title: The effects of TPA023, a GABAAα2,3 subtype-selective partial agonist, on essential tremor in comparison to alcohol.
abstract: Essential tremor (ET) is a relatively frequent neurological disorder that responds in some patients to gamma-aminobutyric acid A (GABA(A)) agonists such as the benzodiazepines. Partial subtype-selective GABA(A) agonists may have an improved side effect profile compared to non-selective GABA(A) agonists. However, it is unknown which GABA(A) subtypes are involved in the therapeutic effects of benzodiazepines in ET. The effects of 2 mg TPA023, a GABA(A) α2,3 subtype-selective partial agonist, on ET were compared to the effects of a stable alcohol level (0.6 g/L) and placebo in nine patients with ET. Tremor evaluation included laboratory accelerometry and a performance-based scale. Additional measurements were performed to evaluate other effects on the central nervous system (CNS). Alcohol significantly diminished tremor symptoms in the postural and kinetic condition, as assessed by laboratory accelerometry, but the performance-based rating scale was unaffected. Tremor was also reduced after TPA023 treatment in the kinetic condition, albeit not significantly. Additionally, TPA023 decreased saccadic peak velocity, while alcohol decreased subjective feelings of alertness. This study showed that alcohol reduced maximum tremor power, as assessed by laboratory accelerometry, unlike TPA023, which decreased tremor symptoms to some extent but not significantly. This study showed that treatment with an α2,3 subunit-selective GABA(A) partial agonist was less effective than a stable level of alcohol in reducing ET symptoms. These results provide no support for a therapeutic role of TPA023 in the suppression of ET symptoms.
authors: Centre for Human Drug Research, Leiden, the Netherlands.
authors: S L
authors: SL
authors: de Haas
authors: R W M
authors: RW
authors: Zoethout
authors: K
authors: K
authors: Van Dyck
authors: M
authors: M
authors: De Smet
authors: L B
authors: LB
authors: Rosen
authors: M G
authors: MG
authors: Murphy
authors: K M
authors: KM
authors: Gottesdiener
authors: R C
authors: RC
authors: Schoemaker
authors: A F
authors: AF
authors: Cohen
authors: J M A
authors: JM
authors: van Gerven
mesh_terms: D001569:Benzodiazepines / Q000009:adverse effects / Q000494:pharmacology; D002490:Central Nervous System / Q000187:drug effects / Q000378:metabolism; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004644:Emotions / Q000187:drug effects; D020329:Essential Tremor / Q000188:drug therapy* / Q000378:metabolism; D000431:Ethanol / Q000627:therapeutic use*; D005260:Female; D058785:GABA-A Receptor Agonists / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011724:Pyridazines / Q000009:adverse effects / Q000627:therapeutic use*; D011963:Receptors, GABA-A / Q000378:metabolism; D012438:Saccades / Q000187:drug effects; D014230:Triazoles / Q000009:adverse effects / Q000627:therapeutic use*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: C507018:7-(1,1-dimethylethyl)-6-(2-ethyl-2H-1,2,4-triazol-3-ylmethoxy)-3-(2-fluorophenyl)-1,2,4-triazolo(4,3-b)pyridazine; D058785:GABA-A Receptor Agonists; D011724:Pyridazines; D011963:Receptors, GABA-A; D014230:Triazoles; D001569:Benzodiazepines; D000431:Ethanol; D005680:gamma-Aminobutyric Acid