Dexpramipexole dihydrochloride

Dexpramipexole, also known as R-(+)-Pramipexole, is a neuroprotective agent and weak non-ergoline dopamine agonist. Dexpramipexole has been found to have neuroprotective effects and is being investigated for treatment of amyotrophic lateral sclerosis (ALS). Dexpramipexole reduces mitochondrial reactive oxygen species (ROS) production, inhibits the activation of apoptotic pathways, and increase cell survival in response to a variety of neurotoxins and β-amyloid neurotoxicity. Compared to the S-(-) isomer, Dexpramipexole has much lower dopamine agonist activity.

Solid Microneedles for Transdermal Delivery of Amantadine Hydrochloride and Pramipexole Dihydrochloride.[Pubmed:26426039]

Pharmaceutics. 2015 Sep 28;7(4):379-96.

The aim of this project was to study the influence of microneedles on transdermal delivery of amantadine hydrochloride and pramipexole dihydrochloride across porcine ear skin in vitro. Microchannel visualization studies were carried out and characterization of the microchannel depth was performed using confocal laser scanning microscopy (CLSM) to demonstrate microchannel formation following microneedle roller application. We also report, for the first time, the use of TA.XT Plus Texture Analyzer to characterize burst force in pig skin for transdermal drug delivery experiments. This is the force required to rupture pig skin. The mean passive flux of amantadine hydrochloride, determined using a developed LC-MS/MS technique, was 22.38 +/- 4.73 microg/cm(2)/h, while the mean flux following the use of a stainless steel microneedle roller was 49.04 +/- 19.77 microg/cm(2)/h. The mean passive flux of pramipexole dihydrochloride was 134.83 +/- 13.66 microg/cm(2)/h, while the flux following the use of a stainless steel microneedle roller was 134.04 +/- 0.98 microg/cm(2)/h. For both drugs, the difference in flux values following the use of solid stainless steel microneedle roller was not statistically significantly (p > 0.05). Statistical analysis was carried out using the Mann-Whitney Rank sum test.

New functional activity of aripiprazole revealed: Robust antagonism of D2 dopamine receptor-stimulated Gbetagamma signaling.[Pubmed:25449598]

Biochem Pharmacol. 2015 Jan 1;93(1):85-91.

The dopamine D2 receptor (DRD2) is a G protein-coupled receptor (GPCR) that is generally considered to be a primary target in the treatment of schizophrenia. First generation antipsychotic drugs (e.g. haloperidol) are antagonists of the DRD2, while second generation antipsychotic drugs (e.g. olanzapine) antagonize DRD2 and 5HT2A receptors. Notably, both these classes of drugs may cause side effects associated with D2 receptor antagonism (e.g. hyperprolactemia and extrapyramidal symptoms). The novel, "third generation" antipsychotic drug, aripiprazole is also used to treat schizophrenia, with the remarkable advantage that its tendency to cause extrapyramidal symptoms is minimal. Aripiprazole is considered a partial agonist of the DRD2, but it also has partial agonist/antagonist activity for other GPCRs. Further, aripiprazole has been reported to have a unique activity profile in functional assays with the DRD2. In the present study the molecular pharmacology of aripiprazole was further examined in HEK cell models stably expressing the DRD2 and specific isoforms of adenylyl cyclase to assess functional responses of Galpha and Gbetagamma subunits. Additional studies examined the activity of aripiprazole in DRD2-mediated heterologous sensitization of adenylyl cyclase and cell-based dynamic mass redistribution (DMR). Aripiprazole displayed a unique functional profile for modulation of G proteins, being a partial agonist for Galphai/o and a robust antagonist for Gbetagamma signaling. Additionally, aripiprazole was a weak partial agonist for both heterologous sensitization and dynamic mass redistribution.

Safety and Tolerability of R(+) Pramipexole in Mild-to-Moderate Alzheimer's Disease.[Pubmed:26682692]

J Alzheimers Dis. 2016;49(4):1179-87.

