ZK 200775

ZK200775(Fanapanel; MPQX) is a highly selective AMPA/kainate antagonist with little activity against NMDA; have Ki values of 3.2 nM, 100 nM, and 8.5 μM against quisqualate, kainate, and NMDA, respectively. IC50 value: Target: AMPAR antagonist in vitro: In the cortical slice preparation assay, ZK200775 gave Ki values of 3.2 nM, 100 nM, and 8.5 μM against quisqualate, kainate, and NMDA, respectively. In the spreading depression assay, it gave IC50 values of 200 nM, 76 nM, 13 μM, and 18 μM against quisqualate, kainate, NMDA, and glycine [1]. in vivo: ZK200775 elevated the threshold for AMPA- and kainate-induced clonic seizures in mice with a THRD50 (threshold dose) of 2.9 (1.7–4.6) and 1.6 (1.3–2.0) mg/kg i.v., whereas the threshold for NMDA-induced seizures was elevated only in doses, THRD50 of 24.1 (21.9–26.5) mg/kg i.v., which affected motor coordination in the rotating rod, ED50 14.6 (12.1–17.6) mg/kg. ZK200775 in doses of 10 and 30 mg/kg i.v. reduced muscle tone in genetically spastic rats [1]. ZK200775 (3.0 but not 1.5 or 6.0 mg/kg) significantly decreased the nicotine-induced (0.6 mg/kg) DA release in the NAcc and nicotine-stimulated LMA. ZK200775 (1.5, 3.0, 6.0 mg/kg) alone influenced neither DA release nor LMA. ZK200775 showed 34-fold selectivity for AMPA receptors compared to NMDA receptors and no affinity to nicotine receptors [2].

References:
[1]. Turski L, et al. ZK200775: a phosphonate quinoxalinedione AMPA antagonist for neuroprotection in stroke and trauma. Proc Natl Acad Sci U S A. 1998 Sep 1;95(18):10960-5. [2]. Kosowski AR, et al. Nicotine-induced dopamine release in the nucleus accumbens is inhibited by the novel AMPA antagonist ZK200775 and the NMDA antagonist CGP39551. Psychopharmacology (Berl). 2004 Aug;175(1):114-23.

The AMPA antagonist ZK 200775 in patients with acute ischaemic stroke: a double-blind, multicentre, placebo-controlled safety and tolerability study.[Pubmed:16131799]

Cerebrovasc Dis. 2005;20(5):304-9.

BACKGROUND AND PURPOSE: ZK 200775 is a selective competitive AMPA receptor antagonist. It has demonstrated neuroprotective efficacy in experimental models of stroke and tolerability in healthy volunteers. We tested the safety and tolerability of ZK 200775 in patients with acute ischaemic stroke. METHODS: In a multicentre double-blind, randomised, placebo-controlled phase II trial, 61 ischaemic stroke patients were treated with either placebo or active drug in a dose finding design. Twenty-five patients received placebo, 12 patients received a total dose of 262.5 mg in 48 h (group 1) and 13 patients received a total dose of 525 mg in 48 h (group 2), and 11 patients received a total dose of 105 mg over a period of 6 h (group 3). We studied the pharmacokinetics of the compound and the effect of the infusion on the neurologic and haemodynamic parameters of the patients. The study was not powered to detect neuroprotective efficacy. RESULTS: In group 2 there was a significant transient worsening in the mean NIH stroke scale score 14- 18 h after the start of treatment. This was due to reduction of consciousness (stupor and coma) in 8 out of 13 patients. Level of consciousness improved approximately 6 h after cessation of infusion. No significant haemodynamic responses were observed. Even after reduction of the administered dose and duration of infusion to 6 h (group 3), 2 patients experienced a reduction in level of consciousness. The effect of ZK 200775 on level of consciousness gave cause for concern and the trial was stopped prematurely for safety reasons. CONCLUSIONS: The AMPA antagonist ZK 200775 reversibly worsened the neurological condition in patients with acute ischaemic stroke. Our results suggest that ZK 200775 exerts significant sedative effects in patients with acute stroke which preclude its further development as a neuroprotective agent in this indication.

Effects of the AMPA antagonist ZK 200775 on visual function: a randomized controlled trial.[Pubmed:20711429]

PLoS One. 2010 Aug 12;5(8):e12111.

