When should levodopa therapy be initiated in patients with Parkinson's disease?

Synthesis of Novel Plant-Derived Encapsulated Radiolabeled Compounds for the Diagnosis of Parkinson's Disease and the Evaluation of Biological Effects with In Vitro/In Vivo Methods

Parkinson's disease (PD) is a neurodegenerative disorder that affects millions of individuals globally. It is characterized by the loss of dopaminergic neurons in Substantia Nigra pars compacta (SNc) and striatum. Neuroimaging techniques such as single-photon emission computed tomography (SPECT), positron emission tomography (PET), and magnetic resonance imaging (MRI) help diagnosing PD. In this study, the focus was on developing technetium-99 m ([99mTc]Tc) radiolabeled drug delivery systems using plant-derived compounds for the diagnosis of PD. Madecassoside (MA), a plant-derived compound, was conjugated with Levodopa (L-DOPA) to form MA-L-DOPA, which was then encapsulated using Poly Lactic-co-Glycolic Acid (PLGA) to create MA-PLGA and MA-L-DOPA-PLGA nanocapsules. Extensive structural analysis was performed using various methods such as Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), liquid chromatography-mass spectrometry (LC-MS), thin layer chromatography (TLC), high performance liquid chromatography (HPLC), dynamic light scattering (DLS), and scanning electron microscopy (SEM) to characterize the synthesized products. Radiochemical yields of radiolabeled compounds were determined using thin layer radio chromatography (TLRC) and high performance liquid radio chromatography (HPLRC) methods. In vitro cell culture studies were conducted on human neuroblastoma (SH-SY5Y) and rat pheochromocytoma (PC-12) cell lines to assess the incorporation of [99mTc]Tc radiolabeled compounds ([99mTc]Tc-MA, [99mTc]Tc-MA-L-DOPA, [99mTc]Tc-MA-PLGA and [99mTc]Tc-MA-L-DOPA-PLGA) and the cytotoxicity of inactive compounds (MA and MA-L-DOPA compounds and encapsulated compounds (MA-PLGA and MA-L-DOPA-PLGA). Additionally, the biodistribution studies were carried out on healthy male Sprague-Dawley rats and a Parkinson's disease experimental model to evaluate the compounds' bioactivity using the radiolabeled compounds. The radiochemical yields of all radiolabeled compounds except [99mTc]Tc-L-DOPA-PLGA were above 95% and had stability over 6 h. The cytotoxic effects of all substances on SH-SY5Y and PC-12 cells increase with increasing concentration values. The uptake values of PLGA-encapsulated compounds are statistically significant in SH-SY5Y and PC-12 cells. The biodistribution studies showed that [99mTc]Tc-MA is predominantly retained in specific organs and brain regions, with notable uptake in the prostate, muscle, and midbrain. PLGA-encapsulation led to higher uptake in certain organs, suggesting its biodegradable nature may enhance tissue retention, and surface modifications might further optimize brain penetration. Overall, the results indicate that radiolabeled plant-derived encapsulated drug delivery systems with [99mTc]Tc hold potential as diagnostic agents for PD symptoms. This study contributes to the advancement of drug delivery agents in the field of brain research.

Levodopa-induced dyskinesia in early-onset Parkinson's disease (EOPD) associates with glucocerebrosidase mutation: A next-generation sequencing study in EOPD patients in Thailand

BACKGROUND

With the benefit of using next-generation sequencing (NGS), our aim was to examine the prevalence of known monogenic causes in early-onset Parkinson's disease (EOPD) patients in Thailand. The association between clinical features, such as levodopa-induced dyskinesia (LID), and genotypes were also explored.

METHOD

NGS studies were carried out for EOPD patients in the Tertiary-referral center for Parkinson's disease and movement disorders. EOPD patients who had LID symptoms were enrolled in this study (n = 47). We defined EOPD as a patient with onset of PD at or below 50 years of age. LID was defined as hyperkinetic movements including chorea, ballism, dystonia, myoclonus, or any combination of these movements resulting from levodopa therapy, which could be peak-dose, off-period, or diphasic dyskinesias.

