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Nishikawa N, Iwaki H, Mukai Y, Takahashi Y. Classification of l-DOPA pharmacokinetics shapes and creating a predictive model. Parkinsonism Relat Disord 2023; 114:105798. [PMID: 37556972 DOI: 10.1016/j.parkreldis.2023.105798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 07/28/2023] [Accepted: 08/04/2023] [Indexed: 08/11/2023]
Abstract
BACKGROUND It is known that the pharmacokinetics (PK) of levodopa (LD) varies considerably. Difference in PK shapes is expected to affect drug efficacy and development of dyskinesia. In this study, the authors aimed to explore correlations between PK series data of LD and clinical characteristics and dyskinesia in patients with Parkinson's disease (PD). METHODS We studied 270 PD patients who underwent PK assessment after administration of LD/carbidopa (100/10 mg) in non-compartmental analysis. The patients were grouped according to similarities in time series data of blood LD concentration. Each group was analyzed with respect to clinical characteristics and PK parameters. We created a model to predict PK patterns based on these findings. RESULTS PD patients were divided into three groups by clustering analysis: blood LD concentration of the patients in Groups 1 (n = 129), 3 (n = 44) and 2 (n = 97) rose rapidly, relatively slowly and at an intermediate rate, respectively. There were no statistically significant differences in patient characteristics except age among the three groups (one-way ANOVA). Multivariate analysis showed that frequency of dyskinesias in Group 1 was significantly higher than that in Group 2. We successfully created a PK pattern prediction model based on body weight and blood LD concentration at 15 and 30 min after administration. CONCLUSIONS The PK series data of LD was classified into three patterns. The rapid absorption was associated with dyskinesias. Patients' PK patterns were successfully predicted based on their body weight and two-point LD concentration.
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Affiliation(s)
- Noriko Nishikawa
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan; Department of Neurology, Juntendo University School of Medicine, Tokyo, Japan.
| | | | - Yohei Mukai
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yuji Takahashi
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
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Nishikawa N, Iwaki H, Shiraishi T, Mukai Y, Takahashi Y, Murata M. Female, aging, difference formulations of DCI, or lower body weight increases AUC 4hr of levodopa in patients with Parkinson's disease. Parkinsonism Relat Disord 2020; 76:16-20. [PMID: 32554330 DOI: 10.1016/j.parkreldis.2020.05.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 05/09/2020] [Accepted: 05/19/2020] [Indexed: 11/21/2022]
Abstract
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.
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Shiraishi T, Nishikawa N, Mukai Y, Takahashi Y. High levodopa plasma concentration after oral administration predicts levodopa-induced dyskinesia in Parkinson's disease. Parkinsonism Relat Disord 2020; 75:80-84. [PMID: 32497995 DOI: 10.1016/j.parkreldis.2020.05.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 05/15/2020] [Accepted: 05/20/2020] [Indexed: 12/21/2022]
Abstract
INTRODUCTION In patients with Parkinson's disease (PD), pulsatile dopaminergic stimulation may be a primary cause of levodopa-induced dyskinesia (LID). We aimed to investigate the correlation between levodopa pharmacokinetics (PK) and LID in PD. METHODS We retrospectively reviewed the consecutive series of 255 PD patients without LID who underwent PK assessments with 100 mg levodopa. The type of peripheral decarboxylase inhibitor used in the PK assessments was determined by the usual prescription of the formulations of levodopa (10 mg carbidopa [n = 185] and 25 mg benserazide [n = 70]). RESULTS During a median follow-up of 32 months (IQR, 16-49 months), 73 patients (29%) developed LID. Compared with patients who did not develop LID (PD-LID-), those who developed LID (PD-LID+) were younger (p = 0.003) and had significantly higher maximum levodopa concentration (Cmax) (p = 0.002) and area under the curve (p < 0.001), LEDD (p < 0.001), and improvement of motor symptoms (p = 0.009). In the multivariate Cox proportional hazards models, Cmax and AUC were associated with incident LID (Hazard Ratio [HR] 1.11, 95% confidence interval [CI] 1.03-1.19 and HR 1.13, 95% CI 1.03-1.24, respectively). In addition, younger age, benserazide use, LEDD, and MAOBI use were associated with incident LID. CONCLUSION High levodopa plasma concentration after oral administration was associated with incident LID in patients with PD.
