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Neuropharmacology Jun 2024Impulsive decision-making has been linked to impulse control disorders and substance use disorders. However, the neural mechanisms underlying impulsive choice are not...
Impulsive decision-making has been linked to impulse control disorders and substance use disorders. However, the neural mechanisms underlying impulsive choice are not fully understood. While previous PET imaging and autoradiography studies have shown involvement of dopamine and D2/3 receptors in impulsive behavior, the roles of distinct D1, D2, and D3 receptors in impulsive decision-making remain unclear. In this study, we used a food reward delay-discounting task (DDT) to identify low- and high-impulsive rats, in which low-impulsive rats exhibited preference for large delayed reward over small immediate rewards, while high-impulsive rats showed the opposite preference. We then examined D1, D2, and D3 receptor gene expression using RNAscope in situ hybridization assays. We found that high-impulsive male rats exhibited lower levels of D2 and D3, and particularly D3, receptor expression in the nucleus accumbens (NAc), with no significant changes in the insular, prelimbic, and infralimbic cortices. Based on these findings, we further explored the role of the D3 receptor in impulsive decision-making. Systemic administration of a selective D3 receptor agonist (FOB02-04) significantly reduced impulsive choices in high-impulsive rats but had no effects in low-impulsive rats. Conversely, a selective D3 receptor antagonist (VK4-116) produced increased both impulsive and omission choices in both groups of rats. These findings suggest that impulsive decision-making is associated with a reduction in D3 receptor expression in the NAc. Selective D3 receptor agonists, but not antagonists, may hold therapeutic potentials for mitigating impulsivity in high-impulsive subjects.
PubMed: 38917939
DOI: 10.1016/j.neuropharm.2024.110051 -
Revista de Neurologia Jun 2024Most patients with Parkinson's disease experience motor fluctuations or 'off' periods, which impact on their daily activities, increase their disability and diminish... (Review)
Review
Most patients with Parkinson's disease experience motor fluctuations or 'off' periods, which impact on their daily activities, increase their disability and diminish their quality of life. They suffer from these fluctuations despite multiple adjustments to the schedules, doses and intake of medication. In this context, on-demand or rescue treatments are necessary to attempt to improve 'off' periods, with drugs that have the pharmacokinetic advantage of a much faster onset of action because their routes of administration are not oral. There are currently three on-demand therapies for the treatment of fluctuations: subcutaneous apomorphine, inhaled levodopa and sublingual apomorphine. Of the three alternatives, subcutaneous apomorphine generally has the fastest onset of action, sublingual apomorphine provides the longest clinical effect, and inhaled levodopa has the most favourable side effect profile. Each of these drugs has its own characteristics: the time before onset of action, the duration of action and different side effect profiles. The choice for each patient will depend on their individual needs and circumstances. To mark the first year of the introduction of inhaled levodopa, we review these therapies, focusing on the experience with this new dosage form of levodopa.
Topics: Humans; Levodopa; Parkinson Disease; Antiparkinson Agents; Administration, Inhalation; Apomorphine
PubMed: 38916176
DOI: 10.33588/rn.78S01.2024196 -
Central Nervous System Agents in... Jun 2024A Non-Ergot Dopamine Agonist (NEDA) rotigotine has been designed as a new transdermal drug delivery system.
BACKGROUND
A Non-Ergot Dopamine Agonist (NEDA) rotigotine has been designed as a new transdermal drug delivery system.
AIM
To maintain optimum homogeneity in drug content, the rotigotine transdermal patch was developed utilizing a solvent casting technique.
METHODS
The characteristics of a transdermal patch, including patch weight, folding endurance, patch thickness, surface morphology, tensile strength, swelling rate, surface pH, in vitro release studies, water retention rate, uniformity of drug content, and ex-vivo permeation studies, were determined.
RESULTS
In vitro drug release studies unequivocally demonstrated that drug release controlled polymer interactions. There was no apparent lag period before the drug release rate started to decline. The developed patch showed 70 ± 1.18 % of prolongation of drug release within 24 hours. The result of the penetration studies demonstrated that 61 ± 2.52% of rotigotine permeated through the epidermal barrier within 24 h.
CONCLUSION
The developed transdermal patch comprising rotigotine was evidently placed on the dermis layer, and an appropriate dose was delivered into circulation for a longer time based on the aforementioned factors. The findings of this study illustrate the effective approach of transdermal patches to treat Parkinson's disease.
