Metabolite profiling of foslevodopa/foscarbidopa in plasma of healthy human participants by LC-HRMS indicates no major differences compared to administration of levodopa/carbidopa intestinal gel.

Analysis was conducted to compare levodopa/carbidopa pharmacokinetics and drug-related material in plasma of healthy participants after receiving a continuous infusion of Levodopa/Carbidopa Intestinal Gel (LCIG) to a continuous subcutaneous infusion of foslevodopa/foscarbidopa. Study samples were from a randomized, open-label, 2-period crossover study in 20 healthy participants. Participants received either 24-h foslevodopa/foscarbidopa SC infusion to the abdomen or LCIG delivered for 24 h to the jejunum through a nasogastric tube with jejunal extension. Serial blood samples were collected for PK. Comparability of the LD PK parameters between the two treatment regimens was determined. Selected plasma samples were pooled per treatment group and per time point for metabolite profiling. LC-MSn was performed using high-resolution mass spectrometry to identify drug-related material across the dosing regimens and time points. The LD PK parameter central values and 90% confidence intervals following the foslevodopa/foscarbidopa subcutaneous infusion were between 0.8 and 1.25 relative to the LCIG infusion. With LCIG administration, LD, CD, 3-OMD, DHPA, DOPAC, and vanillacetic acid were identified in plasma at early and late time points (0.75 and 24 h); the metabolic profile after administration of foslevodopa/foscarbidopa demonstrated the same drug-related compounds with the exception of the administered foslevodopa. 3-OMD and vanillacetic acid levels increased over time in both treatment regimens. Relative quantification of LC-MS peak areas showed no major differences in the metabolite profiles. These results indicate that neither the addition of monophosphate prodrug moieties nor SC administration affects the circulating metabolite profile of foslevodopa/foscarbidopa compared to LCIG.

A Review of Levodopa Formulations for the Treatment of Parkinson's Disease Available in the United States.

Purpose: The safety and efficacy of levodopa formulations are evaluated to inform clinical decision making for the treatment of Parkinson's disease. Summary: Levodopa is a cornerstone of treatment for Parkinson's disease due to its proven efficacy. Although many patients can initially be managed using immediate release tablets, as their disease progresses they often require escalating doses as well as more frequent dosing to prevent wearing off effects. Additionally, patients who experience time in the off state may struggle with the delay between medication administration and onset of action. Therefore, to increase patient convenience as well as to enhance the pharmacokinetic profile of the levodopa, several other formulations have been developed. Levodopa coformulated with carbidopa is supplied as immediate release tablets, oral disintegrating tablets, controlled release tablets, extended release capsules, and a continuous enteral solution. Additionally, there is a levodopa inhalation powder available. As a result of their different absorption profiles, each formulation has unique safety and efficacy attributes. Consequently, while this expansion of levodopa formulations has substantially increased treatment options for patients, it has also increased the complexity of medical decision making for patients, providers, and health systems alike. Conclusion: Knowledge of the different pharmacokinetic, safety and efficacy profiles of the available levodopa formulations is critical for the effective management of Parkinson's disease on both the individual patient and population levels.

Effect of Carbidopa Dose on Levodopa Pharmacokinetics With and Without Catechol-O-Methyltransferase Inhibition in Healthy Subjects.

