Comparative examination of levodopa pharmacokinetics during simultaneous administration with lactoferrin in healthy subjects and the relationship between lipids and COMT inhibitory activity in vitro.

Background: Lactoferrin (bLF) is an iron-binding multifunctional protein that is abundant in milk. In mice, it inhibits catechol-O-methyltransferase (COMT) activity and increases blood levodopa levels. However, the clinical effects are unknown.Objective: The objective of this study was to determine the effect of bLF on the kinetics of levodopa in blood.Design: The effects of the concomitant administration of a combined formulation of levodopa and an aromatic amino acid decarboxylase inhibitor and bLF on the concentration of levodopa in blood and its metabolism were assessed in eight healthy subjects. In addition, we analyzed the association with clinical factors and evaluated whether clinical factors affected the COMT inhibitory activity of bLF in vitro.Results: Although not statistically significant, the peak plasma concentration (Cmax) of levodopa increased by 18.5%. From the results of the stratified analysis of total cholesterol, a relationship with ΔCmax was predicted. Therefore, bLF was reacted with cholesterol in the presence of lecithin and sodium deoxycholate in vitro to evaluate COMT inhibitory activity, and an increase in inhibitory activity was observed. By contrast, the ester compound cholesteryl oleate had no effect. The inhibitory activity of free fatty acids, which are known to interact with bLF, was also enhanced.Conclusion: The COMT inhibitory activity of bLF is not effective in elevating blood levodopa levels. However, in humans with high lipid levels, such as cholesterol, interactions may enhance the inhibitory effect, resulting in the enhanced absorption of levodopa.Trial registration: ID, UMIN000026787, registered 30 March 2017; URL, https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000030749Trial registration: UMIN Japan identifier: UMIN000026787.

Genetic loss of importin α4 causes abnormal sperm morphology and impacts on male fertility in mouse.

Importin α proteins play a central role in the transport of cargo from the cytoplasm to the nucleus. In this study, we observed that male knock-out mice for importin α4, which is encoded by the Kpna4 gene (Kpna4-/- ), were subfertile and yielded smaller litter sizes than those of wild-type (WT) males. In contrast, mice lacking the closely related importin α3 (Kpna3-/- ) were fertile. In vitro fertilization and sperm motility assays demonstrated that sperm from Kpna4-/- mice had significantly reduced quality and motility. In addition, acrosome reaction was also impaired in Kpna4-/- mice. Transmission electron microscopy revealed striking defects, including abnormal head morphology and multiple axoneme structures in the flagella of Kpna4-/- mice. A five-fold increase in the frequency of abnormalities in Kpna4-/- mice compared to WT mice indicates the functional importance of importin α4 in normal sperm development. Moreover, Nesprin-2, which is a component of the linker of nucleus and cytoskeleton complex, was expressed at lower levels in sperm from Kpna4-/- mice and was localized with abnormal axonemes, suggesting incorrect formation of the nuclear membrane-cytoskeleton structure during spermiogenesis. Proteomics analysis of Kpna4-/- testis showed significantly altered expression of proteins related to sperm formation, which provided evidence that genetic loss of importin α4 perturbed chromatin status. Collectively, these findings indicate that importin α4 is critical for establishing normal sperm morphology in mice, providing new insights into male germ cell development by highlighting the requirement of importin α4 for normal fertility.

DRD2 methylation to differentiate dementia with Lewy bodies from Parkinson's disease.

OBJECTIVE: The aim was to clarify whether DRD2 methylation changes in leukocytes of dementia with Lewy bodies (DLB) or Parkinson's disease (PD) patients are seen and can be used to discriminate between them. METHODS: Methylation rates were examined in 23 DLB subjects and 23 age- and sex-matched healthy controls and 37 PD patients and 37 age- and sex-matched healthy controls. RESULTS: Significant DRD2 DNA methylation changes were found in leukocytes of DLB and PD patients compared with healthy subjects. Discriminant analysis between DLB and PD using seven CpG sites demonstrated sensitivity and specificity of 83.8% and 90.9%, respectively. None of the CpG sites were associated with sex, age, age of onset, disease duration, and any of the neuropsychological tests in DLB and PD patients. CONCLUSION: This is the first report showing that DRD2 DNA methylation rates in leukocytes were increased in DLB patients and decreased in PD patients. These results may be an important step in understanding epigenetic mechanisms underlying DLB and PD pathogenesis and providing a novel biomarker for discriminating between them.

