Sex Is the Main Determinant of Levodopa Clinical Pharmacokinetics: Evidence from a Large Series of Levodopa Therapeutic Monitoring

Early effect of onabotulinumtoxinA on EEG-based functional connectivity in patients with chronic migraine: A pilot study

OBJECTIVE

In this pilot prospective cohort study, we aimed to evaluate, using high-density electroencephalography (HD-EEG), the longitudinal changes in functional connectivity (FC) in patients with chronic migraine (CM) treated with onabotulinumtoxinA (OBTA).

BACKGROUND

OBTA is a treatment for CM. Several studies have shown the modulatory action of OBTA on the central nervous system; however, research on migraine is limited.

METHODS

This study was conducted at the Neurology Unit of "Policlinico Tor Vergata," Rome, Italy, and included 12 adult patients with CM treated with OBTA and 15 healthy controls (HC). Patients underwent clinical scales at enrollment (T0) and 3 months (T1) from the start of treatment. HD-EEG was recorded using a 64-channel system in patients with CM at T0 and T1. A source reconstruction method was used to identify brain activity. FC in δ-θ-α-β-low-γ bands was analyzed using the weighted phase-lag index. FC changes between HCs and CM at T0 and T1 were assessed using cross-validation methods to estimate the results' reliability.

RESULTS

Compared to HCs at T0, patients with CM showed hyperconnected networks in δ (p = 0.046, area under the receiver operating characteristic curve [AUC: 0.76-0.98], Cohen's κ [0.65-0.93]) and β (p = 0.031, AUC [0.68-0.95], Cohen's κ [0.51-0.84]), mainly involving orbitofrontal, occipital, temporal pole and orbitofrontal, superior temporal, occipital, cingulate areas, and hypoconnected networks in α band (p = 0.029, AUC [0.80-0.99], Cohen's κ [0.42-0.77]), predominantly involving cingulate, temporal pole, and precuneus. Patients with CM at T1, compared to T0, showed hypoconnected networks in δ band (p = 0.032, AUC [0.73-0.99], Cohen's κ [0.53-0.90]) and hyperconnected networks in α band (p = 0.048, AUC [0.58-0.93], Cohen's κ [0.37-0.78]), involving the sensorimotor, orbitofrontal, cingulate, and temporal cortex.

CONCLUSION

These preliminary results showed that patients with CM presented disrupted EEG-FC compared to controls restored by a single session of OBTA treatment, suggesting a primary central modulatory action of OBTA.

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.

Activation of mGlu2/3 receptors in the striatum alleviates L-DOPA-induced dyskinesia and inhibits abnormal postsynaptic molecular expression

Group II metabotropic glutamate receptors (mGlu2/3 receptors) have been regarded as promising candidates for the treatment of L-DOPA-induced dyskinesia (LID); however, confirmation is still lacking. As the hub of the basal ganglia circuit, the striatum plays a critical role in action control. Supersensitive responsiveness of glutamatergic corticostriatal input may be the key mechanism for the development of LID. In this study, we first examined the potency of LY354740 (12 mg/kg, i.p.) in modulating glutamate and dopamine release in lesioned striatum of stable LID rats. Then, we injected LY354740 (20nmoL or 40nmoL in 4 μL of sterile 0.9 % saline) directly into the lesioned striatum to verify its ability to reduce or attenuate L-DOPA-induced abnormal involuntary movements. In experiment conducted in established LID rats, after continuous injection for 4 days, we found that LY354740 significantly reduced the expression of dyskinesia. In another experiment conducted in parkinsonism rat models, we found that LY354740 attenuated the development of LID with an inverted-U dose-response curve. The role of LY354740 in modulating striatal expressions of LID-related molecular changes was also assessed after these behavioral experiments. We found that LY354740 significantly inhibited abnormal expressions of p-Fyn/p-NMDA/p-ERK1/2/p-HistoneH3/ΔFosB, which is in line with its ability to alleviate abnormal involuntary movements in both LID expression and induction phase. Our study indicates that activation of striatal mGlu2/3 receptors can attenuate the development of dyskinesia in parkinsonism rats and provide some functional improvements in LID rats by inhibiting LID-related molecular changes.