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Affiliation(s)
- Tomotaka Shiraishi
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-higashi-cho, Kodaira-shi, Tokyo, 187-8551, Japan
| | - Noriko Nishikawa
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-higashi-cho, Kodaira-shi, Tokyo, 187-8551, Japan.
| | - Yohei Mukai
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-higashi-cho, Kodaira-shi, Tokyo, 187-8551, Japan
| | - Yuji Takahashi
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-higashi-cho, Kodaira-shi, Tokyo, 187-8551, Japan
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Athauda D, Maclagan K, Budnik N, Zampedri L, Hibbert S, Aviles-Olmos I, Chowdhury K, Skene SS, Limousin P, Foltynie T. Post hoc analysis of the Exenatide-PD trial-Factors that predict response. Eur J Neurosci 2018; 49:410-421. [PMID: 30070753 DOI: 10.1111/ejn.14096] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 06/27/2018] [Accepted: 07/23/2018] [Indexed: 12/25/2022]
Abstract
Exenatide, a glucagon-like peptide-1 agonist and a licensed treatment for Type 2 diabetes significantly reduced deterioration in motor symptoms in patients with Parkinson's disease in a randomized, placebo-controlled trial. In addition, there were trends favouring the exenatide group in assessments of nonmotor symptoms, cognition, and quality of life. The aim of this exploratory post hoc analysis was to generate new hypotheses regarding (a) whether candidate baseline factors might predict the magnitude of response to exenatide; and (b) whether the beneficial effects of exenatide reported for the overall population are consistent in various subgroups of patients. Univariate and multivariate analyses were conducted to determine possible predictors of motor response to exenatide in this cohort. Potential treatment by subgroup interactions for changes in; motor severity, nonmotor symptoms, cognition, and quality of life after 48-weeks treatment with exenatide were evaluated among post hoc subgroups defined by age, motor phenotype, disease duration, disease severity, body mass index (BMI), and insulin resistance. In the subgroup analyses, exenatide once-weekly was associated with broadly improved outcome measures assessing motor severity, nonmotor symptoms, cognition, and quality of life across all subgroups, however, tremor-dominant phenotype and lower Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part-2 scores predicted greatest motor response to exenatide and there was an indication that patients with older age of onset and disease duration over 10 years responded less well. While patients with a range of demographic and clinical factors can potentially benefit from exenatide once-weekly, these data support an emphasis towards recruiting patients at earlier disease in future planned clinical trials of gluacagon-like peptide-1 (GLP-1) receptor agonists in Parkinson's disease (PD).
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Affiliation(s)
- Dilan Athauda
- Sobell Department of Motor Neuroscience, UCL Institute of Neurology & The National Hospital for Neurology and Neurosurgery, London, UK
| | - Kate Maclagan
- UCL Comprehensive Clinical Trials Unit (UCL CCTU), London, UK
| | - Natalia Budnik
- Leonard Wolfson Experimental Neuroscience Centre, London, UK
| | - Luca Zampedri
- Leonard Wolfson Experimental Neuroscience Centre, London, UK
| | - Steve Hibbert
- UCL Comprehensive Clinical Trials Unit (UCL CCTU), London, UK
| | - Iciar Aviles-Olmos
- Sobell Department of Motor Neuroscience, UCL Institute of Neurology & The National Hospital for Neurology and Neurosurgery, London, UK
| | | | - Simon S Skene
- UCL Comprehensive Clinical Trials Unit (UCL CCTU), London, UK.,School of Biosciences and Medicine, University of Surrey, Guildford, UK
| | - Patricia Limousin
- Sobell Department of Motor Neuroscience, UCL Institute of Neurology & The National Hospital for Neurology and Neurosurgery, London, UK
| | - Thomas Foltynie
- Sobell Department of Motor Neuroscience, UCL Institute of Neurology & The National Hospital for Neurology and Neurosurgery, London, UK
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Masellis M, Collinson S, Freeman N, Tampakeras M, Levy J, Tchelet A, Eyal E, Berkovich E, Eliaz RE, Abler V, Grossman I, Fitzer-Attas C, Tiwari A, Hayden MR, Kennedy JL, Lang AE, Knight J. Dopamine D2 receptor gene variants and response to rasagiline in early Parkinson's disease: a pharmacogenetic study. Brain 2016; 139:2050-62. [PMID: 27190009 DOI: 10.1093/brain/aww109] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 03/16/2016] [Indexed: 01/26/2023] Open