Acromioclavicular joint arthritis as the first manifestation of Austrian syndrome.

Austrian syndrome is a rare condition caused by invasive Streptococcus pneumoniae, comprising a triad of pneumococcal meningitis, endocarditis, and pneumonia. Herein, we report a 59-year-old male patient who presented with fever and tenderness of the right shoulder. Although the initial diagnosis was acromioclavicular joint septic arthritis, the present case showed a reduced level of consciousness, pulmonary infiltrates, cerebral infarcts, and destruction of the mitral valve. This case suggests that acromioclavicular joint arthritis could be an initial presentation of pneumococcal infection inclusive of Austrian syndrome, especially in patients with some risk factors of invasive pneumococcal infections, such as chronic alcoholism.

Long-term, open-label, phase 3 study of rasagiline in Japanese patients with early Parkinson's disease.

Rasagiline is a monoamine oxidase B inhibitor with demonstrated efficacy and safety in patients with Parkinson's disease (PD). We recently conducted the first randomized, double-blind, placebo-controlled trial of rasagiline in Japanese patients with early PD and now report the results of its open-label extension (clinicaltrials.gov, NCT02337751). In the double-blind trial, patients aged 30-79 years with PD diagnosis within 5 years and Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part II + Part III total score ≥ 14 were randomized to placebo or rasagiline 1 mg/day for 26 weeks. Of 210 patients who completed the randomized trial, 198 (95 placebo, 103 rasagiline) entered the extension and received rasagiline 1 mg/day for 26 weeks. Analyses included patients who received rasagiline anytime during double-blind and/or extension periods; mean (standard deviation) treatment duration was 169.6 (39.57) and 316.5 (88.89) days in placebo-rasagiline (n = 95) and rasagiline-rasagiline (n = 117) groups, respectively. The incidence of treatment-emergent adverse events (TEAEs; primary outcome) was 53.7% and 77.8% in the placebo-rasagiline and rasagiline-rasagiline groups, respectively. Drug-related TEAEs occurred in 24.2% and 49.6% of patients and serious TEAEs occurred in four (two drug related) and six (one drug related) patients in the placebo-rasagiline and rasagiline-rasagiline groups, respectively. The mean change in MDS-UPDRS Part II + III total score from baseline (before rasagiline) was - 2.8 points in both the placebo-rasagiline (mean [95% confidence interval] - 2.8 [- 4.05, - 1.59]) and rasagiline-rasagiline (- 2.8 [- 4.57, - 1.01]) groups. In conclusion, up to 52 weeks, rasagiline was well tolerated with sustained motor symptom improvement, supporting its use in Japanese patients with early PD.

Long-term safety and efficacy of adjunctive rasagiline in levodopa-treated Japanese patients with Parkinson's disease.

Rasagiline is a monoamine oxidase type-B inhibitor in development in Japan for Parkinson's disease (PD). This open-label study evaluated the long-term safety and efficacy of rasagiline in Japanese patients with PD receiving levodopa. Patients were aged 30-79 years and had wearing-off or weakened effect. Patients received rasagiline 1 mg/day for 52 weeks. The primary objective was to evaluate safety. Secondary endpoints included MDS-UPDRS Part II and Part III total scores (ON-state) and change from baseline in mean daily OFF-time. An additional endpoint was the Parkinson's Disease Questionnaire-39 (PDQ-39) Summary Index (SI) score. In total, 222 patients were enrolled; 52.3% had wearing-off phenomena. Treatment-emergent adverse events (TEAEs) were mostly mild or moderate and occurred in 83.3% of patients; 63.1% had drug-related TEAEs; and 21.2% had TEAEs resulting in discontinuation. Fall (16.7%), nasopharyngitis (14.0%), and dyskinesia (10.8%) were the most frequent TEAEs. Serious TEAEs were reported in 17.6% of patients, and led to discontinuation in 9.5%. At week 52 (last-observation-carried forward), the mean change from baseline in MDS-UPDRS Part III total score (ON-state) was - 7.6; the mean change from baseline in daily OFF-time was - 0.89 h in patients with wearing-off phenomena at the start of the run-in period. The mean change from baseline in PDQ-39 SI was - 0.64. No major safety issues were observed during this 52-week trial of rasagiline as an adjunct to levodopa in Japanese patients. Mean changes in MDS-UPDRS scores and daily OFF-time suggested that adjunctive rasagiline treatment with levodopa was efficacious, with efficacy maintained for at least 52 weeks.