BACKGROUND AND OBJECTIVES: The treatment of Parkinson's disease (PD) is still symptomatic since disease-modifying treatments for PD are not available. Oral levodopa is the gold standard for the treatment of PD motor symptoms. However, incomplete and fluctuating plasma exposure of levodopa leads to suboptimal treatment of the symptoms. The main objective of this study was to investigate to what extent increased carbidopa doses (50 and 100 mg) increase the plasma levels of 100-mg immediate-release (IR) levodopa compared to a 25-mg carbidopa dose with and without co-administration of 200 mg entacapone. METHODS: A double-blind, placebo-controlled, randomized, crossover, phase I, pharmacokinetic study with 25 healthy volunteers was conducted. In addition, a semi-mechanistic pharmacokinetic model was built to theoretically evaluate the effect of inhibiting aromatic amino acid decarboxylase (AADC) and catechol-O-methyltransferase (COMT) mediated metabolism of levodopa on the exposure of levodopa. RESULTS: The effect of increased carbidopa doses 50 and 100 mg on the total exposure (AUC) of 100 mg IR levodopa was +29% and +36%, respectively, when entacapone was co-administered. Without entacapone, the corresponding increases were +13% and +17%. With entacapone co-administration, the increased carbidopa dose also clearly increased levodopa trough concentration. There was no significant effect on the peak concentrations of levodopa. CONCLUSIONS: Increasing carbidopa doses significantly increased the exposure and reduced the fluctuation of IR levodopa in plasma during simultaneous COMT inhibition with entacapone. Theoretical pharmacokinetic simulations suggested that the plasma profile of oral IR levodopa can be even further improved by optimizing AADC and COMT inhibition.

Ascorbic acid can alleviate the degradation of levodopa and carbidopa induced by magnesium oxide.

INTRODUCTION: Levodopa and carbidopa are reported to be degraded by magnesium oxide (MgO), which is often used as a laxative for patients with Parkinson's disease (PD). Ascorbic acid (AsA) can stabilize levodopa and carbidopa solutions; however, the effect of AsA on the degradation of levodopa and carbidopa induced by MgO has not been fully investigated. METHODS: The effect of AsA was evaluated using in vitro examinations, compared with lemon juice, and by measuring the plasma concentration of levodopa in a patient with PD. RESULTS: In vitro experiments showed that the relative concentrations of levodopa remained almost constant, and the relative concentrations of carbidopa decreased with time with addition of MgO. AsA mitigated this effect in a concentration-dependent manner, whereas the addition of lemon juice caused little change, although the pH decreased to the same extent. The results of levodopa pharmacokinetics of the patient showed that the area under the plasma concentration-time curve values from hour 0 to 8 were 53.00 µmol·h/L with regular administration and 67.27 µmol·h/L with co-administration of AsA. CONCLUSIONS: AsA can mitigate the degradation of carbidopa induced by MgO and may contribute to improving the bioavailability of levodopa in patients with PD.

Effects of One-Day Application of Levodopa/Carbidopa/Entacapone versus Levodopa/Carbidopa/Opicapone in Parkinson's Disease Patients.

The catechol-O-methyltransferase inhibitors entacapone and opicapone prolong the efficacy of conventional oral levodopa/dopa decarboxylase inhibitor formulations through an increase in levodopa plasma bioavailability. Catechol-O-methyltransferase inhibitors influence the homocysteine metabolism associated with levodopa/dopa decarboxylase application. The objectives of this study were to compare the impact of additional single-day entacapone or opicapone intake on the pharmacokinetic plasma behaviour of levodopa, 3-O-methyldopa and total homocysteine in 15 Parkinson's disease patients, with concomitant scoring of motor symptoms, under standardized conditions. The patients received opicapone plus two doses of 100 mg levodopa/carbidopa and, one week later, two doses of levodopa/carbidopa/entacapone or vice versa. Levodopa, 3-O-methyldopa and total homocysteine were determined with reversed-phase high-performance liquid chromatography. Levodopa bioavailability and its maximum concentration were higher with opicapone. The computed peak-to-trough difference was lower after the second levodopa administration with entacapone. The fluctuation index of levodopa did not differ between both conditions. 3-O-methyldopa decreased on both days. Homocysteine levels did not significantly vary between both conditions. A significant homocysteine decrease occurred with entacapone, but not with opicapone. Motor behaviour improved with entacapone, but not with opicapone. Opicapone baseline scores were significantly better, and thus the potential for the improvement in motor symptoms was lower compared with the entacapone condition. The higher levodopa bioavailability with opicapone suggests that it is more efficacious than entacapone for the amelioration of "off" phenomena in fluctuating patients when co-administered with a levodopa/dopa decarboxylase inhibitor regimen. Both compounds prevented an increase in homocysteine, which is a metabolic marker for an impaired capacity in the performance of methylation processes.