RESULTS

Pathogenic variants were identified in 17% (8/47) of the Thai EOPD patients, of which 10.6% (5/47) were heterozygous GBA variants (c.1448T>C in 3 patients and c.115+1G>A in 2 patients), 4.3% (2/47) homozygous PINK1 variants (c.1474C>T) and 2.1% (1/47) a PRKN mutation (homozygous deletion of exon 7). The LID onset was earlier in patients with GBA mutations compared to those without (34.8±23.4 vs 106.2±59.5 months after starting levodopa, respectively, p = 0.001). LID onset within the first 30 months of the disease was also found to be independently associated with the GBA mutation (odds ratio [95% confidence interval] = 25.00 [2.12-295.06], p = 0.011).

CONCLUSION

Our study highlights the high prevalence of GBA pathogenic variants in Thai patients with EOPD and the independent association of these variants with the earlier onset of LID. This emphasizes the importance of genetic testing in this population.

Oral berberine improves brain dopa/dopamine levels to ameliorate Parkinson's disease by regulating gut microbiota

The phenylalanine–tyrosine–dopa–dopamine pathway provides dopamine to the brain. In this process, tyrosine hydroxylase (TH) is the rate-limiting enzyme that hydroxylates tyrosine and generates levodopa (l-dopa) with tetrahydrobiopterin (BH₄) as a coenzyme. Here, we show that oral berberine (BBR) might supply H^• through dihydroberberine (reduced BBR produced by bacterial nitroreductase) and promote the production of BH₄ from dihydrobiopterin; the increased BH₄ enhances TH activity, which accelerates the production of l-dopa by the gut bacteria. Oral BBR acts in a way similar to vitamins. The l-dopa produced by the intestinal bacteria enters the brain through the circulation and is transformed to dopamine. To verify the gut–brain dialog activated by BBR’s effect, Enterococcus faecalis or Enterococcus faecium was transplanted into Parkinson’s disease (PD) mice. The bacteria significantly increased brain dopamine and ameliorated PD manifestation in mice; additionally, combination of BBR with bacteria showed better therapeutic effect than that with bacteria alone. Moreover, 2,4,6-trimethyl-pyranylium tetrafluoroborate (TMP-TFB)-derivatized matrix-assisted laser desorption mass spectrometry (MALDI-MS) imaging of dopamine identified elevated striatal dopamine levels in mouse brains with oral Enterococcus, and BBR strengthened the imaging intensity of brain dopamine. These results demonstrated that BBR was an agonist of TH in Enterococcus and could lead to the production of l-dopa in the gut. Furthermore, a study of 28 patients with hyperlipidemia confirmed that oral BBR increased blood/fecal l-dopa by the intestinal bacteria. Hence, BBR might improve the brain function by upregulating the biosynthesis of l-dopa in the gut microbiota through a vitamin-like effect.

DOPA-sparing strategy in the treatment of young onset Parkinson's disease

Context:

Late onset Parkinson's disease (LOPD) is a neurodegenerative disorder afflicting individuals of ages 60 and older. However, 5–10% of cases can begin earlier between the ages 20 to 40, and are classified as young onset Parkinson disease (YOPD).

Aim:

In turn, this study aims to observe the trend in the choice of drug administered to patients with both YOPD and LOPD, with particular emphasis on this trend in its relation to the practice background of the neurologist.

Settings and Design:

A cross-sectional study was conducted in a community based Parkinson's disease and movement disorder clinic.

Statistical Analysis Used:

Using a retrospective chart review data was obtained and analysed.

Results:

The results showed that 83% of general neurologists prescribed levodopa to their patients with YOPD, whereas movement-disorder specialists took a different approach altogether. They opted not to use levodopa and, in its stead, prescribed a mixture of alternate drugs.

Associations Between Cardiovascular Events and Nonergot Dopamine Agonists in Parkinson's Disease

Background

Knowledge of possible cardiovascular risks from Parkinson's disease (PD) medications is critical to informing safe and effective treatment decisions. The objective of our study was to determine whether PD patients treated with nonergot dopamine agonists (DAs) are at increased risk of adverse cardiovascular or cerebrovascular outcomes, relative to PD patients receiving other treatments.