Modafinil alleviates levodopa-induced excessive nighttime sleepiness and restores monoaminergic systems in a nocturnal animal model of Parkinson's disease.

Treatment with dopaminergic agents result excessive daytime sleepiness (EDS) and some studies have shown the benefit of using modafinil for treating excessive daytime sleepiness of Parkinson's disease (PD) patient. We investigated whether modafinil have ameliorative properties against levodopa induced excessive nighttime sleepiness (ENS) in MPTP-treated murine nocturnal PD model. Our EEG analyses of whole day recordings revealed that modafinil reduce ENS of this nocturnal PD models with levodopa medications. Therefore, we investigated whether, modafinil post-treatment followed by MPTP shows any effect on monoamine contents of brain and found to robustly increased noradrenaline (NA) concentration of MPTP treated mice. Modafinil post-treatment, in neurorestorative context (5 days post-lesion) led to increased striatal dopamine (DA) concentrations of MPTP-treated mice. Here, we first confirmed that modafinil ameliorates levodopa induced excessive sleepiness and restores monoaminergic systems. The arousal and anti-parkinsonian effects displayed by modafinil indicate that in combination with dopaminergic agents, modafinil co-administration may be worthwhile in trying to suppress the excessive daytime sleepiness and progressive dopaminergic neuron loss in PD.

Anti-parkinsonian drugs today.

The current pharmacotherapeutic options for Parkinson's disease is described in this article. Newly formulations of levodopa developed to date. Levodopa / carbidopa intestinal gel (Duodopa) was approved recently in Japan. Duodopa permits to maintain plasma concentrations of levodopa at steady levels and prolongs ON time without dyskinesia. IPX066 is a newly developed oral formulation of levodopa, and launched in US. It contains both an immediate-release and a sustained-release levodopa component. Safinamide has an inhibitory activity of glutamate release and antagonism of sodium channel activity in addition to MAO-B inhibitor. Opicapone is a novel third generation COMT inhibitor. Rasagiline is a widely used MAO-B inhibitor in many countries. Clinical trials of the both agents are performed in Japan. Pimavanserin, a 5-HT2A inverse agonist, is the first and only medication approved by FDA for the treatment of psychosis associated with Parkinson's disease.

Downregulation of the small GTPase ras-related nuclear protein accelerates cellular ageing.

BACKGROUND: The small GTPase Ran, Ras-related nuclear protein, plays important roles in multiple fundamental cellular functions such as nucleocytoplasmic transport, mitotic spindle assembly, and nuclear envelope formation, by binding to either GTP or GDP as a molecular switch. Although it has been clinically demonstrated that Ran is highly expressed in multiple types of cancer cells and specimens, the physiological significance of Ran expression levels is unknown. METHODS: During the long-term culture of normal mammalian cells, we found that the endogenous Ran level gradually reduced in a passage-dependent manner. To examine the physiological significance of Ran reduction, we first performed small interfering RNA (siRNA)-mediated abrogation of Ran in human diploid fibroblasts. RESULTS: Ran-depleted cells showed several senescent phenotypes. Furthermore, we found that nuclear accumulation of importin alpha, which was also observed in cells treated with siRNA against CAS, a specific export factor for importin alpha, occurred in the Ran-depleted cells before the cells showed senescent phenotypes. Further, the CAS-depleted cells also exhibited cellular senescence. Indeed, importin alpha showed predominant nuclear localisation in a passage-dependent manner. CONCLUSIONS: Reduction in Ran levels causes cytoplasmic decrease and nuclear accumulation of importin alpha leading to cellular senescence in normal cells. GENERAL SIGNIFICANCE: The amount of intracellular Ran may be critically related to cell fate determination, such as malignant transformation and senescence. The cellular ageing process may proceed through gradual regression of Ran-dependent nucleocytoplasmic transport competency.