Fasting state is one of the factors associated with plasma levodopa fluctuations during levodopa‒carbidopa intestinal gel treatment.

INTRODUCTION: Some patients with Parkinson's disease (PD) undergoing levodopa‒carbidopa intestinal gel (LCIG) treatment experience motor fluctuations in the afternoon. The migrating motor complex, a specific periodic migrating contraction pattern occurring in the stomach and small intestine during the fasting state, can affect drug absorption. We aimed to compare the pharmacokinetic parameters between two conditions (with and without lunch) and assessed the influence of the fasting state on the levodopa pharmacokinetics in LCIG treatment. METHODS: We evaluated the levodopa pharmacokinetics from 12:00 p.m. to 6:00 p.m. in 10 LCIG-treated PD patients in the presence and absence of lunch. RESULTS: The maintenance dose of LCIG correlated strongly with the mean plasma concentration of levodopa in the absence (r = 0.94, coefficient of determination (R2) = 0.89, p < 0.001) or presence of lunch (r = 0.96, R2 = 0.93, p < 0.001). Comparison of the pharmacokinetic parameters revealed that the coefficient of variation was significantly greater in the condition without lunch than in the condition with lunch (p = 0.004): 16.73% (4.88%) without lunch and 9.22% (3.80%) with lunch. There were no significant differences in the mean plasma concentration of levodopa (p = 0.49) and area under the plasma concentration‒time curve (p = 0.27) between the two conditions. CONCLUSIONS: Plasma concentrations of levodopa fluctuated more in patients undergoing LCIG treatment without than with lunch. Our results indicate that a small amount of food intake may be a better corrective approach for worsening of symptoms in the fasting state rather than additional levodopa.

Effect of catechin and commercial preparation of green tea essence on the pharmacokinetics of l-dopa in rabbits.

The aim of this study was to investigate drug interactions of L-dopa/carbidopa with catechin and green tea essence in rabbits following the simultaneous administration via an intramuscular injection of catechin or via an intragastric route for green tea essence with L-dopa/carbidopa. The results indicated that catechin at doses of 10, 20 and 50 mg/kg increased the area under the plasma concentration-time curve from time zero to the time of the last quantifiable concentration (AUC0-t ) of L-dopa by about 69, 78 and 42%, respectively. The metabolic ratios of the AUC0-t for 3-O-methyldopa (3-OMD)/L-dopa significantly decreased by about 56, 68 and 76% (P < 0.05), respectively. In addition, a single dose of 5/1.25 mg/kg L-dopa/carbidopa was co-administrated with 150 mg/kg green tea essence via an intragastric route with an oral-gastric tube. Comparing the related pharmacokinetic parameters of L-dopa, the clearance and metabolic ratio of L-dopa decreased by 20 and 19% (P < 0.05), respectively. In conclusion, catechin and green tea essence can significantly affect the metabolism of L-dopa by the catechol-O-methyltransferase (COMT) metabolic pathway. Catechin can enhance L-dopa bioavailability, and both catechin and green tea essence decreased 3-OMD formation. Therefore, catechin and green tea essence may increase L-dopa efficacy for Parkinson's disease treatment.

Effect of Opicapone Tablets on Levodopa and 3-O-Methyldopa Pharmacokinetics in Healthy Japanese Subjects: Phase 1 Study.