PubMed: 38910418
DOI: 10.2174/0118715249289689240607064642 -
Journal of Controlled Release :... Jun 2024Parkinson's disease (PD), affecting about ten million people globally, presents a significant health challenge. Rotigotine (RTG), a dopamine agonist, is currently...
Parkinson's disease (PD), affecting about ten million people globally, presents a significant health challenge. Rotigotine (RTG), a dopamine agonist, is currently administered as a transdermal patch (Neupro®) for PD treatment, but the daily application can be burdensome and cause skin irritation. This study introduces a combinatorial approach of dissolving microarray patch (MAP) and nanosuspension (NS) for the transdermal delivery of RTG, offering an alternative to Neupro®. The RTG-NS was formulated using a miniaturized media milling method, resulting in a nano-formulation with a mean particle size of 274.09 ± 7.43 nm, a PDI of 0.17 ± 0.04 and a zeta potential of -15.24 ± 2.86 mV. The in vitro dissolution study revealed an enhanced dissolution rate of the RTG-NS in comparison to the coarse RTG powder, under sink condition. The RTG-NS MAPs, containing a drug layer and a 'drug-free' supporting baseplate, have a drug content of 3.06 ± 0.15 mg/0.5 cm and demonstrated greater amount of drug delivered per unit area (∼0.52 mg/0.5 cm) than Neupro® (∼0.20 mg/1 cm) in an ex vivo Franz cell study using full-thickness neonatal porcine skin. The in vivo pharmacokinetic studies demonstrated that RTG-NS MAPs, though smaller (2 cm for dissolving MAPs and 6 cm for Neupro®), delivered drug levels comparable to Neupro®, indicating higher efficiency per unit area. This could potentially avoid unnecessarily high plasma levels after the next dose at 24 h, highlighting the benefits of dissolving MAPs over conventional transdermal patches in PD treatment.
PubMed: 38906420
DOI: 10.1016/j.jconrel.2024.06.039 -
Current Findings and Potential Mechanisms of KarXT (Xanomeline-Trospium) in Schizophrenia Treatment.Clinical Drug Investigation Jun 2024Standard schizophrenia treatment involves antipsychotic medications that target D2 dopamine receptors. However, these drugs have limitations in addressing all symptoms... (Review)
Review
Standard schizophrenia treatment involves antipsychotic medications that target D2 dopamine receptors. However, these drugs have limitations in addressing all symptoms and can lead to adverse effects such as motor impairments, metabolic effects, sedation, sexual dysfunction, cognitive impairment, and tardive dyskinesia. Recently, KarXT has emerged as a novel drug for schizophrenia. KarXT combines xanomeline, a muscarinic receptor M1 and M4 agonist, with trospium, a nonselective antimuscarinic agent. Of note, xanomeline can readily cross blood-brain barrier (BBB) and, thus, enter into the brain, thereby stimulating muscarinic receptors (M1 and M4). By doing so, xanomeline has been shown to target negative symptoms and potentially improve positive symptoms. Trospium, on the other hand, is not able to cross BBB, thereby not affecting M1 and M4 receptors; instead, it acts as an antimuscarinic agent and, hence, diminishes peripheral activity of muscarinic receptors to minimize side effects probably stemming from xanomeline in other organs. Accordingly, ongoing clinical trials investigating KarXT's efficacy in schizophrenia have demonstrated positive outcomes, including significant improvements in the Positive and Negative Syndrome Scale (PANSS) total score and cognitive function compared with placebo. These findings emphasize the potential of KarXT as a promising treatment for schizophrenia, providing symptom relief while minimizing side effects associated with xanomeline monotherapy. Despite such promising evidence, further research is needed to confirm the efficacy, safety, and tolerability of KarXT in managing schizophrenia. This review article explores the current findings and potential mechanisms of KarXT in the treatment of schizophrenia.
PubMed: 38904739
DOI: 10.1007/s40261-024-01377-9 -
BMC Endocrine Disorders Jun 2024An increase of IGF-1 has been reported during therapy with dopamine agonists (DA) for prolactinomas; in such cases a correct diagnosis is pivotal to avoid an unnecessary...
PURPOSE
An increase of IGF-1 has been reported during therapy with dopamine agonists (DA) for prolactinomas; in such cases a correct diagnosis is pivotal to avoid an unnecessary reduction or withdrawal of DA, which are needed to maintain normal prolactin levels. This study was aimed to measure IGF-1 levels, at baseline and during follow-up, in a cohort of patients with prolactinoma, treated with cabergoline, stratified by body mass index.