Triggering neural differentiation of ES cells by subtype switching of importin-alpha.

Nuclear proteins are selectively imported into the nucleus by transport factors such as importin-alpha and importin-beta. Here, we show that the expression of importin-alpha subtypes is strictly regulated during neural differentiation of mouse embryonic stem (ES) cells, and that the switching of importin-alpha subtype expression is critical for neural differentiation. Moreover, reproducing the switching of importin-alpha subtype expression in undifferentiated ES cells induced neural differentiation in the presence of leukaemia inhibitory factor (LIF) and serum, coordinated with the regulated expression of Oct3/4, Brn2 and SOX2, which are involved in ES-neural identity determination. These transcription factors were selectively imported into the nucleus by specific subtypes of importin-alpha. Thus, importin-alpha subtype switching has a major impact on cell differentiation through the regulated nuclear import of a specific set of transcription factors. This is the first study to propose that transport factors should be considered as major players in cell-fate determination.

Effect of concomitant use of esomeprazole on levodopa pharmacokinetics and clinical symptoms in patients with Parkinson's disease.

BACKGROUND: Proton pump inhibitors (PPIs), which inhibit gastric acid secretion, are frequently prescribed to patients with Parkinson's disease (PD). Levodopa, the gold-standard treatment for PD, demonstrates enhanced solubility in acidic environments. Although PPIs increase gastric pH and may affect levodopa absorption, the effect of concomitant PPI use on levodopa pharmacokinetics in patients with PD remains unknown. This study aimed to investigate the effect of the concomitant use of esomeprazole, a PPI, on the pharmacokinetics of levodopa and carbidopa and clinical symptoms in patients with PD. METHODS: We prospectively enrolled 40 patients with PD and compared the pharmacokinetics of levodopa and carbidopa and clinical symptoms before and two weeks after the concomitant use of esomeprazole. RESULTS: The plasma concentrations of levodopa 30 min after concomitant oral administration of levodopa and esomeprazole were significantly lower (4.92 ± 4.10 µmol/L) than those without concomitant esomeprazole use (6.26 ± 3.75 µmol/L; p = 0.027). The plasma concentrations of carbidopa showed no significant differences with respect to concomitant esomeprazole use. Significant elevation was recorded in all subscores of the Movement Disorder Society-sponsored revision of the Unified Parkinson's disease Rating Scale scores after concomitant use of esomeprazole. No significant differences were observed between Helicobacter pylori-negative and Helicobacter pylori-positive patients. Non-elderly patients (age ≤ 70 years) tended to be more susceptible to the effect of esomeprazole on levodopa pharmacokinetics and clinical symptoms. CONCLUSIONS: The unnecessary use of PPIs should be avoided in patients with PD, especially in non-elderly patients, to improve absorption of levodopa.

CSF Neopterin Levels Are Elevated in Various Neurological Diseases and Aging.

Background/Objectives: Cerebrospinal fluid (CSF) neopterin reflects inflammation of the central nervous system (CNS) and is a potentially useful biomarker for neuroinflammatory assessment and differential diagnosis. However, its optimal cut-off level in adult patients with neurological disease has not been established and it has not been adequately studied in controls. We aimed to determine its usefulness as a biomarker of neuroinflammation and the effect of age on its level. Methods: In this retrospective study, CSF neopterin was evaluated in 652 patients in 38 disease groups. Its levels were analyzed with high-performance liquid chromatography with fluorometric detection. Results: A receiver operating characteristic analysis revealed that the optimal cut-off value of 33.57 pmol/mL for CSF neopterin distinguished the control and meningitis/encephalitis groups with a sensitivity of 100.0% and specificity of 94.4%. In the control group, which consisted of 170 participants (99 men and 71 women; mean ± standard deviation age, 52.56 ± 17.99 years), age was significantly positively correlated with CSF protein (r = 0.474, p < 0.001) and CSF neopterin (r = 0.476, p < 0.001) levels but not with CSF cell count (r = 0.144, p = 0.061). Both male and female controls exhibited significant increases in CSF neopterin levels with age. Similarly, the CSF neopterin level was significantly positively correlated with age in patients with amyotrophic lateral sclerosis, independently of disease duration and respiratory function. Conclusions: CSF neopterin levels were elevated in patients with various CNS diseases, reflecting CNS inflammation; they were also elevated with age. Prospective studies are required to establish CSF neopterin as a sensitive biomarker of neuroinflammation.