Abstract
The treatment of early Parkinson's disease with dopaminergic agents remains the mainstay of symptomatic therapy for this incurable neurodegenerative disorder. However, clinical responses to dopaminergic drugs vary substantially from person to person due to individual-, drug- and disease-related factors that may in part be genetically determined. Using clinical data and DNA samples ascertained through the largest placebo-controlled clinical trial of the monoamine oxidase B inhibitor, rasagiline (ClinicalTrials.gov number, NCT00256204), we examined how polymorphisms in candidate genes associate with the clinical response to rasagiline in early Parkinson's disease. Variants in genes that express proteins involved in the pharmacokinetics and pharmacodynamics of rasagiline, and genes previously associated with the risk to develop Parkinson's disease were genotyped. The LifeTechnologies OpenArray NT genotyping platform and polymerase chain reaction-based methods were used to analyse 204 single nucleotide polymorphisms and five variable number tandem repeats from 30 candidate genes in 692 available DNA samples from this clinical trial. The peak symptomatic response to rasagiline, the rate of symptom progression, and their relation to genetic variation were examined controlling for placebo effects using general linear and mixed effects models, respectively. Single nucleotide polymorphisms, rs2283265 and rs1076560, in the dopamine D2 receptor gene (DRD2) were found to be significantly associated with a favourable peak response to rasagiline at 12 weeks in early Parkinson's disease after controlling for multiple testing. From a linear regression, the betas were 2.5 and 2.38, respectively, with false discovery rate-corrected P-values of 0.032. These polymorphisms were in high linkage disequilibrium with each other (r(2) = 0.96) meaning that the same clinical response signal was identified by each of them. No polymorphisms were associated with slowing the rate of worsening in Parkinson symptoms from Weeks 12 to 36 after correction for multiple testing. This is the largest and most comprehensive pharmacogenetics study to date examining clinical response to an anti-parkinsonian drug and the first to be conducted in patients with early stage Parkinson's disease receiving monotherapy. The results indicate a clinically meaningful benefit to rasagiline in terms of the magnitude of improvement in parkinsonian symptoms for those with the favourable response genotypes. Future work is needed to elucidate the specific mechanisms through which these DRD2 variants operate in modulating the function of the nigrostriatal dopaminergic system.media-1vid110.1093/brain/aww109_video_abstractaww109_video_abstract.
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Affiliation(s)
- Mario Masellis
- 1 Cognitive and Movement Disorders Clinic, Sunnybrook Health Sciences Centre, Toronto, Canada 2 Hurvitz Brain Sciences Research Program, Sunnybrook Research Institute, Toronto, Canada 3 Division of Neurology, Department of Medicine, University of Toronto, Toronto, Canada 4 Neurogenetics Section, Centre for Addiction and Mental Health, Toronto, Canada 5 Institute of Medical Science, University of Toronto, Toronto, Canada
| | - Shannon Collinson
- 4 Neurogenetics Section, Centre for Addiction and Mental Health, Toronto, Canada
| | - Natalie Freeman
- 4 Neurogenetics Section, Centre for Addiction and Mental Health, Toronto, Canada
| | - Maria Tampakeras
- 4 Neurogenetics Section, Centre for Addiction and Mental Health, Toronto, Canada
| | | | | | - Eli Eyal
- 6 Teva Pharmaceutical Industries, Israel
| | | | | | | | | | | | - Arun Tiwari
- 4 Neurogenetics Section, Centre for Addiction and Mental Health, Toronto, Canada
| | | | - James L Kennedy
- 4 Neurogenetics Section, Centre for Addiction and Mental Health, Toronto, Canada 5 Institute of Medical Science, University of Toronto, Toronto, Canada 7 Department of Psychiatry, University of Toronto, Toronto, Canada 8 Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Canada
| | - Anthony E Lang
- 3 Division of Neurology, Department of Medicine, University of Toronto, Toronto, Canada 9 Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital, University Health Network, Toronto, Canada 10 The Edmond J. Safra Program in Parkinson's Disease, Toronto Western Hospital, University Health Network, Toronto, Canada
| | - Jo Knight