METHODS
We retrospectively enrolled 35 patients (15 F/20 M; age m ± SD, years: 43.4 ± 13.7) with prolactinoma (21 microadenomas and 14 macroadenomas) who were followed-up at the Endocrinology Unit, in Siena, and with available pituitary hormone assessment at baseline and during follow-up (m ± SD, years: 2.74 ± 0.55).
RESULTS
IGF-1 increased in the whole cohort, but remaining within normal range, except two patients, in whom acromegaly was ruled out with oral glucose tolerance test. After dividing patients by weight, this trend was confirmed only in subjects with overweight and obesity (OV/OB) (p = 0.04). Interestingly, the reduction of prolactin levels was significantly greater in the OV/OB compared to normal-weight patients (median decrease of 97.5% versus 88.2%, p = 0.04).
CONCLUSIONS
Since DA and normalization of prolactin are known to improve insulin sensitivity, we speculated they have favored the increase of IGF-1 in OV/OB. Our results should be confirmed and the hypothesis proven by further studies.
Topics: Humans; Prolactinoma; Insulin-Like Growth Factor I; Female; Male; Adult; Retrospective Studies; Dopamine Agonists; Pituitary Neoplasms; Middle Aged; Cabergoline; Body Weight; Follow-Up Studies; Prolactin; Body Mass Index; Prognosis
PubMed: 38902646
DOI: 10.1186/s12902-024-01622-4 -
Journal of Pharmaceutical and... Jun 2024Traditional Chinese medicines (TCMs) are popular in clinic because of their safety and efficacy. They contain abundant natural active compounds, which are important...
Traditional Chinese medicines (TCMs) are popular in clinic because of their safety and efficacy. They contain abundant natural active compounds, which are important sources of new drug discovery. However, how to efficiently identify active compounds from complex ingredients remains a challenge. In this study, a method combining UHPLC-MS/MS characterization and in silico screening was developed to discover compounds with dopamine D2 receptor (D2R) activity in Stephania epigaea (S. epigaea). By combining the compounds identified in S. epigaea by UHPLC-MS/MS with reported compounds, a virtual library of 80 compounds was constructed for in silico screening. Potentially active compounds were chosen based on screening scores and subsequently tested for in vitro activity on a transfected cell line CHO-K1-D2 model using label-free cellular phenotypic assay. Three D2R agonists and five D2R antagonists were identified. (-)-Asimilobine, N-nornuciferine and (-)-roemerine were reported for the first time as D2R agonists, with EC values of 0.35 ± 0.04 μM, 1.37 ± 0.10 μM and 0.82 ± 0.22 μM, respectively. Their target specificity was validated by desensitization and antagonism assay. (-)-Isocorypalmine, (-)-tetrahydropalmatine, (-)-discretine, (+)-corydaline and (-)-roemeroline showed strong antagonistic activity on D2R with IC values of 92 ± 9.9 nM, 1.73 ± 0.13 μM, 0.34 ± 0.02 μM, 2.09 ± 0.22 μM and 0.85 ± 0.08 μM, respectively. Their kinetic binding profiles were characterized using co-stimulation assay and they were both D2R competitive antagonists. We docked these ligands with human D2R crystal structure and analyzed the structure-activity relationship of aporphine-type D2R agonists and protoberberine-type D2R antagonists. These results would help to elucidate the mechanism of action of S. epigaea for its analgesic and sedative efficacy and benefit for D2R drug design. This study demonstrated the potential of integrating UHPLC-MS/MS with in silico and in vitro screening for accelerating the discovery of active compounds from TCMs.
PubMed: 38901158
DOI: 10.1016/j.jpba.2024.116289 -
Journal of Neurochemistry Jun 20243,4-Methylenedioxymethamphetamine (MDMA, 'ecstasy') is re-emerging in clinical settings as a candidate for the treatment of specific neuropsychiatric disorders (e.g....
