Preparation and Characterization of Tetrabenazine Enantiomers against Vesicular Monoamine Transporter 2.
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ABSTRACT:
SUBMITTER: Yu QS
PROVIDER: S-EPMC2915582 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Tetrabenazine (TBZ) ((±)-1) and dihydrotetrabenazines (DHTBZ) are potent inhibitors of VMAT2. Herein, a practical chemical resolution of (±)-1 and stereoselective synthesis of all eight DHTBZ stereoisomers are described. The result of VMAT2 binding assay revealed that (+)-1 (Ki=4.47 nM) was 8000-fold more potent than (-)-1 (Ki=36,400 nM). Among all eight DHTBZ stereoisomers, (2R,3R,11bR)-DHTBZ ((+)-2: Ki=3.96 nM) showed the greatest affinity for VMAT2. The (3R,11bR)-configuration appeared to play a key role for VMAT2 binding. In summary, (+)-1, (+)-2, and their derivatives warrant further studies in order to develop more potent and safer drugs for the treatment of chorea associated with Huntington's disease and other hyperkinetic disorders.
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Project description:3, 4-Methylenedioxymethamphetamine (MDMA) is a hallucinogenic amphetamine derivative. The acute effects of MDMA are hyperthermia, hyperactivity, and behavioral changes, followed by long-term serotonergic neurotoxicity in rats and primates. However, the underlying mechanisms of MDMA neurotoxicity remain elusive. We reported that pretreatment of rats with Ro 4-1284, a reversible inhibitor of the vesicular monoamine transporter 2 (VMAT2), reduced MDMA-induced hyperactivity in rats, abolished the hyperthermic response, and the long-term neurotoxicity. Current studies focused on the effects of co- and/or postinhibition of VMAT2 on the acute and chronic effects of MDMA and on the dose-response relationship between MDMA-induced elevations in body temperature and subsequent reductions in indolamine concentrations. Sprague Dawley rats were treated with MDMA (20, 25, or 27.5 mg/kg sc), and either co- and/or posttreatment with the VMAT2 inhibitor (10 mg/kg ip). Rats simultaneously treated with Ro 4-1284 and MDMA exhibited a more rapid increase in body temperature compared to just MDMA. However, the duration of the elevated body temperature was significantly shortened (approximately 3 h vs approximately 8 h, respectively). A similar body temperature response was observed in rats posttreated (7 h after MDMA) with Ro 4-1284. Despite decreases in the area under the curve (Δtemp X time) of body temperature caused by Ro 4-1284, there were no significant differences in the degree of indolamine depletion between any of the MDMA-treated groups. The results suggest that the neuroprotective effects of VMAT2 inhibition is likely due to the indirect monoamine depleting effects of the Ro 4-1284 pretreatment, rather than by the direct inhibition of VMAT2 function.
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Project description:Objective:Vesicular monoamine transporter-2 (VMAT2) inhibitors have been proven to be effective for the treatment of tardive dyskinesia and their use is likely to increase. The evidence base of published clinical reports was reviewed to evaluate the possible risk of neuroleptic malignant syndrome (NMS) with these drugs. Methods:Pubmed, Embase, Web of Science and PsycINFO databases were queried for all years using terms for "neuroleptic malignant syndrome", "hyperthermia" AND "vesicular monoamine transporter inhibitors", "reserpine", "tetrabenazine", "valbenazine" or "deutetrabenazine". Results:Thirteen clinical cases, ten of which involved tetrabenazine, were identified in which VMAT2 inhibitors were prescribed in patients with current or past NMS episodes. In most cases, the association was confounded by limited reporting of clinical data, variable temporal correlation with VMAT2 inhibitors, polypharmacy with antipsychotics, and uncertain differential diagnoses. Conclusion:While rare cases of NMS meeting consensus criteria have been reported primarily with tetrabenazine, the risk with recently developed VMAT2 inhibitors may be even less. Evidence of causality of NMS with VMAT2 inhibitors is confounded by concomitant treatment with antipsychotics and diagnostic uncertainties in patients susceptible to basal ganglia dysfunction. Nevertheless, clinicians should remain vigilant for early signs of NMS in all patients treated with any drugs that affect brain dopamine activity.
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