement of 37% in PD-Q39 after 3 months and to 1 year, and a significant reduction in caregiver burden of 10% after 3 months.

CONCLUSION

LCIG infusion is a safe and efficacious treatment for the control of motor fluctuations, and for improvement or nonworsening of nonmotor aspects, long-term sustained, and feasible for use in routine care.

Levodopa-entacapone-carbidopa intestinal gel in Parkinson's disease: A randomized crossover study

BACKGROUND

The addition of oral entacapone to levodopa-carbidopa intestinal gel treatment leads to less conversion of levodopa to 3-O-methyldopa, thereby increasing levodopa plasma concentration. The objective of this study was to compare systemic levodopa exposure of the newly developed levodopa-entacapone-carbidopa intestinal gel after a 20% dose reduction with levodopa exposure after the usual levodopa-carbidopa intestinal gel dose in a randomized crossover trial in advanced Parkinson's disease patients.

METHODS

In this 48-hour study, 11 patients treated with levodopa-carbidopa intestinal gel were randomized to a treatment sequence. Blood samples were drawn at prespecified times, and patient motor function was assessed according to the treatment response scale.

RESULTS

Systemic exposure of levodopa did not differ significantly between treatments (ratio, 1.10 [95% confidence interval, 0.951-1.17]). Treatment response scale scores did not significantly differ between treatments (P = 0.84).

CONCLUSIONS

Levodopa-entacapone-carbidopa intestinal gel allowed a lower amount of levodopa administration and was well tolerated. Long-term studies are needed to confirm the results. © 2016 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.

Clinical management of patients with advanced Parkinson's disease treated with continuous intestinal infusion of levodopa/carbidopa

Patients with Parkinson's disease often have a good initial response to dopaminergic therapy but later usually develop motor fluctuations and dyskinesia. In these patients, continuous infusion of levodopa-carbidopa intestinal gel (LCIG) allows for maintaining adequate dopamine levels and for improving motor and nonmotor symptoms, as well as quality of life and autonomy. Adequate candidate selection and follow-up are crucial for treatment success. Management should be multidisciplinary, and patient and caregiver education is a priority. This expert consensus document has been developed by a team of neurologists, gastroenterologists and nurses who have a vast experience in LCIG therapy, with an intention to provide knowledge and tools to facilitate patient management throughout all phases of LCIG treatment process.

A review of current and novel levodopa formulations for the treatment of Parkinson's disease

Parkinson's disease treatment is characterized by the nearly inevitable development of motor complications, including fluctuations and dyskinesias, in which the duration of benefit of a dose of medication is offset by involuntary movements that can be more disabling than the Parkinsonian features themselves. While levodopa remains the gold standard of therapy, it is the most likely to be associated with these complications. The concept of continuous dopaminergic stimulation has gained increasing acceptance as a potential mechanism by which to avoid or delay the development of motor complications, or to minimize their impact once they have already occurred. This article will explore existing and novel formulations of levodopa to identify their role in the spectrum of Parkinson's disease therapeutics.

Advanced stages of PD: interventional therapies and related patient-centered care

During the last decades, symptomatic treatment of motor symptoms of Parkinson's disease (PD) improved continuously and is reflected by long-range independency of the patient during the disease course. However, advanced stages of PD still represent an important challenge to patients, caregivers and treating physicians. In patients with advanced PD, interventional therapy strategies are increasingly applied. These device-related treatment strategies using pump-based continuous dopaminergic stimulation (CDS) or deep brain stimulation (DBS) opened new treatment options especially if motor complications predominate. Well-designed clinical studies on these interventional therapeutic approaches provided class 1 evidence for the efficacy of DBS and CDS in advanced PD and opened new perspectives for their use in earlier disease stages also. Therefore, careful selection of patients amenable to the (semi)invasive therapy options becomes more and more important and requires an interdisciplinary setting that accounts for (i) optimal patient information and awareness, (ii) selection of best individual treatment modality, (iii) training of relatives and caregivers, (iv) management of complications, and (v) follow-up care. Here, we address these topics by summarizing current state-of-the-art in patient selection, providing specificities of treatment options and troubleshooting, and defining steps towards an optimized patient-centered care. Interventional therapies pioneer in the area of individualized treatment approaches for PD, and may be complemented in the future by biomarker-based improved stratification and by closed-loop systems for adaptive therapeutic strategies. In the present review, we summarize the proceedings of an Expert Workshop on Parkinson's disease held on November 22, 2014 in Frankfurt, Germany.

Non-dopamine receptor ligands for the treatment of Parkinson's disease. Insight into the related chemical/property space

Extensive biochemical and clinical studies have increasingly recognized Parkinson's disease as a highly complex and multi-faceted neurological disorder having branched non-motor symptoms including sleep disorders, pain, constipation, psychosis, depression, and fatigue. A wide range of biological targets in the brain deeply implicated in this pathology resulted in a plethora of novel small-molecule compounds with promising activity. This review thoroughly describes the chemical space of non-dopamine receptor ligands in terms of diversity, isosteric/bioisosteric morphing, and molecular descriptors.