- 4 Neurogenetics Section, Centre for Addiction and Mental Health, Toronto, Canada 5 Institute of Medical Science, University of Toronto, Toronto, Canada 7 Department of Psychiatry, University of Toronto, Toronto, Canada 8 Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Canada 11 Biostatistics Division, Dalla Lana School of Public Health, University of Toronto, Toronto, Canada 12 Lancaster Medical School and Data Science Institute, Lancaster University, Lancaster, UK
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Yamamoto T, Uchiyama T, Higuchi Y, Asahina M, Hirano S, Yamanaka Y, Kuwabara S. Subthalamic Nucleus Deep Brain Stimulation Modulate Catecholamine Levels with Significant Relations to Clinical Outcome after Surgery in Patients with Parkinson's Disease. PLoS One 2015; 10:e0138462. [PMID: 26394059 PMCID: PMC4578924 DOI: 10.1371/journal.pone.0138462] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Accepted: 08/31/2015] [Indexed: 02/05/2023] Open
Abstract
Aims Although subthalamic nucleus deep brain stimulation (STN-DBS) is effective in patients with advanced Parkinson’s disease (PD), its physiological mechanisms remain unclear. Because STN-DBS is effective in patients with PD whose motor symptoms are dramatically alleviated by L-3,4-dihydroxyphenylalanine (L-DOPA) treatment, the higher preoperative catecholamine levels might be related to the better clinical outcome after surgery. We aimed to examine the correlation between the preoperative catecholamine levels and postoperative clinical outcome after subthalamic nucleus deep brain stimulation. The effectiveness of STN-DBS in the patient who responded well to dopaminergic medication suggest the causal link between the dopaminergic system and STN-DBS. We also examined how catecholamine levels were modulated after subthalamic stimulation. Methods In total 25 patients with PD were enrolled (Mean age 66.2 ± 6.7 years, mean disease duration 11.6 ± 3.7 years). Mean levodopa equivalent doses were 1032 ± 34.6 mg before surgery. Cerebrospinal fluid and plasma catecholamine levels were measured an hour after oral administration of antiparkinsonian drugs before surgery. The mean Unified Parkinson’s Disease Rating Scale scores (UPDRS) and the Parkinson’s disease Questionnaire-39 (PDQ-39) were obtained before and after surgery. Of the 25 patients, postoperative cerebrospinal fluid and plasma were collected an hour after oral administration of antiparkinsonian drugs during on stimulation at follow up in 11 patients. Results Mean levodopa equivalent doses significantly decreased after surgery with improvement in motor functions and quality of life. The preoperative catecholamine levels had basically negative correlations with postoperative motor scores and quality of life, suggesting that higher preoperative catecholamine levels were related to better outcome after STN-DBS. The preoperative plasma levels of L-DOPA had significantly negative correlations with postoperative UPDRS- III score in off phase three months after STN-DBS. The preoperative cerebrospinal fluid (CSF) 3,4-dihydroxyphenylacetic acid (DOPAC) and 5-hydroxytryptamine (5-HT) levels had significantly negative correlations with postoperative UPDRS- III score in off phase one year after STN-DBS and the preoperative CSF homovanilic acid (HVA) levels had significant negative correlations with postoperative UPDRS- III score in on phase three months after STN-DBS. In PDQ-39 SI (summary index), preoperative plasma dopamine (DA) level had significantly negative correlations with postoperative PDQ-39 SI one year after STN-DBS suggesting that higher preoperative plasma DA level resulted in better quality of life (QOL) one year after STN-DBS. The stepwise multiple linear regression study revealed that higher preoperative plasma HVA levels had negative influence on the postoperative motor symptoms (i.e., increase in the score of UPDRS), whereas higher preoperative CSF L-DOPA levels had positive influence on the postoperative motor symptoms and QOL (decrease in the score of UPDRS and PDQ-39 SI) The catecholamine levels were not significantly reduced postoperatively in 11 patients despite the significant reduction in levodopa equivalent doses. Unexpectedly, CSF HVA levels significantly increased from 0.00089±0.0003 ng/μl to 0.002±0.0008 ng/μl after STN-DBS. Conclusion The preoperative catecholamine levels might affect the postoperative motor symptoms and quality of life. The catecholamine levels were not significantly reduced postoperatively despite the significant reduction in levodopa equivalent doses.