Alzheimer's disease (AD) is an aging-related, degenerative brain disease of adults. Most ( approximately 95%) of AD occurs sporadically and is associated with early-appearing deficits in brain regional glucose uptake, changes in cerebrospinal fluid (CSF) AD-related proteins, regional brain atrophy, and oxidative stress damage. We treated mild-moderate AD individuals with R(+)-pramipexole-dihydrochloride (R(+)PPX), a neuroprotective, lipophilic-cation, free-radical scavenger that accumulates into brain and mitochondria. 19 subjects took R(+)PPX twice a day in increasing daily doses up to 300 mg/day under a physician-sponsor IND (60,948, JPB), IRB-approved protocol and quarterly external safety committee monitoring. 15 persons finished and contributed baseline and post-treatment serum, lumbar spinal fluid, brain 18F-2DG PET scans, and ADAS-Cog scores. ADAS-Cog scores did not change (n = 1), improved (n = 2), declined 1-3 points (n = 5), or declined 4-13 points (n = 8) over 6 months of R(+)PPX treatment. Serum PPX levels were not related to changes in ADAS-Cog scores. Fasting AM serum PPX levels at 6 months varied considerably across subjects and correlated strongly with CSF [PPX] (r = 0.97, p < 0.0001). CSF [PPX] was not related to CSF [Abeta(42)], [Tau], or [P-Tau]. Regional 18F-2DG measures of brain glucose uptake demonstrated a 3-6% decline during R(+)PPX treatment. 56 mild-moderate adverse events occurred, 26 probably/definitely related to R(+)PPX use, with 4 withdrawals. R(+)PPX was generally well-tolerated and entered brain extracellular space linearly. Further studies of R(+)PPX in AD should include a detailed pharmacokinetic study of peak and trough serum [PPX] variations among subjects prior to planning any larger studies that would be needed to determine efficacy in altering disease progression.

[Feeding difficulty and developmental delay for 8 months and nystagmus for 4 months in an infant].[Pubmed:28100326]

Zhongguo Dang Dai Er Ke Za Zhi. 2017 Jan;19(1):68-72.

Aromatic L-amino acid decarboxylase (AADC) deficiency is a rare autosomal recessive hereditary disease and is a congenital metabolic disorder of neurotransmitter biosynthesis. It is mainly manifested as hypotonia, oculogyric crisis, autonomic dysfunction, and developmental delay. This article reports a boy manifested as delayed motor development, hypotonia, and oculogyric crisis. Gene screening for metabolic disorders revealed new compound heterozygous mutations, c.1063dupA (p.I355fs) and c.250A>C (p.S84R), in the exon of DDC gene. The boy had a significant increase in 3-O-methyldopa as measured by dried blood spot. Therefore, he was diagnosed with AADC deficiency. After treatment with the dopamine receptor agonist pramipexole dihydrochloride, the catechol-O-methyltransferase inhibitor entacapone, and vitamin B6, the boy showed mild improvements in hypotonia, blepharoptosis, and oculogyric crisis. Clinical physicians should enhance their ability for identifying AADC deficiency, so as to facilitate early diagnosis and treatment of this disorder. Genetic counseling for birth health and prenatal diagnosis should be performed for parents in need.

In vivo dopamine agonist properties of rotigotine: Role of D1 and D2 receptors.[Pubmed:27343381]

Eur J Pharmacol. 2016 Oct 5;788:183-191.

Rotigotine acts in vitro as a full agonist of dopamine D1 receptors at concentrations almost superimposable to those at which it acts on D2 receptors. However in vivo evidence of the differences between the agonist activity of rotigotine at D1 receptors from that on the D2 receptors has not been provided yet. In order to test the ability of rotigotine to stimulate dopamine D1 and D2 receptors in vivo, we studied the effect of SCH39166 and eticlopride, selective dopamine D1 and D2/D3 receptor antagonists respectively, on rotigotine-induced contralateral turning behavior in 6-hydroxydopamine lesioned rats. Furthermore, the expression of the immediate-early gene c-fos in the caudate-putamen, was evaluated. As a comparison, we tested the D2/D3 agonist pramipexole. In primed rats, rotigotine (0.035, 0.1 and 0.35mg/kg) induced dose-dependent contralateral turning. Turning induced by 0.1mg/kg of rotigotine was reduced by pretreatment with the D1 antagonist SCH39166 and the D2 antagonist eticlopride. In drug-naive rats, rotigotine was less effective in eliciting turning but SCH39166 still reduced turning induced by rotigotine (0.35mg/kg). Pramipexole induced contralateral turning only in primed rats. SCH39166 potentiated and eticlopride abolished pramipexole-induced turning. Rotigotine induced Fos expression in the caudate-putamen and SCH39166 completely blocked it. Pramipexole failed to induce Fos. These results indicate that rotigotine acts in vivo as an agonist of D1 and D2 receptors while pramipexole is devoid of D1 activity in vivo. Given their differing DA receptor profiles, rotigotine and pramipexole might differ in their spectrum of application to the therapy of Parkinson's disease.

Dexpramipexole dihydrochloride ((R)-Pramipexole dihydrochloride) is a neuroprotective agent and weak non-ergoline dopamine agonist.

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