This study evaluated the effect of a small-tablet formulation of opicapone for use in clinical trials in Japan on the pharmacokinetics of levodopa (l-dopa) and 3-O-methyldopa (3-OMD). In an open-label, 3-period, single-sequence crossover phase 1 study in 80 healthy Japanese males (aged 20-45 years; body mass index, 18.5 to <30.0 kg/m2 ), 10 mg of l-dopa/carbidopa 100 was administered 3 times daily on day 0 (period 1) and day 12 (period 3), and opicapone tablets (5, 10, 25, or 50 mg; n = 20 each group) were administered once daily for 11 days (period 2). During periods 1 and 3, plasma concentrations of l-dopa and 3-OMD were measured and pharmacokinetic parameters (maximum observed plasma concentration, time at which maximum concentration was observed, area under the plasma concentration-time curve from time 0 to 5 hours [AUC5h ] and from time 0 to 24 hours [AUC24h ] following each dose, terminal half-life) of plasma l-dopa and 3-OMD were determined along with the geometric mean ratio (period 3/period 1) of AUC24h for l-dopa and 3-OMD. Maximum concentration of l-dopa for the first, second, or third doses of l-dopa/carbidopa did not significantly increase with increasing opicapone dose. The AUC of l-dopa increased with increasing opicapone dose but tended toward a peak plateau with opicapone doses of 25 mg and higher. Geometric mean ratios (90% confidence intervals) of AUC24h were 5 mg, 1.16 (1.10-1.21); 10 mg, 1.26 (1.23-1.30); 25 mg, 1.51 (1.44-1.57); 50 mg, 1.60 (1.54-1.66). Opicapone tablets were well tolerated. In Japanese healthy subjects, increases in plasma exposure to l-dopa appear to level off with opicapone doses of 25 mg and higher, which may be relevant for optimal dosing among Japanese patients with Parkinson disease.

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.

Carbidopa for Afferent Baroreflex Failure in Familial Dysautonomia: A Double-Blind Randomized Crossover Clinical Trial.

Afferent lesions of the arterial baroreflex occur in familial dysautonomia. This leads to excessive blood pressure variability with falls and frequent surges that damage the organs. These hypertensive surges are the result of excess peripheral catecholamine release and have no adequate treatment. Carbidopa is a selective DOPA-decarboxylase inhibitor that suppresses catecholamines production outside the brain. To learn whether carbidopa can inhibit catecholamine-induced hypertensive surges in patients with severe afferent baroreflex failure, we conducted a double-blind randomized crossover trial in which patients with familial dysautonomia received high dose carbidopa (600 mg/day), low-dose carbidopa (300 mg/day), or matching placebo in 3 4-week treatment periods. Among the 22 patients enrolled (13 females/8 males), the median age was 26 (range, 12-59 years). At enrollment, patients had hypertensive peaks to 164/116 (range, 144/92 to 213/150 mm Hg). Twenty-four hour urinary norepinephrine excretion, a marker of peripheral catecholamine release, was significantly suppressed on both high dose and low dose carbidopa, compared with placebo (P=0.0075). The 2 co-primary end points of the trial were met. The SD of systolic BP variability was reduced at both carbidopa doses (low dose: 17±4; high dose: 18±5 mm Hg) compared with placebo (23±7 mm Hg; P=0.0013), and there was a significant reduction in the systolic BP peaks on active treatment (P=0.0015). High- and low-dose carbidopa were similarly effective and well tolerated. This study provides class Ib evidence that carbidopa can reduce blood pressure variability in patients with congenital afferent baroreflex failure. Similar beneficial effects are observed in patients with acquired baroreflex lesions.

Female, aging, difference formulations of DCI, or lower body weight increases AUC4hr of levodopa in patients with Parkinson's disease.

INTRODUCTION: There is considerable intra- and inter-individual variability in the pharmacokinetics (PK) of levodopa after oral administration. Inter-individual variability in levodopa PK has also been demonstrated in fasting single-dose studies. We examined the factors that affect levodopa PK in patients with Parkinson's disease (PD) and quantified the intensity of their respective effects. METHODS: We studied 220 patients who underwent PK assessment after administration of 1 tablet of levodopa/DOPA decarboxylase inhibitor (DCI) combination, which contained 10 mg carbidopa/100 mg levodopa or 25 mg benserazide/100 mg levodopa. PK was evaluated using non-compartmental analysis. RESULTS: In total, 220 PD patients (including 112 men) were studied. The mean age (±standard deviation) and mean disease duration was 68.1 ± 8.9 and 7.7 ± 5.8 years, respectively. The Cmax of levodopa was 9.0 ± 4.0 ng/mL, Tmax was 41.4 ± 40.2 min, and area under the blood concentration-time curve up to 4 h (AUC4hr) was 12.3 ± 3.7 ng/mL*4hr. Factors affecting AUC4hr were analyzed using multiple linear regression models. Age (1.1 ± 0.23 per +10 years, p = 3.1E-8), sex (2.2 ± 0.5 for female, p = 1.9E-5), DCI (1.4 ± 0.4 for benserazide, p = 0.0028), and body weight (-0.77 ± 0.22 per +10 kg, p = 5.4E-4) were significantly related to AUC4hr, while disease duration, dyskinesia status, and eGFR were not related to AUC4hr and Cmax. CONCLUSION: Female, aging, difference formulations of DCI, or lower body weight independently contributes to increased AUC4hr of levodopa in Japanese patients with PD in this study.