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.

Blepharoptosis As an Early Manifestation of Neuronal Intranuclear Inclusion Disease.

Neuronal intranuclear inclusion disease (NIID) exhibits diverse clinical manifestations. Our patient was a 64-year-old woman with bilateral ptosis as the chief complaint. She had bilateral miosis, and the pupil was only slightly dilated 60 min after 1% phenylephrine administration, suggesting autonomic dysfunction secondary to preganglionic sympathetic impairment. A head-up tilt test revealed asymptomatic orthostatic hypotension. She was diagnosed with NIID based on a skin biopsy and genetic testing. This study suggests that blepharoptosis is an early manifestation of NIID. Furthermore, patients with suspected NIID should be examined carefully for autonomic dysfunction.

A dopamine D1-like receptor-specific agonist improves the survival of septic mice.

In this study, a murine sepsis model was developed using the cecum ligation and puncture (CLP) technique. The expression of the proinflammatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin-1ß (IL-1ß) in the brain increased 6 h after CLP but decreased 24 h later when elevated endogenous dopamine levels in the brain were sustained. Methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride reduced dopamine levels in the striatum and increased mortality in septic mice. Dopamine D1-like receptors were significantly expressed in the brain, but not in the lungs. Intraperitoneally administered SKF-81297 (SKF), a blood-brain barrier-permeable D1-like receptor agonist, prevented CLP-induced death of septic mice with ameliorated acute lung injury and cognitive dysfunction and suppressed TNF-α and IL-1ß expression. The D1-like receptor antagonist SCH-23390 abolished the anti-inflammatory effects of SKF. These data suggest that D1-like receptor-mediated signals in the brain prevent CLP-induced inflammation in both the brain and the periphery.

Multicenter, randomized, double-blind, placebo-controlled phase 3 study of mogamulizumab with open-label extension study in a minimum number of patients with human T-cell leukemia virus type-1-associated myelopathy.

Human T-cell leukemia virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic neurodegenerative disease. This multicenter, randomized phase 3 study evaluated the efficacy and safety of 0.3 mg/kg intravenous mogamulizumab, a monoclonal antibody targeting-CC chemokine receptor 4, every 12 weeks in HAM/TSP patients. This study comprised a 24-week double-blind, placebo-controlled period, 24-week open-label period, and extension treatment period. The primary endpoint was the proportion of patients with a ≥ 1-grade improvement in the Osame motor disability score (OMDS). Secondary endpoints were changes in HTLV-1 proviral load, 10-m timed walk, cerebrospinal fluid (CSF) neopterin levels, and safety. The exploratory endpoint was CSF chemokine C-X-C motif ligand 10 (CXCL10) levels. Thirty-four and 33 patients were randomized to mogamulizumab and placebo arms, respectively. At the end of the double-blind period, no significant difference was found in the OMDS improvement rate or other secondary efficacy endpoints assessing motor activities. However, the mogamulizumab arm showed a significant decrease in HTLV-1 proviral load (- 59.39 ± 29.91% vs. placebo 2.32 ± 36.31%) and CSF neopterin (p < 0.001)/CXCL10 levels (p = 0.004). The baseline OMDS pattern and the 60-80% HTLV-1 proviral load reduction were sustained through the open-label and extension treatment periods. Although a higher incidence of rash (69.2%) was reported, the safety profile was similar compared with a previous phase 1/2a study. We found no significant difference in clinical benefit; however, mogamulizumab may provide long-term clinical benefit by preventing disease progression, as CSF neopterin/CXCL10 levels are associated with long-term prognosis in HAM/TSP.Clinical Trial Registration Number: NCT03191526 (registered date: 6-June-2017).

[Development of disease-modifying drugs for Parkinson's disease. Is it a tough road?]