Levodopa/carbidopa intestinal gel: an effective formulation for the management of advanced Parkinson's disease

SUMMARY 

With disease progression, almost all Parkinson's disease (PD) patients eventually experience motor fluctuations, often posing a significant challenge for patients and caregivers. Majority of these patients end up with complex medication regimens resulting in increased incidence of adverse effects and a poorer quality of life. Treatment options for advanced PD remain limited; thus, providing the optimal treatment for this growing subpopulation of patients continues to be the focus of many drug development efforts. While deep brain stimulation is considered the most significant therapeutic advancement for advanced PD, it remains an expensive and invasive procedure, with its own risks and complications, which limits global applicability to a wider PD population. Levodopa/carbidopa intestinal gel is one option that may offer a therapeutic benefit as significant as that of deep brain stimulation, and to a broader spectrum of PD patients. This article reviews the pharmacological properties, efficacy, safety and tolerability of levodopa/carbidopa intestinal gel in PD.

Fewer fluctuations, higher maximum concentration and better motor response of levodopa with catechol-O-methyltransferase inhibition

Catechol-O-methyltransferase inhibitor addition to levodopa/carbidopa formulations improves motor symptoms and reduces levodopa fluctuations in patients with Parkinson's disease. Objectives were to investigate the effects of entacapone and tolcapone on plasma behaviour of levodopa, its metabolite 3-O-methyldopa and on motor impairment. 22 patients orally received levodopa/carbidopa first, then levodopa/carbidopa/entacapone and finally levodopa/carbidopa plus tolcapone within a 4.5 h interval twice. Maximum concentration, time to maximum level and bioavailability of levodopa did not differ between all conditions each with 200 mg levodopa application as a whole. Catechol-O-methyltransferase inhibition caused less fluctuations and higher baseline levels of levodopa after the first intake and less 3-O-methyldopa appearance. The maximum levodopa concentrations were higher after the second levodopa intake, particularly with catechol-O-methyltransferase inhibition. The motor response to levodopa was better with catechol-O-methyltransferase inhibition than without, tolcapone was superior to entacapone. More continuous levodopa brain delivery and lower 3-O-methyldopa bioavailability caused a better motor response during catechol-O-methyltransferase inhibition.

Human in vivo regional intestinal permeability: importance for pharmaceutical drug development

Both the development and regulation of pharmaceutical dosage forms have undergone significant improvements and development over the past 25 years, due primarily to the extensive application of the biopharmaceutical classification system (BCS). The Biopharmaceutics Drug Disposition Classification System, which was published in 2005, has also been a useful resource for predicting the influence of transporters in several pharmacokinetic processes. However, there remains a need for the pharmaceutical industry to develop reliable in vitro/in vivo correlations and in silico methods for predicting the rate and extent of complex gastrointestinal (GI) absorption, the bioavailability, and the plasma concentration-time curves for orally administered drug products. Accordingly, a more rational approach is required, one in which high quality in vitro or in silico characterizations of active pharmaceutical ingredients and formulations are integrated into physiologically based in silico biopharmaceutics models to capture the full complexity of GI drug absorption. The need for better understanding of the in vivo GI process has recently become evident after an unsuccessful attempt to predict the GI absorption of BCS class II and IV drugs. Reliable data on the in vivo permeability of the human intestine (Peff) from various intestinal regions is recognized as one of the key biopharmaceutical requirements when developing in silico GI biopharmaceutics models with improved predictive accuracy. The Peff values for human jejunum and ileum, based on historical open, single-pass, perfusion studies are presented in this review. The main objective of this review is to summarize and discuss the relevance and current status of these human in vivo regional intestinal permeability values.

Peripheral neuropathy in Parkinson's disease: levodopa exposure and implications for duodenal delivery

In advanced Parkinson's disease (PD) patients, continuous intra-duodenal infusion of levodopa/carbidopa intestinal gel (LCIG) is an established approach in the management of motor complications that cannot be further improved by conventional oral therapy. In general, tolerability of LCIG has resembled that of oral dopaminergic therapy; however, cases of symptomatic peripheral neuropathy (PN), sometimes severe, have been reported in patients receiving LCIG. Cases are generally a sensorimotor polyneuropathy with both subacute and chronic onsets, often associated with vitamin B12 and/or B6 deficiency. Rare cases clinically resemble Guillain-Barré syndrome. In the absence of prospectively collected data on possible associations between LCIG and PN, it is prudent to explore potential mechanisms that may explain a possible relationship. The PN may be linked to use of high-dose levodopa, promoting high levels of homocysteine and methylmalonic acid or reduced absorption of vitamins essential for homocysteine metabolism. Cases of LCIG-associated PN often have responded to vitamin supplementation without need for LCIG cessation, although LCIG cessation is sometimes necessary. It may be advisable to monitor vitamin B12/B6 status before and after patients start LCIG and be vigilant for signs of PN. Prospective, large-scale, long-term studies are needed to clarify whether vitamin supplementation and routine use of a catechol-O-methyltransferase inhibitor may help prevent PN in LCIG recipients and whether these measures should be routine practice in patients with PD on high-dose oral levodopa.