Pharmacokinetics and pharmacodynamics of levodopa/carbidopa cotherapies for Parkinson's disease.

Introduction: Parkinson's disease is a chronic, neurodegenerative disease entity with heterogeneous features and course. Levodopa is the most efficacious dopamine substituting drug. Particularly, long-term application of oral levodopa/decarboxylase inhibitor formulations sooner or later supports onset of fluctuations of movement. It also shifts levodopa turnover to O-methylation, which impairs human methylation capacity and increases oxidative stress.Areas covered: This narrative review summarizes pharmacokinetic and pharmacodynamic features of available levodopa cotherapies on the basis of a literature search with the terms L-dopa, inhibitors of catechol-O-methyltransferase and monoamine oxidase-B.Expert opinion: Long-term levodopa/dopa decarboxylase inhibitor application with concomitant inhibition of both, catechol-O-methyltransferase and monoamine oxidase-B supports a more continuous dopamine substitution, which ameliorates fluctuations of motor behavior. This triple combination also enhances both, antioxidative defense and methylation capacity. Inhibition of monoamine oxidase-B reduces generation of oxidative stress in the brain. Constraint of catechol-O-methyltransferase reduces homocysteine synthesis due to diminished consumption of methyl groups for levodopa turnover at least in the periphery. An additional nutritional supplementation with methyl group donating and free radical scavenging vitamins is recommendable, when future drugs are developed for long-term levodopa/dopa decarboxylase treated patients. Personalized medicine treatment concepts shall also consider nutritional aspects of Parkinson's disease.

Safety and effectiveness of levodopa-carbidopa intestinal gel for advanced Parkinson's disease: A large single-center study.

BACKGROUND: Treatment with levodopa-carbidopa intestinal gel (LCIG) can effectively relieve motor and non-motor symptoms in advanced Parkinson's disease (PD). However, adverse events (AEs) are frequent. OBJECTIVE: To describe AEs associated with LCIG treatment and the main reasons for treatment discontinuation. We also looked for factors that were potentially predictive of serious AEs and assessed the effectiveness of and satisfaction with LCIG. METHOD: We retrospectively analyzed data on AEs in patients treated with LCIG at a French university medical center. For patients still receiving treatment at last follow-up, effectiveness was assessed according to the Clinical Global Impression (CGI) scale and the Movement Disorders Society - Unified Parkinson's Disease Rating Scale motor score. RESULTS: Of the 63 patients treated with LCIG for a mean (range) of 19 months (8-47), 57 (90%) experienced at least one AE (340 AEs in total). Most of the AEs (in 69.8% of the patients) were related to percutaneous endoscopic gastrostomy with a jejunal tube (PEG-J) or affected the gastrointestinal tract (granuloma, leakage, or a local infection). Device-related AEs (such as PEG-J removal and device occlusion) were frequent (in 63.5% of patients). Forty-three patients (68%) required at least one additional endoscopic procedure. Dopatherapy-related AEs occurred in 30 patients (48%). Most of the AEs occurred long after treatment initiations, and only a small proportion led to discontinuation. On the CGI scale, 53 patients (84.4%) considered that their condition had improved during LCIG treatment. CONCLUSION: Despite the high frequency of AEs, patients with advanced PD gain clinical benefit from treatment with LCIG. This treatment requires a competent, multidisciplinary team on site.