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Affiliation(s)
- Tatsuya Yamamoto
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
- * E-mail:
| | - Tomoyuki Uchiyama
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
- Department of Neurology, Dokkyo Medical College, Tochigi, Japan
| | - Yoshinori Higuchi
- Department of Neurosurgery, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Masato Asahina
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Shigeki Hirano
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Yoshitaka Yamanaka
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Satoshi Kuwabara
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
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Wang CL, Fan YB, Lee SE, Lian JF, Liou JP, Wang HP. Systemic and brain bioavailabilities of d-Phenylglycine-l-Dopa, a sustained dopamine-releasing prodrug. J Food Drug Anal 2013. [DOI: 10.1016/j.jfda.2013.05.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Huot P, Johnston TH, Koprich JB, Fox SH, Brotchie JM. l-DOPA pharmacokinetics in the MPTP-lesioned macaque model of Parkinson's disease. Neuropharmacology 2012; 63:829-36. [DOI: 10.1016/j.neuropharm.2012.06.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 05/12/2012] [Accepted: 06/11/2012] [Indexed: 10/28/2022]
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Nomoto M. [The cutting-edge of medicine: diagnosis and treatment of Parkinson's disease in clinical practice]. Nihon Naika Gakkai Zasshi 2012; 101:2065-2071. [PMID: 22897014 DOI: 10.2169/naika.101.2065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Affiliation(s)
- Masahiro Nomoto
- Department of Neurology and Clinical Pharmacology, Ehime University School of Medicine, Japan
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Wang CL, Fan YB, Lu HH, Tsai TH, Tsai MC, Wang HP. Evidence of D-phenylglycine as delivering tool for improving L-dopa absorption. J Biomed Sci 2010; 17:71. [PMID: 20815935 PMCID: PMC2941486 DOI: 10.1186/1423-0127-17-71] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Accepted: 09/06/2010] [Indexed: 11/10/2022] Open
Abstract
Background l-Dopa has been used for Parkinson's disease management for a long time. However, its wide variety in the rate and the extent of absorption remained challenge in designing suitable therapeutic regime. We report here a design of using d-phenylglycine to guard l-dopa for better absorption in the intestine via intestinal peptide transporter I (PepT1). Methods d-Phenylglycine was chemically attached on l-dopa to form d-phenylglycine-l-dopa as a dipeptide prodrug of l-dopa. The cross-membrane transport of this dipeptide and l-dopa via PepT1 was compared in brush-boarder membrane vesicle (BBMV) prepared from rat intestine. The intestinal absorption was compared by in situ jejunal perfusion in rats. The pharmacokinetics after i.v. and p.o. administration of both compounds were also compared in Wistar rats. The striatal dopamine released after i.v. administration of d-phenylglycine-l-dopa was collected by brain microdialysis and monitored by HPLC. Anti-Parkinsonism effect was determined by counting the rotation of 6-OHDA-treated unilateral striatal lesioned rats elicited rotation with (+)-methamphetamine (MA). Results The BBMV uptake of d-phenylglycine-l-dopa was inhibited by Gly-Pro, Gly-Phe and cephradine, the typical PepT1 substrates, but not by amino acids Phe or l-dopa. The cross-membrane permeability (Pm*) determined in rat jejunal perfusion of d-phenylglycine-l-dopa was higher than that of l-dopa (2.58 ± 0.14 vs. 0.94 ± 0.10). The oral bioavailability of d-phenylglycine-l-dopa was 31.7 times higher than that of l-dopa in rats. A sustained releasing profile of striatal dopamine was demonstrated after i. v. injection of d-phenylglycine-l-dopa (50 mg/kg), indicated that d-phenylglycine-l-dopa might be a prodrug of dopamine. d-Phenylglycine-l-dopa was more efficient than l-dopa in lowering the rotation of unilateral striatal lesioned rats (19.1 ± 1.7% vs. 9.9 ± 1.4%). Conclusion The BBMV uptake studies indicated that d-phenylglycine facilitated the transport of l-dopa through the intestinal PepT1 transporter. The higher jejunal permeability and the improved systemic bioavailability of d-phenylglycine-l-dopa in comparison to that of l-dopa suggested that d-phenylglycine is an effective delivery tool for improving the oral absorption of drugs like l-dopa with unsatisfactory pharmacokinetics. The gradual release of dopamine in brain striatum rendered this dipeptide as a potential dopamine sustained-releasing prodrug.
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Affiliation(s)
- Chun-Li Wang
- Taipei Medical University College of Pharmacy, 250 Wu-Hsing St,, Taipei, 110-31, Taiwan
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