BACKGROUND: ZK 200775 is an antagonist at the alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor and had earned attention as a possible neuroprotective agent in cerebral ischemia. Probands receiving the agent within phase I trials reported on an alteration of visual perception. In this trial, the effects of ZK 200775 on the visual system were analyzed in detail. METHODOLOGY: In a randomised controlled trial we examined eyes and vision before and after the intravenous administration of two different doses of ZK 200775 and placebo. There were 3 groups of 6 probands each: Group 1 recieved 0.03 mg/kg/h, group 2 0.75 mg/kg/h of ZK 200775, the control group received 0.9% sodium chloride solution. Probands were healthy males aged between 57 and 69 years. The following methods were applied: clinical examination, visual acuity, ophthalmoscopy, colour vision, rod absolute threshold, central visual field, pattern-reversal visual evoked potentials (pVEP), ON-OFF and full-field electroretinogram (ERG). PRINCIPAL FINDINGS: No effect of ZK 200775 was seen on eye position or motility, stereopsis, pupillary function or central visual field testing. Visual acuity and dark vision deteriorated significantly in both treated groups. Color vision was most remarkably impaired. The dark-adapted ERG revealed a reduction of oscillatory potentials (OP) and partly of the a- and b-wave, furthermore an alteration of b-wave morphology and an insignificantly elevated b/a-ratio. Cone-ERG modalities showed decreased amplitudes and delayed implicit times. In the ON-OFF ERG the ON-answer amplitudes increased whereas the peak times of the OFF-answer were reduced. The pattern VEP exhibited lower amplitudes and prolonged peak times. CONCLUSIONS: The AMPA receptor blockade led to a strong impairment of typical OFF-pathway functions like color vision and the cone ERG. On the other hand the ON-pathway as measured by dark vision and the scotopic ERG was affected as well. This further elucidates the interdependence of both pathways. TRIAL REGISTRATION: ClinicalTrials.gov NCT00999284.

X-ray structure, symmetry and mechanism of an AMPA-subtype glutamate receptor.[Pubmed:19946266]

Nature. 2009 Dec 10;462(7274):745-56.

Ionotropic glutamate receptors mediate most excitatory neurotransmission in the central nervous system and function by opening a transmembrane ion channel upon binding of glutamate. Despite their crucial role in neurobiology, the architecture and atomic structure of an intact ionotropic glutamate receptor are unknown. Here we report the crystal structure of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-sensitive, homotetrameric, rat GluA2 receptor at 3.6 A resolution in complex with a competitive antagonist. The receptor harbours an overall axis of two-fold symmetry with the extracellular domains organized as pairs of local dimers and with the ion channel domain exhibiting four-fold symmetry. A symmetry mismatch between the extracellular and ion channel domains is mediated by two pairs of conformationally distinct subunits, A/C and B/D. Therefore, the stereochemical manner in which the A/C subunits are coupled to the ion channel gate is different from the B/D subunits. Guided by the GluA2 structure and site-directed cysteine mutagenesis, we suggest that GluN1 and GluN2A NMDA (N-methyl-d-aspartate) receptors have a similar architecture, with subunits arranged in a 1-2-1-2 pattern. We exploit the GluA2 structure to develop mechanisms of ion channel activation, desensitization and inhibition by non-competitive antagonists and pore blockers.

Novel alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor antagonists of 2,3-benzodiazepine type: chemical synthesis, in vitro characterization, and in vivo prevention of acute neurodegeneration.[Pubmed:15999999]

J Med Chem. 2005 Jul 14;48(14):4618-27.

Under pathophysiological conditions, alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor activation is considered to play a key role in several disorders of the central nervous system. In the search for AMPA receptor antagonists, the synthesis and pharmacological characterization of a series of novel compounds that are structurally related to GYKI 52466 (1), a well-known selective noncompetitive AMPA receptor antagonist, was performed. In vitro, 2,3-dimethyl-6-phenyl-12H-[1,3]dioxolo[4,5-h]imidazo[1,2-c][2,3]benzodiazepine (ZK 187638, 14a) antagonized the kainate-induced currents in cultured hippocampal neurons with an IC(50) of 3.4 microM in a noncompetitive fashion. When tested in a clinically predictive rat model of acute ischemic stroke, this noncompetitive AMPA receptor antagonist significantly reduced brain infarction, indicating that it is neuroprotective after permanent focal cerebral ischemia.

Fanapanel (ZK200775) is a highly selective AMPA/kainate antagonist with little activity against NMDA; have Ki values of 3.2 nM, 100 nM, and 8.5 μM against quisqualate, kainate, and NMDA, respectively.

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