Pharmacodynamics, Efficacy, and Safety of IPX203 in Parkinson Disease Patients With Motor Fluctuations.

OBJECTIVES: IPX203 is an investigational oral extended-release capsule formulation of carbidopa and levodopa. The pharmacodynamics and efficacy of IPX203 were compared with immediate-release carbidopa-levodopa (IR CD-LD) in this open-label, rater-blinded, multicenter, crossover study in patients with advanced Parkinson disease (PD). METHODS: Twenty-eight patients were randomized to 2 weeks of treatment with IR CD-LD followed by IPX203 or IPX203 followed by IR CD-LD. Pharmacokinetic and motor assessments were conducted on days 1 and 15 of each treatment period. Efficacy was assessed using a 3-day PD diary. Pharmacodynamics were assessed by rater-blinded Movement Disorder Society-Unified Parkinson's Disease Rating Scale Part III and Investigator Assessment of Subject's Motor State. RESULTS: After a single dose, levodopa concentrations were sustained above 50% of peak concentration for 4.6 hours with IPX203 versus 1.5 hours with IR CD-LD (P < 0.0001). Based on the PD diary, patients experienced significantly less Off time with IPX203 as a percentage of waking hours than IR CD-LD (mean 19.3% vs 33.5%, respectively; P < 0.0001), translating into 2.3 hours less Off time than IR CD-LD with most of this improvement (1.9 hours) being Good On time. There was no significant difference in the amount of On time with troublesome dyskinesia between treatments. Pharmacodynamic assessments demonstrated similar outcomes in favor of IPX203 on day 1 and a significant predose benefit on motor examination after multiple dosing. CONCLUSIONS: IPX203 demonstrated a sustained effect to reduce Off time and improve Good On time in patients with PD and motor fluctuations. Both treatments were well tolerated.

Pharmacokinetics and efficacy of a novel formulation of carbidopa-levodopa (Accordion Pill®) in Parkinson's disease.

INTRODUCTION: Dopamine replacement via levodopa (LD) remains the most effective treatment for Parkinson's disease (PD), yet its use is often associated with motor complications within several years of continued use. The Accordion Pill® (AP-CD/LD) is a novel drug delivery system based on gastric retention of multilayer films containing immediate-release (IR) carbidopa (CD) and immediate- and controlled-release LD. The AP-CD/LD was designed to improve the consistency of LD in the bloodstream while offering patients with PD more consistent symptom management. METHODS: This phase 2, multicenter, open-label, two-way randomized crossover study included 4 cohorts of participants with PD, each receiving AP-CD/LD (50/250 mg, 50/375 mg or 50/500 mg) twice daily in one treatment period and an active comparator in the other treatment period. Pharmacokinetics (PK) and efficacy were evaluated for AP-CD/LD vs IR-CD/LD. Treatment-emergent adverse events (TEAEs) and patient- and investigator-reported measures were also evaluated. RESULTS: Compared with IR-CD/LD, treatment with either AP-CD/LD dose resulted in more stable LD plasma concentrations in both fluctuating and non-fluctuating PD patients, and significantly decreased Cmax (57.1% and 66.8% decreases among fluctuating and non-fluctuating patients, respectively). Both AP doses significantly improved standard measures of motor symptoms: (daily OFF time, total ON time, and good ON time), as well as patient- and investigator-assessed measures, versus IR-CD/LD. The safety and tolerability profile of AP-CD/LD was consistent with the known properties of IR-CD/LD. CONCLUSIONS: AP technology demonstrated effective controlled-release PK performance and reduced motor response fluctuations in advanced PD patients. A phase 3 randomized controlled trial is currently underway.

The Accordion Pill®: unique oral delivery to enhance pharmacokinetics and therapeutic benefit of challenging drugs.