Spiral drawing during self-rated dyskinesia is more impaired than during self-rated Off

OBJECTIVE

The purpose of this study was to examine repeated measures of fine motor function in relation to self-assessed motor conditions in Parkinson's disease (PD).

METHODS

One-hundred PD patients, 65 with advanced PD and 35 patients with different disease stages have utilized a test battery in a telemedicine setting. On each test occasion, they initially self-assessed their motor condition (from 'very off' to 'very dyskinetic') and then performed a set of fine motor tests (tapping and spiral drawings).

RESULTS

The motor tests scores were found to be the best during self-rated On. Self-rated dyskinesias caused more impaired spiral drawing performance (mean = 9.8% worse, P < 0.001) but at the same time tapping speed was faster (mean = 5.0% increase, P < 0.001), compared to scores in self-rated Off.

CONCLUSIONS

The fine motor tests of the test battery capture different symptoms; the spiral impairment primarily relates to dyskinesias whereas the tapping speed captures the Off symptoms.

Pharmacokinetics of levodopa, carbidopa, and 3-O-methyldopa following 16-hour jejunal infusion of levodopa-carbidopa intestinal gel in advanced Parkinson's disease patients

Motor complications of Parkinson's disease (PD) are a consequence of pulsatile dopaminergic stimulation from standard oral levodopa therapy. Levodopa-carbidopa intestinal gel (LCIG) is infused continuously via an intrajejunal percutaneous gastrostomy tube. This was the first study designed to characterize the full pharmacokinetic profiles of levodopa, carbidopa, and levodopa metabolite, 3-O-methyldopa (3-OMD) with 16-h LCIG infusion. Nineteen advanced PD patients (mean age, 65 years) who were on LCIG therapy for ≥30 days were enrolled. Patients received their individualized LCIG infusion doses, and serial pharmacokinetic samples were collected. Eighteen patients completed the study; 19 were assessed for safety. Mean (SD) total levodopa and carbidopa doses were 1,580 (403) and 395 (101) mg, respectively. Mean (SD) C(avg) (μg/mL) were 2.9 (0.84) for levodopa, 17.1 (4.99) for 3-OMD, and 0.22 (0.08) for carbidopa. The degree of fluctuation [defined as (C(max)-C(min))/C(avg)] in levodopa, 3-OMD, and carbidopa plasma concentrations was very low (0.52, 0.21, and 0.96, respectively) during hours 2-16 of infusion. Accordingly, the within-subject coefficients of variation in levodopa, 3-OMD, and carbidopa concentrations were low (13%, 6%, and 19%, respectively). Three patients (16%) reported ≥1 treatment-emergent adverse event; none were considered severe. Continuous intrajejunal LCIG infusion maintained stable plasma levodopa levels over 16 h. Consistent exposure has been shown to reduce motor and nonmotor complications associated with oral medications. LCIG was well tolerated, consistent with previous reports.

Duodopa® treatment for advanced Parkinson's disease: a review of efficacy and safety

Enterally administered levodopa/carbidopa gel (Duodopa®) is used for the treatment of advanced Parkinson's disease (PD) in patients with motor fluctuations and dyskinesias. This review summarizes the current efficacy and safety data on this drug. Clinically important differences (CID) have been used to assess whether statistical improvements in symptoms translate into meaningful improvements for the patients. A PubMed search in February 2012 found 23 papers with efficacy data and 33 with safety data. Of 11 studies reporting Unified Parkinson's Disease Rating Scale (UPDRS) III scores, 10 found improvements that met the CID of 10.8 points. Of 7 studies reporting UPDRS IV scores, 5 found improvements meeting the CID of 2.3 points. Quality of life (QoL) was assessed in 6 studies using the 8- or 39-question version of the Parkinson's disease Questionnaire, and all reported improvements meeting the CID (10 points). Due to the nature of the data, it is not possible to give exact numbers for the frequency of adverse events. However, the findings seem to be in line with a previous report stating the majority of adverse events were related to the infusion system or surgical procedure rather than the drug. In conclusion, the large majority of studies have reported that Duodopa® is clinically effective in relieving the symptoms of advanced PD and improving QoL in comparison with conventional therapy. High-quality randomized trials with larger patient numbers will yield greater insights into the efficacy and safety of this treatment.