Methods

Matched case-control studies were conducted within a cohort of 14,122 inpatients receiving treatment for PD who were identified in the Cerner Health Facts database. Primary outcomes were associations between nonergot DA use and diagnosis of adverse cardiovascular events (acute myocardial infarction, heart failure [HF], hypotension, and valvulopathy). Secondary outcomes included associations between nonergot DA use and diagnosis of adverse cerebrovascular events (cerebrovascular accident and ischemic stroke) and odds of significant exposure-outcome relationships by patient factors.

Results

HF was the only adverse event that demonstrated a significant association with nonergot DA use. Individuals treated with pramipexole were more likely to be diagnosed with HF, relative to no use (adjusted odds ratio [AOR]: 1.28; 95% confidence interval [CI]: 1.07-1.53). The association between pramipexole and HF was greater among individuals treated with pramipexole monotherapy (relative to levodopa monotherapy) (AOR, 1.50; 95% CI: 1.09-2.06). Compared to nonusers, men and older individuals treated with pramipexole were more likely to be diagnosed with HF.

Conclusions

Results from our study suggest an association between pramipexole use and HF. Findings warrant replication; however, individuals with PD and independent risk factors for, or a history of, HF may benefit from limited use of this drug.

Trends in inpatient antiparkinson drug use in the USA, 2001-2012

Purpose

Although therapeutic options and clinical guidelines for Parkinson’s disease (PD) have changed significantly in the past 15 years, prescribing trends in the USA remain unknown. The purpose of this population-based cohort study was to examine patterns of inpatient antiparkinson drug use between January 2001 and December 2012 in relation to clinical guideline publication, drug introduction/withdrawal, and emerging safety concerns.

Methods

A total of 16,785 inpatients receiving pharmacological treatment for PD were identified in the Cerner Health Facts database. Our primary outcome was standardized (age, sex, race, and census region) annual prevalence of antiparkinson drug use. We also examined antiparkinson medication trends and polypharmacy by age and sex.

Results

The most frequently prescribed antiparkinson drugs between 2001 and 2012 were levodopa (85 %) and dopamine agonists (28 %). Dopamine agonist use began declining in 2007, from 34 to 27 % in 2012. The decline followed publication of the American Academy of Neurology’s practice parameter refuting levodopa toxicity, pergolide withdrawal, and pramipexole label revisions. Despite safety concerns for cognitive impairment and falls, individuals ≥80 years of age demonstrated stable rates of dopamine agonist use from 2001 to 2012. Polypharmacy was most common in younger patients.

Conclusions

Dopamine agonist use declined from 2007 to 2012, suggesting that increased awareness of safety issues and practice guidelines influenced prescribing. These events appear to have minimally influenced treatment provided to older PD patients. Antiparkinson prescribing trends indicate that safety and best practice information may be communicated effectively.

Electronic supplementary material

The online version of this article (doi:10.1007/s00228-015-1881-4) contains supplementary material, which is available to authorized users.

The effect of deep brain stimulation surgery on repetitive behavior in Parkinson patients: A case series

Repetitive behavior has been increasingly reported in Parkinson's disease (PD) patients. This study evaluates the effect of Deep Brain Stimulation (DBS) treatment on existing repetitive behavior in three PD patients who underwent unilateral STN DBS surgery at the University of Florida Movement Disorders Center. No significant change in repetitive behavior was noted acutely post-surgery; however, all cases were participating less in their repetitive behavior over time. In this series, DBS surgery seemed to have no acute effect on repetitive behavior. It is difficult to ascertain whether DBS improves repetitive behavior chronically because of confounding factors in our three cases.