Accordion Pill® (AP) is a novel gastric-retention oral delivery platform based on folded multilayer films (Intec Pharma, Jerusalem, Israel). Phase II clinical trials have evaluated gastric retention and pharmacokinetics (PK) of AP in healthy volunteers and efficacy and safety of AP containing carbidopa and levodopa (AP-CD/LD) in patients with Parkinson's disease (PD). AP was retained in the stomach for approximately 8 h, without special meal requirements. AP-CD/LD demonstrated improved absorption, more stable levodopa exposure and improved ON time compared with immediate-release CD/LD in advanced PD patients. AP provides a novel treatment platform for improving PK and efficacy for drugs with narrow absorption windows or poor solubility. Furthermore, AP allows multiple drug release profiles in a single capsule and can provide fixed-dose combinations.

Levodopa-carbidopa intestinal gel high concentration formulation is clinically bioequivalent to commercial formulation.

A new levodopa-carbidopa intestinal gel (LCIG) system featuring a higher levodopa/carbidopa (LD/CD) concentration and viscosity, LCIG-HV, is being developed to reduce the intrajejunal volume of LD/CD that is administered as compared to the current commercial formulation, LCIG-LV. This study characterizes the LCIG-HV formulation and compares it to the LCIG-LV formulation via dissolution testing and a clinical pharmacokinetic bioequivalence study. In vitro release profiles of LD/CD were determined using a USP Dissolution Apparatus 2 with 500 mL of phosphate buffer (pH 4.5) operating at 25 RPM. A single dose, open-label study was conducted according to a two-period, randomized, crossover design in 28 healthy subjects. The point estimate (PE) of the levodopa Cmax geometric mean for the LCIG-HV formulation was 4% higher than that of the LCIG-LV formulation. PEs of levodopa AUCt and AUCinf geometric means were comparable for both formulations. PEs of carbidopa Cmax , AUCt and AUCinf geometric means for the LCIG-HV formulation were 3%-5% higher than those of the LCIG-LV formulation. For both formulations, the median Tmax for levodopa was 1.0 and 3.0 hours for carbidopa. The levodopa half-life harmonic mean was 1.6 hour for both formulations. The carbidopa half-life harmonic mean was 1.9 and 2.0 hour, respectively, for the LCIG-HV and LCIG-LV formulations. Cmax , AUCt and AUCinf of LD/CD carbidopa were comparable for both formulations. The current study demonstrates that the LCIG-LV and LCIG-HV formulations are clinically bioequivalent for LD/CD according to FDA guidance. However, the dissolution method was over discriminatory of formulation differences.

Contemporary Options for the Management of Motor Complications in Parkinson's Disease: Updated Clinical Review.

Parkinson's disease (PD) is a chronic, progressive condition affecting around 1% of the population older than 60 years. Upon long-term treatment with levodopa, the mainstay of treatment in PD, most patients, especially younger ones exposed to higher doses, will experience symptoms related to end-of-dose deterioration, peak-dose dyskinesias, and other motor fluctuations. Therapeutic strategies are grounded on modification of oral levodopa pharmacokinetics to extend levodopa benefit and development of new routes of drug delivery (e.g., levodopa/carbidopa intestinal gel infusion) or long-acting formulations of existing dopaminergic drugs to prolong the duration of striatal dopamine receptors stimulation. As our understanding of the pathophysiology of motor complications evolves, our therapeutic armamentarium is actively expanding and the focus of research is now actively pointing to the new non-dopaminergic agents acting both within the basal ganglia and in other brain regions (e.g., drugs acting on glutamate, GABA, serotonin, and calcium channels). Despite the fact that trials comparing the different therapeutic strategies are lacking, we aimed at devising practical evidence- and experience-guided suggestions for the clinical management of motor complications, emphasizing that this should always be an individualized endeavor. This review summarizes the pharmacological management of motor complications in PD, including new formulations and routes of delivery, and the newer released drugs such as istradefylline, opicapone, safinamide, and zonisamide. Advanced therapeutic strategies for selected cases such as treatment with apomorphine and surgical techniques (deep brain stimulation) are also discussed. A comprehensive knowledge of the available options and evidence is fundamental for the successful management of these challenging complications.