3,4-Methylenedioxymethamphetamine (MDMA, 'ecstasy') is re-emerging in clinical settings as a candidate for the treatment of specific neuropsychiatric disorders (e.g. post-traumatic stress disorder) in combination with psychotherapy. MDMA is a psychoactive drug, typically regarded as an empathogen or entactogen, which leads to transporter-mediated monoamine release. Despite its therapeutic potential, MDMA can induce dose-, individual-, and context-dependent untoward effects outside safe settings. In this study, we investigated whether three new methylenedioxy bioisosteres of MDMA improve its off-target profile. In vitro methods included radiotracer assays, transporter electrophysiology, bioluminescence resonance energy transfer and fluorescence-based assays, pooled human liver microsome/S9 fraction incubations, metabolic stability studies, isozyme mapping, and liquid chromatography coupled to high-resolution mass spectrometry. In silico methods included molecular docking. Compared with MDMA, all three MDMA bioisosteres (ODMA, TDMA, and SeDMA) showed similar pharmacological activity at human serotonin, dopamine, and norepinephrine transporters (hSERT, hDAT, and hNET, respectively) but decreased agonist activity at 5-HT receptors. Regarding their hepatic metabolism, they differed from MDMA, with N-demethylation being the only metabolic route shared, and without forming phase II metabolites. In addition, TDMA showed an enhanced intrinsic clearance in comparison to its congeners. Additional screening for their interaction with human organic cation transporters (hOCTs) and plasma membrane monoamine transporter (hPMAT) revealed a weaker interaction of the MDMA analogs with hOCT1, hOCT2, and hPMAT. Our findings suggest that these new MDMA bioisosteres might constitute appealing therapeutic alternatives to MDMA, sparing the primary pharmacological activity at hSERT, hDAT, and hNET, but displaying a reduced activity at 5-HT receptors and alternative hepatic metabolism. Whether these MDMA bioisosteres may pose lower risk alternatives to the clinically re-emerging MDMA warrants further studies.
PubMed: 38898705
DOI: 10.1111/jnc.16149 -
Movement Disorders Clinical Practice Jun 2024Dopaminergic responsiveness is a defining feature of Parkinson's disease (PD). However, there is limited information on how this evolves over time.
BACKGROUND
Dopaminergic responsiveness is a defining feature of Parkinson's disease (PD). However, there is limited information on how this evolves over time.
OBJECTIVES
To examine serial dopaminergic responses, if there are distinct patterns, and which factors predict these.
METHODS
We analyzed data from the Parkinson's Progression Markers Initiative on repeated dopaminergic challenge tests (≥24.5% defined as a definite response). Growth-mixture modeling evaluated for different response patterns and multinomial logistic regression tested for predictors of these clusters.
RESULTS
1525 dopaminergic challenge tests were performed in 336 patients. At enrolment, mean age was 61.2 years (SD 9.6), 66.4% were male and disease duration was 0.5 years (SD 0.5). 1 to 2 years after diagnosis, 48.0% of tests showed a definite response, but this proportion increased with longer disease duration (51.1-74.3%). We identified 3 response groups: "Striking" (n = 29, 8.7%); "Excellent" (n = 110; 32.7%) and "Modest" (n = 197, 58.6%). Significant differences were as follows: striking responders commenced treatment earlier (P = 0.02), were less likely to be on dopamine agonist monotherapy (P = 0.01), and had better cognition (P < 0.01) and activities of daily living (P = 0.01). Excellent responders had higher challenge doses (P = 0.03) and were more likely to be on combination therapy (P < 0.01).
CONCLUSION
Three distinct patterns of the dopaminergic response were observed. As the proportion of PD cases with definite dopa responsiveness increased over time, the initial treatment response may be an unreliable diagnostic aid.
PubMed: 38898616
DOI: 10.1002/mdc3.14139 -
International Journal of Molecular... May 2024Until the late 1800s, drug development was a chance finding based on observations and repeated trials and errors. Today, drug development must go through many iterations... (Review)
Review
Until the late 1800s, drug development was a chance finding based on observations and repeated trials and errors. Today, drug development must go through many iterations and tests to ensure it is safe, potent, and effective. This process is a long and costly endeavor, with many pitfalls and hurdles. The aim of the present review article is to explore what is needed for a molecule to move from the researcher bench to the patients' bedside, presented from an industry perspective through the development program of cariprazine. Cariprazine is a relatively novel antipsychotic medication, approved for the treatment of schizophrenia, bipolar mania, bipolar depression, and major depression as an add-on. It is a D3-preferring D3-D2 partial agonist with the highest binding to the D3 receptors compared to all other antipsychotics. Based on the example of cariprazine, there are several key factors that are needed for a molecule to move from the researcher bench to the patients' bedside, such as targeting an unmet medical need, having a novel mechanism of action, and a smart implementation of development plans.
Topics: Humans; Antipsychotic Agents; Piperazines; Receptors, Dopamine D3; Schizophrenia; Animals; Bipolar Disorder; Drug Development
PubMed: 38891871
DOI: 10.3390/ijms25115682