Acute effect of levodopa on orthostatic hypotension and its association with motor responsiveness in Parkinson's disease: Results of acute levodopa challenge test

OBJECTIVE

Levodopa administration can induce or worsen orthostatic hypotension (OH) in patients with Parkinson's disease (PD). Understanding of acute OH post levodopa (AOHPL) is important for rational drug use in PD patients. Primary objective of this study was to investigate the incidence of AOHPL in PD patients. The secondary objectives were a) hemodynamic character of AOHPL; b) risk factors of AOHPL; c) relationship between motor responsiveness and blood pressure (BP) change.

METHODS

490 PD inpatients underwent acute levodopa challenge test (LCT). Supine-to-standing test (STS) was done 4 times during LCT, including before levodopa and every hour post levodopa intake within 3 h. Patients were classified into two groups, AOHPL and non-AOHPL. A comprehensive set of clinical features scales was assessed, including both motor (e.g., motor response, wearing-off) and nonmotor symptoms (e.g., autonomic dysfunction, neuropsychology).

RESULTS

33.1% PD patients had OH before drug, 50.8% the same subjects had AOHPL during levodopa effectiveness. PD patients who had better response to levodopa likely to have lower standing mean artery pressure (MAP) and severer systolic BP drop after levodopa intake. BP increased when the motor performance worsened and vice versa. Beneficial response was a risk factors of AOHPL (OR = 1.624, P = 0.017).

CONCLUSIONS

AOHPL was very common in PD patients. We suggested that PD patients with risk factors should monitor hemodynamic change during LCT to avoid AOHPL following the introduction or increase of oral levodopa. The fluctuations of BP were complicated and multifactorial, likely caused by the process of PD and levodopa both.

Classification of l-DOPA pharmacokinetics shapes and creating a predictive model

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.

An update on the pharmacogenetic considerations when prescribing dopamine receptor agonists for Parkinson's disease

INTRODUCTION

Parkinson's disease is a chronic neurodegenerative multisystemic disorder that affects approximately 2% of the population over 65 years old. This disorder is characterized by motor symptoms which are frequently accompanied by non-motor symptoms such as cognitive disorders. Current drug therapies aim to reduce the symptoms and increase the patient's life expectancy. Nevertheless, there is heterogeneity in therapy response in terms of efficacy and adverse effects. This wide range in response may be linked to genetic variability. Thus, it has been suggested that pharmacogenomics may help to tailor and personalize drug therapy for Parkinson's disease.

AREAS COVERED

This review describes and updates the clinical impact of genetic factors associated with the efficacy and adverse drug reactions related to common medications used to treat Parkinson's disease. Additionally, we highlight current informative recommendations for the drug treatment of Parkinson's disease.

EXPERT OPINION

The pharmacokinetic, pharmacodynamic, and safety profiles of Parkinson's disease drugs do not favor the development of pharmacogenetic tests with a high probability of success. The chances of obtaining ground-breaking pharmacogenetics biomarkers for Parkinson's disease therapy are limited. Nevertheless, additional information on the metabolism of certain drugs, and an analysis of the potential of pharmacogenetics in novel drugs could be of interest.

To restrict or not to restrict? Practical considerations for optimizing dietary protein interactions on levodopa absorption in Parkinson's disease

Administration of levodopa for Parkinson's disease (PD) has remained the most effective therapy for symptom management despite being in use for over 50 years. Advancing disease and age, changing tolerability and gastrointestinal (GI) dysfunction may result in change in dietary habits and body weight, as well as unpredictable motor fluctuations and dyskinesias. Dietary proteins which convert into amino acids after digestion are implicated as major factors that inhibit levodopa absorption. For people living with PD (PwP) who experience motor fluctuations, low protein diets (LPD) and protein redistribution diets (PRD) may be effective and are often recommended as a non-pharmacologic approach for improving levodopa bioavailability. However, there is a lack of consensus on a standard definition of these diets and appropriate treatment algorithms for usage. This may be due to the paucity of high-level evidence of LPD and PRD in PwP and whether all or specific subgroups of patients would benefit from these strategies. Managing diet and protein intake with proper education and monitoring may reduce complications associated with these diets such as dyskinesias and unintentional weight loss. Additionally, alterations to medications and GI function may alter levodopa pharmacokinetics. In this narrative review we focus on 1) mechanisms of dietary protein and levodopa absorption in the intestine and blood brain barrier, 2) dietetic approaches to manage protein and levodopa interactions and 3) practical issues for treating PwP as well as future directions to be considered.