The sigma-1 antagonist BMY-14802 inhibits L-DOPA-induced abnormal involuntary movements by a WAY-100635-sensitive mechanism

RATIONALE

Levodopa (L-DOPA), the gold standard treatment for Parkinson's disease (PD), eventually causes L-DOPA-induced dyskinesia (LID) in up to 80% of patients. In the 6-hydroxydopamine (6-OHDA) rat model of PD, L-DOPA induces a similar phenomenon, which has been termed abnormal involuntary movement (AIM). We previously demonstrated that BMY-14802 suppresses AIM expression in this model.

OBJECTIVES

Although BMY-14802 is widely used as a sigma-1 antagonist, it is also an agonist at serotonin (5-HT) 1A and adrenergic alpha-1 receptors. The current study was conducted to determine which of these mechanisms underlies BMY-14802's AIM-suppressing effect. This characterization included testing the 5-HT1A agonist buspirone and multiple sigma agents. When these studies implicated a 5-HT1A mechanism, we subsequently undertook a pharmacological reversal study, evaluating whether the 5-HT1A antagonist WAY-100635 counteracted BMY-14802's AIM-suppressing effects.

RESULTS

Buspirone dose-dependently suppressed AIM, supporting past findings. However, no AIM-suppressing effects were produced by drugs with effects at sigma receptors, including BD-1047, finasteride, SM-21, DTG, trans-dehydroandrosterone (DHEA), carbetapentane, and opipramol. Finally, we show for the first time that the AIM-suppressing effect of BMY-14802 was dose-dependently prevented by WAY-100635 but not by the alpha-1 antagonist prazosin.

CONCLUSIONS

BMY-14802 exerts its AIM-suppressing effects via a 5-HT1A agonist mechanism, similar to buspirone. Other 5-HT1A agonists have failed clinical trials, possibly due to submicromolar affinity at other receptors, including D2, which may exacerbate PD symptoms. BMY-14802 is a promising candidate for clinical trials due to its extremely low affinity for the D2 receptor and lack of extrapyramidal effects during prior clinical trials for schizophrenia.

Tolcapone: review of its pharmacology and use as adjunctive therapy in patients with Parkinson's disease

Levodopa has been the gold standard therapy for the motor symptoms of Parkinson’s disease for more than three decades. Although it remains the most effective treatment, its long-term use is associated with motor fluctuations and dyskinesias that can be disabling for patients and difficult for physicians to manage medically. In the last 10 years, the catechol-O-methyltransferase (COMT) inhibitor tolcapone has been studied for its efficacy as an adjunctive treatment to levodopa plus a dopa decarboxylase inhibitor. Adjunctive therapy with tolcapone can significantly reduce the dose of levodopa required. Moreover, treatment with tolcapone significantly reduces wearing off and on-off periods in fluctuating patients and improves ‘on’ time in patients with stable disease. Tolcapone has assumed a new place in the arsenal of medications for Parkinson’s disease. This paper reviews the pharmacology, safety and efficacy of tolcapone in patients with advanced Parkinson’s disease. After some initial concerns about its safety, tolcapone has been shown to be safe if used and monitored according to guidelines regarding liver function. Tolcapone produces expected dopaminergic side effects, including headache, nausea, insomnia, as well as diarrhea; however, these side effects are generally mild and as a rule do not result in discontinuation of therapy.

COMT inhibition with tolcapone in the treatment algorithm of patients with Parkinson's disease (PD): relevance for motor and non-motor features

Levodopa is the most effective treatment in Parkinson's disease and the association with COMT inhibitors widens its plasma bioavailability and effectiveness. Tolcapone is a potent COMT inhibitor whose utilization in PD is limited due to safety concerns on liver toxicity. However, recent data indicate that if liver function is actively monitored, tolerability is no worse than other currently available therapies. By contrast, administration of tolcapone is associated with significant clinical improvement and benefit involves also non-motor features. In this review we discuss the rationale for the use of tolcapone in association with levodopa and other treatments in PD, and we provide an indirect comparison of current strategies to reduce "off" time. We propose that future guidelines include a trial with tolcapone in all PD patients who continue to complain about motor fluctuations despite treatment with entacapone and/or MAO-B inhibitors. Moreover, we suggest that tolcapone should be considered before surgical or infusional strategies are applied.