The treatment of diseases can be broadly classified into causal and symptomatic therapies. All the drugs currently on the market for Parkinson's disease are symptomatic treatments. Levodopa, a dopamine precursor, is the mainstay of treatment for Parkinson's disease to correct the malfunction of basal ganglia circuits caused by dopamine deficiency in the brain. In addition, dopamine agonists, anticholinergics, NMDA receptor antagonists, adenosine A2A receptor antagonists, COMT inhibitors, and MAO-B inhibitors have been marketed. With regard to the causal therapies, 57 out of 145 clinical trials for Parkinson's disease registered on ClinicalTrials.gov in January 2020 were related to disease-modifying drugs. Anti-α-synuclein antibodies, GLP-1 agonists, and kinase inhibitors have been examined in clinical trials as disease-modifying drugs, but no drug has been obviously demonstrated to inhibit the progression of Parkinson's disease to date. It is not easy to prove the beneficial results obtained from basic research in clinical trials. Especially for neurodegenerative disorders such as Parkinson's disease, it is more difficult to demonstrate clinical efficacy of disease-modifying drugs because there is no useful biomarker to quantify the degree of neuronal degeneration in clinical practice. In addition, the difficulty of using placebos for long periods in a clinical trial also makes proper assessment difficult.

Serum GDF-15 Levels in Patients with Parkinson's Disease, Progressive Supranuclear Palsy, and Multiple System Atrophy.

Serum growth differentiation factor 15 (GDF-15) levels are elevated in patients with Parkinson's disease (PD) and may help differentiate these patients from healthy individuals. We aimed to clarify whether serum GDF-15 levels can help differentiate PD from atypical parkinsonian syndromes and determine the association between serum GDF-15 levels and clinical parameters. We prospectively enrolled 46, 15, and 12 patients with PD, progressive supranuclear palsy (PSP), and multiple system atrophy (MSA), respectively. The serum GDF-15 level in patients with PD (1394.67 ± 558.46 pg/mL) did not differ significantly from that in patients with PSP (1491.27 ± 620.78 pg/mL; p = 0.573) but was significantly higher than that in patients with MSA (978.42 ± 334.66 pg/mL; p = 0.017). Serum GDF-15 levels were positively correlated with age in patients with PD (r = 0.458; p = 0.001); PSP (r = 0.565; p = 0.028); and MSA (r = 0.708; p = 0.010). After accounting for age differences, serum GDF-15 levels did not differ significantly between patients with PD and MSA (p = 0.114). Thus, age has a strong influence on serum GDF-15 levels, which may not differ significantly between patients with PD and atypical parkinsonian syndromes such as PSP and MSA.

Concomitant use of magnesium oxide significantly decreases absorption of levodopa preparations in patients with Parkinson's disease.

Introduction: Constipation is one of the most frequent non-motor symptoms of Parkinson's disease (PD), and magnesium oxide (MgO) is a frequently used laxative. This study aimed to investigate the effect of concomitant use of MgO on the pharmacokinetics of levodopa preparations in patients with PD. Methods: We prospectively enrolled 35 patients with PD and compared the pharmacokinetics of levodopa and carbidopa and motor symptoms with and without MgO. The impact of alterations in pH and the addition of MgO on the solubility of levodopa formulations were also evaluated under in vitro conditions. Results: Concomitant use of MgO significantly reduced the maximum plasma concentration of levodopa (Cmax) (from 7.66 ± 3.74 µmol/L to 5.82 ± 3.69 µmol/L; p = 0.006) and area under the plasma concentration-time curve 3 h after drug administration (AUC3h, from 9.64 ± 3.23 µmol·h/L to 7.39 ± 3.15 µmol·h/L; p < 0.001), and further decreased carbidopa Cmax (from 64.02 ± 27.02 ng/mL to 38.83 ± 21.94 µmol/L; p < 0.001) and AUC3h (from 130.58 ± 65.64 ng/mL to 76.48 ± 52.24 ng·h/mL; p < 0.001). The Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale part III score also deteriorated significantly (from 30.71 ± 11.34 to 32.06 ± 11.22; p = 0.007). MgO significantly affected the pharmacokinetics of levodopa and carbidopa. This also applied when the findings were analyzed by sex and age. In vitro dissolution experiments revealed a decrease in the relative concentrations of levodopa, carbidopa, and benserazide as the pH increased and in the presence of MgO suspension, with the most prominent impact on benserazide. Conclusions: Concomitant use of MgO and levodopa should be discouraged to improve levodopa absorption.